GB693407A - Improvements in and relating to the partial hydrogenation of polyunsaturated organiccompounds - Google Patents

Abstract

Unsaturated organic compounds are produced by reacting a polyunsaturated organic compound, i.e. an organic compound with a plurality of double or triple bonds between carbon atoms, at least one such double or triple bond being other than a double bond in an aromatic ring and in which none of the carbon atoms between the said double or triple bonds is attached to four carbon atoms, with hydrogen at elevated temperature in the presence of a molybdenum sulphide catalyst formed by reduction of a higher molybdenum sulphide. Preferably a support or carrier for the molybdenum sulphide catalyst is used, e.g. alumina, silica gel, pumice, diatomite, activated charcoal, activated clays and silica alumina complexes. Promoters for the alumina, e.g. silica, may be used and the alumina may be treated with an acid or acid salt. Preferably the selective hydrogenation of the unsaturated compounds is carried out in the liquid phase and may be carried out at atmospheric or superatmospheric pressure. The process may be performed at 100-200 DEG C. and preferably excess hydrogen is used. In the examples: (a) limonene, (b) 1,5-hexadiene, (c) myrcene, (d) 1,3-cyclohexadiene are hydrogenated to give unsaturated products containing only one double bond. Other polyolefinic hydrocarbons which may be reduced to the mono-olefins are, for example, the hexadienes, isoprene, piperylene, cyclohexadiene, methyl cyclohexadiene, dipentene and terpinene. Compounds having an acetylenic and an olefinic group, e.g. vinyl acetylene, may also be reduced to the mono-olefin. Polyolefinic acids, alcohols, esters, ethers, ketones, aldehydes, amines, nitro compounds, halides, sulphides and mercaptans may also be reduced to the corresponding mono-olefinic compounds, e.g. sorbic acid may be converted to 3-hexenoic acid, geraniol to the corresponding decylenol and phorone to isobutenyl isobutyl ketone. Further examples of the process are the reduction of styrene to ethyl benzene, a -propenyl benzene to propyl benzene, indene to indane and vinyl thiophene to ethyl thiophene. Specification 589,915 is referred to.ALSO:A catalyst for use in the production of unsaturated organic compounds by reacting a poly-unsaturated compound with hydrogen consists of molybdenum sulphide formed by the reduction of a higher molybdenum sulphide. Preferably a support or carrier, e.g. alumina, for the catalyst is used. A promoter for the alumina, e.g. silica is advantageous. Other carriers which may be used are silica gel, pumice, diatomite, activated charcoal and activated acid-treated clays. The preferred catalysts are prepared by reducing the initially produced higher sulphides of molybdenum to the disulphide. The higher sulphide may be reduced with hydrogen or decomposed by heating an in inert atmosphere. In the examples the catalyst is prepared by impregnating an alumina carrier containing about 5 per cent of silica with ammonium molybdate solution. The mixture is dried and ground, treated with hydrogen sulphide and reduced with hydrogen in a fluidized fixed-bed treater. Specification 589,915 is referred to.