Propylene cyanohydrin

Processes rendered obsolete by the propylene ammoxidation process (51) include the ethylene cyanohydrin process (52—54) practiced commercially by American Cyanamid and Union Carbide in the United States and by I. G. Farben in Germany. The process involved the production of ethylene cyanohydrin by the base-cataly2ed addition of HCN to ethylene oxide in the liquid phase at about 60°C. A typical base catalyst used in this step was diethylamine. This was followed by liquid-phase or vapor-phase dehydration of the cyanohydrin. The Hquid-phase dehydration was performed at about 200°C using alkah metal or alkaline earth metal salts of organic acids, primarily formates and magnesium carbonate. Vapor-phase dehydration was accomphshed over alumina at about 250°C. 

Other Derivatives. Ethylene carbonate, made from the reaction of ethylene oxide and carbon dioxide, is used as a solvent. Acrylonitrile (qv) can be made from ethylene oxide via ethylene cyanohydrin however, this route has been entirely supplanted by more economic processes. Urethane intermediates can be produced using both ethylene oxide and propylene oxide in their stmctures (281) (see Urethane polymers). 

Ethyl tert-butvl ether. Ethylene dibromide, Ethyl ether, Ethvl sulfide. 2-Heptanone, Methanol, 2-Methyl-1,3-butadiene, 2-Methvl-2-butene. Methyl chloride, Methylene chloride, Methyl iodide. Methyl mercaptan, 2-Methylphenol, Methyl sulfide. Monuron. Nitromethane, 2-Nitropropane, A-Nitrosodimethylamine, 1-Octene, 2-Pentanone, Propylene oxide, Styrene, Thiram, Toluene, Vinyl chloride, o-Xylene, tn-Xylene Formaldehyde cyanohydrin, see Acetontrile,... 

Other chemicals present in acrylonitrile production or in other non-acrylonitrile operations on sites of the companies in the epidemiological study by Blair et al. (1998) include acetylene, hydrogen cyanide, propylene, ammonia, acetic acid, phosphoric acid, lactonitrile, hydroquinone, sodium hydroxide, sulfuric acid, acrylamide, acetone cyanohydrin, melamine, methyl methaciydate, zweto-methylstyrene, urea, methacrylonitrile, butadiene, ammonium hydroxide and ammonium sulfate (Zey et al., 1989, 1990a,b Zey McCammon, 1990). 

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... 

The initial drive for acrylonitrile (AN) production (6.2 Mt/a in 2004 worldwide) was the discovery, in the late 1930s, of the synthetic rubber Buna N. Today nitrile rubbers represent only a minor outlet for AN which is utilized primarily for polymerization to give textile fibres (50%) and ABS resins (24%), and for dimerization to adiponitrile (10%). Early industrial processes depended on the addition of hydrogen cyanide to acetylene or to ethylene oxide, followed by the dehydration of intermediate ethylene cyanohydrin. Both processes are obsolete and are now supplanted by the ammoxidation of propylene (Equation 34) introduced in 1960 by Standard Oil of Indiana (Sohio). The reason for the success stems from the effectiveness of the catalyst and because propylene,... 

Derivation (1) From propylene oxygen and ammonia with either bismuth phosphomolybdate or a uranium-based compound as catalysts (2) addition of hydrogen cyanide to acetylene with cuprous chloride catalyst (3) dehydration of ethylene cyanohydrin. 

Acryclic acid is obtained by the catalytic oxidation of propylene and acrylates (methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate...) by alcohol esterification of the acid. The preparation of methacrylic acid involves the acidic hydrolysis of acetone cyanohydrin and methyl methacrylate is obtained by a similar process involving the methanolysis of acetone cyanohydrin. 

In the petrochemical industry the introduction of unsaturations in hydrocarbons is mainly obtained by dehydrogenation. This kind of reaction is less suitable for the functionalization of fine chemicals, because the high temperature necessary for the endothermic reaction can lead to the decomposition of thermally unstable compounds. An alternative reaction consists in the oxidative dehydrogenation, that can be carried out at lower temperatiu es. An example of this kind of reaction is constituted by the synthesis of methacrylic add (MAA, intermediate of methylmethacrylate production) via the oxidative dehydrogenation of isobutyric add (IBA), itself obtained from isobutyraldehyde (by-product of the oxo synthesis of nbutyraldehyde from propylene). This process constitutes one of the economically most interesting routes, alternative to the acetone-cyanohydrin process, which nowadays is the predominant process for the MAA production. 

In fact, over the last 30 years, the market as well as the supply situation for formic acid has been very dynamic. It has been affected by the development of several other major technologies. The commercialization of acetic acid by the carbonylation of methanol and the development of the Propylene ammoxidation process for acrylonitrile which replaced the cyanohydrin process both had a large impact on formic acid. 

In 1893, the French chemist Moreau described two routes for the synthesis of acrylonitrile that were based on the dehydration of either acrylamide or ethylene cyanohydrin [10]. There was very little interest in acrylonitrile until 1937 when synthetic rubber based on acrylonitrile-butadiene copolymers was first developed in Germany. A process based on the addition of hydrogen cyanide to acetylene was developed at that time and in the 1950s, the acrylic fiber industry provided the stimulus for further process developments. Today acrylonitrile is made commercially by one of three possible methods (a) from propylene, (b) from acetylene and hydrogen cyanide, and (c) from acetaldehyde and hydrogen cyanide. 

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