Patent GB-1529619-A (GB)
Title: Process for the preparation of unsaturated alcohols
IPC: C07C41/00
Filed: 1976-11-02
Abstract: 1529619 α,# - Unsaturated alcohols RHONEPOULENC INDUSTRIES 2 Nov 1976 [3 Nov 1975] 45559/76 Heading C2C A process for the preparation of an α,#- ethylenic alcohol of the general formula comprises hydrogenation of an α,#-ethylenic aldehyde of the general formula in a liquid solvent in the presence of a platinumbased catalyst, prepared by prior reduction with hydrogen, of platinum, used in metallic form or in the form of a platinum-based compound, at a temperature of at least 50 C., wherein R 1  is hydrogen, or (a) a linear or branched alkyl radical having from 1 to 8 carbon atoms; or (b) an alkoxy radical containing 1-4 carbon atoms or (c) a cycloalkyl or cycloalkenyl radical containing from 5 to 6 ring carbon atoms and, when unsaturated, 1 or 2 ethylenic double bonds, the radical optionally being substituted by 1 to 3 alkyl or alkoxy radicals each containing 1-4 carbon atoms or (d) an aryl radical containing 1 benzene nucleus or 2 fused benzene nuclei, and optionally substituted by 1 to 3 alkyl or alkoxy radicals each containing 1-3 carbon atoms; or (e) an aralkyl radical containing from 1 to 2 carbon atoms in the alkyl radical and 1 benzene nucleus or 2 fused benzene nuclei in the aryl radical; R 2  and R 3 , which may be the same or different, each is hydrogen; or (a) a linear or branched alkyl radical containing 1 to 30 carbon atoms and optionally substituted by alkoxy radicals containing 1-4 carbon atoms, cycloalkyl or cycloalkenyl radical containing 5 to 8 ring carbon atoms (which radicals can optionally carry 1 to 3 alkyl, alkoxy or alkenyl radicals each containing up to 4 carbon atoms), or a heterocyclic radical with 5 or 6 ring atoms and optionally having 1 or 2 double bonds); or (b) an alkoxy radical containing 1-4 carbon atoms; or (c) a linear or branched alkenyl radical containing from 2 to 30 carbon atoms and from 1 to 12 conjugated or non- conjugated ethylenic double bonds, these radicals optionally being substituted by alkoxy radicals containing 1-4 carbon atoms or by cycloalkyl, cycloalkenyl or heterocyclic radicals, as defined under (a) above; or (d) a cycloalkyl or cycloalkenyl radical containing from 5 to 8 ring carbon atoms and, when unsaturated ,1 or 2 ethylenic double bonds, these radicals optionally being substituted by 1 to 3 alkyl, alkoxy or alkenyl radicals each containing 1-4 carbon atoms; or (e) an aryl radical containing 1 or 2 fused or non-fused benzene nuclei, these radicals optionally being substituted by 1 to 3 alkyl, alkoxy or alkenyl radicals each containing 1-4 carbon atoms; or (f) an aralkyl radical containing 1 to 5 carbon atoms in the alkyl radical and 1 benzene nucleus or 2 fused or non-fused benzene nuclei, the benzene nucleus or nuclei optionally being substituted by 1 to 3 alkyl, alkoxy or alkenyl radicals each containing 1-4 carbon atoms; or (g) a heterocyclic radical with 5 or 6 ring atoms and optionally having 1 or 2 double bonds, the radicals being optionally substituted by 1 or 2 alkyl or alkoxy radicals each containing 1-4 carbon atoms; or wherein R 2  or R 3  form, with R 1  and the carbon atoms to which R 1  and R 2  or R 1  and R 3  are bonded, an aliphatic hydrocarbon ring containing from 5 to 7 ring carbon atoms and 1 or 2 ethylenic double bonds, the ring optionally being substituted by 1 to 3 alkyl or alkoxy radicals containing 1-4 carbon atoms; or wherein R 2  or R 3  form, with R 1  and the carbon atoms to which R 1  and R 2  or R 1  and R 3  are bonded, a heterocyclic ring with 5 or 6 ring atoms and containing 1 or 2 double bonds, and at least one hetero-atom which is oxygen, sulphur or nitrogen; or wherein R 2  and R 3  together with the carbon atom to which they are bonded, form an aliphatic hydrocarbon ring containing 5-7 ring carbon atoms and 1 or 2 ethylenic double bonds, the ring optionally being substituted by 1-3 alkyl or alkoxy radicals containing 1-4 carbon atoms. The hydrogenation of cinnaraldehyde and of citral is exemplified, and a number of other suitable aldehydes of the above general formula are listed in which substituents are alkyl, alkenyl, alkylene, cyclohexyl, cyclohexenyl, phenyl, methoxy and furyl groups. The catalyst may be recycled for further use.