Outline of the lesson "Introduction to Organic Chemistry". Methodical development of the lesson "introduction to organic chemistry" Open lesson introduction to organic chemistry
Algorithm for constructing evidence: 1. An idea is stated that requires proof or refutation (thesis); 2. Arguments, judgments, explanations are given that prove or refute the previously expressed thought (arguments); 3. A conclusion is made about the truth or falsity of the answer.
Arguments… There are 13 classes of substances to be studied… To get 7-10 points in chemistry, you need to be able to think… We will have to be able to write the formulas of methylcyclopentadecanone, methylphenyl ether, aspartyl aminomalonic acid… We will encounter the sweetest and most odorous substances… We will write equations of reactions that allow turn cellulose into rayon, low-quality gasoline into high-quality high-octane ...
Theory of the structure of organic compounds Atoms in the molecules of organic substances are connected in a certain sequence, according to their valency. The properties of organic substances depend not only on the qualitative and quantitative composition, but also on the order of connection of atoms in molecules. Atoms and groups of atoms in the molecules of organic substances mutually influence each other.
Lesson on the topic: Introductory briefing on T / B. Subject of organic chemistry. Formation of organic chemistry as a science.
Lesson Objectives :
1. To form an idea of the composition and structure of organic compounds, their distinctive features.
2. Reveal the reasons for the diversity of organic substances.
3. Continue the formation of the ability to compose structural formulas using the example of organic substances.
4. Form an idea of isomerism and isomers.
Lesson equipment : samples of organic compounds, matches, porcelain cup, tongs, ball-and-stick models of representatives of alkanes, alkenes, cycloalkanes.
During the classes.
What is "organic chemistry" and how did the term "organic substances" come about?
Organic chemistry is the science of organic compounds and their transformations. Initially, substances found in living organisms and animals were considered organic. Such naturally occurring substances necessarily contain carbon. For a long time it was believed that in order to obtain complex carbon compounds, a certain “driving force” is used, acting only in living matter. In laboratories, it was possible to synthesize only the simplest carbon-containing compounds, such as carbon dioxide CO 2, calcium carbide CaC 2, potassium cyanide KCN. The beginning of the synthesis of organic substances is considered to be the synthesis of urea from an inorganic salt - ammonium cyanate NH 4 CNO, produced by Wöhler in 1828. This led to the need to determine organic substances. Today, they include more than a million carbon-containing compounds. Some of them are isolated from plant and animal sources, but many more have been synthesized in laboratories by organic chemists.
On what basis are organic substances classified as a separate group? What are their distinguishing features?
Because carbon is necessarily present in all organic substances, since the middle of the 19th century organic chemistry has often been called chemistry of carbon compounds.
The term “organic chemistry” was introduced by the Swedish scientist J. Berzelius at the beginning of the 19th century. Prior to this, substances were classified according to the source of their production. Therefore, in the 18th century, three chemistry were distinguished: “vegetative”, “animal” and “mineral”. Back in the 16th century, scientists did not distinguish between organic and inorganic compounds. Here, for example, is the classification of substances based on the knowledge of that time:
Oils: vitriol (sulfuric acid), olive;
Alcohols: wine, ammonia, hydrochloric (hydrochloric acid), nitrate (nitric acid);
Salts: table salt, sugar, etc.
Despite the fact that this classification, to put it mildly, does not correspond to the current one, many modern names came to us from that time. For example, the name "alcohol" (from the Latin "spiritus" - spirit) was assigned to all volatile liquids. Already in the 19th century, chemists not only conducted an intensive search for new substances and methods for their preparation, but also paid special attention to determining the composition of substances. A list of the most important discoveries in organic chemistry of that time could be presented as follows:
1845 Kolbe synthesizes acetic acid in several stages, using inorganic substances as starting materials: charcoal, hydrogen, oxygen, sulfur and chlorine.
1854 Berthelot synthesizes a fat-like substance.
1861 Butlerov, acting with lime water on paraformaldehyde (polymer of formic aldehyde), carried out the synthesis of "methylenenitane" - a substance belonging to the class of sugars.
1862 Berthelot, passing hydrogen between carbon electrodes, obtains acetylene.
These experiments confirmed that organic substances are of the same nature as all simple substances, and no vital force is required for their formation.
Organic and inorganic substances are composed of the same chemical elements and can be turned into each other.
The teacher gives examples of organic substances, names their molecular formula (the formulas are written in advance on the board and closed): acetic acid CH 3 -COOH, ethyl alcohol CH 3 CH 2 OH, sucrose C 12 H 22 O 11, glucose C 6 H 12 O 6 , acetylene HC = CH, acetone
Question: What do you notice in common in the composition of these substances? Which chemical property can you guess for these substances?
Students answer that all of the listed compounds include carbon and hydrogen. They are supposed to be on fire. The teacher demonstrates the burning of an alcohol lamp (C 2 H 5 OH), pays attention to the nature of the flame, introduces a porcelain cup into the flame of an alcohol lamp, urotropine and a candle in succession, shows that soot is formed from the flame of a candle. Next, the question of what substances are formed during the combustion of organic substances is discussed. Students come to the conclusion that carbon dioxide or carbon monoxide, pure carbon (soot, soot) can be formed. The teacher reports that not all organic substances are capable of burning, but they all decompose when heated without access to oxygen, charring. The teacher demonstrates the charring of sugar when heated. The teacher asks to identify the type chemical bond in organic substances, based on their composition.
Question: How many organic compounds do you think are known now? (Students give the estimated amount of known organic matter. These numbers are usually lower than the actual amount of organic matter.) In 1999, the 18 millionth organic matter.
Question: What are the reasons for the diversity of organic substances? Students are invited to try to find them in what is already known about the structure of organic substances. Pupils name such reasons as: the combination of carbon in chains of different lengths; connection of carbon atoms by simple, double and triple bonds with other atoms and among themselves; many elements that make up organic matter. The teacher gives another reason - the different nature of carbon chains: linear, branched and cyclic, demonstrates models of butane, isobutane and cyclohexane.
Students write in their notebooks: Causes of the diversity of organic compounds.
1. The connection of carbon atoms in chains of different lengths.
2. Formation by carbon atoms of simple, double and triple bonds with other atoms and among themselves.
3. Different nature of carbon chains: linear, branched, cyclic.
4. Many elements that make up organic substances.
5. The phenomenon of isomerism of organic compounds.
Question: What is isomerism?
This has been known since 1823. Berzelius (1830) proposed to call isomers substances that have a qualitative and quantitative composition, but have different properties. For example, about 80 different substances were known that corresponded to the composition C 6 H 12 O 2 . In 1861, the riddle of isomerism was solved.
At the congress of German naturalists and doctors, a report was read, called "Something in the chemical structure of bodies." The author of the report was Professor of Kazan University Alexander Mikhailovich Butlerov.
It was this very “something” that constituted the theory of chemical structure, which formed the basis of our modern ideas about chemical compounds.
Now organic chemistry has received a solid scientific basis, which ensured its rapid development in the next century up to the present day. The prerequisites for its creation were the successes in the development of atomic and molecular theory, ideas about valency and chemical bonding in the 50s of the 19th century. This theory made it possible to predict the existence of new compounds and their properties.
The concept of the chemical structure, or, ultimately, of the bond order of atoms in a molecule, made it possible to explain such a mysterious phenomenon as isomerism.
Definitions of the concepts “chemical structure”, “isomers” and “isomerism” are written in a notebook.
The ability to build structural formulas of isomers is practiced using examples:
C 2 H 6 O (ethanol and dimethyl ether), C 4 H 10 (butane and isobutane). The teacher shows how to write a short structural formula
On the board is a poster depicting isomers of butane and pentane.
The teacher proposes to build isomers of the composition C 6 H 14 if it is known that there are five of them. After putting all the isomers on the board, the teacher draws the students' attention to the method of constructing isomers: each time the main chain decreases and the number of radicals increases.
Homework: learn the notes in the notebook, build all possible isomers of the composition C 7 H 16.
"Lesson 10"
Topic: "CYCLOPARAFFINS: STRUCTURE, PROPERTIES, APPLICATION». Finding the molecular formula of a gaseous hydrocarbon by its relative density and mass fractions of elements
Goals lesson: 1. Give students the concept of cyclic hydrocarbons. 2. Know the physical and chemical properties of cycloparaffins in comparison with saturated hydrocarbons, be able to write reaction equations that prove the chemical properties of cycloparaffins. 3. Know the practical application of cycloparaffins, based on the properties of these substances, methods of obtaining.
movelesson
I . Preparing for the perception of new material
1 . Checking homework.
At the blackboard 1st student - task number 1, page 50. 2nd student - task 7, page 23.
2. Class work.
Solve a problem:
When burning 2.1 g of a substance, 6.6 g of carbon monoxide (IV) and 2.7 G water. The vapor density of this substance in air is 2.91. Determine the molecular formula of this substance.
3. Frontal conversation on the following issues:
a) What substances are called homologues? isomers?
b) Why are hydrocarbons called marginal?
c) Why does the hydrocarbon chain (for saturated hydrocarbons) have a zigzag structure? Why can this chain take different forms in space?
d) Why do carbon atoms join in chains?
e) What is the reason for the diversity of organic compounds? And other questions.
II . Learning new material (lecture)
1 . The concept of cycloparaffins .
In addition to the considered saturated hydrocarbons with an open chain of atoms - paraffins, there are hydrocarbons of a closed, cyclic structure. They are called cycloparaffins, For example:
The general formula of cycloparaffins: C p H 2p.
They have two hydrogen atoms less, than the limit. Why?
Cycloparaffins are also called cycloalkanes. Five- and six-membered cycloparaffins were first discovered in oil by V. V. Markovnikov, a professor at Moscow University. Hence their other name - naphthenes.
Cycloparaffin molecules often contain side carbon chains:
2. The structure of cycloparaffins .
According to the structure of molecules, cycloparaffins are similar to saturated hydrocarbons. Each carbon atom in cycloalkanes is in a state of sp 3 hybridization and forms four δ-bonds C - C and C - H. The angles between the bonds depend on the size of the cycle. In the simplest C 3 and C 4 cycles, the angles between the C - C bonds are very different from the tetrahedral angle of 109 ° 28, which creates tension in the molecules and ensures their high reactivity.
Free rotation around connections S-S, forming a cycle impossible.
3. Isomerism and nomenclature .
Cycloalkanes are characterized by two types of isomerism.
A) 1st view- structural isomerism- isomerism of the carbon skeleton (as for all classes of organic compounds). But structural isomerism can be due to various reasons.
Firstly, cycle size. For example, for the C 4 H 8 cycloalkane, there are two substances:
Also referred to as structural isomerism interclass. For example, for a substance C 4 H 8, one can write down the structural formulas of substances belonging to different classes of hydrocarbons.
b) 2nd view- spatial isomerism in some substituted cycloalkanes, it is due to the absence of free rotation around the C - C bonds in the cycle.
For example, in a 1,2-dimethylcyclopropane molecule, two CH 3 groups can be on the same side of the ring plane (cis-isomer) or on opposite sides (trans-isomer).
The names of cycloalkanes are formed by adding the prefix cyclo- to the name of an alkane with the appropriate number of carbon atoms. The numbering in the cycle is carried out in such a way that the substituents receive the smallest numbers.
Structural formulas of cycloalkanes are usually written in abbreviated form, using the geometric form of the cycle and omitting the symbols of carbon atomsYes And hydrogen.
4. Physical properties of cycloparaffins .
Under normal conditions, the first two members of the series (C 3 and C 4) are gases, C 5 - C 10 are liquids, higher - solids. The boiling and melting points of cycloalkanes, as well as their densities, are somewhat higher than those of paraffins with an equal number of carbon atoms. Like paraffins, cycloalkanes are practically insoluble in water.
5. Chemical properties.
According to the chemical properties of cycloalkanes, in particular cyclopentane And cyclohexane, similar to saturated hydrocarbons. They are chemically inactive, combustible, enter into a substitution reaction with halogens.
c) They also enter into a dehydrogenation reaction (hydrogen abstraction) in the presence of a nickel catalyst.
By chemical nature, small cycles (cyclopropane and cyclobutane) are prone to addition reactions, as a result of which the cycle breaks and paraffins and their derivatives are formed, which they resemble unsaturated compounds.
a) Addition of bromine
6. Obtaining cycloparaffins .
a) Cyclopentane, cyclohexane and their derivatives make up the bulk of some oils. Therefore, they are obtained mainly from oil. But there are also synthetic methods of obtaining.
b) A common way to obtain cycloalkanes is the action of metals on dihalogenated alkanes.
7. Use of cycloalkanes. Of the cycloparaffins, cyclopentane, cyclohexane, methyl cyclohexane, their derivatives, and others are of practical importance. In the process of aromatization of oil, these compounds are converted into aromatic hydrocarbons - into benzene, toluene and other substances that are widely used for the synthesis of dyes, medicines, etc. Cyclopropane is used for anesthesia. Cyclopentane used as an additive to motor fuel to improve the quality of the latter and in various syntheses.
Oil also contains carboxyl derivatives of cyclopentane - cyclopentcarboxylic acid and its homologues, called naphthenic acids. When refining petroleum products with alkali, sodium salts of these acids are formed, which have a detergency (soap oil). Cyclohexane is used mainly for the synthesis of adipic acid and caprolactam, intermediates for the production of synthetic fibers nylon and kapron.
III . Consolidation of knowledge and skills.
Task 2. When a substance weighing 4.2 g is burned, 13.2 g of carbon monoxide (IV) and 5.4 g of water are formed. The vapor density of this substance in air is 2.9. Determine the molecular formula of this substance.
Problem 3. When burning 7.5 g of a substance, 11 g of carbon monoxide (IV) and 4.5 g of water are formed. The hydrogen vapor density of this substance is 14 Determine the molecular formula of this substance.
Ass to house §
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"10.1"
Lesson No. 11 Grade 10 Practical work: "Qualitative determination of carbon, hydrogen and chlorine in organic compounds."
Goals. Learn to experimentally prove the qualitative composition of hydrocarbons and their halogen derivatives, to justify the experimental data.
Equipment and reagents. Spatulas (2 pcs.), A piece of cotton wool, U- and L-shaped gas outlet tubes, a capillary gas outlet tube, a spirit lamp, matches, an iron stand with a tray, a wide-mouth test tube, a pipette, a wash bottle, a stand with test tubes, crucible tongs, filter paper , porcelain cup, blue glass (Co), sanitary bottle, 50 ml glass; litmus paper (violet), C 2 H 5 OH (3–4 ml), lime water Ca (OH) 2 or barite water Ba (OH) 2, paraffin (crushed), sucrose C 12 H 22 O 11, CuO ( powder), CuSO 4 (anhydrous), HNO 3 (conc.), chloroform CHCl 3 or carbon tetrachloride CCl 4 , Na metal (2–3 peas, freshly cleaned), AgNO 3 (solution, = 1%), Cu (thin wire, twisted into a spiral at the end).
Halogens are determined according to Beilstein and Stepanov. Beilstein test
. When heated with CuO, halogen-containing substances burn to form volatile copper compounds with halogen, which color the flame blue-green.
Stepanov's reaction
. The presence of a halogen is determined by reducing the halogen compound with hydrogen (atomic, at the time of isolation). The halogen is cleaved off in the form of hydrogen halide, which is detected by reaction with silver (I) nitrate on a white cheesy AgCl precipitate, insoluble in acids. Hydrogen is produced by the action of metallic Na on alcohol.
| Operating procedure | Tasks | Observations and Conclusions |
| 1. In a test tube, mix (1:3) a little sugar C 12 H 22 O 11 with copper (II) oxide, pouring the mixture with oxide and on top.
| Prove empirically that the composition of the issued organic matter contains carbon and hydrogen. Name signs of observed chemical reactions. | |
| 3. Close the test tube with a stopper with a gas outlet tube, the end of which should be in the collector above the level of lime water. Heat the whole tube first, then the mixture. Observe | Write the equations of the ongoing reactions. Additionally, write the equations for combustion reactions with CuO substances | |
| copper wire, taken with tongs, calcined in a burner flame to form a layer of copper (II) oxide on its surface. If the flame turns blue-green, heat until the color disappears. After cooling, soak the tip of the wire in the test substance CCl 4 and introduce into a non-luminous flame | Prove experimentally the presence of halogen atoms in the composition of carbon tetrachloride. The proof can be done in two ways. Explain the results of the experiment, write down the equations for recognition reactions | |
| Demo Experience . Dissolve a few drops (grains) of the test substance in 2-3 ml of C 2 H 5 OH (dehydrated with anhydrous CuSO 4) and add a piece of metallic Na (a pea). At the end of hydrogen evolution, making sure that sodium is completely dissolved, dilute the mixture with an equal volume of water, acidify with a concentrated solution of HNO 3 and add a 1% solution of silver (I) nitrate |
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"10kachreakzii"
Qualitative reactions in organic chemistry" (Grade 10)
The purpose of the lesson: generalize students' knowledge on the recognition of organic substances using qualitative reactions, be able to solve experimental problems.
Equipment: educational electronic publication "Organic Chemistry", (laboratory of multimedia systems), cards with individual tasks for the recognition of organic substances.
Lesson type:generalization and testing of students' knowledge on this topic.
Lesson form: the lesson is held for two academic hours of 45 minutes: in the first lesson, the disk is viewed and reaction equations are written, with the help of which organic substances can be recognized, in the second lesson, experimental problems are solved, during the last 15 minutes of the lesson, students perform
individual assignments.
During the classes:
Teacher: Today in the lesson we will remember all the qualitative reactions that we studied this academic year, we will learn how to solve experimental problems. The educational electronic manual "Organic Chemistry" will help us to remember and consolidate our knowledge. You will need to look at and write down the reaction equations in order to then solve problems.
I . Viewing the disc and recording reaction equations. (First lesson)
1. Unsaturated hydrocarbons.
1. Discoloration of bromine water when ethylene is passed through it. (Theme "Alkenes", section "Chemical properties", slide 4.)
2. Discoloration of potassium permanganate in an aqueous and acidic environment when an alkene is passed through it. (Theme "Alkenes", section "Chemical properties", slides 11, 12, 13.)
3. Alkyne oxidation and acetylene production. (Theme "Alkynes", section "Oxidation of alkynes", slides 1 and 8.)
2. Oxygen-containing organic substances.
1. Interaction of monohydric saturated alcohols with sodium and oxidation of alcohols. (Students write the equations themselves.)
2. Intramolecular dehydration of monohydric alcohols - obtaining alkenes. (Theme "Alcohols", section "Chemical properties of alcohols", slide 17.)
3. Polyhydric alcohols. (Topic "Polyols", slides 2 and 4.)
4. Qualitative reactions to phenol - interaction with bromine water and iron chloride (III). (Theme "Phenol", slides 2 and 4.)
5. Oxidation of aldehydes. Silver and copper mirror reactions. (Theme "Aldehydes", section "Chemical properties of aldehydes", slides 12, 13, 14, 15.)
6. Recognition of limiting monobasic carboxylic acids. Reactions to indicators, interaction with carbonates and ferric chloride (III). (Theme "Carboxylic acids", section "Chemical properties", slides 2, 3, 4.)
7. Qualitative reactions to formic acid. Discoloration of potassium permanganate in an acidic environment and the "silver mirror" reaction. (Section "Formic acid", slide 2.)
8. Recognition of higher unsaturated carboxylic acids and soap solution (sodium stearate) - discoloration of bromine water with oleic acid and precipitation of stearic acid when mineral acid acts on soap. (Students write the equations themselves.)
9. Recognition of glucose. Reactions with copper(II) hydroxide, "silver and copper mirror" reactions. (Equations are written independently.)
10. Action of iodine solution on starch. (Theme "Carbohydrates", section "Starch", slide 6.)
3. Nitrogen-containing organic compounds.
1. Recognition of primary and secondary amines. (Theme "Amines", section "Chemical properties", slide 7.)
2. Discoloration of bromine water with aniline. (Theme "Amines", section "Obtaining and properties of amines", slide 9.)
3. Qualitative reactions to amino acids. (Theme "Amino acids", section "Physical and chemical properties", slide 6.)
4. Color reactions of proteins. (Theme "Proteins", section "Protein properties", slides 21 and 22.)
II . Solution of experimental problems. (30 minutes of the second lesson)
To solve problems, the material of the textbook by O. S. Gabrielyan “Organic Chemistry”, grade 10, pp. 293-294, is used. (Practical work No. 8.) To solve problems, it is not enough to know qualitative reactions, it is necessary to determine the course of recognition.
III . Verification work students. (15 minutes of the second lesson)
Work is carried out on cards containing 4 options for tasks. It is necessary to write the course of determining substances and the equation of qualitative reactions.
1 option. Recognize solutions of starch, formaldehyde, soap and glucose.
Option 2. Recognize solutions of glycerol, hexene, acetic acid and protein.
3 option. Recognize solutions of acetaldehyde, ethanol, phenol and ethylene glycol.
4 option. Recognize solutions of formic acid, acetic acid, starch and aniline.
Teacher: Qualitative analysis of substances is an important topic in the study of organic chemistry. Knowing it helps not only chemists, but also doctors, ecologists, biologists, epidemiologists, pharmacists, and food industry workers. I hope that this knowledge will help you in Everyday life.
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"11-12 lesson"
Lesson 11-12 Grade 10
Subject. "Alkenes: structure, isomerism and nomenclature».
Target
Tasks: educational developing: educational
Methods: verbal (explanation, story, conversation);
visual (demonstration of tables, short-rod models of molecules).
Lesson type: learning new material.
Equipment
During the classes.
Introductory speech of the teacher
The lesson begins with poetic lines.
Nature gives us every day
Touching the Altar.
Thank you, Earth.
The rotation of the planet
touch of the elements,
All - north, south, winter and summer,
Road, work, love, poems,
Interweaving of soul and thought,
Falls, ups and downs...
And today, as in other lessons, we will learn new things. And we learn in order to be able to apply our knowledge in life.
According to Butlerov's theory, the properties of substances depend on their structure.
Reporting lesson objectives.
1 .
2 . .
Level A (task for "4")
A. Alkanov. B. Alkenov.
The homologues are:
A. Etana. B. Ethena.
Determine the type of reaction:
Level B (tasks for "5")
The homologues of pentane are:
A. C 3 H 8 . B. C 2 H 4 . V. C 6 H 6. G. C 7 H 12.
The industrial process for processing hard coal is:
A. Rectification. B. Coking.
B. Electrolysis. G. Cracking.
2,3-dimethylbutane has the molecular formula:
A. C 4 H 10 . B. C 5 H 12. V. S 6 N 14. G. S 7 N 16
All carbon atoms are in sp 3 - hybrid state in:
A. Arenach. B. Alkanah. V. Alkenakh. G. Alkinakh.
Add the reaction equation and determine its type:
Al 4 C 3 + H 2 O → ...
A. Hydration. B. Hydrogenation.
B. Hydrolysis. D. Oxidation.
The molecular formula of an organic substance containing 52.17% carbon, 13.04% hydrogen, 34.78% oxygen, having a hydrogen vapor density of 23, is:
A. C 2 H 4 O. B. C 2 H 6 O. V. C 2 H 4 O 2. G. C 2 H 6 O 2.
Key. Level A: 1.A. 2. B. 3. A. 4. A. 5. B. 6. B.
6 points - "4", 5 points - "3".
Level B: 1. A. 2. C. 3. C. 4. B 5. B. 6. B.
5. Al 4 C 3 + 12 H 2 O → 3CH 4 + 4Al (OH) 3
7 points - "5", 6 points - "4", 5 points - "3"
Students check test tasks on the key and self-assess themselves.
3. Knowledge update.
Why are alkanes classified as saturated hydrocarbons?
What bonds are formed between atoms in alkane molecules?
What types of hybridization are characteristic of carbon atoms in alkanes?
What other types of hybridization of carbon atoms exist?
Learning new material.
Homologous series of alkenes.
Isomerism of alkenes.
Alkene nomenclature.
Independent work according to the textbook (2 minutes)
? 1- what hydrocarbons can be classified as unsaturated?
2 - what does the term unsaturated hydrocarbons mean?
3 - name the simplest representative of unsaturated hydrocarbons of the alkene class.
CH 2 \u003d CH 2 ethene (ethylene).
Student message.
“Ethylene was first obtained in 1669 by the German chemist Johann Joachim Becher by heating ethyl alcohol with concentrated sulfuric acid. Contemporaries could not appreciate the discovery of the scientist. After all, Becher not only synthesized a new hydrocarbon, but also for the first time used a chemical catalyst (sulfuric acid) in the reaction process. Before that, only biological catalysts of natural origin – enzymes – were used in scientific practice and everyday life.
For more than 100 years after its discovery, ethylene had no own name. At the end of the 18th century, it turned out that when interacting with chlorine, "Becher's gas" turns into an oily liquid, after which it was called olefin, which means producing oil. Then this name was extended to all hydrocarbons that had an ethylene-like structure.
Define the class alkenes.
Alkenes (olefins) - acyclic hydrocarbons containing in the molecule, in addition to single bonds, one double bond between carbon atoms and corresponding to the general formula C n H 2n.
2. Electronic and spatial structure of ethylene.
Demonstration of ball-and-stick models of hexane and ethylene molecules
Table explanation.
In the ethylene molecule CH 2 \u003d CH 2, both carbon atoms connected by a double bond are in the sp 2 state - hybridization. That is, 1 s-cloud and 2 p-clouds participate in hybridization (unlike ethane, in which 1 s-cloud and 3 p-clouds participate in hybridization), and one p-cloud for each carbon atom remains unhybridized.
The axes of sp 2 orbitals lie in the same plane (unlike alkanes, in which the carbon atom has a three-dimensional form - a tetrahedron).
The angle between them is 120 0 (in alkanes 109 0 28 /).
The length of the double bond is less than the single bond and is 0.133 nm (for alkanes l = 0.154 nm).
Due to the presence of a double bond, free rotation about the C \u003d C bond is impossible (whereas alkanes can freely rotate around a single bond).
3. Homologous series of alkenes.
?
ethene propene butene-1
4. Isomerism of alkenes.
?
Isomerism of alkenes
Structural Spatial
Butene-1 Butene-1 Butene-1
N N N 3 C N
CH 3 butene-2 CH 2 - CH 2
! .
5. Nomenclature of alkenes.
Table explanation"Nomenclature of alkenes".
1. Main circuit selection
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"Lesson 12"
Grade 10
Subject. Electronic and spatial structure of alkenes, homologous series of alkenes. Alkenes: structure, isomerism and nomenclature ».
Target: to continue the formation of concepts about hydrocarbons in order to clarify the influence of the electronic structure of alkenes on the appearance a large number isomers of this class of substances.
Tasks: educational: to promote the formation of students' concepts of the chemical and electronic structure, the homological series, isomerism and the nomenclature of alkenes;
developing: continue to develop the concept of the structure of matter, isomerism and its types; continue to develop the ability to give names to organic compounds according to the IUPAC nomenclature and build formulas of substances by name; work with tests continue to develop the ability to compare the structure and types of isomerism of alkanes and alkenes;
educational: to continue the education of cognitive interest in science.
Methods: verbal (explanation, story, conversation); visual (demonstration of tables, short-rod models of molecules).
Lesson type: learning new material.
Equipment: tables "Structure of the ethylene molecule", "Structure of the carbon atom", "Nomenclature of alkenes"; keys to tests and graphic dictation; ball-and-stick models of molecules of hexane, ethene, butene-2 (cis- and trans).
During the classes.
Organizing time.
Reporting lesson objectives.
Checking the material covered.
1 . Two students work at the blackboard: 1st student - carries out a chain of transformations; 2nd student - writes down the conditions for the reactions in this chain. The rest of the students complete the task in their notebooks.
Carry out a chain of transformations according to the following scheme:
Ethane → Bromoethane → n-Butane → Isobutane → Carbon monoxide (IV).
Specify the reaction conditions, if necessary.
2 . Multi-level test control.
Students choose their own difficulty level.
Level A (task for "4")
Substances with the general formula CnH2n+2 belong to the class:
A. Alkanov. B. Alkenov.
The homologues are:
A. Methane and chloromethane. B. Ethane and propane.
Pi - the bond is absent in the molecule:
A. Etana. B. Ethena.
Alkanes are characterized by reactions:
A. Substitutions. B. Connections.
Determine the type of reaction:
CO + 3H 2 Ni, t C H 4 + H 2 O
A. Hydrohalogenation. B. Hydrogenation.
Oil refining is carried out in order to obtain:
A. Gasoline and methane only. B. Various petroleum products.
Learning new material.
The concept of unsaturated hydrocarbons.
Electronic and spatial structure of ethylene.
Homologous series of alkenes.
Isomerism of alkenes.
Alkene nomenclature.
What is the difference between saturated hydrocarbons and unsaturated hydrocarbons?
What unsaturated hydrocarbons do you know?
1. The concept of unsaturated hydrocarbons.
Alkenes
Alkenes (unsaturated hydrocarbons, ethylene hydrocarbons, olefins) - unsaturated aliphatic hydrocarbons, the molecules of which contain a double bond. The general formula for a number of alkenes C n H 2n.
According to the systematic nomenclature, the names of alkenes are derived from the names of the corresponding alkanes (with the same number of carbon atoms) by replacing the suffix – en on - en: ethane (CH 3 -CH 3) - ethene (CH 2 \u003d CH 2), etc. The main chain is chosen so that it necessarily includes a double bond. The numbering of carbon atoms starts from the end of the chain closest to the double bond.
In an alkene molecule, the unsaturated carbon atoms are in sp 2 -hybridization, and the double bond between them is formed by σ- and π-bond. sp 2 -Hybrid orbitals are directed to each other at an angle of 120 °, and one unhybridized 2p-orbital, located at an angle of 90 ° to the plane of hybrid atomic orbitals.
Spatial structure of ethylene:
C=C bond length 0.134 nm, C=C bond energy E s=s = 611 kJ/mol, π-bond energy Еπ = 260 kJ/mol.
Types of isomerism: a) chain isomerism; b) double bond position isomerism; V) Z, E (cis, trans) - isomerism, a type of spatial isomerism.
Methods for obtaining alkenes
1. CH 3 -CH 3 → Ni, t→ CH 2 \u003d CH 2 + H 2 (dehydrogenation of alkanes)
2. C 2 H 5 OH →H,SO 4 , 170 °C→ CH 2 \u003d CH 2 + H 2 O (dehydration of alcohols)
3. (dehydrohalogenation of alkyl halides according to the Zaitsev rule)
4. CH 2 Cl-CH 2 Cl + Zn → ZnCl 2 + CH 2 \u003d CH 2 (dehalogenation of dihalogen derivatives)
5. HC≡CH + H 2 → Ni, t→ CH 2 \u003d CH 2 (alkyne reduction)
Chemical properties of alkenes
For alkenes, addition reactions are most characteristic; they are easily oxidized and polymerized.
1. CH 2 \u003d CH 2 + Br 2 → CH 2 Br-CH 2 Br
(addition of halogens, qualitative reaction)
2. (addition of hydrogen halides according to the Markovnikov rule)
3. CH 2 \u003d CH 2 + H 2 → Ni, t→ CH 3 -CH 3 (hydrogenation)
4. CH 2 \u003d CH 2 + H 2 O → H + → CH 3 CH 2 OH (hydration)
5. ZCH 2 \u003d CH 2 + 2KMnO 4 + 4H 2 O → ZCH 2 OH-CH 2 OH + 2MnO 2 ↓ + 2KOH (mild oxidation, qualitative reaction)
6. CH 2 \u003d CH-CH 2 -CH 3 + KMnO 4 → H + → CO 2 + C 2 H 5 COOH (hard oxidation)
7. CH 2 \u003d CH-CH 2 -CH 3 + O 3 → H 2 C \u003d O + CH 3 CH 2 CH \u003d O formaldehyde + propanal → (ozonolysis)
8. C 2 H 4 + 3O 2 → 2CO 2 + 2H 2 O (combustion reaction)
9. (polymerization)
10. CH 3 -CH \u003d CH 2 + HBr → peroxide→ CH 3 -CH 2 -CH 2 Br (addition of hydrogen bromide against Markovnikov's rule)
11. (substitution reaction in α-position)
View document content
"12.1 lesson"
12 lesson 10 class
Subject. « Nomenclature and isomerism of alkenes» .
Target: to continue the formation of concepts about hydrocarbons in order to clarify the influence of the electronic structure of alkenes on the appearance of a large number of isomers in this class of substances.
Tasks:
educational: to promote the formation of students' concepts of the chemical and electronic structure, the homological series, isomerism and the nomenclature of alkenes;
developing: continue to develop the concept of the structure of matter, isomerism and its types;
continue to develop the ability to give names to organic compounds according to the IUPAC nomenclature and build formulas of substances by name; work with tests continue to develop the ability to compare the structure and types of isomerism of alkanes and alkenes;
educational: to continue the education of cognitive interest in science.
Methods: verbal (explanation, story, conversation); visual (demonstration of tables, short-rod models of molecules).
Lesson type: learning new material.
Equipment: tables "Structure of the ethylene molecule", "Structure of the carbon atom", "Nomenclature of alkenes"; keys to tests and graphic dictation; ball-and-stick models of molecules of hexane, ethene, butene-2 (cis- and trans).
During the classes.
Organizing time.
Introductory speech of the teacher - The lesson begins with poetic lines.
Nature gives us every day
Touching the Altar.
For life - a cosmic gift -
Thank you, Earth.
The rotation of the planet
touch of the elements,
All - north, south, winter and summer,
Road, work, love, poems,
Interweaving of soul and thought,
Falls, ups and downs...
What is the meaning of searching for meaning?
The process of knowing is the point.
And today, as in other lessons, we will learn new things. And we learn in order to be able to apply our knowledge in life. According to Butlerov's theory, the properties of substances depend on their structure.
The topic of today's lesson is "Alkenes: structure, isomerism and nomenclature."
And in the next lessons we will study their properties and application.
Reporting lesson objectives.
Checking the material covered.
1 . Two students work at the blackboard: 1st student - carries out a chain of transformations; The 2nd student writes down the conditions for the reactions in this chain. The rest of the students complete the task in their notebooks.
Exercise. Carry out a chain of transformations according to the following scheme:
Ethane → Bromoethane → n-Butane → Isobutane → Carbon monoxide (IV).
Learning new material.
Plan.
Homologous series of alkenes.
Isomerism of alkenes.
Alkene nomenclature.
1 . Homologous series of alkenes.
? What substances are called homologues?
Write down the structural formulas of ethylene homologues and give them a name.
CH 2 = CH 2; CH 2 \u003d CH - CH 3; CH 2 \u003d CH - CH 2 - CH 3, etc.
ethene propene butene-1
2 . Isomerism of alkenes.
? What types of isomerism are characteristic of alkanes?
What do you think, what types of isomerism are possible in alkenes?
Isomerism of alkenes
Structural Spatial
Carbon Position Interclass Geometric
double skeleton (with cycloalkanes) (cis- and trans-)
CH 2 \u003d CH-CH 2 -CH 3 CH 2 \u003d CH-CH 2 -CH 3 CH 2 \u003d CH-CH 2 -CH 3 H 3 C CH 3 H CH 3
Butene-1 Butene-1 Butene-1
CH 2 \u003d CH - CH 3 CH 3 -CH \u003d CH - CH 3 CH 2 - CH 2
N N N 3 C N
CH 3 butene-2 CH 2 - CH 2
2-methylpropene cyclobutane cis-butene -2 trans-butene -2
The diagram is drawn on the board during the explanation, the students write it down in a notebook.
! Physical education: exercises for the muscles of the eyes, head, shoulder, hands.
3 . Alkene nomenclature.
Table explanation"Nomenclature of alkenes".
The nomenclature of alkenes developed by IUPAC is similar to the nomenclature of alkanes.
Rules for naming alkenes.
Main circuit selection. In the case of alkenes, the longest chain of carbon atoms must contain a double bond.
Homework:
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"Lesson 13"
"___" _____________ 2011 Lesson 13
Lesson topic:Alkenes. Obtaining, chemical properties and application of alkenes.
Goals and objectives of the lesson:
Equipment:
DURING THE CLASSES
I. Organizational moment
1. Methods for obtaining alkenes
C 4 H
octane butene butane
butane butene hydrogen
potassium potassium
Remember!
a) Addition reactions
Remember!
Remember!
ethene polyethylene
b) oxidation reaction
Laboratory experience.
– catalytic oxidation
Remember the main thing!
3. Use of alkenes
2 - plastics;
3 - explosives;
4 - antifreeze;
5 - solvents;
7 - obtaining acetaldehyde;
8 - synthetic rubber.
Homework:
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"Lesson 14"
"___" _____________ 2011 Lesson 14
Lesson topic: Obtaining alkenes and their applicationAlkenes. Obtaining, chemical properties and application of alkenes.
Goals and objectives of the lesson:
consider the specific chemical properties of ethylene and the general properties of alkenes;
deepen and concretize the concepts of pi-bonds, the mechanisms of chemical reactions;
give initial ideas about polymerization reactions and the structure of polymers;
analyze laboratory and general industrial methods for obtaining alkenes;
continue to develop the ability to work with a textbook.
Equipment: device for obtaining gases, KMnO 4 solution, ethyl alcohol, concentrated sulfuric acid, matches, spirit lamp, sand, tables "Structure of the molecule of ethylene", "Basic chemical properties of alkenes", demonstration samples "Polymers".
DURING THE CLASSES
I. Organizational moment
We continue to study homologous series alkenes. Today we have to consider the methods of obtaining, chemical properties and applications of alkenes. We must characterize the chemical properties due to the double bond, get an initial understanding of polymerization reactions, consider laboratory and industrial methods for obtaining alkenes.
II. Activation of students' knowledge
What hydrocarbons are called alkenes?
What are the features of their structure?
In what hybrid state are the carbon atoms that form a double bond in an alkene molecule?
Bottom line: alkenes differ from alkanes in the presence of one double bond in the molecules, which determines the features of the chemical properties of alkenes, methods for their preparation and use.
III. Learning new material
1. Methods for obtaining alkenes
Compose reaction equations confirming the methods for obtaining alkenes
– cracking of alkanes C 8 H 18 –– C 4 H 8 + C 4 H 10 ; (thermal cracking at 400-700 o C)
octane butene butane
– dehydrogenation of alkanes C 4 H 10 –– C 4 H 8 + H 2 ; (t, Ni)
butane butene hydrogen
– dehydrohalogenation of haloalkanes C 4 H 9 Cl + KOH –– C 4 H 8 + KCl + H 2 O;
chlorobutane hydroxide butene chloride water
potassium potassium
– dehydrohalogenation of dihaloalkanes 
- dehydration of alcohols C 2 H 5 OH - C 2 H 4 + H 2 O (when heated in the presence of concentrated sulfuric acid)
Remember!
In the reactions of dehydrogenation, dehydration, dehydrohalogenation and dehalogenation, it must be remembered that hydrogen is predominantly detached from less hydrogenated carbon atoms (Zaitsev's rule, 1875)
2. Chemical properties of alkenes
The nature of the carbon - carbon bond determines the type of chemical reactions that organic substances enter into. The presence of a double carbon-carbon bond in the molecules of ethylene hydrocarbons determines the following features of these compounds:
- the presence of a double bond makes it possible to classify alkenes as unsaturated compounds. Their transformation into saturated ones is possible only as a result of addition reactions, which is the main feature of the chemical behavior of olefins;
- a double bond is a significant concentration of electron density, so the addition reactions are electrophilic in nature;
- a double bond consists of one - and one -bond, which is quite easily polarized.
Reaction equations characterizing the chemical properties of alkenes
a) Addition reactions
Remember! Substitution reactions are characteristic of alkanes and higher cycloalkanes having only single bonds, addition reactions are characteristic of alkenes, dienes and alkynes having double and triple bonds.
Remember! The following break-link mechanisms are possible:
a) if the alkenes and the reagent are non-polar compounds, then the -bond breaks with the formation free radical:
H 2 C \u003d CH 2 + H: H - - + +
b) if the alkene and the reagent are polar compounds, then breaking the bond leads to the formation of ions:
c) when connecting at the site of the break-bond of reagents containing hydrogen atoms in the molecule, hydrogen always attaches to a more hydrogenated carbon atom (Morkovnikov's rule, 1869).
- polymerization reaction nCH 2 \u003d CH 2 - n - CH 2 - CH 2 - - (- CH 2 - CH 2 -) n
ethene polyethylene
b) oxidation reaction
Laboratory experience. Obtain ethylene and study its properties (instruction on student desks)
Instructions for obtaining ethylene and experiments with it
1. Place 2 ml of concentrated sulfuric acid, 1 ml of alcohol and a small amount of sand into a test tube.
2. Close the test tube with a stopper with a gas outlet tube and heat it in the flame of an alcohol lamp.
3. Pass the escaping gas through a solution of potassium permanganate. Note the change in color of the solution.
4. Ignite the gas at the end of the gas tube. Pay attention to the color of the flame.
- Alkenes burn with a luminous flame. (Why?)
C 2 H 4 + 3O 2 - 2CO 2 + 2H 2 O (with complete oxidation, the reaction products are carbon dioxide and water)
Qualitative reaction: "mild oxidation (in aqueous solution)"
- alkenes decolorize a solution of potassium permanganate (Wagner reaction)
Under more severe conditions in an acidic environment, the reaction products can be carboxylic acids, for example (in the presence of acids):
CH 3 - CH \u003d CH 2 + 4 [O] -– CH 3 COOH + HCOOH
– catalytic oxidation
Remember the main thing!
1. Unsaturated hydrocarbons actively enter into addition reactions.
2. The reactivity of alkenes is due to the fact that - the bond is easily broken under the action of reagents.
3. As a result of the addition, the transition of carbon atoms from sp 2 - to sp 3 - hybrid state occurs. The reaction product has a limiting character.
4. When ethylene, propylene and other alkenes are heated under pressure or in the presence of a catalyst, their individual molecules are combined into long chains - polymers. Polymers (polyethylene, polypropylene) are of great practical importance.
3. Use of alkenes(student's message according to the following plan).
1 - obtaining fuel with a high octane number;
2 - plastics;
3 - explosives;
4 - antifreeze;
5 - solvents;
6 - to accelerate the ripening of fruits;
7 - obtaining acetaldehyde;
8 - synthetic rubber.
III. Consolidation of the studied material
Homework:§§ 15, 16, ex. 1, 2, 3 p. 90, ex. 4, 5 p. 95.
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"Lesson 15"
23.10.2011 Lesson 15 Grade 10
Lesson on the topic: Calculations according to chemical equations characterizing the properties and methods for obtaining alkenes, provided that one of the reactants is given in excess.
Goals: Teach students how to write and solve chemistry problems.
Lesson type: Combined.
During the classes
I. Class Organization
II. Updating knowledge, skills and abilities
III. Learning new material:
Solution:
H 2 O H 2 Na 5.6 g
C 2 H 5 OH96%;
112 ml;
0.8 g/ml.
m (C 2 H 5 OH, p-p) \u003d Vp \u003d 112.5. 0.8=90(g); m (C 2 H 5 OH) \u003d m (C 2 H 5 OH, rr). w (C 2 H 5 OH)=90. 0.96=86.4(g); n(C 2 H 5 OH)=m/M=86.4:46=1.8(mol).
m (H 2 O) \u003d m (C 2 H 5 OH, p-p) - m (C 2 H 5 OH) \u003d 90-86.4 \u003d 3.6 (g); n(H 2 O) \u003d m / M \u003d 3.6: 18 \u003d 0.2 (mol).
n (Na) \u003d m / M \u003d 5.6: 23 \u003d 0.24 (mol).
according to the condition 0.24mol 0.2mol
2Na + 2H 2 O 2NaOH + H 2
according to the equation 2mol 2mol
excess deficiency
| after-tion |
according to the condition 0.04mol 1.8mol
2Na + 2C 2 H 5 OH 2C 2 H 5 ONa + H 2
according to the equation 0.04 mol 0.04 mol
deficiency excess
| after-tion |
m (solution) \u003d m (C 2 H 5 OH, solution) + m (Na) -m (H 2) \u003d 90 + 5.6-(0.02 + 0.1) . 2=95.36(g).
Those. after reaction in solution:
m (C 2 H 5 OH)=n. M=1.76. 46=80.96(g),
w (C 2 H 5 OH )=m (C 2 H 5 OH ) / m (solution)=80.96:95.36=0.85;
m (C 2 H 5 ONa)= n. M=0.04. 68=2.72(g),
w(C 2 H 5 ONa)= m (C 2 H 5 ONa)/ m(p-pa)=2.72:95.36=0.03;
w(NaOH)= 1- w(C 2 H 5 OH)- w(C 2 H 5 ONa)=1-0.85-0.03=0.12.
As a result of the oxidation of 12.32 g of methanol and the dissolution of the resulting aldehyde in 224 ml of water, 3% formalin was obtained. Determine mass fraction the yield of the reaction product.
Solution: because the condition of the problem is voluminous, we analyze it in the figure-scheme.
224 ml H2O
CH 3 OH [O]CH 2 O
12.32 g 3%
n(CH 3 OH)=m/M=12.32:32=0.385(mol);
m (CH 2 O, theor.) \u003d M n \u003d 30. 0.385=11.55(g)
m (H 2 O) \u003d Vp \u003d 224. 1=224(g), w(H 2 O )=100-3=97(%)
m (CH 2 O) - 3%, \u003d x - 3%, \u003d m (CH 2 O, practice) \u003d 224. 3:97= 6.93(g)
m (H 2 O ) - 97%.224 - 97%
w out. (CH 2 O )= m (CH 2 O , pract.)/ m (CH 2 O , theor.)= 6.93:11.55=0.6.
To check on the basis of the previous problem, we compose a new condition and solve it.
What concentration solution will be obtained if, after the oxidation of 12.32 g of methanol, the resulting formaldehyde (the yield was 60% of the theoretically possible) was dissolved in 224 ml of water?
Solution:
n (CH 3 OH)=m /M =12.32:32=0.385(mol);
n (CH 2 O) \u003d n (CH 3 OH) \u003d 0.385 (mol), because the number of atoms is the same.
m (CH 2 O, theor.) \u003d M n \u003d 30. 0.385=11.55(g);
m (CH 2 O, pract.) \u003d m (CH 2 O, theor.) . w out. (CH 2 O ): 100%=11.55. 60:100=6.93(g);
m (H 2 O) \u003d Vp \u003d 224. 1=224(g):
m (solution) \u003d m (CH 2 O, pract.) + m (H 2 O) \u003d 6.93 + 224 \u003d 230.93 (g);
w (CH 2 O) \u003d m (CH 2 O, practice): m (p-ra). 100%=6.93:230.93 . 100=3(%).
Homework: P.12? 3, 5-9
Organic chemistry
The concept of organic chemistry and the reasons for its separation into an independent discipline
Isomers- substances of the same qualitative and quantitative composition (i.e., having the same total formula), but of a different structure, therefore, different physical and chemical properties.
Phenantrene (right) and anthracene (left) are structural isomers.
Brief outline of the development of organic chemistry
The first period in the development of organic chemistry, called empirical(from the middle of the 17th to the end of the 18th century), covers a long period of time from the initial acquaintance of man with organic substances to the emergence of organic chemistry as a science. During this period, the knowledge of organic substances, methods of their isolation and processing took place empirically. According to the definition of the famous Swedish chemist I. Berzelius, the organic chemistry of this period was "the chemistry of plant and animal substances." By the end of the empirical period, many organic compounds were known. Citric, oxalic, malic, gallic, lactic acids were isolated from plants, urea from human urine, and hippuric acid from horse urine. The abundance of organic substances served as an incentive for an in-depth study of their composition and properties.
next period, analytical(the end of the 18th - the middle of the 19th century), is associated with the emergence of methods for determining the composition of organic substances. The most important role in this was played by the law of conservation of mass discovered by M. V. Lomonosov and A. Lavoisier (1748), which formed the basis of quantitative methods of chemical analysis.
It was during this period that it was found that all organic compounds contain carbon. In addition to carbon, elements such as hydrogen, nitrogen, sulfur, oxygen, phosphorus, which are currently called organogenic elements, were found in organic compounds. It became clear that organic compounds differ from inorganic compounds primarily in composition. At that time, there was a special relationship to organic compounds: they continued to be considered the products of the vital activity of plant or animal organisms, which can only be obtained with the participation of non-material "life force". These idealistic views have been refuted by practice. In 1828, the German chemist F. Wehler synthesized the organic compound urea from inorganic ammonium cyanate.
From the moment of the historical experience of F. Wöhler, the rapid development of organic synthesis begins. I. N. Zinin obtained by the reduction of nitrobenzene, thereby laying the foundation for the aniline-dye industry (1842). A. Kolbe synthesized (1845). M, Berthelot - substances like fats (1854). A. M. Butlerov - the first sugary substance (1861). Today, organic synthesis forms the basis of many industries.
Importance in the history of organic chemistry has structural period(the second half of the 19th - the beginning of the 20th century), which was marked by the birth of a scientific theory of the structure of organic compounds, the founder of which was the great Russian chemist A. M. Butlerov. The main provisions of the theory of structure had great importance not only for their time, but also serve as a scientific platform for modern organic chemistry.
At the beginning of the 20th century, organic chemistry entered into modern period development. Currently, in organic chemistry, quantum mechanical concepts are used to explain a number of complex phenomena; chemical experiment is increasingly combined with the use of physical methods; the role of various calculation methods has increased. Organic chemistry has become such a vast field of knowledge that new disciplines are separated from it - bioorganic chemistry, chemistry of organoelement compounds, etc.
Theory of the chemical structure of organic compounds A. M. Butlerova
The decisive role in the creation of the theory of the structure of organic compounds belongs to the great Russian scientist Alexander Mikhailovich Butlerov. On September 19, 1861, at the 36th Congress of German naturalists, A.M. Butlerov published it in the report "On the chemical structure of matter."
The main provisions of the theory of the chemical structure of A.M. Butlerov:
- All atoms in the molecule of an organic compound are connected to each other in a certain sequence in accordance with their valency. A change in the sequence of arrangement of atoms leads to the formation of a new substance with new properties. For example, two different compounds correspond to the composition of the substance C2H6O: - see.
- The properties of substances depend on their chemical structure. The chemical structure is a certain order in the alternation of atoms in a molecule, in the interaction and mutual influence of atoms on each other - both neighboring and through other atoms. As a result, each substance has its own special physical and chemical properties. For example, dimethyl ether is an odorless gas, insoluble in water, t°pl. = -138°C, bp = 23.6°C; ethyl alcohol - a liquid with an odor, soluble in water, t ° pl. = -114.5°C, bp = 78.3°C.
This position of the theory of the structure of organic substances explained the phenomenon, which is widespread in organic chemistry. The given pair of compounds - dimethyl ether and ethyl alcohol - is one of the examples illustrating the phenomenon of isomerism. - The study of the properties of substances allows us to determine their chemical structure, and the chemical structure of substances determines their physical and chemical properties.
- Carbon atoms can join together to form carbon chains. different kind. They can be both open and closed (cyclic), both straight and branched. Depending on the number of bonds spent by carbon atoms to connect with each other, chains can be saturated (with single bonds) or unsaturated (with double and triple bonds).
- Each organic compound has one specific structural formula or structural formula, which is built based on the position of tetravalent carbon and the ability of its atoms to form chains and cycles. The structure of a molecule as a real object can be studied experimentally by chemical and physical methods.
A.M. Butlerov did not limit himself to theoretical explanations of his theory of the structure of organic compounds. He conducted a series of experiments, confirming the predictions of the theory by obtaining isobutane, tert. butyl alcohol, etc. This made it possible for A.M. Butlerov to declare in 1864 that the available facts make it possible to vouch for the possibility of synthetic production of any organic substance.
IXClass
Topic: “GENERAL VIEWSABOUT ORGANIC SUBSTANCES»
(Lesson learning new material)
Lesson form: teacher's story and demonstration of samples and models of organic substances.
In connection with the transition to concentric programs in the ninth grade, the basics of organic chemistry are studied, ideas about organic substances are laid. Below is a development of a two-hour lesson that was held in the IX grade after studying the topic "Carbon and its compounds".
Lesson Objectives: to form an idea of the composition and structure of organic compounds, their distinctive features; identify the causes of the diversity of organic substances; to continue the formation of the ability to compose structural formulas using the example of organic substances; form an idea of isomerism and isomers.
Preliminary homework: remember how a covalent bond is formed in the molecules of inorganic substances, how its formation can be graphically shown.
Materials and equipmentTo lesson: samples of organic substances (acetic acid, acetone, ascorbic acid, sugar - in factory packages with labels, paper, candle, spirit lamp with alcohol, dry fuel (urotropine), oil; samples of plastic products and synthetic fibers (rulers, pens, bows, buttons, flower pots, plastic bags, etc.); matches, porcelain cup, crucible tongs. Ball-and-stick models of methane, ethylene, acetylene, propane, butane, isobutane, cyclohexane. For each student table - a bath with ball-and-stick models.
During the classes:
I. The teacher tells how the term "organic matter" came about.
Until the beginning of the 19th century, substances were divided by origin into mineral, animal and vegetable. In 1807, the Swedish chemist J. J. Berzelius introduced the term “organic substances” into science, combining substances of plant and animal origin into one group. He proposed to call the science of these substances organic chemistry. At the beginning of the 19th century, it was believed that organic substances could not be obtained under artificial conditions; they were formed only in living organisms or under their influence. The erroneousness of this idea was proved by the synthesis of organic substances in the laboratory: in 1828, the German chemist F. Wöder synthesized urea, his compatriot A. V. Kolbe obtained acetic acid in 1845, in 1854 the French chemist P. E. Berthelot - fats, in 1861 the Russian chemist A. M. Butlerov - a sugary substance. (This information is pre-recorded on the board and closed; during the message, the teacher opens this record.)
It turned out that there is no sharp boundary between organic and inorganic substances, they consist of the same chemical elements and can be converted into each other.
Question: On what basis are organic substances classified as a separate group, what are their distinguishing features?
The teacher invites the students to try to figure it out together.
II. The teacher shows samples of organic substances, names them and, if possible, indicates the molecular formula. (for some substances, the formulas are written in advance on the board and closed during the demonstrationwalkie-talkies these records open): acetic acid C 2 H 4 O 2 acetone C 3 H 6 O, ethyl alcohol (in an alcohol lamp) C 2 H 6 O, dry fuel urotropin C 6 H 12 N 4, vitamin C or ascorbic acid C 6 H 8 O 6, sugar C 12 H 22 O 11, paraffin candle and oil, which include substances with the general formula C X H Y, paper consisting of cellulose (C 6 H 10 O 5) p.
Questions: What do you notice in common in the composition of these substances? What chemical property can you assume for these substances?
Students answer that all of the listed compounds include carbon and hydrogen. They are supposed to be on fire. The teacher demonstrates the burning of urotropine, a candle and a spirit lamp, pays attention to the nature of the flame, introduces a porcelain cup into the flame of an alcohol lamp, urotropine and a candle, shows that soot is formed from the flame of a candle. Next, the question of what substances are formed during the combustion of organic substances is discussed. Students come to the conclusion that carbon dioxide or carbon monoxide, pure carbon (soot, soot) can be formed. The teacher reports that not all organic substances are capable of burning, but they all decompose when heated without access to oxygen, charring. The teacher demonstrates the charring of sugar when heated. The teacher asks to determine the type of chemical bond in organic substances, based on their composition.
Next, the students write in their notebooks signs of organic mattersubstances: 1. Contain carbon. 2. Burn and (or) decompose with the formation of carbonaceous products. 3. The bonds in the molecules of organic substances are covalent.
III. The teacher asks the students to define the
concept of "organic chemistry". The definition is written in a notebook. Orga
chemical chemistry- the science of organic substances, their composition, structure,
properties and methods of obtaining.
Syntheses of organic substances in the laboratory accelerated the development of organic chemistry, scientists began to experiment and obtain substances that do not occur in nature, but correspond to all the signs of organic substances. These are plastics, synthetic rubbers and fibers, varnishes, paints, solvents, medicines. (The teacher demonstrates plastic and fiber products.) By origin, these substances are not organic. Thus, the group of organic substances has expanded significantly, while the old name has been preserved. In the modern sense, organic substances are not those that are obtained in living organisms or under their action, but those that correspond to the characteristics of organic substances.
IV. The study of organic substances in the 19th century faced a number of
difficulties. One of them is the "incomprehensible" valency of carbon. Yes, on
for example, in methane CH 4 the valency of carbon is IV. In ethylene C 2 H 4, acetylene
C 2 H 2, propane C 3 H 8 the teacher offers to determine the valence by yourself
students. Students find valences, respectively, II, I and 8/3. Semi
actual valences are unlikely. So for organic matter
methods of inorganic chemistry cannot be used. Indeed, in the building
organic matter is peculiarities: the valency of carbon is always IV,
carbon atoms are connected to each other in carbon chains. Teacher
proposes to construct structural formulas of these substances. Students in
Structural formulas are built in notebooks and put on the board:
For comparison, the teacher demonstrates ball-and-stick models of these substances.
After that, the teacher asks to graphically depict the education of
valence bonds in the molecules of methane, ethylene and acetylene. Images
brought to the board and discussed. ,
V. The teacher draws the students' attention to the periodic system.
Now more than 110 chemical elements have been discovered, all of them are included in
composition of inorganic substances. About 600 thousand inorganic compounds are known. The composition of natural organic substances includes a few elements: carbon, hydrogen, oxygen, nitrogen, sulfur, phosphorus, and some metals. Recently, organoelement substances have been synthesized, thereby expanding the range of elements that make up organic substances.
Question: How many organic compounds do you think are known now? (Students name the estimated number of knownorganic substances. Usually these numbers are underestimated compared to the actualtic number of organic substances.) In 1999, the 18 millionth organic matter was registered.
Question: What are the reasons for the diversity of organic substances? Students are invited to try to find them in what is already known about the structure of organic substances. Pupils name such reasons as: the combination of carbon in chains of different lengths; connection of carbon atoms by simple, double and triple bonds with other atoms and among themselves; many elements that make up organic matter. The teacher gives another reason - the different nature of carbon chains: linear, branched and cyclic, demonstrates models of butane, isobutane and cyclohexane.
Students write in their notebooks: Causes of Organic Diversitysky connections.
1. The connection of carbon atoms in a chain of different lengths.
The formation of simple, double and triple bonds by carbon atoms
zei with other atoms and among themselves.
Different nature of carbon chains: linear, branched,
cyclic.
Many elements that make up organic substances.
There is another reason. (We must leave a place for her entry in tetsake.) The students must find it themselves. To do this, you can perform laboratory work.
VI. Laboratory work.
Students are given balls and rods: 4 black balls with 4 holes each are carbon atoms; 8 white balls with one hole each - hydrogen atoms; 4 long rods for connecting carbon atoms to each other; 8 short rods - for connecting carbon atoms with hydrogen atoms.
Task: using all the "building material", build a model of an organic molecule. Draw the structural formula of this substance in your notebook. Try to make as many different models as possible from the same " building material».
The work is done in pairs. The teacher checks the correctness of the assembly of models and the representation of structural formulas, helps students who have difficulties. 10-15 minutes are allotted for work (depending on the success of the class), after which the structural formulas are put on the board and the following questions are discussed: What is the same for all these substances? How are these substances different?
It turns out that the composition is the same, the structure is different. The teacher explains that such substances, the composition of which is the same, but the structure and therefore the properties are different, are called isomers. Under structure substances means the order of connection of atoms, their mutual arrangement in molecules. The phenomenon of the existence of isomers is called isomeria.
VII. Definitions of the concepts "chemical structure", "isomers" and "isomerism" are written by students in a notebook after the structural formulas of isomers. And in reasons for the diversity of chemicals is brought fifthpoint - the phenomenon of isomerism of organic compounds.
The ability to build structural formulas of isomers is practiced on the following examples: C 2 H 6 O (ethanol and dimethyl ether), C 4 H 10 (butane and isobutane). Using these examples, the teacher shows how to write an abbreviated structural formula:
The teacher suggests constructing isomers of the composition C 5 H 12) if it is known that there are three of them. After putting all the isomers on the board, the teacher draws the students' attention to the method of constructing isomers: each time the main chain decreases and the number of radicals increases.
Homework: learn the notes in the notebook, build isomers of the composition C 6 H M (there are 5 of them).
In chemistry class we learn a lot of new and interesting things. Assistants are on your tables - lesson notes, make notes in them during the lesson.
- Carbon is called the "element of life"
What are the oxidation states of carbon?
These modulo numbers will be called VALENCE.
Inorganic chemistry studies the substances of inanimate nature - mineral. How to call substances of living nature - plant and animal origin, contained in living organisms?
The science that studies such substances is organic chemistry.
1 slide
The topic of the lesson is "Introduction to the course of organic chemistry."
Lesson objectives: 1. Acquaintance with a new section of chemistry - organic chemistry.
2. Study the composition, structure, properties of substances.
3. Required for ____________
2 slide
For the first time, the concept of OB was introduced into science by J. Ya. Berzelius.
Is there a sharp boundary between organic and inorganic substances?
3 slide
At one time, foreign and Russian scientists synthesized organic substances from inorganic substances in laboratories.
How can organic compounds be combined?
4 slide
Here are the names and formulas of organic substances. What is the similarity.
What type of chemical bond, melting point?
5 slide
Let's do an experiment: charring sugar
Let's write point 3.
Several hundreds of inorganic substances are known
thousand, and how many organic?
6slide
Why so much?
I demonstrate: Pens, rulers - from what substance? This is also an organic substance synthesized in the laboratory; it does not exist in nature. but the name "organic" remained.
7 slide
As a result of the synthesis, fibers, varnishes, paints and other substances can be obtained.
What conclusion can be drawn: what are the similarities and differences between OM and inorganic ones?
3.
Can the laws and concepts of inorganic chemistry be applied to organic matter?
For example, the concept of valency?
On the OB formula board:
Task: Set the valency of carbon.
CH 4 C 2 H 4 C 2 H 2 C 3 H 8
Valence "incomprehensible" ...
Scientists accepted the valence of carbon equal to IV. Task: Write the structural formulas of substances.
N N N N N
/ / / / / /
H-C-H H-C = C - H H-C=
S-N H-S -S -S -N
/ / / /
N N N N
Conclusion: observing the valency, in addition to a simple (single) bond, double and triple bonds appear, namely between carbon atoms.
8slide
Let's write down the reasons for diversity:
To understand the meaning of paragraph 5, let's turn to the letters: FLASK - make a new word from the same letters.
What is the difference?
What is the similarity?
The quantitative and qualitative composition is the same, but the sequence of the connection, i.e. the structure is different.
In chemistry, this phenomenon is called isomerism.
4.
9 slide
Laboratory work. Assemble the molecule as in the picture and find the corresponding formula on the slide.
Report: 1 gr. 2 gr. 3 gr. 4 gr. 5 gr.
So, what are the similarities and what are the differences between isomers?
10 slide
Welcome to the world of organic chemistry.
5. Lesson summary:
What branch of chemistry are you familiar with?
What is she studying?
Why is it necessary
Testing:
- Valency of carbon in OM?
- The name of the scientist who introduced the concept of OB?
- A phenomenon in which the qualitative and quantitative composition is the same, but the connection sequence is different?
- How are atoms connected in a molecule?
- The method of obtaining new substances is called? We check on our own.
No errors at all or one, then raise your hand.
6.
11slide
Compose composition C isomers 6 H 14 (there are 5 of them)