Hydrocyanation

The hydrocyanation is the chemical reaction of alkenes, alkynes, or carbonyl compounds with hydrogen cyanide to form nitriles. The reaction is catalyzed by homogeneous nickel catalysts and gives access to various organic intermediates, since a variety of different starting materials used and the nitrile group of the product easily into other functional groups (- CH2 - NH2 ,-COOH ) can be converted.

General catalytic cycle:

From the precatalyst NiL4, a tetrakis ( phosphite ) nickel ( 0) complex, first formed by ligand dissociation, the catalytically active species NiL2. This is followed by oxidative addition of HCN (1), the coordination of the olefin ( π - complex) ( 2), the insertion ( anti -Markovnikov ) (3) the reductive elimination and finally (4). Another ligand can also be bis-1 ,2- diarylphosphinit.

As a cocatalyst, the Lewis acids may be added. These accelerate the reaction and increase the proportion of linear product, as they coordinate to the nitrile group, thus increasing the steric hindrance at the metal atom.

Hydrocyanation is used on a large scale for the production of polyamides. DuPont is selected from butadiene and HCN using the catalyst Ni [( ArO ) 3 P ] 4 adiponitrile forth, then hydrogenation is carried out according to the reaction of hexamethylene diamine with adipic acid to nylon (polyamide 66).