Hydrolysis of ethylene cyanohydrin

The first commercial process for manufacture of acryHc acid (qv) and acrylates involved hydrolysis of ethylene cyanohydrin in aqueous sulfuric acid. 

J-Chloropropionic acid has been prepared by the hydrolysis of ethylene cyanohydrin with hydrochloric acid,1 and by the oxidation of /S-chloropropionaldehyde2 or of trimethylene chlorohydrin 3 by nitric acid. 

Hydrolysis of ethylene cyanohydrin, of which the last installation in activity (Cnion Carbide Institute, West Virginia) was shut down in 1971 fsee Section 11.3JL2) it is based on the production of cyanohydrin by the reaction of hydrogen cyanide with ethylene oxide ... 

The production of ethylene oxide is described in section 9.4.1. The addition of hydrogen cyanide to ethylene oxide takes place at 55-60°C in the presence of a basic catalyst such as diethylamine. The reaction is exothermic and is carried out in solution to facilitate control the solvent is conveniently ethylene cyanohydrin. The reaction mixture is neutralized and ethylene cyanohydrin is separated by distillation. The second stage of the synthesis involves the dehydration and hydrolysis of ethylene cyanohydrin these reactions are carried out in one step by heating the cyanohydrin with aqueous sulphuric acid at about 175°C. (It is possible, of course, that the... 

Acrylics. Acetone is converted via the intermediate acetone cyanohydrin to the monomer methyl methacrylate (MMA) [80-62-6]. The MMA is polymerized to poly(methyl methacrylate) (PMMA) to make the familiar clear acryUc sheet. PMMA is also used in mol ding and extmsion powders. Hydrolysis of acetone cyanohydrin gives methacrylic acid (MAA), a monomer which goes direcdy into acryUc latexes, carboxylated styrene—butadiene polymers, or ethylene—MAA ionomers. As part of the methacrylic stmcture, acetone is found in the following major end use products acryUc sheet mol ding resins, impact modifiers and processing aids, acryUc film, ABS and polyester resin modifiers, surface coatings, acryUc lacquers, emulsion polymers, petroleum chemicals, and various copolymers (see METHACRYLIC ACID AND DERIVATIVES METHACRYLIC POLYMERS). 

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... 

Ethylene chlorohydrin vapors form an explosive mixture with air the LEE and UEL values are 4.9% and 15.9% by volume of air, respectively. Among the hazardous reaction products are ethylene oxide, formed by internal displacement of the chlorine atom by the alkoxide ion, ethylene glycol formed by hydrolysis with sodium bicarbonate at 105°C (221°F), and ethylene cyanohydrin resulting from the reaction with alkali metal cyanides. 

Methacrylic acid can also be produced by a variety of processes including oxidation of ethylene, propylene, and isobutylene. The most common commercial process for making methacrylic acid is the acetone cyanohydrin (ACN) process. The feedstocks for this process are acetone, hydrogen cyanide, and sulfuric acid. The acetone and HCN are reacted under alkaline conditions to produce the cyanohydrin. Reaction of the cyanohydrin with sulfuric acid ultimately produces methacrylamide sulfate, hydrolysis of which produces methacrylic acid. Methyl methacrylate can be made either by esterifying the acid or directly by reacting the amide sulfate with methanol. 

Merck and Maeder have patented the manufacture of arecaidine by loss of water from l-methyl-4-hydroxypiperidine-3-carboxylic acid. A method of producing the latter has been describd by Mannich and Veit and has been developed by Ugriumov for the production of arecaidine and arecoline. With the same objective, Dankova, Sidorova and Preobrachenski use what is substantially McElvain s process,but start by converting ethylene oxide, via the chlorohydrin and the cyanohydrin, into -chloropropionic acid. The ethyl ester of this with methylamine in benzene at 140° furnishes methylbis(2-carbethoxyethyl) amine (I) which on refluxing with sodium or sodium Moamyloxide in xylene yields l-methyl-3-carbethoxy-4-piperidone (II). The latter is reduced by sodium amalgam in dilute hydrochloric acid at 0° to l-methyl-3-carbethoxy-4-hydroxypiperidine (III) which on dehydration, and hydrolysis, yields arecaidine (IV R = H), convertible by methylation into arecoline (IV R = CH3). 

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