71 O-R.] 



QUINOL 



149 



into methylacetoacetic ester (Geuther, 

 Jahresber. 1865, 303; Isbert, Ann. 234, 

 1 88; Roubleff, Ann. 259, 254; Nef, 

 Ann. 266, 90), and the latter converted 

 by the action of nitrous acid into iso- 

 nitrosomethylethyl ketone = butadione- 

 oxime (Meyer and Ziiblin, Ber. 11, 322). 

 The latter on decomposition by heating 

 with dilute sulphuric acid gives diacetyl 

 [113] (v. Pechmann, Ber. 2O, 2539 ; 

 2904; 3162; 3213; 21, 1411; 22, 

 2115; 24,3954). On heating diacetyl 

 with excess of dilute caustic soda solu- 

 tion it yields p-xyloquinone (Ibid, 21, 

 1420), from which dihydroxyterephthalic 

 acid and quinol can be obtained as below 

 under R. 



Or diacetyl under the influence of 

 hydrochloric acid gives a trimolecular 

 polymeride, and this yields p-xyloquinol 

 among other products on reduction with 

 sodium amalgam (Diels and Jost, Ber. 

 35, 3292). 



NOTE : Generators of diaeetyl [113] thus be- 

 come generators of quinol. 



Or acetoacetic ester can be converted 

 into acetosuccinic ester by the action of 

 ethyl chloracetate on the sodium com- 

 pound (Conrad, Ann. 188, 218), and 

 then into /6-isonitrosolaevulic acid by the 

 action of nitrous acid (Thai, Ber. 25, 

 1718). The isonitroso-compound gives 

 diacetyl on boiling with dilute sulphuric 

 acid (Ibid. 1723), and this can be con- 

 verted into p-xyloquinone, &c., as above. 



Or methylacetoacetic ester can be 

 brominated and the y-bromo-derivative 

 converted into tetrinic = a-methyl- 

 tetronic acid by heating with alcoholic 

 potash, or per ,<?<? at 100 (Demar^ay, 

 Ann. Chim. [5] 2O, 451; Bull. Soc. 

 [2] 33, 518; Pawloff, Ber. 16, 486; 

 Conrad and Kreichgauer, Ber. 29, 1047 > 

 Wolff, Ann. 288, 16). Tetrinic acid 

 gives diacetyl on oxidation with nitric 

 acid, potassium permanganate, or with 

 chromic acid (Wolff, Ber. 26, 2220 ; 

 Ann. 288, 27). 



Or from acetoacetic ester through 

 Isevulic acid (see under erythritol [50 ; 

 D]). The latter on bromination gives 

 the /3-dibromo-acid (Hell and Kehrer, 

 Ber. 17, 1981 ; Wolff, Ann. 229, 266), 

 and this on boiling with water yields 



diacetyl among other products (Wolff, 

 loc. cit.; Ber. 26, 2216). 



Or from acetoacetic acid and glycerol 

 [48] via allylacetone (see under ery- 

 thritol [50 j G-]), Isevulic acid, and 

 diacetyl as above. 



Or from acetoacetic ester through the 

 y-bromo-derivative and succinylsuccinic 

 acid (see under n-propyl alcohol [15 ; 

 AA]), and then through dihydroxytere- 

 phthalic ester, &c., as above. 



[P.] Tliymol [67] can by various pro- 

 cesses of oxidation be converted into 

 thymoquinone (Lallemand, Jahresber. 

 1854, 592 ; Carstanjen, Journ. pr. Ch. 

 [2] 3, 53 ; 15, 410 ; Andresen, Journ. 

 pr. Ch. [2] 23, 172; Armstrong, Ber. 

 1O, 297 ; Liebermann and Ilinski, Ber. 

 18, 3 1 94), which easily reduces to thymo- 

 quinol [82]. The latter on heating with 

 phosphorus oxychloride gives a diphos- 

 phoric ester, the potassium salt of which 

 on oxidation with potassium perman- 

 ganate yields dihydroxyterephthalic acid 

 (Heymann and Kb'nigs, Ber. 20, 2393). 



[Q.] Carvacrol [66] on oxidation also 

 gives thymoquinone (Glaus, Journ. pr. 

 Ch. [2] 39, 356 ; Reychler, Bull. Soc. 

 [3] 7, 32), which can be treated as 

 above. 



[R.] From acetone [106] through 

 pseudocumene (see under o-cresol [61 ; 

 B]), nitropseudocumene, and pseudo- 

 cumidine (5-amino-i : 2 : 4-trimethyl- 

 benzene) by nitration and reduction 

 (Schaper, Zeit. [2] 3, 12). The latter 

 on oxidation gives p-xyloquinone (Noel- 

 ting and Baumann, Ber. 18, 1151; 

 Sutkowski, Ber. 2O, 977), which reduces 

 to p-xyloquinol. The latter is converted 

 by phosphorus oxychloride into a di- 

 phosphoric ester of which the potassium 

 salt is oxidised by permanganate to 

 dihydroxyterephthalic acid (Heymann 

 and Konigs, Ber. 2O, 2396). 



Or from acetone and ethyl acetate 

 through acetylacetone and Isevulic acid 

 (see under erythritol [50 ; G-]). From 

 the latter through diacetyl [113] as above 

 under O. 



NOTE: Xylidines derived from the xylenes 

 (61, A ; 62, A ; 63, A) can, by heating their 

 hydrochlorides with methyl alcohol at a high 

 temperature (300-320), be made to furnish 

 pseudocumidine (Hofmann, Ber. 15, 2895 ; 

 Noelting and Forel, Ber. 18, 2680). 



