Abstract: 1,5-Dimethyl-hexa-1,5-dienylene compounds, and especially Vitamin A and derivatives thereof, are made by desuphonylating with a basic reagent a sulphone of the formula: ##STR1## in which the sulphonyl group --SO.sub.2 R replaces a hydrogen atom on carbon atom (a) or (b), R represents a phenyl or napthyl group, A is 2-(2,6,6-trimethylcyclohex-1-enyl)ethenyl, and Q is --CH.sub.2 OH or an ether or ester thereof, CHO, or an acetal group.

Abstract: Sulphones useful for preparing polyenes have the formula: ##STR1## where the sulphonyl group replaces a hydrogen atom on carbon atom (a) or (b), R represents alkyl, aralkyl or aryl, optionally substituted, A and Q represent an optionally substituted hydrocarbon of 5n+1 carbon atoms (n is 1-5), methyl, optionally substituted by halogen, sulphide or sulphone, CH.sub.2 OH (or an ether or ester thereof), CHO (optionally protected), COOH (or an acid chloride, ester or nitrile thereof), with the proviso that when A represents a 2-(2,6,6-trimethylcyclohex-1-enyl) ethenyl radical, Q cannot represent --COOH or an ester thereof.

Abstract: Sulphones useful for preparing polyenes have the formula: ##STR1## where the sulphonyl group replaces a hydrogen atom on carbon atom (a) or (b), R represents alkyl, aralkyl or aryl, optionally substituted, A and Q represent an optionally substituted hydrocarbon of 5n+1 carbon atoms (n is 1-5), methyl, optionally substituted by halogen, sulphide or sulphone, CH.sub.2 OH (or an ether or ester thereof), CHO (optionally protected), COOH (or an acid chloride, ester or nitrile thereof), with the proviso that when A represents a 2-(2,6,6-trimethylcyclohex-1-enyl) ethenyl radical, Q cannot represent --COOH or an ester thereof.

Abstract: Sulphones of the formula:RSO.sub.2 CH.sub.2 CX.dbd.CYCH.sub.2 OR.sub.1where R is alkyl, aralkyl, alkylaryl or aryl, R.sub.1 is hydrogen or -COR.sub.2 where R.sub.2 is hydrogen, alkyl or aryl, and one of X and Y is methyl and the other is hydrogen are useful for converting terpene and carotenoid compounds into the immediately higher isoprenologue, useful as perfumes, foodstuff dyes, and pharmaceuticals.

Abstract: Sulphones of the formula: ##STR1## in which R is a substituted or unsubstituted alkyl, alkylaryl, aralkyl, or aryl radical, A is a radical containing one or more isoprene units which is saturated, unsaturated, or of the conjugated or unconjugated polyene type, which is unsubstituted or substituted by one or more functional groups, halogen atoms or alkyl groups, and which may be cyclic when the number of isoprene units is at least 2, and Q is hydrogen or a cyclic or acyclic hydrocarbon radical which is saturated, unsaturated, or of the conjugated or unconjugated polyene type, and which is unsubstituted or substituted by one or more functional groups, halogen atoms or alkyl groups are useful intermediates in the production of terpene compounds such as .beta.-carotene and canthaxanthine.

Abstract: Sulphones of the formula: ##STR1## in which R is a substituted or unsubstituted alkyl, alkylaryl, aralkyl, or aryl radical, A is a radical containing one or more isoprene units which is saturated, unsaturated, or of the conjugated or unconjugated polyene type, which is unsubstituted or substituted by one or more functional groups, halogen atoms or alkyl groups, and which may be cyclic when the number of isoprene units is at least 2, and Q is hydrogen or a cyclic or acyclic hydrocarbon radical which is saturated, unsaturated, or of the conjugated or unconjugated polyene type, and which is unsubstituted or substituted by one or more functional groups, halogen atoms or alkyl groups are useful intermediates in the production of terpene compounds such as .beta.-carotene and canthaxanthine.

Abstract: Sulphones of formula QSO.sub.2 CH.sub.2 CY=CY.sub.1 CH.sub.2 CHRR.sub.1 wherein one of Y and Y.sub.1 is hydrogen the other methyl, R and R.sub.1 are CHO, COR.sub.2, COOH, COOR.sub.3, CONR.sub.5 R.sub.5, CN, SO.sub.2 R.sub.4, SO.sub.3 R.sub.5 and NO.sub.2, wherein R.sub.2 -R.sub.5 are alkyl or aryl and R.sub.5 can be hydrogen, and Q is alkyl, substituted alkyl, aryl, aralkyl or alkaryl or optionally substituted, optionally unsaturated terpene of 5n carbon atoms (n being 1-9), but excluding 2- or 3-methylbutadienyl and 2-butadienylmethyl, are intermediates for preparing terpenes.