71 Y-72 B.] 



QUINOL 



151 



[Y.] From crotonic aldehyde [102] 

 through Isevulic acid [50 ; O]. 



[Z.] From methylheptenone [ill] 

 through Isevulic acid [5O ; Q]. 



[AA.] From dimethylheptenol [35] 

 through laevulic acid [50 ; W]. 



[BB.] From tartar ic or racemic acid 

 [Vol. II] through pyroracemic acid 

 (see under benzyl alcohol [54 ; N]). 

 Potassium pyroracemate gives diacetyl 

 among the products of electrolysis 

 (Hofer and Uhl, Ber. 33, 653). 



[CO.] From ethyl alcohol [14] and 

 hydrogen cyanide [172] through propio- 

 nitrile (see under benzyl alcohol [54 ; I] 

 and acetone [1O6 ; S]), aa-dichlorpro- 

 pionic and pyroracemic acids, and then 

 diacetyl as above. 



[DD.] From acetic or acetoacetie acid 

 [Vol. II] and hydrogen cyanide [172] 

 through acetyl cyanide and pyroracemic 

 acid [54 ; I], and then as above. 



[EE.] From citric acid [Vol. II] 

 through citraconic or mesaconic acid 

 and pyroracemic acid [54 ; M] (see also 

 other generators of citraconic acid, p. 63). 



[FF.] From propionic acid [Vol. II] 

 through the aa-dibromo-acid and pyro- 

 racemic acid [54 ; O]. 



[GO-.] From tactic acid [Vol. II] 

 through pyroracemic acid [54; P]. 



[HH.] From normal or isopropyl 

 alcohol [15 ; 16] through propylene, 

 acrole'in [101], acrylic acid, a-chlorlactic 

 acid, glyceric acid, and pyroracemic acid 

 [54; E]. 



NOTE : For generators of propylene see under 

 glycerol [48 ; B ; C ; D, &c.]. 



72. Toluquinol ; Hydrotoluquinone ; 



Methylquiuol ; 



P ar a dih ydroxy toluene ; 



Methyl- 2 : 5-Pheiiediol. 



HO 



CH, 



HO 



NATURAL SOURCE. 



The complex is possibly contained in 

 excoecarin, a colouring-matter obtained 

 from green ebony, the wood of Excoe- 



caria glandulosa or Jacaranda ovalifolia 

 (A. G. Perkin and Briggs, Proc. Ch. 

 Soc. 18, II ; Trans. 81, 210). 



SYNTHETICAL PROCESSES. 



[A.] From toluene [54; A, &c.] 

 through o-nitrotoluene and o-toluidine. 

 The latter gives toluquinone on oxida- 

 tion with ferric chloride (Ladenburg, 

 Ber. 10, 1128), or with sulphuric acid 

 and manganese dioxide (Clark, Am. Ch. 

 Journ. 14, 565 : see also Schniter, Ber. 

 20, 2283 ; Nietzki, Ann. 215, 158). 

 Toluquinone is reduced to the hydro- 

 quinone by sulphurous acid (Nietzki, 

 loc* cit.}. 



o-Toluidine gives toluquinone on 

 oxidation with chromic acid mixture 

 (Nietzki, Ber. 10, 1935). Or o-toluidine 

 can be acetylated and nitrated, the 

 nitre-derivative hydrolysed to 5-nitro- 

 2-toluidine (Beilstein and Kuhlberg, 

 Ann. 158, 345), and the latter reduced 

 to 2 : 5-toluylenediamine, which gives 

 toluquinone on oxidation with sulphuric 

 acid and manganese dioxide (Nietzki, 

 Ber. 10, 833). 



NOTE : Both o- and p-nitrotoluene are gene- 

 ratorsof m-nitrotoluene through the correspond- 

 ing toluidines and nitrotoluidines (see under 

 vanillin [121 ; J]). m-Nitrotoluene gives 5- 

 aminocresol by electrolytic reduction in sul- 

 phuric acid solution (Gattermann, Ber. 27, 

 1930) and this yields toluquinol by the diazo- 

 method as below under B. p-Nitrotoluene on 

 mild reduction gives p-toluylhydroxylamine 

 (Bamberger, Ber. 28, 245 ; 1221 ; Lumiere and 

 Seyewitz, Bull. Soc. [3] 11, 1040), and this on 

 heating with dilute sulphuric acid yields tolu- 

 quinol (Bamberger, loc. cit. 246). p-Toluidine 

 also gives p-toluylhydroxylamine on oxidation 

 by monopersulphuric acid (Bamberger and 

 Tschirner, Ber. 32, 1677). 



[B.] From o- or m-cresol [61; 62] 

 through toluquinone by oxidation with 

 sulphuric acid and manganese dioxide 

 (Carstanjen, Journ. pr. Ch. [2] 23, 

 425). Also by oxidation with alkaline 

 potassium persulphate and hydrolysis 

 of the sulphate formed (Ch. Fab. Scher- 

 ing, Germ. Pat. 81068 of 1894; Ber. 

 28, Ref. 666). 



Or o-cresol on nitration in acetic 

 acid gives (with 3-nitro-) 5~ n itrocresol 

 (Hirsch, Ber. 18, 1512), which reduces 

 to 5-aminocresol (Nevile and Winther, 

 Ber. 15, 2979). The latter gives tolu- 

 quinol by the diazo-method (Ibid.}. Or 



