ORGANIC CHEMISTRY PRACTICALS PSCH P103 -...

ORGANIC CHEMISTRY PRACTICALS PSCH P103

One step preparation includes planning of synthesis, including reaction conditions,

stoichiometry, and safety aspects including MSDS. During preparation of an organic

compound by using given procedure, crystallize the product and measurement of mass,

recording the melting point and check purity by TLC.

Experiment No. 1. Preparation of m-dinitrobenzene from nitrobenzene.

Chemicals: conc. Sulphuric acid, sodium nitrate, nitrobenzene, distilled water, ethanol,

acetone, ethyl acetate, pet ether, etc.

Reaction:

2 NaNO 3 + H2SO4 H2O + Na2SO4 + NO3

- + NO2

+∆

NO2

ΝΟ2

+

C+

NO2O2N

H

H NO3

-

- HNO3

NO2O2N

Procedure:

1. Place 5 ml of sulfuric acid and 4.5 g of sodium nitrate in a dry 100 ml conical flask.

2. Add 1.0 ml nitrobenzene in small portions with constant stirring.

3. Keep the funnel in flask and heat the reaction mixture with frequent shaking on a

boiling water bath for about 30 minutes.

4. Cool the reaction mixture and pour into 40 ml ice cold distilled water with stirring.

5. Filter the crude product by using suction pump and wash with 2-3 times with cold

distilled water.

6. Dry the crude product and record its yield.

7. Recrystalize the product by using ethanol, determine its m.p. and perform TLC in

suitable mobile phase.

TLC: Dissolve small amount of nitrobenzene and purified 1,3-dinitrobenzene in acetone in

separate sodium fusion tube and use them for the spotting on TLC plate. Chose the mobile

phase __________________________________and run the TLC plate in it. Find the Rf

values of reactant and product.

Results:

1. Yield of the product = ______________ g

2. % Practical yield of the product =_____________ %

3. m.p. of the product =______________ 0C

4. Solvent used for TLC =____________________________

5. Rf value of reactant =________________

6. Rf value of product =________________

Experiment No. 2. Preparation of 5-nitrosalicylic acid from salicylic acid.

Chemicals: Nitric acid, salicylic acid, distilled water, acetone, ethyl acetate, pet ether, etc.

Procedure:

1. Take 2 g of salicylic acid in 250 ml conical flask and add small amount of hot

distilled water in it.

2. Add slowly 5 ml conc. Nitric acid with constant shaking of the flask.

3. Heat the flask on boiling water bath for about 5 minutes till no more brown fumes

comes out form the reaction mixture.

4. Cool the content and pour into 50 ml ice cold distilled water with constant stirring.


distilled water. Dry the crude product and record its yield.

6. Recrystalize the product by using hot distilled water, determine its m.p. and perform

TLC in suitable mobile phase.

TLC: Dissolve small amount of salicylic acid and purified 5-nitrosalicylic acid in acetone in




Results:







Experiment No. 3. Preparation of 4-bromonitrobenzene from bromobenzene.

Chemicals: Nitric acid, sulphuric acid, bromobenzene, distilled water, ethanol, acetone, ethyl

acetate, pet ether, etc.

Procedure:

1. Take 2 ml of conc. Sulfuric acid and 2 ml conc. nitric acid in a 250 ml conical flask.

2. To this solution, add 1.0 ml of bromobenzene slowly with vigorous stirring during

time 45 minutes.

3. Keep the funnel on the flask and heat it on a boiling water bath for 30 minutes.

4. Cool the reaction mixture and pour slowly into 20 ml ice cold distilled water with

constant stirring.



7. Recrystalize the product by using hot distilled water, determine its m.p. and perform

TLC in suitable mobile phase.

TLC: Dissolve small amount of bromobenzene and purified 4-bromonitrobenzene in acetone

in separate sodium fusion tube and use them for the spotting on TLC plate. Chose the mobile



Results:







Experiment No. 4. Preparation of 4-nitroacetanilide from acetanilide.

Chemicals: Nitric acid, sulphuric acid, acetanilide, glycial acetic acid, distilled water,

ethanol, acetone, ethyl acetate, pet ether, etc.

Procedure:

1. Take 5 g of actanilide in a dry 250 ml beaker and add 3 ml glycial acetic acid in it, stir

well to get clear solution.

2. Add 5 ml of conc. Sulfuric acid with vigorous stirring and cool the reaction content

into ice salt mixture.

3. Add drop wise precooled mixture of 1.5 ml of conc. Nitric acid and 1.0 ml of conc.

Sulfuric acid with vigorous stirring, taking care that temperature does not rise above

100C.

4. After addition of nitrating mixture, keep the reaction mixture at room temperature for

30 minutes.

5. Pour the reaction mixture into 100 ml of ice cold distilled water with stirring.



7. Recrystalize the product by using ethanol, determine its m.p. and perform TLC in


TLC: Dissolve small amount of acetanilide and purified 4-nitroacetanilide in acetone in




Results:







Experiment No. 5. Preparation of benzoic acid from benzaldehyde.

Chemicals: benzaldehyde, sodium carbonate, potassium permanganate, conc. HCl, distilled

water, acetone, ethyl acetate, chloroform, etc.

Procedure:

1. Take 2 ml (2.088 g) of benzaldehyde in 250 ml dry conical flask.

2. Add 100 ml of distilled water and 3 g of sodium carbonate in it and stir.

3. Boil the reaction mixture and add slowly saturated solution of potassium

permanganate solution till a pink color persists.

4. Heat the reaction mixture further on a sand bath for 30 minutes by using low flame.

5. Allow it to cool and filter to remove the solid impurity.

6. Acidify the filtrate with conc. HCl (add dropwise, check by using litmus paper).



8. Recrystalize the product by using hot water, determine its m.p. and perform TLC in


TLC: Dissolve small amount of benzaldehyde and purified benzoic acid in acetone in




Results:







Experiment No. 6. Preparation of 9,10-anthraquinone from anthracene.

Chemicals: Anthracene, glycial acetic acid, chromium trioxide, sodium hydroxide, distilled

water, acetone, ethyl acetate, pet ether, etc.

Procedure:

1. Place 1 g of anthracene and 10 ml glycial acetic acid in dry 100 ml round bottom flask

fitted with a reflux condenser.

2. Heat the reaction mixture on boiling water bath till all anthracene get dissolve i.e.

solution become clear and cool it to normal temperature.

3. In separate beaker, dissolve 2 g of chromium trioxide in 1.6 ml distilled water and add

5 ml of glycial acetic acid in it.

4. Add chromium trioxide solution in anthracene solution slowly with stirring and reflux

the resultant solution for about 15 minutes.

5. Cool it and pour into 50 ml of cold distilled water with stirring.


distilled water and then 10 ml hot 1N sodium hydroxide solution and finally again

with cold distilled water. Dry the crude product and record its yield.

7. Recrystalize the product by using glycial acetic acid or sublimize it, determine its m.p.

and perform TLC in suitable mobile phase.

TLC: Dissolve small amount of anthracene and purified 9,10-anthraquinone in acetone in




Results:







Experiment No. 7. Preparation of p-nitrobenzoic acid from p-nitrotoluene.

Chemicals: p-Nitro toluene, Sodium dichromate dehydrate, conc. Sulphuric acid, etc.

Procedure:

1. Place 2.3 g of p-nitrotoluene, 6.65 g of sodium dichromate dehydrate and 15 ml of

water in a 50 ml, two-necked round-bottomed flask.

2. Add 17 g (9.2 ml) of concentrated sulphuric acid dropping funnel during about 30

minutes to the well-stirred mixture.

3. The heat of dilution of the acid causes the p-nitrotoluene to melt and oxidation takes

place; if the reaction shows signs of becoming vigorous, the rate of addition must be

reduced.

4. When all the sulphuric acid has been introduced and the temperature of the mixture

commences to fall, attach a reflux condenser to the flask, and reflux for half an hour.

5. Cool and pour the reaction mixture into 20-25 ml of water.

6. Filter the crude p-nitrobenzoic acid at the pump and wash it with about 12-15 ml of

water.

Purification of product: Transfer the solid to a 50 ml beaker, add about 10 ml of 5 per cent

sulphuric acid and digest on a water bath, with agitation, in order to remove the chromium

salts as completely as possbile; allow to cool and filter again. Transfer the acid to a beaker,

break up any lumps of material and treat it with 5 per cent sodium hydroxide solution until

the liquid remains alkaline. Add about 0.300 g of decolourising carbon, warm to about 500C

with stirring for 5 minutes and filter with suction. Run the alkaline solution of sodium p-

nitrobenzoate into about 25 ml of well stirred 15 per cent sulphuric acid. Do not add the acid

to the alkaline solution, for in this way the acid is liable to be contaminated by the sodium

salt. Filter the purified acid at the pump, wash it thoroughly with cold water and dry it in the

oven.

TLC: Dissolve small amount of p-nitrotoluene and purified p-nitrobenzoic acid in acetone in




Results:







Experiment No. 8. Preparation of benzil from benzoin.

Chemicals: Benzoin, conc. Nitric acid, ethanol, etc.

Procedure: A. By using fuming nitric acid:

1. Place 2.0 g of crude benzoin and 10 ml of fuming nitric acid in 50 ml round bottom

flask fitted with air condenser.

2. Heat it on a boiling water bath (in the fume cupboard) with occasional shaking until

the evaluation of oxides of nitrogen has caused (about 1.5 hours).

3. Cool the reaction mixture and pour into 30-40 ml of cold water containing in beaker

and stir until yellow solid product is obtained.

4. Filter the crude benzil at the pump and wash with water till it is free from nitric acid.

5. Recrystalize the product from ethanol or rectified spirit. Record the yield and m.p. of

the product.

B. By using copper acetate:

1. Place 20 mg of copper acetate, 1.0 g of ammonium nitrate, 2.12 g of benzoin and 7 ml

of an 80% (v/v) aqueous acetic acid solution in 50 ml round bottom flask fitted with a

reflux condenser.

2. Heat the reaction mixture with occasionally shaking.

3. When reaction occurs, a vigorous evaluation of nitrogen is observed. Continue the

reflux for 90 minutes.

4. Cool the reaction mixture, shake well and allow standing for 1 hour. Filter at the

pump and keep mother liquor (mother liquor should not be concentrated as an

explosion may result), wash it well with water and dry.

5. Recrystalize it from ethanol or carbon tetrachloride. Record the yield and m.p.

Test for unreacted benzoin:

Dissolve about 0.5 mg of crude or purified benzil in 0.5 mL of 95% ethanol or methanol, and

add one drop of 10% sodium hydroxide. If benzoin is present, the solution soon acquires a

purplish color. If no color develops in 2 to 3 min, an indication that the sample is free from

benzoin, add a small amount of benzoin, observe the color that develops, and note that if the

test tube is stoppered and shaken vigorously, the color momentarily disappears; when the

solution is then let stand, the color reappears.

TLC: Dissolve small amount of benzoin and purified benzil in acetone in separate sodium

fusion tube and use them for the spotting on TLC plate. Chose the mobile phase

__________________________________and run the TLC plate in it. Find the Rf values of

reactant and product.

Results:







Experiment No. 9. Preparation of anthracene-maleic anhydride from anthracene and

maleic anhydride (Diels Alder reaction).

Chemicals: Anthracene, maleic anhydride, xylene, activated carbon, acetone, ethyl acetate,

pet ether, etc.

Procedure:

1. Place 1 g of anthracene (pure) and 0.55 g of maleic anhydride in 13 ml of dry xylene

in dry round bottom flask fitted with a reflux condenser.

2. Reflux the reaction mixture in oil bath for 20 minutes (if possible, use assembly

having mechanical stirrer arrangement).

3. Cool it and add 0.5 g of activated charcoal (to remove colored impurities) and boil it

again for 5 minutes.

4. Filter the solution in hot condition and cool the filtrate to get solid product.

5. Filter the solid product by using suction pump and dry it in a vaccum desicator

containing paraffin wax to absorb the traces of xylene. Record the yield and m.p. of

the product.

TLC: Dissolve small amount of anthracene and purified adduct in acetone in separate sodium

fusion tube and use them for the spotting on TLC plate. Chose the mobile phase

__________________________________and run the TLC plate in it. Find the Rf values of

reactant and product.

Results:







Experiment No. 10. Preparation of dibenzylideneacetone from acetone and

benzaldehyde (Aldol condensation).

Chemicals: Acetone, benzaldehyde, sodium hydroxide, distilled water, ethanol, acetone,

ethyl acetate, pet ether, etc.

Procedure:

1. In a 250 ml conical flask, add a cold solution of 2.5 g of sodium hydroxide in 25 ml

water and 20 ml ethanol, shake well till solution become clear.

2. Cool the aqueous alcoholic NaOH solution in water bath and add few drops of

mixture of 2.55 ml (density 1.044 g/ml) of pure benzaldehyde and 0.815 ml of

acetone slowly with vigorous stirring, a fluocculent precipitate forms in 2,3-minutes.

Stir further at room temperature for 15 minutes.

3. After 15 minutes, add the remaining mixture of benzaldehyde-acetone mixture and

continue the stirring for further 30 minutes.

4. Filter the solid product by using Buckner funnel and wash it with cold distilled water.

Record the yield of the product.

5. Recrystallize the product by using hot ethyl acetate, record the m.p. and perform the

TLC of compound in suitable mobile phase, record the Rf value of reactant and

products.

TLC: Dissolve small amount of benzaldehyde and dibenzylideneacetone in acetone in




Results:







Experiment No. 11. Preparation of 1,2,4-triacetoxybenzene from p-benzoquinone.

Chemicals: Acetic anhydride, conc. Sulphuric acid, p-benzoquinone, cold distilled water,

ethanol, acetone, ethyl acetate, pet ether, etc.

Procedure:

1. Take 3 g acetic anhydride and 1 drop of concentrated sulfuric acid in a dry 100 ml

conical flask.

2. Add 1 g of p-benzoquinone to it slowly with continuous shaking of conical flask. The

reaction is exothermic so that temperature of the reaction mixture rises to 40-500C and

this temperature is maintained during the further addition (if necessary use water bath

to control the temperature).

3. Allow the reaction mixture to cool about 250C and pour into 15 ml of cold water with

stirring.

4. Filter the product at the suction pump, dry it and record the yield of the product.

5. Recrystallize the product by using ethyl alcohol and determine its m.p. (970C).

TLC: Dissolve small amount of benzoquinone and purified 1,2,4-triacetoxybenzene in

acetone in separate sodium fusion tube and use them for the spotting on TLC plate. Chose the

mobile phase __________________________________and run the TLC plate in it. Find the

Rf values of reactant and product.

Results:







Experiment No. 12.

Preparation of p-bromoacetanilde from acetanilide.

Chemicals: Acetanilide, Bromine, Acetic acid, Sodium metabisulfide, etc.

Procedure:

1. Dissolve 1.35 g of finely powdered acetanilide in 4.5 m1 of glacial acetic acid in a 50

m1 conical flask.

2. In another small flask dissolve 1.7 g (0.53 ml) of bromine in 2.5 m1 of glacial acetic

acid.

3. Add the bromine solution slowly into above acetanilde solution with constant shaking

to ensure thorough mixing: stand the flask in cold water.

4. Allow the final reaction mixture to stand at room temperature for 30 minutes with

occasional shaking.

5. Pour the reaction product into 400 m1 of water; rinse the flask with about 100 m1 of

water. Stir the mixture well and if it is appreciably coloured, add just sufficient

sodium metabisulphite solution to remove the orange colour.

6. Filter the crystalline precipitate with suction on a Buchner funnel, wash thoroughly

with cold water and press as dry as possible with a wide glass stopper.

7. Recrystallise from dilute methanol or ethanol (industrial spirit). Record the yield and

m.p. of p-bromoacetanilide.

TLC: Dissolve small amount of acetanilide and purified p-bromoacetanilide in acetone in




Results:







Experiment No. 13. Preparation of 5,5-diphenyl hydantoin from benzil and urea.

Chemicals: Benzil, urea, sodium hydroxide, hydrochloric acid, etc.

Procedure:

1. Place 0.53 g of benzil, 0.30 g of urea, 1.5 m1 of 30 per cent aqueous sodium

hydroxide solution and 7.5 m1 of ethanol in a 25 m1 round-bottomed flask. Attach a

reflux condenser and boil under reflux for at least 2 hours.

2. Cool it to room temperature, pour the reaction product into 12.5 m1 of water and mix

thoroughly.

3. Allow to stand for 15 minutes and then filter under suction to remove an insoluble by-

product.

4. Render the filtrate strongly acidic with concentrated hydrochloric acid, cool in ice-

water and immediately filter off the precipitated product under suction.

5. Recrystalize at least once from industrial spirit. Record the yield and m.p. of product.

TLC: Dissolve small amount of benzil and purified 5,5-diphenylhydantoin in acetone in




Results:







Experiment No.14. Preparation of 3-methyl-1-phenylpyrazol-5-one from ethyl

acetoacetate.

Chemicals: Ethyl acetoacetate, phenyl hydrazine, pet ether, alcohol, etc.

Procedure:

1. Mix together 0.50 g (0.49 ml) of redistilled ethyl acetoacetate and 0.40 g (0.365 ml)

of phenylhydrazine (CAUTION in handling) in a large evaporating dish.

2. Heat the mixture on a boiling water bath in the fume cupboard for about 2 hours and

stir from time to time with a glass rod.

3. Allow the heavy reddish syrup to cool somewhat (if solid is formed, grind it and then

go for next step), add about 100 m1 of ether and stir the mixture vigorously for

solidification. The syrup, which is insoluble in ether, will solidify within 15 minutes.

4. Filter the solid at the pump and wash it thoroughly with ether to remove coloured

impurities.

5. Recrystallise it from hot water or from a mixture of equal volumes of ethanol and

water. Record the yield and m.p. of 3-methyl-1-phenylpyrazol-5-one.

TLC: Dissolve small amount of phenyl hydazine and purified 3-methyl-1-phenylpyrazol-5-

one in acetone in separate sodium fusion tube and use them for the spotting on TLC plate.

Chose the mobile phase __________________________________and run the TLC plate in

it. Find the Rf values of reactant and product.

Results:







Experiment No. 15. Preparation of 2-methylbenzimidazole from o-phenylenediamine.

Chemicals: o-Phenylenediamine dihydrochloride, acetic acid, alcohol, etc.

Procedure:

1. Heat together a mixture of 1.086 g of o-phenylenediamine dihydrochloride, 4.0 ml of

water and 1.080 g of acetic acid under reflux for 45 minutes.

2. Cool the reaction mixture and immediately make basic by the gradual addition of

concentrated ammonia solution.

3. Collect the precipitated product and recrystallise it from 10 per cent aqueous ethanol.

4. Record the yield and m.p. of product.

TLC: Dissolve small amount of o-phenylenediamine dihydrochloride and purified 2-

Methylbenzimidazol in acetone in separate sodium fusion tube and use them for the spotting

on TLC plate. Chose the mobile phase __________________________________and run the

TLC plate in it. Find the Rf values of reactant and product.

Results:







Experiment No. 16. Preparation of 2,3-diphenylquinoxaline from o-phenylenediamine.

Chemicals: o-Phenylenediamine, benzil, rectified spirit, etc.

Procedure:

1. To a warm solution of 1.05 g of benzil in 4 m1 of rectified spirit add a solution of

0.55 g of o-phenylenediamine in 4 m1 of rectified spirit.

2. Warm in a water bath for 30 minutes, add water until a slight cloudiness persists and

allow to cool.

3. Filter and recrystallise from aqueous ethanol to give 2,3-diphenylquinoxaline.

4. Record the yield and m.p. of the product.

TLC: Dissolve small amount of o-phenylenediamine and purified 2,3-diphenylquinoxaline in

acetone in separate sodium fusion tube and use them for the spotting on TLC plate. Chose the

mobile phase __________________________________and run the TLC plate in it. Find the

Rf values of reactant and product.

Results:







ORGANIC CHEMISTRY PRACTICALS PSCH P103 -...

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