Acrylonitrile hydroformylation

The hydroformylation of unsaturated nitriles such as crotonitrile and allyl cyanide is a potential route towards chiral amino alcohols, which are building blocks in the synthesis of pharmaceuticals. The hydroformylation of acrylonitrile was studied in the early years [5], but lately the hydroformylation of allyl cyanide and crotonitrile have also been investigated [25,81]. 

Acrylonitrile has now been successfully hydroformylated (76). The j3-cyanopropionaldehyde which was formed, polymerized unless the cobalt carbonyls were decomposed before work-up. Yields were highest in Lewis base solvents, which were said to suppress reduction of acrylonitrile and give higher rates of hydroformylation than hydrocarbon solvents. 

Hydroformylation of acrylonitrile (75) and of fluoroolefins (133) also suffer from hydrogenation as a serious side reaction. 

To simulate the effects of reaction kinetics, mass transfer, and flow pattern on homogeneously catalyzed gas-liquid reactions, a bubble column model is described [29, 30], Numerical solutions for the description of mass transfer accompanied by single or parallel reversible chemical reactions are known [31]. Engineering aspects of dispersion, mass transfer, and chemical reaction in multiphase contactors [32], and detailed analyses of the reaction kinetics of some new homogeneously catalyzed reactions have been recently presented, for instance, for polybutadiene functionalization by hydroformylation in the liquid phase [33], car-bonylation of 1,4-butanediol diacetate [34] and hydrogenation of cw-1,4-polybutadiene and acrylonitrile-butadiene copolymers, respectively [10], which can be used to develop design equations for different reactors. 

From 1974 onwards the scope of different reactions using biphasic catalyst systems, preferably with precious metals, was tested in laboratory-scale experiments. Among these were butadiene hydrodimerization, hydrogenation of acrylonitrile or cyclohexene, hydroformylation of propene, and some other conversions to fine... 

Some recent patents describe improvements to existing processes. Addition of dialkylaluminium hydrides to conventional hydroformylation catalysts gave an increased yield of linear products from internal alkenes, Co/porphyrin catalysts were shown to hydroformylate acrylonitrile, addition of R2P(0)H gave higher conversions in undecene hydroformy-lation, acetal yield was improved by addition of quaternary ammonium salts and the stability of phosphine-modified Co catalysts was improved by addition of arylalkylsulphonate salts. ... 

Hydroformylation of acrylonitrile Co-carbonyl complex NC-(CH2)-CH0—an intermediate in sodium glutamate synthesis Bott i et al. (1987)... 

The technical Co-catalyzed hydroformylation-acetalization of acrylonitrile with methanol has been claimed by Dow [60]. It was found that the addition of a basic promoter, such as HN(CH2CN)2, enhances the product selectivity with Co2(CO)g as catalyst at 100 at syngas and 100 C. Alternatively, quaternary ammonium salts, such as N-benzyl-MdVdV-trimethylammonium methoxide, have been suggested to increase the rate of the reaction with long-chain olefins [61]. Up to 90% yield of acetal was noted at 100% conversion of the olefin. Sn[Co(CO)4]4 is an efficient catalyst for the hydroformylation-acetalization of 1-hexene [62]. It was proven that the acetalization reaction is mediated by the Lewis-acidic Sn moiety. 

Conjugated and unconjugated unsaturated nitriles are both susceptible to hydroformylation. Few examples are found in the literature and most of the work has been with acrylonitrile (table 21). The aldehyde group is incorporated mainly in the -position, but the reaction is strongly solvent dependent and byproducts are frequently produced, mainly propionitrile, acrolein, propyl amine and ammonia (see also ref. [972, 973] and [985]). 

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