| 摘要 |
1-Hepten-4-yne is obtained by reacting butyne with magnesium ethyl bromide and reacting the resulting compound with allyl bromide in the presence of cuprous chloride.ALSO:Aliphatic aldehydes having an unbranched carbon chain containing 5-12 carbon atoms and a double bond in the b -g position with cis-configuration, are used as flavouring agents for alcoholic and non-alcoholic beverages. The aldehydes may be mixed with ionone derivatives and, if desired, 4-p-hydroxyphenyl/-butan-2-one and the resulting compositions may be used for importing a raspberry flavour to beverages.ALSO:The invention comprises aliphatic aldehydes having a straight carbon chain containing 5-12 carbon atoms and an ethylenic double bond in the b -g position. They may be made by (a) hydrolysing a 1-alkoxy-1,3-cis-alkadiene, having 5-12 carbon atoms in the alkadienyl group or a 1,1-dialkoxy-cis-3-alkene in which the alkenylidene group contains 5-12 carbon atoms, by treating it with an acid catalyst in a homogeneous organic-aqueous medium, the acidity, the reaction temperature and the duration of the reaction being adjusted in such a manner that the speed of isomerization of the formed b ,g -unsaturated aldehyde is lower than the speed of the hydrolysis reaction, or (b) by the oxidative scission of a cis-alkene-diol of formula R-CH2-CH=CH-CH2-CHOH-CHOH-R in which R represents hydrogen or an unbranched C1-C7 alkyl group and R1 represents hydrogen or a cis-2-alken-1-yl group containing 4-11 carbon atoms, the diol being symmetric when R1 is a cis-2-alken-1-yl group. The hydrolysis step in (a) may be carried out by dissolving the starting material in acetic acid and adding water at such a rate that the mixture remains homogenous. The oxidative scission in (b) may be carried out by treatment with sodium metaperiodate in water or lead tetraacetate in aqueous acetic acid. The starting 1,1-dialkoxy-cis-3-alkane used in (a) above may be obtained by the action of an alkanol on a 1-alkoxy-1-alkene-3-yne, containing 5-12 carbon atoms in the alkenylnyl group, in the presence of a basic catalyst and partial reduction of the triple bond of the 1,1-dialkoxy-3-alkyne so obtained by means of catalytic hydrogenation. The cis-alkene-diol used as the starting material in (b) above may be obtained by hydroxylation of an alkenylyne of the formula R-CH2-C=C-CH2-CH=CH-R2 in which R has the meaning given above and R2 is H or a 2-alkyn-1-yl group containing 4-11 carbon atoms, the alkenylyne being symmetric in the case where R2 is a 2-alkyn-1-yl group, and by semi-reduction of the resulting diol. The hydroxylation may be carried out by means of a solution of performic acid in concentrated formic acid and the reduction by catalytic hydrogenation. Examples are given of the preparation of cis-3-hexen-1-al, cis-3-penten-1-al, cis-3-nonen-1-al, cis-3-dodecen-1-al, cis-3-hepten-1-al, cis-3-octen-1-al and cis-3-undecen-1-al.ALSO:Aliphatic aldehydes having an interacted carbon chain containing 5-12 carbon atoms and a double bond with cis-configuration in the b ,g -position may be used in perfume compositions. |
