Benzoyl chloride, physical properties

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. 

Production of cellulose esters from aromatic acids has not been commercialized because of unfavorable economics. These esters are usually prepared from highly reactive regenerated cellulose, and their physical properties do not differ markedly from cellulose esters prepared from the more readily available aHphatic acids. Benzoate esters have been prepared from regenerated cellulose with benzoyl chloride in pyridine—nitrobenzene (27) or benzene (28). These benzoate esters are soluble in common organic solvents such as acetone or chloroform. Benzoate esters, as well as the nitrochloro-, and methoxy-substituted benzoates, have been prepared from cellulose with the appropriate aromatic acid and chloroacetic anhydride as the impelling agent and magnesium perchlorate as the catalyst (29). 

Ethers are unaffected by sodium and by acetyl (or benzoyl) chloride. Both the purely aliphatic ethers e.g., di-n-butyl ether (C4H, )30 and the mixed aliphatic - aromatic ethers (e.g., anisole C3HSOCH3) are encountered in Solubility Group V the purely aromatic ethers e.g., diphenyl ether (C,Hj)20 are generally insoluble in concentrated sulphuric acid and are found in Solubility Group VI. The purely aliphatic ethers are very inert and their final identification may, of necessity, depend upon their physical properties (b.p., density and/or refractive index). Ethers do, however, suffer fission when heated with excess of 67 per cent, hydriodic acid, but the reaction is generally only of value for the characterisation of symmetrical ethers (R = R ) ... 

Table I compares the important physical properties of the currently used acrylic resin denture bases - the heat cured and self cured bases. These are typically powder/liquid mixtures containing benzoyl peroxide redox systems activated by a tertiary aromatic amine. Among these are the vinyl chloride - vinyl acetate - methyl methacrylate mixtures and the newer pour type denture bases - the latter designed for laboratory convenience and model fit by control of polymerization shrinkage. On this half of the table the important comparative properties are transverse deflection, failure and water sorption.

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