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The first-generation Grubbs metathesis catalyst (PCy3)2Ru(CHPh)(Cl)2 (1) was reacted with primary alcohols at 70 °C to give the monohydride species (PCy3)2(CO)Ru(Cl)(H) (4) in ∼20% yield. Addition of either an inorganic or organic base greatly facilitated the formation of the hydride, and 4 could be isolated in >70% yield in the case of 1-propanol and triethylamine. Analysis of the reaction products and labeling experiments revealed that 4 was formed via a noncatalytic alcohol dehydrogenation pathway. When benzyl alcohol was used, (PCy3)2(CO)Ru(Cl)(Ph) (5) was formed, this also being one of the products of the decomposition of 1 by oxygen in both solid and solution states. Complexes 4 and 5 were found to be active and selective alkene double-bond isomerization catalysts.

Reaction of the second‐generation Grubbs metathesis catalyst [RuCl2(=CHPh)(H2IMes)(PCy3)] (2) (H2IMes = 1,3‐dimethyl‐4,5‐dihydroimidazol‐2‐ylidene) with primary alcohols in the presence of a base produced the complexes [RuClH(CO)(PCy3)2] (3) and [RuClH(CO)(H2IMes)(PCy3)] (5). When benzyl alcohol was used, the ruthenium phenyl complexes [RuClPh(CO)(PCy3)2] (4) and [RuClPh(CO)(H2IMes)(PCy3)] (7) were formed in addition to 3 and 5. Complex 7, characterised by an X‐ray structure analysis, was also formed on exposure of 2 to oxygen. The isomerization and hydrogenation activity of 7 was determined and compared with that of 3 and 4. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

The metathesis of natural oils and fats and their derivatives is a clean catalytic reaction that can be considered as an example of green chemistry. Using this reaction, oleochemical feedstocks can be converted into valuable chemical products, directly or in only a few reaction steps. With the development of catalysts that are active and highly selective under mild reaction conditions, there are favourable perspectives for the application of the metathesis reaction in the oleochemical industry.

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