GB529082A - Improvements in chromanes and method of producing the same - Google Patents

Abstract

529,082. Chromanes. MINNESOTA, REGENTS OF THE UNIVERSITY OF. May 22,1939, No. 15117. Convention date, May 31, 1938. Addition to 529,081. [Class 2 (iii)] Chromanes are prepared by a modification of the process disclosed in the parent Specification which comprises reacting at an elevated temperature a substituted or an unsubstituted hydroquinone or hydroquinone derivative which has 'vacant at least one position ortho to the hydroxyl group with a diene or with a compound containing diene linkage. The reaction is preferably carried out in the presence of an acid catalyst which may be an organic acid such as formic acid or acetic acid, a substituted organic acid such as a halogenated acetic acid, an inorganic acid such as sulphuric acid or phosphoric acid, or organic, or acidic, or inorganic salts such as amine salts, aluminium chloride, zinc chloride, mercuric chloride, acid sulphates or boron trifluoride. Starting materials mentioned include hydroquinones, substituted hydroquinones and hydroquinone monoethers. Diene compounds mentioned include dimethyl butadiene, isoprene, and phytadiene. The diene may be produced as a preliminary step in the procedure or it may be produced in situ in the principal reaction. There may be used any alcohol such as an alkylic alcohol, or any compound which will produce a diene constituent either directly by the use of acid catalysts with or without heat, or after rearrangements in the presence of acids. There is particularly mentioned the use of an ene-ol such as primary alkylic alcohols having the general structure or teriary alkylic compounds having the general structurewhere X may either be a hydroxyl group or a substituted hydroxyl group. There may also be used as the source of the diene component a 1:2-, or a 1:3- disubstituted hydroxyl or halogen compound. In this modincstion, the diene yielding compound is substituted for the diene in the general reaction, and as the diene is formal its rests. In examples (1) dimethyl butadiene is reacted with hydroquinone monomethyl ether in the presence of mercuric chloride first on a water bath, and then on a wire gauze at 240‹ C. The reaction product is taken up in ether, washed with alkali and then with water. (2) Dimethyl butadiene is reacted with hydroquinone monomethyl ether in glacial acetic acid solution saturated with dry hydrogen chloride. The product is worked up as in example (1). (3) Trimethyl-hydroquinone is reacted with isoprene in glacial acetic acid solution in the presence of zinc chloride. The reaction product is poured into water and the other solid precipitate re-crystallized from alcohol. (4) Phytadiene is substituded for dimethyl butadiene in example (1), the reaction being otherwise similar. (5) Nerolidol which is the alkylic isomer of tetrahydrofarnesol may be substituted as a diene in any of the examples 1-4. A particular reaction of this compound with trimethyl hydroquinone in a mixed formic acid-acetic acid solution is described.