Verfahren zur Herstellung von gamma,delta-ungesaettigten Aldehyden oder Ketonen

摘要

The invention comprises g ,d -unsaturated aldehydes having at least 8 carbon atoms of the formula in which R1 is a saturated or unsaturated aliphatic group (which may carry a free, esterified or etherified hydroxyl group), an aralkyl group or an aryl group, R2 is a saturated or unsaturated aliphatic group containing 1-8 carbon atoms, or R1 and R2 together may form a carbocyclic group with the carbon atom to which they are attached; R3 is a hydrogen atom or a saturated or unsaturated aliphatic group containing 1-8 carbon atoms and R4 is hydrogen or a saturated or unsaturated aliphatic group containing 1-8 carbon atoms; and 2-[31 - methyl - 21 - butenyl - (1)] - cyclohexanone. The aldehydes and ketones of formula in which R5 is hydrogen or a saturated or unsaturated aliphatic group containing 1-8 carbon atoms or forms a carbocyclic group with C4, may be prepared by heating a tertiary allyl alcohol of formula with either an enol ether of the formula CH(R4) = C(R5)-OR6 or an acetal or ketal of the formula in which R6 is an alkyl group, in the presence of an acidic catalyst. The esterified hydroxy groups referred to include acyloxy groups in which the acyl group is derived from an aliphatic or aromatic carboxylic and the preferred etherified groups are alkoxy groups containing 1-8 carbon atoms and aryloxy groups. The preferred acidic catalyst is phosphoric acid but other suitable catalysts are sulphuric acid, oxalic acid, trichloracetic acid, paratoluene sulphonic acid, potassium bisulphite, boron-trichloride, boron trifluoride and zinc chloride. The preferred temperature range for the process is 120-200 DEG C. The process may be carried out in the presence of a solvent, e.g. hexane, cyclohexane, iso-octane, benzene, toluene, petroleum ether, and ligroin.