Establish a correspondence between the reacting substances and the carbon-containing product that is formed during the interaction of these substances: for each position indicated by a letter, select the corresponding position indicated by a number.
Write down the numbers of the selected substances under the corresponding letters in the table.
Answer: 5462
Explanation:
A) 2CH 3 COOH + Na 2 S = 2CH 3 COONa + H 2 S
Acetic acid, also known as ethanoic acid, has the formula CH 3 COOH. As a result of its interaction with basic and amphoteric oxides/hydroxides, as well as when interacting with salts of other weaker acids, salts of acetic acid are formed. Salts and esters of acetic acid are called acetates or ethanoates. In our case, the salt CH 3 COONa can be called sodium acetate or sodium ethanoate.
B) HCOOH + NaOH = HCOONa + H 2 O
Formic acid, also known as methane acid, has the formula HCOOH. As a result of its interaction with basic and amphoteric oxides/hydroxides, as well as when interacting with salts of other weaker acids, salts of formic acid are formed. Salts and esters of formic acid are called formates or methanoates. In our case, the HCOONa salt can be called sodium formate or sodium methanoate.
C) Formic acid, despite the small size of its molecule, contains two functional groups at once - aldehyde and carboxyl:
In this regard, it can react with copper hydroxide in two ways: both as an aldehyde and as a simple carboxylic acid. By acid type, i.e. to form a salt, formic acid reacts with copper hydroxide without heating. This creates formate, or methanoate, copper:
2HCOOH + Cu(OH) 2 = (HCOO) 2 Cu + 2H 2 O (without heating)
In order for formic acid to exhibit the properties of an aldehyde in a reaction with copper hydroxide, the reaction should be carried out with heating. In this case, a reaction will occur that is qualitative for aldehydes. Copper hydroxide is partially reduced by the aldehyde group, and a brick-red precipitate of copper(I) oxide is formed:
HCOOH + 2Cu(OH) 2 = Cu 2 O + CO 2 + 3H 2 O
D) Alcohols are capable of reacting with alkali and alkaline earth metals. In this case, hydrogen is released and the corresponding alcoholate metal When using ethyl alcohol(ethanol) and sodium are respectively formed ethylate sodium and hydrogen:
2C 2 H 5 OH + 2Na = 2C 2 H 5 ONa + H 2
The material discusses the classification of oxygen-containing organic substances. Issues of homology, isomerism and nomenclature of substances are discussed. The presentation is full of tasks on these issues. Reinforcement of the material is offered in the compliance test exercise.
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Lesson objectives: get acquainted with the classification of oxygen-containing organic compounds; construction of homologous series of substances; identification possible types isomerism; construction of structural formulas of isomers of substances, nomenclature of substances.
Classification of substances C x H y O z carboxylic acids aldehydes ketones esters alcohols phenols monoatomic - many R – OH R–(OH) n simple complex OH = R – C - O OH = R – C - O H - oic acid -al R – C – R || O -one R – O – R = R – C - O O – R - ol - n ol
Homologous series CH 3 – OH C 2 H 5 – OH C 3 H 7 – OH C 4 H 9 – OH C 5 H 11 – OH methanol ethanol propan ol-1 butan ol-1 pentane ol-1 Alcohols C n H 2n+2 O
Carboxylic acids = H – C - O OH = CH 3 – C - O OH = CH 3 – CH 2 – C - O OH methane acid (formic) ethanoic acid (acetic) propanoic acid (propionic) C n H 2n O2
Aldehydes = H – C - O H = CH 3 – C - O H = CH 3 – CH 2 – C - O H methane al formic aldehyde (formaldehyde) ethane al acetaldehyde (acetaldehyde) propane al propionaldehyde C n H 2n O
Ketones CH 3 – C – CH 3 || O CH 3 – CH 2 – C – CH 3 || O CH 3 – CH 2 – CH 2 – C – CH 3 || O propane he (acetone) butane he pentane he-2 C n H 2n O
Ethers CH 3 – O –CH 3 C 2 H 5 – O –CH 3 C 2 H 5 – O –C 2 H 5 C 3 H 7 – O –C 2 H 5 C 3 H 7 – O –C 3 H 7 dimethyl ether methyl ethyl ether diethyl ether ethyl propyl ether dipropyl ether C n H 2n+2 O Conclusion: ethers are derivatives of saturated monohydric alcohols.
Esters = H – C - O O – CH 3 = CH 3 – C - O O – CH 3 = CH 3 – CH 2 – C - O O – CH 3 formic acid methyl ester (methyl formate) acetic acid methyl ester (methyl acetate) ) methyl ester of propionic acid C n H 2n O 2 Conclusion: esters are derivatives of carboxylic acids and alcohols.
alcohols ethers ketones aldehydes carboxylic acids Isomerism and nomenclature isomerism of the carbon skeleton interclass (esters) carbon skeleton interclass (ketones) carbon skeleton position f-group (-C = O) interclass (aldehydes) carbon skeleton position f-group (-OH) interclass (ethers) carbon skeleton interclass
Drawing up formulas of isomers. Nomenclature of substances. Task: make up structural formulas possible isomers for substances of the composition C 4 H 10 O; C 4 H 8 O 2; C 4 H 8 O. What classes do they belong to? Name all substances using systematic nomenclature. C 4 H 10 O C 4 H 8 O 2 C 4 H 8 O C n H 2n+2 O C n H 2n O 2 C n H 2n O alcohols and ethers carboxylic acids and esters aldehydes and ketones
CH 3 – CH 2 – CH – CH 3 | OH CH 3 | CH 3 – C – CH 3 | OH CH 3 – O – CH 2 – CH 2 – CH 3 CH 3 – CH 2 – O – CH 2 – CH 3 butanol-1 2-methylpropanol-1 butanol-2 2-methylpropanol-2 methylpropyl ether diethyl ether I alcohols II alcohol III alcohol
CH 3 – CH 2 – CH 2 – C - O OH = CH 3 – CH – C - O OH | CH3 = CH 3 – CH 2 – C - O O – CH 3 = CH 3 – C - O O – CH 2 – CH 3 butanoic acid 2-methylpropanoic acid methyl ester of propionic acid ethyl ester of acetic acid
CH 3 – CH 2 – CH 2 – C - O H = CH 3 – CH – C - O H | CH3 CH 3 – CH 2 – C – CH 3 || O butanal 2-methylpropanal butanone-2
Test yourself! 1. Match: general formula class substance R – COOH R – O – R R – COH R – OH R – COOR 1 R – C – R || O words ethers alcohols carb. ketones, aldehydes, etc. esters a) C 5 H 11 –OH b) C 6 H 13 –SON c) C 4 H 9 –O–CH 3 d) C 5 H 11 –COOH e) CH 3 –CO– CH 3 e) CH 3 –COOC 2 H 5 2. Name the substances according to systematic nomenclature.
Test yourself! I II III IV V VI 3 6 5 2 1 4 G V B A E D
Homework Paragraph (17-21) – parts 1 and 2 of exercise. 1,2,4,5 pp. 153-154 2 pp. 174 Lesson over!
Target: develop the ability to make observations and draw conclusions, write down the equations of the corresponding reactions in molecular and ionic forms .
Occupation availability
1. Collection methodological instructions for students to complete practical classes and laboratory work on academic discipline"Chemistry".
2. Sodium hydroxide solution, sodium carbonate, calcium carbonate, copper (II) oxide, acetic acid, blue litmus, zinc; rack with test tubes, water bath, heating device, matches, test tube holder.
Theoretical material
Carboxylic acids are organic compounds whose molecules contain one or more carboxyl groups connected to a hydrocarbon radical or hydrogen atom.
Preparation: In the laboratory, carboxylic acids can be obtained from their salts by treating them with sulfuric acid when heated, for example:
2CH 3 – COONa + H 2 SO 4 ® 2CH 3 – COOH + Na 2 SO 4
In industry it is obtained by the oxidation of hydrocarbons, alcohols and aldehydes.
Chemical properties:
1. Due to the shift in electron density from the hydroxyl group O–H to strongly
polarized carbonyl group C=O, molecules of carboxylic acids are capable of
electrolytic dissociation: R–COOH → R–COO - + H +
2.Carboxylic acids have properties characteristic of mineral acids. They react with active metals, basic oxides, bases, and salts of weak acids. 2СH 3 COOH + Mg → (CH 3 COO) 2 Mg + H 2
2CH 3 COOH + CaO → (CH 3 COO) 2 Ca + H 2 O
H–COOH + NaOH → H–COONa + H 2 O
2СH 3 CH 2 COOH + Na 2 CO 3 → 2CH 3 CH 2 COONa + H 2 O + CO 2
CH 3 CH 2 COOH + NaHCO 3 → CH 3 CH 2 COONa + H 2 O + CO 2
Carboxylic acids are weaker than many strong mineral acids
CH 3 COONa + H 2 SO 4 (conc.) → CH 3 COOH + NaHSO 4
3. Formation of functional derivatives:
a) when interacting with alcohols (in the presence of concentrated H 2 SO 4), esters are formed.
Education esters When an acid and an alcohol react in the presence of mineral acids, it is called an esterification reaction. CH 3 – –OH + HO–CH 3 D CH 3 – –OCH 3 + H 2 O
acetic acid methyl methyl ester
acetic acid alcohol
General formula esters R– –OR’ where R and R" are hydrocarbon radicals: in formic acid esters – formates –R=H.
The reverse reaction is hydrolysis (saponification) of the ester:
CH 3 – –OCH 3 + HO–H DCH 3 – –OH + CH 3 OH.
Glycerol (1,2,3-trihydroxypropane; 1,2,3-propanetriol) (glycos - sweet) chemical compound with the formula HOCH2CH(OH)-CH2OH or C3H5(OH)3. The simplest representative of trihydric alcohols. It is a viscous transparent liquid.
Glycerin is a colorless, viscous, hygroscopic liquid, infinitely soluble in water. Sweet in taste (glycos - sweet). It dissolves many substances well.
Glycerol is esterified with carboxylic and mineral acids.
Esters of glycerol and higher carboxylic acids are fats.
Fats -
These are mixtures of esters formed by the trihydric alcohol glycerol and higher fatty acids. General formula of fats, where R are higher radicals fatty acids:
Most often, the composition of fats includes saturated acids: palmitic acid C15H31COOH and stearic acid C17H35COOH, and unsaturated acids: oleic acid C17H33COOH and linoleic acid C17H31COOH.
The general name for compounds of carboxylic acids with glycerol is triglycerides.
b) when exposed to water-removing reagents as a result of intermolecular
dehydration produces anhydrides
CH 3 – –OH + HO– –CH 3 →CH 3 – –O– –CH 3 + H 2 O
Halogenation. When exposed to halogens (in the presence of red phosphorus), α-halogen-substituted acids are formed:
Application: in the food and chemical industries (production of cellulose acetate, from which acetate fiber, organic glass, film are produced; for the synthesis of dyes, medicines and esters).
Questions to reinforce theoretical material
1 What organic compounds are classified as carboxylic acids?
2 Why are there no gaseous substances among carboxylic acids?
3 What determines the acidic properties of carboxylic acids?
4 Why does the color of indicators change in a solution of acetic acid?
5 What chemical properties are common for glucose and glycerol, and how do these substances differ from each other? Write the equations for the corresponding reactions.
Exercise
1. Repeat theoretical material on the topic of the practical lesson.
2. Answer questions to reinforce theoretical material.
3. Investigate the properties of oxygen-containing organic compounds.
4. Prepare a report.
Instructions for implementation
1. Read the safety rules when working in a chemical laboratory and sign the safety log.
2. Perform experiments.
3. Enter the results into the table.
Experience No. 1 Testing a solution of acetic acid with litmus
Dilute the resulting acetic acid with a small amount of water and add a few drops of blue litmus or dip indicator paper into the test tube.
Experience No. 2 Reaction of acetic acid with calcium carbonate
Pour some chalk (calcium carbonate) into a test tube and add a solution of vinegar
Experiment No. 3 Properties of glucose and sucrose
a) Add 5 drops of glucose solution, a drop of copper (II) salt solution into the test tube and, while shaking, a few drops of sodium hydroxide solution until a light blue solution is formed. This experiment was done with glycerin.
b) Heat the resulting solutions. What are you observing?
Experiment No. 4 Qualitative reaction to starch
Add a drop to 5-6 drops of starch paste in a test tube alcohol solution Yoda.
Sample report
Laboratory work No. 9 Chemical properties of oxygen-containing organic compounds.
Goal: to develop the ability to make observations and draw conclusions, write down the equations of the corresponding reactions in molecular and ionic forms .
Draw conclusions in accordance with the purpose of the work
Literature 0-2 s. 94-98
Laboratory work No. 10
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Oxygen gives organic substances a whole range of characteristic properties.
Oxygen is divalent, has two valence electron pairs and is characterized by high electronegativity (x = 3.5). Strong chemical bonds are formed between carbon and oxygen atoms, as can be seen in the example of CO 2 molecules. Single bond C-0 (£ sv = 344 kJ/mol) is almost as strong as S-S connection (E sa = 348 kJ/mol), and the double bond C=0 ( E St = 708 kJ/mol) is significantly stronger than the C=C bond (E St == 620 kJ/mol). Therefore, transformations leading to the formation of C=0 double bonds are common in molecules of organic substances. For the same reason, carbonic acid is unstable:
The hydroxo group located at the double bond is converted into an hydroxy group (see above).
Oxygen will give polarity to the molecules of organic substances. The attraction between molecules increases, and the melting and boiling points increase significantly. At normal conditions Among the oxygen-containing substances there are very macho gases - only ether CH 3 OCH 3, formaldehyde CH 2 0 and ethylene oxide CH 2 CH 2 0.
Oxygen promotes the formation of hydrogen bonds both as a donor and acceptor of hydrogen. Hydrogen bonds enhance the attraction of molecules, and in the case of fairly complex molecules give them a certain spatial structure. The influence of polarity and hydrogen bonds on the properties of a substance can be seen in the example of hydrocarbons, ketones and alcohols
Polarity and the formation of hydrogen bonds determine the good solubility of oxygen-containing organic substances in water.
Oxygen, to one degree or another, imparts acidic properties to organic substances. In addition to the class of acids, the properties of which are obvious from the name, phenols and alcohols exhibit acidic properties.
One more thing general property oxygen-containing substances lies in the easy oxidability of the carbon atom, which is associated with both oxygen and hydrogen. This is evident from the following chains of reactions, which are terminated when the carbohydrate loses its last water atom:
contains a hydroxy group and is considered a heterofunctional acid.
The name of a whole class of organic substances alcohols(from the Latin "spiritus" - spirit) comes from the "active principle" of the mixture obtained by fermenting fruit juices and other systems containing sugar. This active principle - wine alcohol, ethanol C2H5OH, is separated from water and non-volatile solutes during distillation of the mixture. Another name for alcohol is alcohol - Arabic origin.
Alcohols are organic compounds that contain a hydroxo group bonded to the $p 3 carbon atom of the hydrocarbon radical.
Alcohols can also be considered as products of the replacement of one hydrogen atom in water by a hydrocarbon radical. Alcohols form homologous series (Table 22.5), differing in the nature of the radicals and the number of hydroxo groups.
Table 22.5
Some homologous series of alcohols
“Tlycols and glycerols are polyfunctional alcohols with OH groups at adjacent carbon atoms.
The hydroxo group at unsaturated carbon atoms is unstable, as it turns into a carbonyl group. Vinyl alcohol is in negligible quantities in equilibrium with the aldehyde:
There are substances in which the hydroxo group is bonded to the r/g carbon atom of the aromatic ring, but they are considered as a special class of compounds - phenols.
In alcohols, isomerism of the carbon skeleton and the position of the functional group is possible. In unsaturated alcohols, isomerism of the position of the multiple bond and spatial isomerism also occur. Compounds of the ether class are isomeric to alcohols. Among alcohols there are varieties called primary, secondary And tertiary alcohols. This is due to the nature of the carbon atom at which the functional group is located.
Example 22.12. Write the formulas for primary, secondary and tertiary alcohols with four carbon atoms.
Solution.
Let us consider in more detail the homologous series of saturated alcohols. The first 12 terms of this series are liquids. Methanol, ethanol and propanol are miscible with water in any ratio due to their structural similarity to water. Further along the homologous series, the solubility of alcohols decreases, since large (by the number of atoms) hydrocarbon radicals are increasingly displaced from the aqueous environment, like hydrocarbons. This property is called hydrophobicity. In contrast to the radical, the hydroxo group is attracted to water, forming a hydrogen bond with water, i.e. shows hydrophilicity. Higher alcohols (five or more carbon atoms) exhibit the property surface activity- the ability to concentrate at the surface of the water due to the expulsion of a hydrophobic radical (Fig. 22.3).
Rice. 22.3.
Surfactants coat liquid droplets and promote the formation of stable emulsions. This is what the action is based on. detergents. Not only alcohols, but also substances of other classes can exhibit surface activity.
Most water-soluble alcohols are poisonous. The least toxic are ethanol and glycerin. But, as you know, ethanol is dangerous because it causes a person to become addicted to its use. The simplest of alcohols, methanol, is similar in smell to ethanol, but is extremely poisonous. There are many known cases of human poisoning as a result of mistaken ingestion.
methanol instead of ethanol. This is facilitated by the huge volume of industrial use of methanol. The simplest diatomic alcohol is ethylene glycol C 2 H 4 (OH) 2 in large quantities used for the production of polymer fibers. Its solution is used as antifreeze for cooling automobile engines.
Preparation of alcohols. Let's look at a few common methods.
1. Hydrolysis of halogenated hydrocarbons. Reactions are carried out in an alkaline environment:
Example 22.13. Write the reactions for the production of ethylene glycol by the hydrolysis of halogen derivatives, taking the starting material ethylene.
2. Addition of water to alkenes. Highest value has the reaction of adding water to ethylene to form ethanol. The reaction occurs quite quickly when high temperature, but at the same time the equilibrium shifts greatly to the left and the alcohol yield decreases. Therefore, it is necessary to create high pressure and the use of a catalyst that allows the same process speed to be achieved at a lower temperature (similar to the conditions for ammonia synthesis). Ethanol is produced by hydration of ethylene at -300°C and a pressure of 60-70 atm:
The catalyst is phosphoric acid supported on aluminum oxide.
3. Available special ways producing ethanol and methanol. The first is obtained by the well-known biochemical method of fermenting carbohydrates, which are first broken down into glucose:
Methanol is obtained synthetically from inorganic substances:
The reaction is carried out at 200-300°C and a pressure of 40-150 atm using a complex catalyst Cu0/2n0/Al203/Cr203. The importance of this industrial process is clear from the fact that more than 14 million tons of methanol are produced annually. It is used mainly in organic synthesis for the methylation of organic substances. Ethanol is produced in approximately the same quantities.
Chemical properties of alcohols. Alcohols can be a handful and oxidize. A mixture of ethyl alcohol and hydrocarbons is sometimes used as fuel for automobile engines. The oxidation of alcohols without damaging the carbon structure is reduced to the loss of hydrogen and the addition of oxygen atoms. In industrial processes, alcohol vapors are oxidized by oxygen. In solutions, alcohols are oxidized by potassium permanganate, potassium dichromate and other oxidizing agents. From the primary alcohol, upon oxidation, an aldehyde is obtained:
If there is an excess of oxidizing agent, the aldehyde is immediately oxidized to an organic acid:
Secondary alcohols are oxidized to ketones:
Tertiary alcohols can only be oxidized under harsh conditions with partial destruction of the carbon skeleton.
Acidic properties. Alcohols react with active metals to release hydrogen and form derivatives with common name alkoxides (methoxides, ethoxides, etc.):
The reaction proceeds more calmly than a similar reaction with water. The hydrogen released does not ignite. This method destroys sodium residues after chemical experiments. A reaction of this kind means that alcohols exhibit acidic properties. This is a consequence of polarity O-N connections. However, alcohol practically does not react with alkali. This fact allows you to clarify the strength of the acidic properties of alcohols: these are weaker acids than water. Sodium ethoxide is almost completely hydrolyzed to form a solution of alcohol and alkali. The acidic properties of glycols and glycerols are somewhat stronger due to the mutual inductive effect of OH groups.
Polyhydric alcohols form complex compounds with ions of some ^/-elements. In an alkaline environment, a copper ion immediately replaces two hydrogen ions in a glycerol molecule to form a blue complex:
When the concentration of H + ions increases (acid is added for this), the equilibrium shifts to the left and the color disappears.
Reactions of nucleophilic substitution of hydroxo group. Alcohols react with hydrogen chloride and other hydrogen halides:
The reaction is catalyzed by a hydrogen ion. First, H+ attaches to oxygen, accepting it electron pair. This shows the main properties of alcohol:
The resulting ion is unstable. It cannot be isolated from solution in a solid salt like ammonium ion. The addition of H+ causes an additional displacement of the electron pair from carbon to oxygen, which facilitates the attack of the nucleophilic species on carbon:
The bond between carbon and chloride ion increases as the bond between carbon and oxygen is broken. The reaction ends with the release of a water molecule. However, the reaction is reversible, and when hydrogen chloride is neutralized, the equilibrium shifts to the left. Hydrolysis occurs.
The hydroxo group in alcohols is also replaced in reactions with oxygen-containing acids to form esters. Glycerol with nitric acid forms nitroglycerine, used as a remedy to relieve spasms of heart vessels:
From the formula it is clear that the traditional name of the substance is inaccurate, since in fact it is glycerol nitrate - an ester of nitric acid and glycerin.
When ethanol is heated with sulfuric acid, one alcohol molecule acts as a nucleophilic reagent relative to the other. As a result of the reaction, ethoxyethane ether is formed:
Some atoms are highlighted in the diagram to make it easier to trace their transition into reaction products. One molecule of alcohol first attaches the catalyst - the H + ion, and the oxygen atom of another molecule transfers an electron pair to carbon. After the elimination of water and dissociation of H4, an ether molecule is obtained. This reaction is also called intermolecular dehydration of alcohol. There is also a method for preparing ethers with different radicals:
Ethers are more volatile substances than alcohols because hydrogen bonds do not form between their molecules. Ethanol boils at 78°C, and its isomer, ester CH3OCH3, boils at -23.6°C. Ethers do not hydrolyze to alcohols when boiled with alkali solutions.
Dehydration of alcohols. Alcohols can decompose with the elimination of water in the same way as halogen derivatives of hydrocarbons decompose with the elimination of hydrogen halide. In the production of alcohols from alkene and water (see above), there is also a reverse reaction of water elimination. The difference in the conditions for the addition and elimination of water is that the addition occurs under pressure with an excess of water vapor relative to the alkene, and elimination occurs from a separate alcohol. This dehydration is called intramolecular. It also comes in a mixture of alcohol and sulfuric acid at ~150°C.
