EXPERIMENT 1. AIM: To prepare benzilic acid from benzyl using Green approach.

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1 EXPERIMENT 1 AIM: To prepare benzilic acid from benzyl using Green approach. Requirements: 100 ml conical flask, 200ml beakers, filter paper, oven,0.5 g benzil,20% alc KH, dil.sulfuric acid, benzene for recrystallisation Procedure: 1. Take 0.1 g of benzil in a 100 ml conical flask. 2. To this add 12 ml of alc. KH(20%). 3. Cover the conical flask with funnel and place it in the microwave oven. 4. Place 100 ml beaker containing 50 ml water next to conical flask in microwave oven. This acts as a heating source for reaction mixture. 5. Heat the reaction mixture in microwave at 60%(540W) intensity for one minute. 6. Cool the reaction mixture, fine crystals of pot.benzillate separate out. Filter the crystals and dissolve in 30 ml of distilled water. Filter again to remove any insoluble impurities. 7. To the clear filtrate, add dil. H2S4 dropwise till the solution becomes acidic and benzilic acid separates out as ppts. 8. Let the reaction mixture cool down for complete pptn. 9. Filter the ppt. Wash with hot distilled watwer. 10. Dry the ppts.and recrystallise from benzene and note the yield. 11. Determine the m.pt (150 degrees) of pure product.

2 EXPERIMENT 2 AIM; Preparation of p-nitroacetanilide from acetanilide. THERY In this step you first form the nitronium ion in situ by dehydration of nitric acid. Sulfuric acid is the dehydrating agent. The nitronium ion is a very powerful electrophile and will react with the π electrons of the aromatic ring of aniline. These reactions are shown in Figure Procedure: In a 125 ml Erlenmeyer flask, dissolve 3.4 g of acetanilide in 4 ml glacial acetic acid. warm the solution gently in order to get all the solid material to dissolve. Use your Bunsen burner for this purpose. Stir with your glass stirring rod and pass the Erlenmeyer back and forth through a low flame. Do not overheat. Figure 14.5 Nitration of Acetanilide H N S H H N + - S H N + H H + H 2 N NH C CH 3 H 2 H NH C CH 3 NH C CH 3 H N Add 5 ml of concentrated ice cold sulfuric acid. Add the sulfuric acid slowly 1 ml at a time using a medicine dropper or pipette. In a separate 25 ml Erlenmeyer flask, prepare a nitrating mixture by adding 1.8 ml of concentrated nitric acid (caution!!) to 2.5 ml of ice cold sulfuric acid. Do this in an ice bath. Be careful. The addition reaction is exothermic. Add the nitric acid slowly using your medicine dropper. If you spill any acid on your hands wash them immediately. Cool the nitrating mixture to room temperature. Add the nitrating mixture dropwise using a medicine dropper. Swirl the flask to mix the reagents thoroughly. Keep the temperature in the C range as you add the nitrating mixture. If the temperature gets too hot, cool the flask in the ice bath. Add 1-2 drops and swirl, monitoring the temperature carefully. After all the nitrating mixture has been added, allow the solution to stand at room temperature for 40 minutes in order for the reaction to go to completion. Do not leave it more than one hour or decomposition or a second nitration may start to occur. Pour the reaction mixture slowly, with stirring, into a mixture of 50 ml of water and 10 g of ice. Collect the product by suction filtration using your Buchner funnel. Press the solid firmly with your spatula to help remove as much liquid as possible. Since there is still a lot of the nitric/sulfuric acid mixture remaining, we need to wash the product thoroughly with water. To do this, transfer the solid filter cake to a N 2

3 beaker containing 40 ml of ice cold water. Mix the suspension thoroughly to help wash off the acid and do another suction filtration using a new piece of filter paper in your Buchner funnel. Disconnect the filter flask from the vacuum and add an additional 10 ml cold water. Reconnect the vacuum and filter off this water. Using your spatula, spread the material on a clean, dry watch glass and leave it to dry in your locker until the following lab period. Recrystallize a small sample a spatula tip is enough from 95% ethanol using a small test tube, a hot palate and hot water bath, and then take a melting point. Result : yield...

4 EXPERIMENT 3 Aim - Preparation of p-bromoacetanilide (Bromination reaction). Theory This mechanism is a classic example of electrophilic aromatic substitution. An amine may lead to di and trisubstituted products. If an amide is used in place of the amine, monosubstitution usually predominates (the electron-withdrawing carbonyl group makes the benzene ring less nucleophilic). This ortho-, para- directing group will tend to only add groups para- to itself because of the steric bulk of the amide group. HN Br 2 HN Acetanilide Br Bromoacetanilide Experimental Procedure: - Place 3 g (0.022 mol) of acetanilide into a 100 ml conical vial. Add 10 ml of glacial acetic acid.stirring with a glass rod may be necessary to help dissolve the acetanilide (r.t). - prepare the bromine solution by adding 1.5 ml of bromine into 10 ml of acetic acid (first but 10 ml of the acid then 1.5 ml of bromine using dropper Fast ) - add bromine-acetic acid solution to acetanilide solution with stirring then leave the mixture 15 min. - Transfer the mixture into beaker contain 100 ml of water with stirring. - Collect the product by vacuum filtration using Büchner funnel. - Purify the product by crystallization method using ethanol. - Collect the white crystals by vacuum filtration, dried and weigh and calculate the percent yield. - btain melting point and compare with literature data.

5 EXPERIMENT 4 Aim- To separate the leaf pigments from spinach leaves by column chromatography. Theory- The juice of spinach leaves contain a number of colored compounds namely chlorophyll (Green), Xanthophylls (Yellow), Cartenoid (orange or red). These can be separated by column chromatography. The Extract of spinach leaves is added at the top of the chromatographic column containing alumina using acetone as a solvent. Different pigment travel with the different speed, they get adsorbed to form separate bands. These are eluted with suitable solvent and the pigments are recovered by evaporating the solvent. Apparatus- Chromatographic column, beaker, glass rod. Alumina, acetone, spinach leaves. Procedure 1. Mix about 25g of alumina with40-50 ml of acetone; stir the mixture until slurry is obtained. 2. Place a small cotton wool plug in the lower part of the column. 3. Pour the slurry into the column. 4. Drain out the excess of the solvent from the column, keeping the alumina at the top of the column immersed in the solvent. 5. Crush 10-15ml of spinach leaves with pestle and mortar. 6. Add 20 ml of acetone to the crushed leaves stir the contents with glass rod and filter. 7. Add slowly about 10 ml of spinach leaves extract on the top of the column. 8. When the extract goes down the column start adding acetone from the top. 9. Colored components of spinach leaves extract get adsorbed and appear as different bands at different places in the columns. 10. Separates different bands by elution with a mixture of acetone and petroleum ether.