Patent GB-1059386-A (GB)
Title: Hydrogenation of carbon-carbon multiple bonds in the liquid phase
Inventor: BECK FRITZ
IPC: C07C5/08
Filed: 1964-05-05
Abstract: Unsaturated hydrocarbons are selectively hydrogenated in a liquid containing hydrogen ions and in the presence of a finely-divided metallic catalyst, the electrochemical hydrogen reference potential being measured during hydrogenation and the hydrogenation being stopped when the change in the reference potential with respect to time reaches or approximates to a maximum value at the prevailing pH value.  Hydrogenation is carried out either by saturating the catalyst with hydrogen in a shaker prior to the addition of the organic compound, or the organic compound/catalyst mixture is put into an autoclave and the hydrogen forced in.  For suitable catalysts, solvents, electrolytes and buffers (see Division B1). Examples of suitable unsaturated compounds are cyclic, mono- or polyunsaturated hydrocarbons, particularly cycloolefins and cyclo-diolefins with 5-12 C atoms, phenylacetylene; 1,3,5-triethinyl benzene, cyclohexene, cyclooctadiene. The following hydrogenations are exemplified.  Example 3, one double bond in cyclooctadiene, and cyclohexene; Example 10, phenylacetylene to phenylethylene (i.e. styrene).ALSO:The electrochemical hydrogen reference potential is measured during the hydrogenation of C-C multiple bonds in organic compounds in a liquid containing hydrogen ions and in the presence of a finely divided metallic catalyst, and selective hydrogenation is effected by stopping the hydrogenation when the change in the reference potential with respect to time reaches or approximates to a maximum value at the prevailing pH value.  Hydrogenation is carried out either by saturating the catalyst with hydrogen in a shaker prior to the addition of the organic compound, or the organic compound/catalyst mixture is put into an autoclave and the hydrogen forced in.  For suitable catalysts, solvents, electrolytes and buffers (see Division B1).  Compounds that may be hydro-genated are aralkyl compounds having acetylenic side chains, particularly those having a benzene radical and one to three side chains each having a triple bond, the side chains containing from 2-6 C atoms; acetylene alcohols, particularly acetylene alcohols with 3-16 C atoms, 1-2 triple bonds and 1-2 hydroxy groups; olefine alcohols with 3-16 C atoms, 2-3 double bond and 1-2 hydroxy groups; esters of these acetylene or olefine alcohols with lower fatty acids with 1-4 C atoms; vinyl esters; olefinically and acetylenically unsaturated carboxylic acids, particularly acetylene carboxylic acids with one to two acid groups and 3-10 C atoms; olefine carboxylic acids with 1-3 double bonds, 1-2 carboxylic groups and 3-12 C atoms; derivatives of these acids, e.g. esters of lower alcohols with 1-4 C atoms in each alkyl; unsaturated ketones, e.g. alkylalkenyl ketones and alkylalkinyl ketones with 1-6 C atoms in the alkyl and 2-6 C atoms in the unsaturated radical.  Preferred compounds are named.  The following hydrogenations are exemplified Ex. 1 the triple bond in 2-butinediol-(1,4) to a double bond; Ex. 2 the terminal double bond in linalool; Ex. 4 the triple bond in 1,1,4,4 - tetramethyl - 2 - butinediol - (1,4) to a double bond; Ex. 5 dimethyl ethinyl carbinol to dimethylvinyl carbinol; Ex. 6-9 (1,4)-butinediol to butenediol; Ex. 12 one double bond in farnesylacetone; Ex. 13 acetylene dicarboxylic acid to ethylene dicarboxylic acid.