Methyl methacrylate acetone cyanohydrin

Methyl methacrylate is obtained commercially from acetone cyanohydrin HCN CH.OH,... 

The action of sulphuric acid alone upon acetone cyanohydrin affords a-methylacrylic acid. The methyl methacrylate polymers are the nearest approach to an organic glass so far developed, and are marketed as Perspex (sheet or rod) or Dialcon (powder) in Great Britain and as Plexiglass and Luciie in the U.S.A. They are readily depolymerised to the monomers upon distillation. The constitution of methyl methacrylate polymer has been given as ... 

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). 

Selected physical properties of various methacrylate esters, amides, and derivatives are given in Tables 1—4. Tables 3 and 4 describe more commercially available methacrylic acid derivatives. A2eotrope data for MMA are shown in Table 5 (8). The solubiUty of MMA in water at 25°C is 1.5%. Water solubiUty of longer alkyl methacrylates ranges from slight to insoluble. Some functionalized esters such as 2-dimethylaniinoethyl methacrylate are miscible and/or hydrolyze. The solubiUty of 2-hydroxypropyl methacrylate in water at 25°C is 13%. Vapor—Hquid equiUbrium (VLE) data have been pubHshed on methanol, methyl methacrylate, and methacrylic acid pairs (9), as have solubiUty data for this ternary system (10). VLE data are also available for methyl methacrylate, methacrylic acid, methyl a-hydroxyisobutyrate, methanol, and water, which are the critical components obtained in the commercially important acetone cyanohydrin route to methyl methacrylate (11). 

Until 1982, almost all methyl methacrylate produced woddwide was derived from the acetone cyanohydrin (C-3) process. In 1982, Nippon Shokubai Kagaku Kogyo Company introduced an isobutylene-based (C-4) process, which was quickly followed by Mitsubishi Rayon Company in 1983 (66). Japan Methacryhc Monomer Company, a joint venture of Nippon Shokubai and Sumitomo Chemical Company, introduced a C-4-based plant in 1984 (67). Isobutylene processes are less economically attractive in the United States where isobutylene finds use in the synthesis of methyl /i / butyl ether, a pollution-reducing gasoline additive. BASF began operation of an ethylene-based (C-2) plant in Ludwigshafen, Germany, in 1990, but favorable economics appear to be limited to conditions unique to that site. 

The handling of toxic materials and disposal of ammonium bisulfate have led to the development of alternative methods to produce this acid and the methyl ester. There are two technologies for production from isobutylene now available ammoxidation to methyl methacrylate (the Sohio process), which is then solvolyzed, similar to acetone cyanohydrin, to methyl methacrylate and direct oxidation of isobutylene in two stages via methacrolein [78-85-3] to methacryhc acid, which is then esterified (125). Since direct oxidation avoids the need for HCN and NH, and thus toxic wastes, all new plants have elected to use this technology. Two plants, Oxirane and Rohm and Haas (126), came on-stream in the early 1980s. The Oxirane plant uses the coproduct tert-huty alcohol direcdy rather than dehydrating it first to isobutylene (see Methacrylic acid). 

The outstanding chemical property of cyanohydrins is the ready conversion to a-hydroxy acids and derivatives, especially a-amino and a,P-unsaturated acids. Because cyanohydrins are primarily used as chemical intermediates, data on production and prices are not usually pubUshed. The industrial significance of cyanohydrins is waning as more direct and efficient routes to the desired products are developed. Acetone cyanohydrin is the world s most prominent industrial cyanohydrin because it offers the main route to methyl methacrylate manufacture. 

Cyanohydrins are used primarily as intermediates in the production of other chemicals. Manufacture of methyl methacrylate, used to make acrylic mol ding resins and clear sheet, eg, Plexiglas acrylic sheet, from acetone cyanohydrin is the most economically important cyanohydrin process (see Methacrylic polymers). Cyanohydrins are also used as solvents in appHcations including fiber-spinning and metals refining. Cyanohydrins and derivatives reportedly act as antiknock agents in fuel oil and motor fuels and serve as electrolytes in electrolytic capacitors. 

Acetone Cyanohydrin. This cyanohydrin, also known as a-hydroxyisobutyronitnle and 2-methyUactonitrile [75-86-5], is very soluble in water, diethyl ether, and alcohol, but only slightly soluble in carbon disulfide or petroleum ether. Acetone cyanohydrin is the most important commercial cyanohydrin as it offers the principal commercial route to methacrylic acid and its derivatives, mainly methyl methacrylate [80-62-6] (see Methacrylic acid AND derivatives). The principal U.S. manufacturers are Rohm and Haas Co., Du Pont, CyRo Industries, and BP Chemicals. Production of acetone cyanohydrin in 1989 was 582,000 metric tons (30). 

Conversion of acetone cyanohydrin to methyl methacrylate produces a large amount of ammonium bisulfate by-product which lacks ready marketabihty and is usually converted to sulfuric acid for reuse in the conversion of acetone cyanohydrin to methacrylates. The nitrogen values of the... 

One of the most important appHcations of this process is that of methyl methacrylate manufacture. In this process (81), acetone cyanohydrin is treated with sulfuric acid at 100°C, affording the corresponding methacrylamide sulfate which is esterified with methanol. After purification, methyl methacrylate (99.8% purity) is obtained in a yield of ca 85%. 

A plant produced methyl methacrylate by reacting hydrogen cyanide with acetone to produce acetone cyanohydrin followed by further processing to produce methyl methacrylate. The hydrogen cyanide was produced at another site and was transported to the methyl methacrylate plant by railcar. A hydrogen cyanide plant was subsequently installed at the methyl methacrylate plant site to eliminate the need for shipping hydrogen cyanide or acetone cyanohydrin. 

Methyl Methacrylate (CH2=C-COOCH3). This is produced by the hydrocyanation of acetone using HCN. The resulting cyanohydrin is then reacted with sulfuric acid and methanol, producing methyl methacrylate ... 

Addition of HCN to acetone to form the cyanohydrin is still the main route to methyl methacrylate. Hydrocyanins can be converted to amino acids as well. The nitrile group can be easily converted to amines, carboxylic acids, amides, etc. Addition to aldehydes and activated alkenes can be done with simple base, but addition to unactivated alkenes requires a transition metal catalyst. The methods of HCN addition have been discussed by Brown [2],... 

DIHYDROFURAN DIVINYL ETHER METHACROLEIN 2-BUTYNE-1,4-DIOL ganna-BUTYROLACTONE cis-CROTONIC ACID trans-CROTONIC ACID METHACRYLIC ACID METHYL ACRYLATE VINYL ACETATE ACETIC ANHYDRIDE SUCCINIC ACID DIGLYCOLIC ACID MALIC ACID TARTARIC ACID n-BUTYRONITRILE ISOBUTYRONITRILE ACETONE CYANOHYDRIN... 

The only method used in the U.S. for the production of methyl methacrylate is the acetone cyanohydrin process. Acetone cyanohydrin (from the reaction of acetone with hydrogen cyanide) is reacted with sulfuric... 

Acetone cyanohydrin is an intermediate in the manufacture of methyl methacrylate. 

Acetone Cyanohydrin Methyl Mercaptan Methyl Methacrylate Methyl Methacrylate Ethane... 

The price of butanes and butylenes fluctuates seasonally depending on the demand for gasoline in the United States. Since much chemical-product usage is determined by price—performance basis, a shift to development of butylene-based technology may occur. Among the butylenes, demand for isobutylene is likely to increase (and so its price) as more derivatives such as methyl methacrylate and methacrylic acid are produced from isobutylene instead of the conventional acetone cyanohydrin process. 

Inhibitors are introduced al specific points in the process to prevent polymerization Sulfuric acid serves as catalyst in a combined hydrolysis-esterilieaiion of methacrylamide sulfate to a mixture of methyl methacrylate and methacrylic acid. Conversion of methacrylamide sulfate to methyl methacrylate can be carried out using a variety of procedures for die recovery of crude methyl methacrylate and fur separation of methanol and methacrylic acid for recycling. A schematic of the overall process is given in Figure I. The overall yield based on acetone cyanohydrin is approximately 90D Most of Ihe world supply of MMA is still produced by this process. 

HCN is usually consumed at its production site, and most consumers without on-site HCN production capability are believed to be developing plans to eliminate HCN shipments. For example, BASF in the United Kingdom produces by-product HCN in an ACRN plant and ships HCN railcars to Lucite. This HCN is used to produce acetone cyanohydrin (ACH) in a methyl methacrylate plant. To eliminate these shipments, BASF and Lucite plan to 1) install an ACH plant on the BASF plant site and 2) transfer the ACH to Lucite via a 9 km pipeline136. 

Acetone Cyanohydrin (ACH). ACH is made when HCN reacts with acetone. It is a key ingredient in many methyl methacrylate (MMA) plants. MMA is used to make acrylic sheeting and related products. 

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