The Reaction Network of the Base-Catalyzed Homogeneous Hydration of Acrylonitrile in Liquid Phase

Abstract

Both reaction network and selectivity on homogeneous hydration of acrylonitrile were investigated under the basic catalysts. The hydration was carried out in the large excess of water at a pH range of 0.9-12.1 and at a temperature range of 45-65°C. Only acrylamide was produced by the hydration of the cyano group in the acidic media, which agrees with the results reported in the literatures. Acrylamide, which was first identified in this experiment, ethylene cyanohydrin and bis(2-cyanoethyl) ether were obtained by the hydration at either cyano group or vinyl group in the basic catalysts.
A computer simulation method was applied to analyze t he kinetics of the base-catalyzed hydration of acrylonitrile. It was confirmed that the hydration proceeded by the following mechanism:
CH2=CHC≡N+H₂O_??_HOCH₂CH₂C≡N (1)
HOCH₂CH₂C≡N+CH₂=CHC≡N_??_(N≡CCH₂CH₂)₂O (2)
CH₂=CHC≡N+H₂O_??_CH2=CHCONH₂ (3)
where κ₁, κ₂2, κ₃, and κ₄, show the reaction rate constants. The value of k2 was 14---77 times greater than that of others. It is concluded that the main product in the basic catalysts is the bis(2-cyanoethyl) ether.
The hydration mechanis m of both cyano and vinyl group was considered by use of the resonance hybrid model of acrylonitrile molecule.