Catalysis Database

Selective hydrogenation of unsaturated aldehydes and ketones

S , Narayanan (2003) Selective hydrogenation of unsaturated aldehydes and ketones. Bulletin of the Catalysis Society of India, 2 . pp. 107-121.

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Abstract

Selective hydrogenation of α, β unsaturated aldehydes, ketones and esters, in general, is useful in perfumery, hardening of fats, drugs and in synthesis of organic chemical intermediates. This is an important and interesting area of research especially if there are two or more C=C bonds. The reaction becomes challenging in olefinic compounds having functional groups, since the hydrogenation of C=C is thermodynamically more favourable than C=O or CHO. The product selectivity depends on stereo-chemistry as well as the preferential hydrogenation of either the C=C or the functional group. The selectivity for α, β unsaturated alcohol is not easy and requires specific reaction conditions and catalyst system. Chemeoselective hydrogenation catalysts are mostly based on supported metals involving Pt, Ru, Rh and Pd. The physico-chemical properties of a support, its acid-base character, metal reducibility and the extent of metal-support interaction play an important role in the complex chemistry of supported metal catalysts. It is therefore important to understand the supported catalysts and its preparation from the point of view of support. Mixed basic layered hydroxides for example, Hydrotalcite (HT) types of materials are being tried as novel supports in place of conventional oxides. The advantage in using HT type material is the layered structure with specific Mg2+/Al3+ ratios and basic characteristics. Metals can be incorporated during synthesis (in situ synthesis) of the layered oxides or following post synthesis procedures. Synthesis of basic support itself is an interesting and challenging job. It will be useful to study the nature of metal species present on the support from the point of view of reduction characteristics, dispersion and metal support interaction. A few simple and complex hydrogenation reactions are discussed to highlight the usefulness of hydrotalcite and metal - hydrotalcite systems. Conversion and selectivity of products are compared with the conventional catalyst systems.

Item Type:Article
Subjects:Science > Chemistry
ID Code:185
Deposited By:INVALID USER
Deposited On:28 Feb 2007 16:52
Last Modified:20 Mar 2007 21:47

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