CRESOLS  or METHYL PHENOLS, C7H80 or C6H4•

CH3.0H . The three isomeric cresols are found in the tar obtained in the destructive distillation of coal, beech-wood and pine . The crude cresol obtained from tar cannot be separated into its different constituents by fractional distillation, since the boiling points of the three isomers are very close together . The pure substances are best obtained by fusion of the corresponding toluene sulphonic acids with potash . Ortho-cresol, CH3(1)•CsH4.0H(2), occurs as sulphate in the urine of the horse . It may be prepared by fusion of ortho-toluene sulphonic acid with potash; by the action of phosphorus pent-oxide on carvacrol; or by the action of zinc chloride on camphor . It is a crystalline solid, which melts at 30° C. and boils at 19o.8° C . Fusion with alkalis converts it into salicylic acid . Meta-cresol,CH3(1) • C6H4.0H(3), is formed when thymol (paraisopropyl-meta-cresol) is heated with phosphorus pentoxide . Propylene is liberated during the reaction, and the phosphoric acid ester of meta-cresol which is formed is then fused with potash . It can also be prepared by distilling meta-oxyuvitic acid with lime, or by the action of air on boiling toluene in the presence of aluminium chloride (C . Friedel and J .

M . Crafts,

Ann . Chien . Phys., 1888 [6], 14, p . 436) . It solidifies in a freezing mixture, on the addition of a crystal of phenol, and then melts at 3°-4° C . It boils at 2o2°•8 C . Its aqueous solution is coloured bluish-violet by ferric chloride . Para-cresol, CH3(f)•C6H4.0H(4), occurs as sulphate in the urine of the horse . It is also found in horse's liver, being one of the putrefaction products of tyrosine . It may be prepared by the fusion of para-toluene sulphonic acid with potash; by the action of nitrous acid on para-toluidine; or by heating para-oxyphenyl acetic acid with lime . It crystallizes in prisms which melt at 36° C, and boil at 2010.8 C .

It is soluble in

water, and the aqueous solution gives a blue coloration with ferric chloride . When treated with hydrochloric acid and potassium chlorate, no chlorinated quinones are obtained (M . S . Southworth, Ann . (1873), 168, p . 271), a behaviour which distinguishes it from ortho- and meta-cresol . On the composition of commercial cresylic acid see A . H . Allen, Jour . Soc . Chem . Industry (1890), 9, p .

141 . See also

CREOSOTE .