Acetanilide crystal

The significance of polar axes can be demonstrated, for example, in crystal morphology. A few examples will be mentioned here following Curtin and Paul s review of the chemical consequences of the polar axis in organic crystal chemistry [37], Figure 2-32a shows a centrosymmetric acetanilide crystal. The faces occur in parallel pairs and the crystal is non-polar. On the other hand, the p-chloroacetanilide crystal shown in Figure 2-32b is noncentrosymmetric and some of the... 

FIGURE 12.1. Hydrogen-bonding along the long axis of acetanilide crystals... 

Acetanilide crystallizes from hot water in white prisms. It melts at 116° and boils at 304°. It is used in medicine in cases of fever, and in headache powders. ... 

White crystals, m.p. 114" C. Manufactured by reacting aniline with excess ethanoic acid or ethanoic anhydride. Chief use is in the manufacture of dye intermediates such as p-nitro-acetanilide, p-nitroaniline and p-phenylene-diamine, in the manufacture of rubber, and as a peroxide stabilizer. 

Anilides, (a) To 1 ml. of aniline in a small conical flask add very slowly and carefully about i ml. of acetyl chloride. A vigorous reaction occurs and a solid mass is formed. Add just sufficient water (about 15 ml.) to dissolve the solid completely on boiling. On cooling, crystals of acetanilide separate out filter and determine the m.p. 

Cool the flasks in cold water, and then titrate the contents of each with /i/.t a()H solution, using phenolphthalein as an indicator. Shake the contents of the flask A repeatedly during the titration in order to keep the fine crystals of acetanilide dispersed in the aqueous solution. 

Add two drops of acetyl chloride to a drop of aniline. A vigorous action occurs, and a solid separates. This is acetanilide, and may be obtained in larger crystals by dissolving in boiling water and cooling slowly. 

Dissolve the acetanilide in the acetic acid in a flask (-J litre), and add gradually the bromine, dissolved in. bout twice its volume of glacial acetic acid, and shake well. When tlie bromine has been added, let the mixture stand hour mid then pour into 200 c.c. water and rinse out with writer. Filter the crystalline precipitate at the pump and wash three or four times with water. Press it well down and let it cl min. Dissohe the moist substance in spirit (about 60 c.c.) incl pour into a beaker to crystallise. Filter the crystals, w ish with a little dilute spirit, and dry on filter paper. Yield 6—7 grams. 

To a solution of 42 g of 2.amino.2 -chlorobenzophenone in 500 ml of benzene, 19 ml of bromoacetyl bromide was added dropwise. After refluxing for 2 hours, the solution was cooled, washed with 2N sodium hydroxide and evaporated. The residue was recrystallized from methanol giving crystals of 2-bromo.2. (2-chlorobenzoyl) acetanilide melting at 119° to 121°C. 

To a solution of 14.5 g of 2-bromo-2 -(2-chlorobenzoyl)acetanilide in 100 ml of tetrahy-drofuran, an excess of liquid ammonia (ca 150 ml) was added. The ammonia was kept refluxing with a dry-ice condenser for 3 hours after which time the ammonia was allowed to evaporate and the solution was poured into water. Crystals of 2-amino-2 -(2-chloro-benzoyOacetanilide were collected, which after recrystallization from ethanol melted at 162° to 164 C. 

A solution of 3 g of 2-amino-2 -(2-chlorobenzoyl)acetanilide in 50 ml of pyridine was refluxed for 24 hours after which time the pyridine was removed in vacuo. The residue was recrystallized from methanol and a mixture of dichloromethane and ether giving crystals of 5-(2-chlorophenyl)-3H-1,4-benzodiazepin-2( 1 H)-one melting at 212° to 213°C. 

In a 500-cc. round-bottomed, three-necked flask fitted with a reflux condenser, dropping funnel, and a mercury-sealed stirrer (Note 1) is placed a solution of 46 g. (0.5 mole) of dry aniline in 125 cc. of pure dry benzene. Stirring is started, and a solution of 42 g. (0.5 mole) of ketene dimer (p. 64) in 75 cc. of pure dry benzene is added dropwise over a period of half an hour. The reaction mixture is then heated under reflux on the steam bath for one hbur. After the major portion of the benzene has been removed by distillation from the steam bath, the remainder is removed under reduced pressure. The residue is dissolved in 500 cc. of hot 50 per cent aqueous alcohol from which the aceto-acetanilide separates on cooling. The mixture is cooled to 0° before filtration. A second crop of crystals can be obtained by adding 250 cc. of water to the mother liquor and cooling again (Note 2). The total yield of product, m.p. 82-83.5°, is 65 g. (74 per cent of the theoretical amount). Further purification by recrystallization from 300 cc. of 50 per cent alcohol yields 55 g. of a product which melts at 84-85°. 

The crude -acetaminobenzene sulfonyl chloride (p. 3) obtained from 67.5 g. (0.5 mole) of acetanilide is shaken for two hours with a solution of 250 g. (1 mole) of crystallized sodium sulfite (Na2S03 7H2O) in 500 cc. of water. The reaction mixture is kept slightly alkaline by the addition at intervals of small portions of 50 per cent sodium hydroxide solution. The total volume of alkali used varies from 10 to 50 cc. After the alkaline mixture has been shaken for the two-hour period (Note 1) it is filtered, and the filtrate is acidified with 60 per cent sulfuric acid. If the acid is added slowly, the sulfinic acid comes down in fine crystals which after filtering and drying, melt at 1550 with decomposition (Note 2). The yield is 50-55 g. (43-47 per cent of the theoretical amount based on the acetanilide used). 

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