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      Permanent link:
      https://www.ias.ac.in/article/fulltext/seca/027/04/0245-0257

    • Keywords

       

      Methyl Ether; Wogonin; Aqueous Sodium Hydroxide; Quinol; Dimethyl Sulphate

    • Abstract

       

      Using typical examples, some of which are new, oxidative demethylation of methoxy benzenes, ketones, chalkones and flavones with nitric acid is discussed. The flavones without exception undergo simple conversion into para quinones. The others fall into two categories: (a) 1∶2∶4∶5-Tetramethoxy benzene and its derivatives suffer only oxidative demethylation like the flavones to yield the corresponding para quinones: (b) 1∶2∶3∶5-Tetramethoxy benzene and its derivatives, either ketones or chalkones, on the other hand undergo further change involving demethylation of another methoxyl group yielding hydroxy quinones. In the case of ketones and chalkones this second stage demethylation involves the methoxyl which is situated ortho to the ketonic carbonyl and which is subjected to the combined influence of this carbonyl and the one in the quinone group. These results are of importance in the study of pedicellin-pedicinin conversion.

      Under favourable conditions hydroxy quinones can be methylated by means of dimethyl sulphate and potassium carbonate to the corresponding methyl ethers,e.g. lawsone. In some cases fully methylated ethers of the corresponding quinols could be obtainede.g. gossypetone. This is obviously due to the preliminary dismutation of the quinone into the corresponding quinol and complex products. The action of alkali on benzoquinone and tetramethyl gossypetone has been studied using different conditions.

    • Author Affiliations

       

      G S Krishna Rao1 K Visweswara Rao1 T R Seshadri1

      1. Department of Chemistry, Andhra University, Waltair
    • Dates

       
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