Methodical instruction
for the students of pharmaceutical faculty
LESSON № 12 (practical – 6 hours)
Carboxylic acids. Usage of malonic ester in organic synthesis. Functional derivates of carboxylic acids.
The aim:
to formulate knowledge about the nomenclature, isomery, methods of extraction, physical and chemical properties of carboxylic acids; to formulate knowledge about the nomenclature, isomery, methods of extraction, physical and chemical properties of functional derivatives of carboxylic acids and their usage in the pharmacy.
Practical skills:
а) to master the laboratory methods of receiving and study of chemical properties of carboxylic acids and its functional derivatives;
b) to be able to construct the devices and execute major operations which are used for determination of organic matters.
Students independent study program.
1. Classification, the nomenclature and isomery of carboxylic acids.
2. Laboratory methods of receiving of carboxylic acids.
3. Physical and chemical properties of carboxylic acids.
4. Identification of carboxylic acids.
5. The representatives and their usage.
6. Esthers. Fats and waxes as complex esthers.
7. Amides. Acido-alkaline properties.
8. Identification of functional derivatives of carboxylic acids.
9. The representatives of functional derivatives of carboxylic acids and their usage in pharmacy.
Home task. 2, 4, 5, 8.
Test and real – life situations for self-assessment
Tests:
1. Choose the proper names for the following compounds (make the accordance structure-name).
А. N,N-dimethylformamide
B. acetic anhydride
C. о-toluilic acid
D. diethylmalonate
E. cyclohexanecarbonylbromide
2. Which of the following compounds will interact with acrylic acid (propenoic acid)?
- HBr
- CH3Br
- Н2О (H+)
- CH3OН (Н+)
- СН3Cl (AlCl3)
3. Which of the following reactions leads to esters formation?
Tasks:
1. Write the structural formulas of the next compounds:
a) ethanoic acid;
b) ethylacetate;
c) a,b-dimethylvalerianic acid;
d) anhydride of acetic acid;
e) dimethylformamide;
f) chloranhydride of butanoic acid;
g) acrylonitryl;
h) metacrylic acid.
a) Bromoanhydride of propionic acid;
b) Ethyl acetate;
c) Monohydroxyamide of succinic acid;
d) N,N-diethylethanamide;
e) Acetonitryl;
f) Anhydride of acetic acid;
g) Chloroanhydride of butanoic acid;
2. Write the schemes of reactions:
a) СН3–СН=СН2 ® (СН3)2СНСОNНОН
b) HCºCH ® CH3CONHCH3
c) CH3–Cº
3. Give the names of the next compounds:
4. Write the schemes of extraction of isovalerianic acid from the certain compounds next ways:
a) oxidation of alcohols;
b) hydrolysis of trihalogenderivative of hydrocarbon;
c) alkylation of malonic esther;
d) hydrolysis of nitryl;
e) Greenuar reaction.
5. What group of atoms is named acylic?
6. Write the schemes of extraction of acetic, propionic, vinylacetic, isobutanoic and acrylic acids from propylene.
7. Give the right names of the next structural formulas:
8. Make chemical transformations and give the name formed compounds
1) СH2 = CH2 ® CH3CH2OH ® CH3CH2Br ® CH3CH2CN ® CH3CH2COOH
6) CH3 – CH = CH2 ABC
9. Write the reaction between butanoic acid and following reagents: 1) PCl5; 2) CH3OH (H+); 3) NH3 (t); 4) P2O5; 5) KHCO3; 6) Na2O; 7) FeCl3; 8) Cl2 (PCl3).
10. Make chemical transformations and give the name formed compounds:
а) СН3СООН ® (Н5С2ООС)2СН2;
d) HCOONa A B C D.
11. What compounds are formed under the action of atсetamide these reagents: а) H2O (H+); б) P2O5, t; в) NaNH2; г) LiAlH4; д) H2O (
Answers on the self-assessment
Tests:
1. 1-C, 2-D,3-A, 4-E, 5-B
2. A, C, D
3. A, C, D
Practical part.
Experiment 1. The solubility of the monocarboxylic acids.
Reagents: carboxylic acids: formic, acetic, trichloracetic, butanoic, stearinic.
Technique of experiment. In test-tubes bring several drops or crystals of carboxylic acids (formic, acetic, trichloracetic, butanoic, stearinic) and add 2 ml of water. Shake the mixtures. If acid do not solve in water, heat the mixture. Higher carboxylic acids (stearinic) does not solve in water. To determine pH of medium of carboxylic acids it is necessary to use litmus paper.
What do you see?
Keep the solutions of carboxylic acids for the next experiments.
Experiment 2. The extraction of formic acid and studying of its properties.
Reagents: chloroform, NaOH (10% solution), KMnO4 (5% solution), Ba(OH)2 or Ca(OH)2, AgNO3 (1% solution), HNO3 (10% solution), ammonium (5% solution), Na2CO3 (10% solution), H2SO4 (10% solution), concentrated H2SO4, formic acid (80% solution).
Technique of experiment.
a) the extraction of formic acid using hydrolysis of chloroform. In a test-tube bring 5-6 drops of chloroform and add 2-3 ml of NaOH (10% solution). Shaking the mixture heat it in a boiling water to disappearing phase of chloroform (lower chloroform), but not to boiling of the mixture. Cool the mixture.
To determine anions of HCOO– and Cl– it is necessary to do the next experiments. Divide the mixture to 2 parts. In the first test-tube with the first part of the mixture add 2 ml of HNO3 (10% solution) and several drops of AgNO3 (1% solution). The precipitate of AgCl forms. So, anions of Cl– are present in the mixture.
In the second test-tube with the second part of the mixture add 2 ml of KMnO4 (5% solution) and 1 ml of 10% H2SO4. Close the test-tube by the cork with gas-pipeline and deep the end of it into the third test-tube with 2 ml of Ba(OH)2 or Ca(OH)2. Heat the mixture. The violet colour disappears and white precipitate forms in the third test-tube with Ba(OH)2 or Ca(OH)2. So, KMnO4 can oxidize formic acid to H2CO3 (it destroys to CO2 and H2O).
b) reaction of “silver mirror” (this reaction is characteristic only for formic acid because it contain carbonyl group –CHO as aldehyde). In a test-tube bring 1 ml of AgNO3 (1% solution) and add by drops ammonium (5% solution) to disappearing of precipitate Ag2O. Then add 0,5 ml of formic acid (80% solution). Heat the mixture. The precipitate of silver forms. So, formic acid has reductive properties as aldehydes.
c) destroying of formic acid by concentrated H2SO4. In a dry test-tube bring 1 ml of formic acid (80% solution) and add 1 ml of concentrated H2SO4. Close the test-tube by the cork with gas-pipeline and heat very carefully. The gas CO forms and evaporates. Burn the gas near the opening of gas-pipeline.
What colour of flame do you see?
d) reaction of formic acid and Na2CO3. In a test-tube bring 2 ml Na2CO3 (10% solution) and add by drops formic acid. Close the test-tube by the cork with gas-pipeline and deep the end of it into the test-tube with 2 ml of Ba(OH)2 or Ca(OH)2. The gas CO2 evaporates and white precipitate forms in the third test-tube with Ba(OH)2 or Ca(OH)2.
Experiment 3. The extraction of acetic acid and studying of its properties.
Reagents: sodium acetate, concentrated H2SO4, concentrated CH3COOH, Na2CO3 (10% solution), Ba(OH)2 or Ca(OH)2, CH3COONa (10% solution), FeCl3 (3% solution).
Technique of experiment.
a) the extraction of acetic acid from its salts. In a test-tube bring 1 g of sodium acetate. Add 1 ml of concentrated H2SO4. Smell the mixture very carefully.
b) reaction of acetic acid and Na2CO3. In a test-tube bring 1 ml of Na2CO3 (10% solution) and add by drops concentrated CH3COOH. Close the test-tube by the cork with gas-pipeline and deep the end of it into the test-tube with 2 ml of Ba(OH)2 or Ca(OH)2. The gas CO2 evaporates and white precipitate forms in the third test-tube with Ba(OH)2 or Ca(OH)2.
c) qualitative reaction to acetic acid. In a test-tube bring 1 ml of CH3COONa (10% solution) and add 5-6 drops of FeCl3 (3% solution). Red-brown colour appears. Boil the mixture during 1-2 minutes. Red-brown precipitate forms.
Experiment 4. The extraction of higher carboxylic acids and studying of their properties.
Reagents: stearinic acid, phenolphthalein, diethyl ether, NaOH (10% solution), soap, 1% alcohol solution of soap, H2SO4 (10% solution), CaCl2 (5% solution), (CH3COO)2Pb (5% solution), CuSO4 (5% solution), oleic acid, bromine water, KMnO4 (2% solution).
Technique of experiment.
a) acidic properties of higher carboxylic acids. In a dry test-tube solve 0,5 g of stearinic acid in 2 ml of diethyl ether. In the second test-tube bring 3 drops of NaOH (10% solution) and add 2 drops of phenolphthalein. Red colour appears. Then add the mixture from the first test-tube. The colour disappears. So, stearinic acid reacts with alkalis.
b) hydrolysis of soap. In a dry test-tube bring 1 ml of 1% alcohol solution of soap and add several drops of phenolphthalein. The solution is colourless. Add several drops of distil water by drops. The mixture becomes red. It means that soap is the salt of weak acid and strong alkali, it can hydrolyze in water forming alkaline medium.
c) extraction higher carboxylic acids from soap. In a dry test-tube bring several pieces of soap and add 2 ml of water. Mix the mixture. Then add 2 ml of H2SO4 (10% solution). The precipitate forms. Heat the mixture. All higher carboxylic acids form upper oil phase in the mixture. After cooling it becomes hard. Take it out and put it in water to clean. Look at this product of reaction. It is like paraffin.
d) forming of dissolved salts of higher carboxylic acids. In each of 3 test-tubes bring several pieces of soap and add 2 ml of water. Mix the mixture in each test-tubes. In the first test-tube add 5 drops of CaCl2 (5% solution), in the second one add 5 drops of (CH3COO)2Pb (5% solution) and in the third one add 5 drops of CuSO4 (5% solution). The precipitates of salts of higher carboxylic acids.
e) the determination of saturated carboxylic acids. In each of 2 test-tubes bring 2 drops of oleic acid. In the first test-tube add 4 drops of bromine water, and in the second one add 2 drops of KMnO4 (2% solution). Shake the mixtures. The colours of mixtures disappear.
Experiment 5. Properties of oxalic acid.
Reagents: sodium oxalate, CaCl2 (5% solution), oxalic acid, Ba(OH)2 or Ca(OH)2, concentrated H2SO4, KMnO4 (5% solution), H2SO4 (10% solution).
Technique of experiment.
a) the determination of oxalic acid. In a dry test-tube bring several crystals of sodium oxalate and add 10 drops of water. Bring 1 drop of this solution on the glass and add 1 drop of CaCl2 (5% solution). Colourless crystals form (see through microscope).
b) destroying of oxalic acid by heating. In a dry test-tube bring 1 g of oxalic acid. Close the test-tube by the cork with gas-pipeline and deep the end of it into the test-tube with 2 ml of Ba(OH)2 or Ca(OH)2. The gas CO2 evaporates and white precipitate forms in the third test-tube with Ba(OH)2 or Ca(OH)2.
c) destroying of oxalic acid by H2SO4. In a dry test-tube bring 1 g of oxalic acid and add 1 ml of concentrated H2SO4. Close the test-tube by the cork with gas-pipeline and deep the end of it into the test-tube with 2 ml of Ba(OH)2 or Ca(OH)2. The gases CO, CO2 evaporate and white precipitate forms in the third test-tube with Ba(OH)2 or Ca(OH)2. Burn the gas near the opening of gas-pipeline.
What colour of flame do you see?
d) the oxidation of oxalic acid by KMnO4. In a dry test-tube bring 2-3 ml of KMnO4 (5% solution) and 2 ml of H2SO4 (10% solution). Close the test-tube by the cork with gas-pipeline and deep the end of it into the test-tube with 2 ml of Ba(OH)2 or Ca(OH)2. Heat the mixture in the first test-tube. The gas CO2 evaporates and white precipitate forms in the third test-tube with Ba(OH)2 or Ca(OH)2.
Experiment 6. Reaction of acetic anhydride with water and alcohol.
Reagents: ethyl alcohol, acetic anhydride, sodium chloride (solid).
Technique of experiment.
a) In a test-tube bring 1 ml of distil water and add 1 ml of acetic anhydride. Two phases appear. Shake the mixture and heat it to boiling.
What do you see? Write the equations of reactions.
b) In a test-tube bring 1 ml of ethyl alcohol and add 1 ml of acetic anhydride. Heat the mixture to boiling. After cooling add 2-3 ml of cool distil water. If two phases do not appear add sodium chloride (solid).
What do you see? Write the equations of reactions.
Experiment 7. The receiving and hydrolysis of ethyl acetate.
Reagents: acetic acid (concentrated), ethyl alcohol, H2SO4 (concentrated), H2SO4 (10% solution), NaOH (10% solution).
Technique of experiment.
a) In a test-tube bring 2 ml of ethanol, add 2 ml of acetic acid (concentrated) and 0,5 ml of H2SO4 (concentrated). Shake the mixture and heat it in boiling water during 10 minutes. After cooling add 2 ml of cool distil water.
What do you see? Write the equations of reactions.
b) In 2 test-tubes bring 6 drops of ethylacetate (from previous experiment), add 1 ml of distil water. In the first test-tube add 2 drops of H2SO4 (10% solution), in the second one add 2 drops of NaOH (10% solution). Shake the mixtures and heat it in boiling water.
Write the equations of reactions.
Experiment 8. The reactions of acetamide.
Reagents: acetamide (10% solution), NaOH (5% solution), HCl (concentrated), H2SO4 (10% solution), hydroxylamine hydrochloride, FeCl3 (1% solution).
Technique of experiment.
a) In a test-tube bring 1 ml of 10% acetamide, add 10 drops of 5% NaOH. Heat the mixture.
Write the equations of reactions.
b) In a test-tube bring 1 ml of acetamide (10% solution) and add 3-4 drops of H2SO4 (10% solution). Heat the mixture.
Write the equations of reactions.
c) In a test-tube bring several crystals of hydroxylamine hydrochloride, add 10 drops of water and add 3 drops of 10% acetamide. Heat the mixture. After cooling add 2 ml of FeCl3 (1% solution).
Write the equations of reactions.
Experiment 9. Amidolysis.
Reagents: acetamide (10% solution), NaOH (10% solution), bromine water, CuSO4 (2% solution).
Technique of experiment. In a test-tube bring 1 ml of acetamide (10% solution) and add 10 drops of water. Shake the mixture and add 5 drops of bromine water and 10 drops of NaOH (10% solution). Close the test-tube by a cork with gas-pipeline. Deep the end of the gas-pipeline into the test-tube with 1 ml of water. Heat the mixture in the first test-tube during 3-5 minutes.
Write the equations of reactions.
For determination of amine in the mixture it is necessary to add several drops of 2% CuSO4.
2[СH3NH3]+
A student must know:
– the structure, nomenclature, isomery, methods of extraction and chemical properties of carboxylic acids and its functional derivatives.
A student must be able:
– to be able to do the chemical reactions to carboxylic acids and functional derivatives.
References:
1. The lecture’s material.
2. Andrew Streltwieser, Jr. Clayton H. Hcathcocr. Introduction to Organic Chemistry. –
3. David Gutsche C., Baniel J. Pasto. Fundamentals of Organic Chemistry. –
4. Lehningera A.L. Principles of biochemistry. – New York.–1982. – 1011p.
5. Lewis D.E. Organic chemistry. A modern perspective. –
6. Halkerston I.D.K. Biochemistry: 2nd edition. The National medical series for independent study. – 1988. – 522 р.
7. Seyhan N.E. Organic chemistry. – Copyright, 1984. 1165 p.
8. Stryer L. Biochemistry. – W.H. Freeman and Company. New York. – 1995. – 1064 p.
Prepared by assist.
Adopted at the Chair Sitting Minutes № 5
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