GB321161A - Improvements in the production of highly halogenated derivatives of pyranthrone - Google Patents

Abstract

321,161. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). July 30, 1928. Polyhalogenated pyranthrones containing more than 4 halogen atoms are prepared by halogenating pyranthrone or its derivatives in sulphuric acid or a derivative thereof by means of so much halogen or halogenating agents as to produce pyranthrones containing more than four halogen atoms, preferably at elevated temperatures and in the presence of a halogen transferrer. The latter include iodine, sulphur, selenium, iron, manganese, antimony, mercury and their compounds, and they may be employed singly or several introduced simultaneously or successively in the process. Mixed halogen derivatives may be obtained by using halogenated pyranthrones containing 1 to 4 halogen atoms in the molecule as starting materials, or by brominating pyranthrones in presence of chlorsulphonic acid, when simultaneous chlorination mav occur. Products prepared in examples are, (1) pentabrompyranthrone by brominating in chlorsulphonic acid solution in presence of iodine; the product dyes cotton in scarlet shades; (2) pentabrommonochlorpyranthone by brominating in chlorsulphonic acid solution first in the presence of selenium and followed by the addition of antimony; phosphorus or molybdenum may replace the selenium; (3) hexabromdichlorpyranthrone by brominating tetrabrompyranthrone (prepared by brominating pyranthrone under pressure) in chlorsulphonic acid solution in presence of iodine. Specifications 10505/06, 12568/09, and 285,502 are referred to. Reference has been directed by the Comptroller to Specification 282,481.