Patent GB-1007828-A (GB)
Title: Cyclohexadiene derivatives
IPC: C07C45/65
Filed: 1962-06-20
Abstract: Conjugated cyclohexadienes of the formula <FORM:1007828/C4-C5/1> in which at least one of X and Y is aryl or C8-C12 aralkyl or alkaryl are obtained by dehydrohalogenation of a 3-halo-4-cyclohexene having an aryl, aralkyl or alkaryl radical in the 1- and/or 2-position, by treatment with an alkali.  In an example 1-phenyl-1, 3-cyclohexadiene is prepared by heating with potassium hydroxide 3-bromo-2-phenylcyclohexene-4.ALSO:Conjugated cyclohexadienes of a general formula <FORM:1007828/C2/1> wherein X and Y are the same or different and are hydrogen atoms, -COOH radicals, -COOR radicals wherein R is an alkyl or an aryl group, -CN, -CHO, radicals -RCO wherein R is an alkyl or an aryl group, haloalkyl radicals having from 1 to 8 carbon atoms, or aryl, or aralkyl or alkaryl radicals having from 8 to 12 carbon atoms, are produced by dehydrohalogenating by treatment with an alkaline substance, e.g. potassium hydroxide a 3-halo-4-cyclohexene, e.g. 3-chloro-4-cyclohexene substituted in at least one of the positions 1 and 2 of the hexene nucleus by carboxylic, carboxylic anhydride, carboxylic ester, cyano, keto, aldehyde, dioxolan, haloalkyl, aryl, alkaryl or aralkyl groups. The 2,4-cyclohexadiene-1,2-dicarboxylic acids produced may be converted to the corresponding anhydride, e.g. by refluxing acetic anhydride or to the half ester or di-ester.  In example, 2,4 - cyclohexadiene - 1 - 2 - dicarboxylic acid is prepared by treating with alcoholic potassium hydroxide 3 - chloro - 4 - cyclohexene - 1,3 - dicarboxylic anhydride obtained by reacting trans - 1 - chloro - butadiene with maleic anhydride. In another example the Diels-Alder adduct of 1-chlorobutadiene and dibutyl maleate was treated with alcoholic potassium hydroxide to produce dibutyl - 2,4 - cyclohexadiene - 1,2-dicarboxylate. In other examples, 1,3-cyclohexadiene-1-nitrile is obtained from 2 chloro-3-cyclohexene (produced by reacting 1 chlorobutadiene and acrylonitrile); 1,3-cyclohexadienyl methyl ketone from 2-chloro-3-cyclohexene (produced by reacting 1-chlorobutadiene and acrylonitrile); 1,3-cyclohexadienyl methyl ketone from 2-chloro-3-cyclohexene (produced by reacting 1-chlorobutadiene and acrylonitrile; 1,3-cyclohexadienyl methyl ketone from 2-chloro-3-cyclo-hexenyl-1 methyl ketone (produced by reacting 1-chlorobutadiene with methyl vinyl ketone).  In the above examples, 1-bromo or 1-iodo may be used instead of 1-chlorobutadiene-1,3. In other examples, 1,3-cyclohexadiene - 1 - carboxaldehyde is obtained from 2 - (2 - chloro - 3 - cyclohexenyl)-dioxolan obtained by reacting p-toluene sulphonic acid with 2-chlorocylohex-3-ene-1-carboxaldehyde (produced by reacting 1 chlorobutadiene with acrolein); 2-benzoyl 2,4-cyclohexadiene from phenyl 2-chloro-3 cyclo hexenyl ketone (produced by reacting 1-chlorobutadiene with acrylophenone); 1-trifluoromethyl-2-4-cyclohexadiene from 1-trifluoromethyl-2 chloro 3-cyclohexene (produced by reacting 1-chlorobutadiene and 1,1,1-trifluoropropene); 6-(4-methylphenyl) - 2,4 - cyclohexadiene - 1 - carboxylic acid from 2-chloro-6-(4-methyl-phenyl)-3-cyclohexene carboxylic acid (produced by reacting 1 - chlorobutadiene and 4 - methyl cinnanic acid).