132 



AROMATIC ALCOHOLS AND PHENOLS 



[63 A-F. 



tion with potassium permanganate gives 

 4-brom-m-toluic acid (Glaus, Journ. pr. 

 Ch. [2] 46, 21), and this can be con- 

 verted into p-cresol as before. 



Toluene or m- or p-xylene can, by 

 further methylation, be converted into 

 pseudocumene = i : 2 : 4-trimethylben- 

 zene (Fittig and Ernst, Ann. 139, 187 ; 

 Eittig and Jannasch, Ann. 151, 286 ; 

 Eittig and Laubinger, Ibid. 257 ; Jan- 

 nasch, Ann. 176, 286 ; Friedel and 

 Crafts, Ann. Chim. [6] 1, 461 ; Ador and 

 Rilliet, Ber. 12, 329), the sulphonic acid 

 of which (Jacobsen, Ann. 184, 199) 

 gives a sulphonamide, which, by oxida- 

 tion with alkaline permanganate, gives 

 4-sulphamidemethylbenzene-2 : 5-dicarb- 

 oxylic (methylterephthalic = a-xylid- 

 ic) acid (Jacobsen and Meyer, Ber. 

 16, 190). The latter (sulphamide) on 

 potash fusion gives methyl-4-phenol- 

 2 ': 5-dicarboxylic (s-hydroxy methyltere- 

 phthalic) acid (Ibid.], and this on heat- 

 ing with lime gives p-cresol. 



NOTE : All generators of toluene thus become 

 generators of p-cresol, 



[B.] From p-liydmxyphenylacetic acid 

 [Vol. II] by heating with lime (Sal- 

 kowsld, Ber. 12, 1440). 



[C.] From acetone [106] through 

 mesitylene (see under benzyl alcohol 

 [54 ; D]), mesitylenesulphonic acid 

 (Jacobsen, Ann. 146, 95), 4-hydroxy- 

 mesitylenic (i : 3-dimethyl-4-phenol-5- 

 carboxylic) acid by potash fusion of the 

 sulphonic acid (Fittig and Hoogewerff:, 

 Ann. 150, 333), 4-hydroxyuvitic (4- 

 methylphenol-3 : 5-dicarboxylic) acid by 

 potash fusion of hydroxymesitylenic 

 acid (Jacobsen, Ann. 195, 285), and 

 decomposition of the hydroxyuvitic acid 

 by heating with hydrochloric acid at 

 200 (Ibid. 206, 196). 



Or from mesitylene through mesityl- 

 enic acid (see under o-cresol [61 ; B]), 

 4-nitro- and 4-aminomesitylenic acid 

 (Schmitz, Ann. 193, 162; 171), 4-hy- 

 droxymesitylenic acid by the diazo-reac- 

 tion (Jacobsen, Ber. 11, 2055), and then 

 4-hydroxyuvitic acid and p-cresol as 

 above. 



Or 4-hydroxymesitylenic acid may 

 be converted into 1:3: 4-xylenol by 

 heating with hydrochloric acid at 200 



(Jacobsen, Ber. 11, 2052 ; Fittig and 

 Hoogewerff, Ann. 150, 330), and the 

 xylenol converted into 4-hydroxy-m- 

 toluic acid and p-cresol as under A. 



Or mesitylene may be converted into 

 mesitol (1:3: 5-trimethyl-2-phenol) by 

 potash fusion of mesitylenesulphonic 

 acid, or by the diazo-reaction from 

 aminomesitylene (Biedermann and 

 Ledoux, Ber. 8, 59 and 250; Jacob- 

 sen, Ann. 195, 268). Mesitol on potash 

 fusion gives 4-hydroxymesitylenic acid 

 (Jacobsen, loc. cit. 274), from which 

 p-cresol can be obtained as above. 



Or from mesitylenic acid through 

 a-sulphomesitylenic acid by sulphona- 

 tion (Remsen and Brown, Am. Ch. 

 Journ. 3, 218), 4-hydroxymesitylenic 

 acid by potash fusion (Ibid. 220), and 

 then as above. 



Or mesitylene may be oxidised to 

 uvitic acid (see under benzyl alcohol 

 [54 j D]), which, by distillation with 

 lime, gives m-toluic acid (Bottinger and 

 Ramsay, Ann. 168, 255). The latter 

 can be converted into 4-hydroxy-m- 

 toluic acid and p-cresol as under A. 



NOTE : Generators of mesitylene and uvitic 

 acid (see under benzyl alcohol [54 ; D to Q,]) 

 thus also become generators of p-cresol. 



Acetone may also be converted 

 through phorone into pseudocumene 

 (see under o-cresol [61; B]), and the 

 latter into s-hydroxymethylterephthalic 

 acid and p-cresol as under A. 



[D.] Parahydroxybenzoic aldeliyde 

 [119] gives, among other products, p- 

 cresol when heated with acetic acid and 

 zinc dust (Tiemann, Ber. 24, 3170). 



[E.] Metacresol [62] on nitration 

 yields a mixture of 4- and 6-nitro-m- 

 cresol (Stadel, Ann. 217, 5 1 ; 259, 210). 

 The ethyl ether of the former gives, on 

 heating with strong aqueous ammonia 

 at 140-150, 4-nitro-m-toluidine (Stadel 

 and Kolb, Ann. 259, 224). The latter 

 on replacement of the NH 2 -group by 

 hydrogen by the diazo-method would 

 give p-nitrotoluene, which can be con- 

 verted into p-toluidine and p-cresol as 

 under A. 



[P.] Anetliole [68] when heated under 

 pressure to 250-275 gives, among other 

 products, p-cresol methyl ether (Orn- 



