Process for the manufacture of aliphatic aralkyl-ketones

摘要

In Example 2 phenyl-1 propene-2 is prepared by reaction between allyl chloride and phenyl magnesium bromide in absolute ether. The compound is then isomerized by refluxing with potassium hydroxide in methanol to yield phenyl-1 propene-1.ALSO:Aliphatic aralkyl ketones of formula where X1, X2 and X3 each represent a hydrogen atom, a linear or branched alkyl radical containing 1 to 5 carbon atoms, an aryl or aralkyl radical, an alkoxy radical containing 1 to 5 carbon atoms, a fluorine atom or a bifluoromethyl group or a chlorine atom; Y represents a hydrogen atom or an alkyl radical containing 1 to 5 carbon atoms, and Z represents a hydrogen atom or a linear or branched alkyl radical containing 1 to 5 carbon atoms are prepared by (a) reacting an organo-magnesium compound of the formula with an allyl halide to give a compound of the formula (b) isomerizing the compound of Formula III to give the compound of the formula (c) converting the compound of the Formula IV by reaction with an organic peroxide or with an organic compound containing a peroxy group to 1,2-diol of the formula and (d) converting the compound of Formula V into a ketone of the Formula I by heating it in the presence of an acid catalyst, in which formula X1, X2, X3, Y and Z have the meanings given above and Hal represents a chlorine, bromine or iodine atom. In step (a) the preferred allyl halide is allyl chloride and the reaction is preferably carried out in an anhydrous solvent at 0 DEG to 80 DEG C. Step (b) is preferably carried out by an alkaline agent in a solvent at the solvent's reflux temperature. The preferred organic compound containing a peroxy group used in step (c) is performic acid, the reaction preferably being carried out in an aqueous medium. The preferred temperature range for step (d) is 100 DEG to 160 DEG C. and the preferred acid catalyst is an arylsulphonic acid. Examples describe the preparation of (metatrifluoromethyl - phenyl) 1 - - propan - 2 - one, phenyl - 1 - propan - 2- one, (p - fluorophenyl)-1-propan-2-one and (p-chlorophenyl)-1-propan-2-one. Intermediates formed in the examples are: Example 1 (meta - trifluoromethyl) -phenyl-3-propene and its -1-propene isomer and meta - trifluoromethyl) - phenyl - propane-1,2 diol; Example 2: phenyl-1 diol-1,2; Example 3: (p-fluorophenyl)-1 propene-2 and its -propene-1 isomer and (p-fluorophenyl)-1 propane - diol - 1,2; Example 4: (p-chlorophenyl)-1 propene-2 and its -propene-1 isomer and (p-chlorophenyl)-1 propane diol-1,2.