Improvements in the manufacture of substituted para-quinones and hydroquinones with particular reference to the improved manufacture of ªÎ-cumoquinone and ªÎ-cumohydroquinone

摘要

519,398. Para-quinones and para-hydroquinones. BRITISH DRUG HOUSES, Ltd., FRASER, H. B., and SKRIMSHIRE, G. E. H. Oct. 21, 1938, No. 30551. [Class 2 (iii)] A benzene compound having two parapositions free and substituted in the remaining nuclear positions by alkyl groups or halogen atoms, at least one substituent being halogen, is nitrated to the corresponding p-dinitro compound, the latter reduced to the p-diamine, this oxidized to the p-quinone and the latter, if desired, reduced to the hydroquinone, the process including the step of dehalogenation at any suitable stage after the nitration. It has been found impossible to dehalogenate a nitro compound or quinone without prior or simultaneous reduction, but otherwise dehalogenation may occur at any suitable stage after nitration. In examples : (1) 5 - bromo - 3.6 - dinitro -# - cumene (produced by brominating # cumene in carbon tetrachloride, followed by nitration) is converted to the stannichloride of 5-bromo-3.6-diamino- #-cumene followed by dehalogenation to the diamine and oxidation to #-cumoquinones; (2) and (3) 5 - bromo - 3.6 - dinitro - # - cumene is reduced and dehalogenated and the product oxidised to #-cumoquinone ; (4) and (5) 5 - bromo - # - comuquinone .(obtained by oxidation of the diamine stannichloride described. in example (1) ) is reduced and dehalogenated to #-cumohydroquinone (6) 2.5 - dinitro - 4.6 - dibromo - 1.3 - dimethyl benzene (prepared by dibrominating 1.3-dimethyl benzene in presence of iodine, followed by nitration) is reduced to the stannichloride of the corresponding diamine, and the latter oxidized to 4.6 - dibromo - 1.3 - dimethyl - 2.5 - benzo-quinone, followed by debromination and reduction to give 1.3-dimethyl-2.5-dihydroxy-benzene.