128 



AROMATIC ALCOHOLS AND PHENOLS reu-62 A. 



oxidation gives hexahydro-m-hydroxy- 

 p-toluic acid, which is converted by 

 bromine into 2-hydroxy-p-toluic acid 

 (Tiemann and Semmler, Ber. 28, 2141). 

 The latter gives o-cresol as above 

 under A. 



[K.] From acetylene [l ; A, &c.], the 

 copper compound of which gives a mix- 

 ture of cresols among the products of 

 distillation with zinc dust (Erdmann 

 and Kb'thner, Zeit. anorg. Ch. 18, 48). 



NOTE : Orthocresylsulphuricacid is obtained 

 from o-cresol by treating the potassium salt 

 with potassium pyrosulphate (Baumann, Ber. 

 11, 1911). 



62. Metacresol ; 3-Methylplienol. 

 HO 



NATURAL SOURCE. 



Possibly occurs (as salt of cresylsul- 

 phuric acid) in urine of horse (Preusse, 

 Zeit. physiol. Ch. 2, 356). 



SYNTHETICAL PROCESSES. 



[A.] From toluene (see under benzyl 

 alcohol [54; A]) by passing air through 

 the boiling hydrocarbon in presence of 

 aluminium chloride (Friedel and Crafts, 

 Ann. Chim. [6] 14, 436). 



Toluene on sulphonation (preferably 

 with chlorosulphonic acid) gives o- 

 (with p-) toluenesulphonic acid (Claesson 

 and Wallin, Ber. 12, 1848; Noyes, 

 Am. Ch. Journ. 8, 176 : see also under 

 61; A), which can be converted into 

 o-cyanotoluene (nitrile) by distilling the 

 potassium salt with potassium cyanide 

 [172] (Fittig and Ramsay, Zeit. [2] 7, 

 584 ; Ann. 168, 246) and into o-toluic 

 acid by hydrolysis (Cahn, Ann. 24O, 

 280). The latter on bromination gives 

 3-brom- o-toluic acid (Jacobsen and 

 Wierss, Ber. 16, 1956; Racine, Ann. 

 239, 74), which by potash fusion yields 

 the corresponding hydroxytoluic acid 

 (Jacobsen, Ber. 16, 1963), and this on 

 heating with strong hydrochloric acid 

 at 200 gives m-cresol (Hid.]. 



Or toluene can be nitrated, the o- 

 nitrotoluene (separated from the para-) 

 reduced to o-toluidine, converted into 

 the nitrile by the diazo- (Sandmeyer) 

 method and the nitrile converted into 

 the acid (Cahn, loc. cit.) } the bromo-acid, 

 &c v as before. 



From Toluene through the Xylenes and 

 Hydroxytoluic Acids. 



Toluene can be converted into o-xylene 

 by the action of sodium on a mixture of 

 o-bromtoluene and methyl iodide (Jan- 

 nasch and Hiibner, Ann. 170, 117; 

 Reymann, Bull. Soc. [2] 26, 532) or by- 

 passing methyl chloride into warm tol- 

 uene in presence of aluminium chloride 

 (Jacobsen, Ber. 14, 2625). Ortho- 

 xylene gives o-toluic acid on oxidation 

 with dilute nitricacid (Fittig and Bieber, 

 Zeit. [2] 6, 496; Ann. 156, 242), and 

 this can be treated as above. 



Orthoxylene also on sulphonation 

 (Jacobsen, Ber. 11, 22) and conversion 

 into the sulphonamide gives on oxida- 

 tion of the latter with alkaline perman- 

 ganate a mixture of 4- and 5-sulph- 

 amide-o-toluic acid (Ibid. Ber. 14, 39); 

 the latter on fusion with potash gives 

 5-hydroxy-o-toluic acid, which on heat- 

 ing with hydrochloric acid at 200 yields 

 m-cresol (Ibid.). 



Or from o-xylene through 5-nitro-o- 

 xylene (Jacobsen, Ber. 17, 160), 5-nitro- 

 o-toluic acid by oxidising the latter with 

 dilute nitric acid (Ibid. 162), 5-amino-o- 

 toluic acid by reduction (Ibid. 164), 

 5-hydroxy-o-toluic acid by the diazo- 

 method (Ibid.), and then as above. 



From toluene through m-xylene (see 

 under orthocresol [61 ; A]), m-toluic 

 acid by oxidation with dilute nitric acid 

 (Tawildaroff, Zeit. [2] 6, 419; Ber. 4, 

 410; Bruckner, Ber. 9, 406; Reuter, 

 Ber. 17, 2028), 5-sulpho-m-toluic acid 

 by sulphonation (Jacobsen, Ber. 14, 

 2355), 5-hydroxy-m-toluic acid by pot- 

 ash fusion (Ibid. 2357), and decompo- 

 sition of the latter by heating with 

 lime. 



Or toluene can be nitrated, the p- 

 nitrotoluene reduced to p-toluidine, the 

 latter acetylated,* nitrated, and hydro- 

 lysed to 3-nitro-p-toluidine (Beilstein 



