Benzoyl chlorid

Prepared by the action of ammonia on benzoyl chloride or benzoic esters, or by partial hydrolysis of benzonitrile. 

Prepared by the dehydration of benzamide. Hydrolysed by dilute acids and alkalis to benzoic acid. Good solvent. benzopheDone,C]3HioO,PhC(0)Ph. Colourless rhombic prisms, m.p. 49 C, b.p. 306°C. Characteristic smell. It is prepared by the action of benzoyl chloride upon benzene in the presence of aluminium chloride (Friedel-Crafts reaction) or by the oxidation of di-phenylmethane. It is much used in perfumery. Forms a kelyl with sodium. 

CfiHi 05 0 C6H4 CH20H. Colourless, bitter crystals, m.p. 20 PC soluble in water and alcohol, insoluble in chloroform. It occurs in the leaves, bark and twigs of species of willow and poplar. On oxidation with dilute nitric acid it is converted into helicin, the glucoside of salicylaldehyde, which has been made the starting point of further syntheses. Gives populin with benzoyl chloride. 

Carry out this preparation in precisely the same way as the above preparation of oxamide, using 2 ml. (2-4 g.) of benzoyl chloride instead of the ethyl oxalate, and observing the same precautions. Considerably more heat is generated in this reaction therefore hold the cork very securely in position during the shaking. After vigorous shaking for 15 minutes, no trace of oily benzoyl chloride remains. Filter off the fine flakes of benzamide, wash with cold water, and then recrystallise from hot water yield, 1-5 g. Colourless crystals, m.p. 130°. 

Now distil the contents of C by heating carefully over a gauze. A small initial fraction of unchanged thionyl chloride boiling at 78-80° comes over, and the temperature then rises rapidly to 194°. Directly this happens, stop the distillation, allow the condenser to drain thoroughly, and then replace G by the duplicate receiver. Run the water out of the condenser so that it acts as an air-condenser, and then continue the distillation. Collect the benzoyl chloride as the fraction boiling at 194-198°. Yield, 19 g. 

Benzoyl chloride is a colourless highly refractive liquid, having... 

Assemble in a fume-cupboard the apparatus shown in Fig. 67(A). Place 15 g. of 3,5-dinitrobenzoic acid and 17 g. of phosphorus pentachloride in the flask C, and heat the mixture in an oil-bath for hours. Then reverse the condenser as shown in Fig. 67(B), but replace the calcium chloride tube by a tube leading to a water-pump, the neck of the reaction-flask C being closed with a rubber stopper. Now distil off the phosphorus oxychloride under reduced pressure by heating the flask C in an oil-bath initially at 25-30, increasing this temperature ultimately to 110°. Then cool the flask, when the crude 3,5-dinitro-benzoyl chloride will solidify to a brown crystalline mass. Yield, 16 g., i.e,y almost theoretical. Recrystallise from caibon tetrachloride. The chloride is obtained as colourless crystals, m.p. 66-68°, Yield, 13 g Further recrystallisation of small quantities can be performed using petrol (b.p. 40-60°). The chloride is stable almost indefinitely if kept in a calcium chloride desiccator. 

In the Schotten-Baumann method of benzoylation, the hydroxyl- or amino-compound (or a salt of the latter) is dissolved or suspended in an excess of 10% aqueous sodium hydroxide solution, a small excess (about 10% more than the theoretical amount) of benzoyl chloride is then added and the mixture vigorously shaken. Benzoylation proceeds smoothly under these conditions, and the solid benzoyl compound, being insoluble in water, separates out. The sodium hydroxide then hydrolyses the excess of benzoyl chloride, giving sodium... 

When these benzoyl compounds separate in the course of the Schotten-Baumann reaction, they frequently occlude traces of unchanged benzoyl chloride, which thus escapes hydrolysis by the alkali it is advantageous there fore to recrystallise the benzoyl compounds whenever possible from ethanol or methylated spirit, since these solvents will esterify the unchanged chloride and so remove the latter from the recrystallised material. 

Occasionally benzoyl chloride gives a product which does not crystallise well in such cases the difficulty may frequently be overcome by using p-nitrobenzoyl chloride, N02C,H4C0C1, or 3,5-dinitrobenzoyl chloride, (NOiljCjHjCOCl (p. 240), which usually give highly crystalline derivatives. 

Add I ml. (1 04 g.) of aniline to 15 ml. of 10% aqueous sodium hydroxide solution contained in a wide-necked bottle as before, and then add 1-5 ml. (1-7 g.) of benzoyl chloride, and shake vigorously for 15-20 minutes. The mixture becomes warm, and the crude benzoyl derivative separates as a white... 

A crystalline derivative of benzyl alcohol cannot be obtained by using benzoyl chloride, because the benzyl benzoate, C HiCOOCHiCaHj, so obtained has m.p. 18°, and is thus usually liquid the present preparation illustrates therefore the use of a substituted benzoyl chloride (p-nitrobenzoyl chloride, m.p. 75°) in order to obtain a crystalline derivative of suitably high m.p. 

The Schotten-Baumann reaction may also be carried out, using, for example, benzene sulphonyl chloride, CeH,SO,Cl (. e., the acid chloride of benzene sulphonic acid, C H5SOjOH) in place of benzoyl chloride, and similar deri a-tives are obtained. Thus when phenol is dissolved in an excess of 10% sodium hydroxide solution, and then shaken with a small excess of benzene sulphonyl... 

Acetyl chloride, benzoyl chloride (and substituted derivatives). 

Dinitrobenzoylation. To 0 5 g. of powdered 3,5-dinitro benzoyl chloride (preparation, p. 240) in a dry test-tube, add 2 ml. of dry methanol and warm the mixture until a clear solution is obtained. Cool and filter off the solid ester which separates. Recrystallise from petroleum (b.p. 60-80 ), and take the m.p. (M.ps., pp. 536, 537.)... 

Physical properties. Colourless liquids when pure, benzoyl chloride, CjHjCOCl, is frequently pale yellow. Acetyl chloride, CH3COCI, has a pungent odour, fumes in moist air and is immediately hydrolysed by cold water. Benzoyl chloride also has a pungent odour, is lachry matory, and is hydrolysed only slowly by cold water, in which it is insoluble. 

Action of silver nitrate. Acidify 2 ml. of aqueous AgNOj solution with dil. HNO3 and add the acid chloride drop by drop with shaking. Acetyl chloride and benzoyl chloride give a precipitate of AgCl. Filter, wash with water, and then with methylated spirit to remove any benzoic acid the AgCl remains. 

Form derivatives with benzoyl chloride and (more rapidly and conveniently) with 3,5-dinitrobenzoyl chloride. 

B) Benzoyl derivatives. Most amino-acids can be benzoyl-ated when their solutions in 10% aqueous sodium hydroxide are shaken with a small excess of benzoyl chloride until a clear solution is obtained (Schotten-Baumann reaction, p. 243). Acidification of the solution then precipitates the benzoyl derivative and the excess of benzoic acid, and the mixture must be filtered off, washed with water, and recrystallised (usually from ethanol) to obtain the pure derivative. (M.ps., p. 555 )... 

A) Benzoyl Derivative. Since acetylation and benzoylation do not always proceed smoothly with nitrophenols, it is best to reduce them to the aminophenol as in (3) above. Add an excess of 20% aqueous sodium hydroxide to the reaction mixture after reduction, cool and then add a small excess of benzoyl chloride, and shake in the usual way. The dibenzoyl derivative wiU separate. Filter, wash with water and recrystalUse. (M.ps., p. 551.)... 

The dibenzoyl derivatives can be prepared by the normal Schotten-Baumann method, using 10% aqueous sodium hydroxide and an excess of benzoyl chloride, but the m.ps. of the dibenzoyl derivatives are inconveniently high (p- ssO-... 

Heat together under very efficient water reflux 1 g. of freshly fused dry powdered ZnClg, 2 ml. of diethyl ether and 0 5 g. of 3,5 -dinitrobenzoyl chloride for 2 hours. Shake the product with 5 ml. of water and ther add 10% NaOH solution until all the ZnCl, and excess of 3,5-dinitro> benzoyl chloride and 3,5-dinitrobenzoic acid have gone into solution. Filter at the pump and recrystallise from petroleum (b.p. 40-60°) to obtain ethyl 3,5-dinitrobenzoate, m.p. 93°. (M ps. of other 3,5 dinitro-benzoates, p. 536.)... 

Pungent odour. Formic acid, acetic acid, acetyl chloride, acetic anhydride, benzoyl chloride, benzyl chloride, pyridine. Benzoquinone (when warmed with water). 

Benzoates. Alcohols react with benzoyl chloride in the presence of pyridine or of sodium hydroxide solution to produce esters of benzoic acid ... 

The experimental technique is similar to that given under Aromatic Amines, Section IV,100,2. The following alternative method may also be used. Mix together 0 -5-0 - 8 ml. of the polyhydroxy compound, 5 ml. of pyridine and 2 -5 ml. of redistilled benzoyl chloride in a 50 ml. flask. 

Experimental details for the preparation of derivatives with benzoyl chloride and with 3-nitrophthalic anhydride are given in Section IV,100,2 and 7. 

Benzoates. Dissolve 0-5 g. of the amino acid in 10 ml. of 10 per cent, sodium bicarbonate solution and add 1 g. of benzoyl chloride. Shake the mixture vigorously in a stoppered test-tube remove the stopper from time to time since carbon dioxide is evolved. When the odour of benzoyl chloride has disappeared, acidify with dilute hydrochloric acid to Congo red and filter. Extract the solid with a little cold ether to remove any benzoic acid which may be present. RecrystaUise the benzoyl derivative which remains from hot water or from dilute alcohol. 

Method 1. Place in a test-tube or small flask 1-3 g. of glycerol and 30 ml. of 10 per cent, sodium hydroxide solution add gradually, with simultaneous shaking, 1-2 g. of benzoyl chloride. Stopper the vessel, shake for several minutes and allow to stand. Decant the solution from the pasty solid and wash the latter with cold water by decantation. Recrystallise the solid tribenzoate from dilute rectified (or methylated) spirit or from light petroleum, b.p. 40-60° the pure compound has m.p. 76°. 

---