Linear Relationship between Activity of a New Ru-catalyst and Acidity of Substituted Benzoic Acids in the Dimerization of Acrylonitrile

Abstract

A new type of catalyst system using ruthenium and carboxylic acid is useful for the tail-to-tail dimerization of acrylonitrile, proceeding without the formation of undesired by-product propionitrile. Carboxylic acids having pKa 3.5–5 are suitable as co-catalysts for the dimerization of acrylonitrile. The relationship between the logarithm of the relative rate in the dimer formation and the pKa of m- and p-substituted benzoic acids (Brønsted plot) was linear (R2 = 0.946) with a slope of −0.199. The role of the carboxylic acids can be considered to be effective protonation in the protonolysis of the carbon–ruthenium bond of an intermediate Ru complex.

Catalytic Approaches to Monomers for Polymers Based on Renewables

“…Synthetic procedures also exist where acrylonitrile is directly converted to adiponitrile. , One efficient way to perform this reaction is by using CoI 2 (PPh 3 ) 2 as catalyst and Zn/H 2 O as the reducing agent . Alternatively, this can be performed via two steps: first the dimerization of acrylonitrile to 1,4-dicyanobutene (with a ruthenium catalyst), , and further hydrogenation of the alkene to adiponitrile in the presence of a rhodium or palladium catalyst (Scheme ). , …”

“…454,455 One efficient way to perform this reaction is by using CoI 2 (PPh 3 ) 2 as catalyst and Zn/H 2 O as the reducing agent. 454 Alternatively, this can be performed via two steps: first the dimerization of acrylonitrile to 1,4-dicyanobutene (with a ruthenium catalyst), 456,457 and further hydrogenation of the alkene to adiponitrile in the presence of a rhodium or palladium catalyst (Scheme 68). 458,459 Diaminoisomannide (DAM5) is a renewable C6 diamine which can be prepared via catalytic routes.…”