Acrolein cyanohydrin

The upper layer which contains, in addition to acrylonitrile, hydrogen cyanide, acrolein, acetonitrile, and small quantities of other impurities, passes to a second reactor (E) where, at a suitable pH, all the acrolein is converted to its cyanohydrin. (Cyanohydrins are sometimes known as cyanhydrins.) The product from the reactor (E) is fed to a cyanohydrin separation column (F), operating at reduced temperature and pressure, in which acrolein cyanohydrin is separated as the bottom product and returned to the ammox-idation reactor (A) where it is quantitatively converted to acrylonitrile and hydrogen cyanide. 

E) is fed to a cyanohydrin separation column (E), operating at reduced temperature and pressure, in which acrolein cyanohydrin is separated as the bottom product and returned to the ammoxidation reactor (A) where it is quantitatively converted to acrylonitrile and hydrogen cyanide. 

Acrolein cyanohydrin (vinyl glycolonitrile, 2-hydroxy-3-butenenitrile) [5809-59-6]... 

Acetoxy-3-butene nitrile (acrolein cyanohydrin acetate) [22581-05-1]... 

Hydroxy-4-methylthiobutyric acid [583-91 -5] the hydroxy analogue of the amino acid methionine, is manufactured by acid hydrolysis of 3-methylthiopropionaldehyde cyanohydrin [17773-41-0] which is produced by the reaction of methyl mercaptan with acrolein (qv). 

S (2)-hydroxy-3-butenenitrile from acrolein and HCN trans hydrocyanation using, for instance, acetone cyanohydrin Hydrolysis of nitriles to amides, e.g. acrylonitrile to acrylamide Isomerization of glucose to fructose Esterifications and transesterifications Interesterify positions 1 and 3 of natural glycerides Oxidation of glucose to gluconic acid, glycolic acid to glyoxalic acid... 

Acrolein and condensable by-products, mainly acrylic acid plus some acetic acid and acetaldehyde, are separated from nitrogen and carbon oxides in a water absorber. However in most industrial plants the product is not isolated for sale, but instead the acrolein-rich effluent is transferred to a second-stage reactor for oxidation to acrylic acid. In fact the volume of acrylic acid production ca. 4.2 Mt/a worldwide) is an order of magnitude larger than that of commercial acrolein. The propylene oxidation has supplanted earlier acrylic acid processes based on other feedstocks, such as the Reppe synthesis from acetylene, the ketene process from acetic acid and formaldehyde, or the hydrolysis of acrylonitrile or of ethylene cyanohydrin (from ethylene oxide). In addition to the (preferred) stepwise process, via acrolein (Equation 30), a... 

Other carbonyl compounds carrying a second functional group undergo this reaction, e.g., acrolein, chloroacetone, -hydroxybenzaldehyde, acetoacetic ester, and -dimethylaminobenzaldehyde. The method is important in the synthesis of sugars (Kiliani cyanohydrin synthesis). ... 

Purification this step features the second innovation of the process which, to eliminate the by-product acrolein, favors the formation of cyanohydrin by means of the hydrogen cyanide which is also present This operation takes place at low temperature (20 Q in agitated reactors, either continuously in the presence of a copper-based catalyst, or semi-continuously with a reaction phase in basic medium (caustic soda addition), followed by a neutralization period (sulfuric acid addition). The cyanohydrin obtained is then removed by vacuum distillation. The withdrawal may be sent to a thin layer evaporator to recover entrained acrylonitrile. These treatments must be conducted in the presence of a polymerization inhibitor and at a temperature below 55 C to prevent the rede-composition of cyanohydrin.... .. ... 

Some substrates, e. g. acrolein, gave only low optical purity with the P. amygdalus HNL. The catalytic capability of (R)-specific HNL from I. usitatissimum for the preparation of aliphatic cyanohydrins was investigated[S0- S1, 651 and gave encouraging results (ee of up to 99%). 

Acrylonitrile is miscible in a wide range of oiganic solvents, including acetone, benzene, carbon tetrachloride, diethyl ether, ethyl acetate, ethylene cyanohydrin, petroleum ether, toluene, some kerosenes, and methanol. Compositions of some common azeotropes of acrylonitrile are given in Table 3. Table 4 presents the solubility of acrylonitrile in water as a function of temperature (6). Vapor—liquid equilibria for acrylonitrile in combination with acetonitrile, acrolein, HCN, and water have been published (6—9). Table 5 gives the vapor pressure of acrylonitrile over aqueous solutions. 

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