Hydrogenation of Alcohols Hydrogenation of aldehydes

having the structure shown in Fig. 2, by hydrogenating the compound having structure given in Fig. 3, in the presence of copper chromite catalyst. Such mixtures are used in augmenting or enhancing the aroma of perfume compositions, colognes and perfumed articles including fabric softener compositions, cosmetic powders and solid or liquid anionic, cationic, non ionic and zwitteronic detergents. Giersch and Ohloff [84] discovered the bicyclic alcohol of formula as shown in the Fig. 4. The alcohol possesses a natural woody odour with an ambary character. The woody note is reminiscent in particular of cedar wood without however possessing the “sawdust” character of latter. The ambary note, on the other hand, is reminiscent of certain aspects presented by precious materials such as grey amber. Owing to their odour properties, the alcohols find an utilisation of wide scope, both in alcoholic perfumery and in technical applications such as, in the perfuming of soaps, powder or liquid detergents, fabric softeners, household materials, cosmetics, shampoos, beauty creams, body deodorizers or air fresheners. A process for the preparation of bicyclic aliphatic alcohols comprises the following reaction steps shown in Fig. 5 [84]: a the addition of ethyl methacrylate to mycrene under the conditions of a Diels Alder type reaction and the treatment of the resulting reaction mixture with an acidic cyclization catalyst; b the reduction of the obtained ester by Ni CuCr 2 O4 hydrogenation, and c the reduction of the resulting by means of a usual reduction reagent of the ester formation.

2.1.1.4 Hydrogenation of Alcohols

Long chain alcohols can be converted directly to N,N dimethylalkylamines by the reaction with dimethylamine at 36 C in the presence of of Cu Cr catalyst and hydrogen at elevated temperatures and pressure as shown by eqn. 4 [85,86]. Cu Cr RCH 2 OH + HNCH 3 2 → RCH 2 NCH 3 2 + H 2 O 4 H 2 Ethoxylated tertiary amines can be produced by the reaction of primary or secondary amines with ethylene oxide. The asymmetrical tertiary amines are used exclusively as starting materials for the manufacture of quaternary ammonium compounds, cationic and amphoteric surfactants, and amine oxides. Quaternary ammonium compounds used as bactericides and algaecides are produced by the reaction of tertiary amines with benzyl chloride, methyl chloride, or dimethyl sulphate. Of these, the benzyl ammonium chloride salt is the most widely used [87].

2.1.1.5 Hydrogenation of aldehydes

Copper chromium oxide catalyst is effective for the hydrogenation of aldehydes [88] at a temperature of 125 150 C. The hydrogenation of benzaldehyde over copper chromium gives a high yield of benzyl alcohol even at 180 C without hydrogenolysis [44] to give toluene eqn. 5. C 6 H 5 CHO + H 2 → C 6 H 5 CH 2 OH 5 Vapour phase hydrogenation of furfural over copper chromite catalyst is perhaps the best method of producing furfuryl alcohol [1,89]. Furfuryl alcohol is an important fine chemical for polymer industry. It is widely used in production of various synthetic fibres, rubbers, resins, e.g., dark thermostatic resins resistant to acids, bases and resins used for strengthening ceramics. It is also used as solvent for furan resin, pigment, varnish Copyright © 2011, BCREC, ISSN 1978 2993 Fig. 3. Compound formed by hydrogenation of 2 campholenylidenbutanol [83] Fig. 4. Bicyclic alcohol [84] Fig. 5. Preparation of bicyclic aliphatic alcohols [84] and as rocket fuel. Pramottana et al. [39] observed Cu as the active phase in the copper chromite particles for the selective hydrogenation of furfural to furfuryl alcohol.

2.1.1.6 Hydrogenation of ketone