with ether, the combined liquids were filtered and the solvents were evaporated. The r&idue, crystallized from dilute ethanol, melted at 84-87', and weighed 10.75 g. (88%). Several crystallizations from dilute ethanol gave a product which melted at 89-90.5".Anal. Calcd. for C&uOn: C, 83.10; H, 7.28. Found: C, 83.31; H, 7.16.2,3-Dimethyl-S-benzhydrylhydroquinone (Xnr ) . -A mixture of the dimethyl ether XVIII (4.78 g.), hydrobromic acid (48 cc., 48%), and acetic acid (66 cc.) was rehxed for two and one-half hours. The dark solution was poured into water, and the solid was removed and crystallized from benzene-petroleum ether (b. p. 30-60;) (Norit). The product (2.74 g., 63%) melted at 139-141 .A sample, recrystallized several times, melted at 142-143'.Anal. Calcd. for C P~H~O~: C, 82.86; H, 6.62.Found: C, 83.15; H, 6.40. Cleavage of the ether XVIII by action of hydriodic acid in acetic acid gave XIX in only 19% yield, in contrast with the excellent yield of XVI obtained from XIV by means of this procedure. Use of 40% hydrobromic acid in acetic acid also gave poor results (19%) when applied to the cleavage of XVIII. The hydroquinone XIX could not be condensed with isoprene hydrobromide or with isoprene. Four attempts were made to carry out the condensation with the hydrobromide; three in ligroin, and one in acetic acid. Condensation with isoprene was attempted twice, but no chroman was formed.
2,3-Dimethyl-5-benzhydrylhgdroquinone Diacetate (XX).-Sulfuric acid (1 drop) was added to a solution of the hydroquinone XIX (120 mg.) in acetic anhydride ( 5 cc.).After standing for three minutes, the solution was poured into water. The solid was removed and crystallized three times from benzene-petroleum ether (b. p. 3040'); it then melted a t 185.5-186.5'.Anal. Calcd. for C Z~I I~O , : C, 77.30; H, 6.23. Found: C , 77.15; H, 6.41. Summary 1. 2,2,7,8 -Tetramethyl -5-benzyl-6-hydroxychroman (11) has been prepared from 2,3-dimethylnitrobenzene.This chroman has been oxidized, by action of silver nitrate, to the yellow p-benzoquinone V. Vigorous oxidation of the chroman
2.by action of silver nitrate in ethanol, or of nitric acid in the same solvent, produced red solutions but none of the red o-quinone VI could be isolated from these solutions.3. Oxidation of the yellow p-benzoquinone V by action of silver nitrate in ethanol or of nitric acid in the same solvent did not produce the red o-quinone VI-indeed, did not even produce red solutions. The p-quinone V, therefore, is not an intermediate in the production of the red solutions by oxidation of the chroman 11.
4.The only evidence obtained for the existence of a tautomeric form of the yellow p-quinone V was its solubility in Claisen alkali.
5.Several intermediates, leading to 2,2,7,8-tetramethyl-5-benzhydryl-6-hydroxychrornan I11 have been prepared, but the chroman itself could not be prepared because the corresponding hydroquinone could not be condensed with isoprene or isoprene hydrobromide.6. The results of this work have necessitated some modifications of previous statements...
