Crotonaldehyde hydration

Butyrchloral has been prepared by chlorination of acetaldehyde 2 and of paraldehyde. Butyrchloral hydrate has been prepared by treatment of a,j8-dichlorobutyraldehyde with chlorine and water.3 Butyrchloral has also been prepared4 by treatment of crotonaldehyde with hydrogen chloride followed by chlorination. Brown and Plump have used a procedure similar to the one described here.3... 

Girard-T derivatives of chloroacetaldehyde, crotonaldehyde, and acrolein were not stable. Alternative methods were developed based upon the derivative formed by reaction of crotonaldehyde with hydroxylamine, and the formation of the hydrate of chloroacetaldehyde. 

Rhone-Poulenc operates another biphasic process, the hydrogenation of a, 8-unsaturated aldehydes (64). The catalyst is readily made from hydrated RuC13 and tppts in water. The hydrogenation of various reactants (cinna-maldehyde, crotonaldehyde, or prenal) proceeds smoothly at low temperatures and under moderate partial pressures. It is possible to recycle the aqueous catalytic phase. The process is said to operate in a pilot plant, but the capacities are not known. 

CM reactions with terpenoids containing two double bonds such as citronellene are hampered by low yields because of RCM competition among other side reactions. Mauduit et al. performed the CM of several terpenoids with n-butyl acrylate and crotonaldehyde using Hoveyda-Grubbs type catalysts containing an aminocarbonyl function [89]. Yields below 43% were obtained in all cases with 1 mol% catalyst. In contrast to these results, the hydrated masked form of citronellene, i.e., dihydromyrcenol, gave 71% yield of the CM product. It was thus proposed that in order to avoid selectivity problems in the CM of terpenoids containing two double bonds, masked derivatives can be used followed by a simple elimination step to recover the olefin functionality. 

The models described above assume that the reaction occurs only in the liquid phase. In some cases, such as isomerization of cyclopropane to propylene on a silica-alumina catalyst,43 reduction of crotonaldehyde over a palladium catalyst,45 and hydration of olefins to alcohols over tungsten oxide,58 the reactions could occur in the gas as well as in the liquid phases. 

Most acetone is manufactured today in the United States by thermochemical cumene oxidation. It is a co-product with phenol. Acetone is also manufactured by dehydrogenation of 2-propanol, which is made by hydration of propylene. Most 1-butanol is manufactured today by hydrogenation of n-butyraldehyde, which is obtained by the hydroformylation of propylene (0x0 reaction). It is also manufactured by hydrogenation of crotonaldehyde, which is obtained by the... 

The unexpectedly low K value of crotonaldehyde can be easily explained on the basis of electronic effects, excepting for the observation that its rate of hydration is considerably greater than those of crotonic acid or of propene. A mechanism involving proton attack upon the ethylenic bond would require the sequence of reactivity... 

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