Methyl - 3-hydroxyisobutyrate

Methyl 2-hydroxyisobutyrate Lactic acid, 2-methyl-, methyl ester (8) Propanoic acid, 2-hydroxy-2-methy1-, methyl ester (9) (2110-78-3)... 

Sodium hydride, 2-methylpropane-2-thiol, diketene, methyl 2-hydroxyisobutyrate and tetrabutylammonium fluoride were purchased from Aldrich Chemical Company, Inc. Diketene was distilled prior to use to remove polymeric species. 

Safont VS, Andres J, Castillo R, Chuchani G, Rotinov A, Dominguez RM, Herize A (2004) A joint experimental and theoretical study on the mechanisms of methyl 2-hydroxypiopionate and methyl 2-hydroxyisobutyrate decomposition in the gas phase. J Phys Chem A 108 996-1007... 

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). 

Arguably the key step in the MGC process is the conversion of a-hydroxyisobutyramide to methyl a-hydroxyisobutyrate using methyl formate as the methylating agent. Methyl formate is made commercially by MGC via vapor-phase dehydrogenation of methanol (72). 

The reaction is mn for several hours at temperatures typically below 100°C under a pressure of carbon monoxide to minimise formamide decomposition (73). Conversions of a-hydroxyisobutyramide are near 65% with selectivities to methyl a-hydroxyisobutyrate and formamide in excess of 99%. It is this step that is responsible for the elimination of the acid sludge stream characteristic of the conventional H2SO4—ACH processes. Because methyl formate, and not methanol, is used as the methylating agent, formamide is the co-product instead of ammonium sulfate. Formamide can be dehydrated to recover HCN for recycle to ACH generation. 

The methyl a-hydroxyisobutyrate produced is dehydrated to MMA and water in two stages. First, the methyl a-hydroxyisobutyrate is vaporized and passed over a modified zeoHte catalyst at ca 240°C. A second reactor containing phosphoric acid is operated at ca 150°C to promote esterification of any methacrylic acid (MAA) formed in the first reactor (74,75). Methanol is co-fed to improve selectivity in each stage. Conversions of methyl a-hydroxyisobutyrate are greater than 99%, with selectivities to MMA near 96%. The reactor effluent is extracted with water to remove methanol and yield cmde MMA. This process has not yet been used on a commercial scale. 

The first methacrylic esters were prepared by dehydration of hydroxyisobutyric esters, prohibitively expensive starting points for commercial synthesis. In 1932 J. W. C. Crawford discovered a new route to the monomer using cheap and readily available chemicals—acetone, hydrocyanic acid, methanol and sulphuric acid— and it is his process which has been used, with minor modifications, throughout the world. Sheet poly(methyl methacrylate) became prominent during World War II for aircraft glazing, a use predicted by Hill in his early patents, and since then has found other applications in many fields. 

Methyl alcohol. See Methanol Methyl a-cyclogeranate, 24 569 Methyl a-hydroxyisobutyrate, 16 247 Methyl allyl carbonate, molecular formula, 6 305t... 

The ACH process has recently been improved, as stated by Mitsubishi Gas. Acetone-cyanohydrin is first hydrolized to 2-hydroxyisobutylamide with an Mn02 catalyst the amide is then reacted with methylformiate to produce the methyl ester of 2-hydroxyisobutyric acid, with coproduction of formamide (this reaction is catalyzed by Na methoxide). The ester is finally dehydrated with an Na-Y zeolite to methylmethacrylate. Formamide is converted to cyanhydric acid, which is used to produce acetone-cyanohydrin by reaction with acetone. The process is very elegant, since it avoids the coproduction of ammonium bisulphate, and there is no net income of HCN. Problems may derive from the many synthetic steps involved, and from the high energy consumption. 

Paramethadione Paramethadione, 5-ethyl-3,5-dimethyloxazolidine-2,4-dione (9.8.3), differs from trimethadione only in the substitution of one methyl group with an ethyl gronp. It is synthesized in a completely analogons manner, except that it comes from 2-hydroxy-2-methylbntyric acid instead of 2-hydroxyisobutyric acid [29]. 

At a considerably later date. Frankland prepared ethyl methacrylate and methacrylic acid from ethyl a-hydroxyisobutyrate and phosphorus trichloride. Tollen prepared aciylate esters from 2,3-dibromopropionate esters and zinc. Otto Rohm, in 1901. described the structures of the liquid condensation products (including dimers and timers) obtained from the action of sodium alkoxides on methyl and ethyl acrylate. Shortly after World War 1, Rohm introduced a new acrylate synthesis, noting that an acrylate is formed in good yield from heating ethylene cyanohydrin and sulfuric acid and alcohol. A major incentive for the development of a clear, tough plastic acrylate was for use in the manufacture of safety glass. 

A paired-ion, reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of sweeteners (dulcin, saccharin-Na, and acesulfame-K), preservatives (sodium dehydroacetate, SA, salicyclic acid, BA, succinic acid, methyl-para-hydroxybenzoic acid, ethyl-para-hydroxybenzoic acid, n-propyl-para-hydroxybenzoic acid, n-butyl-para-hydroxybenzoic acid, and isobutyl-para-hydroxybenzoic acid), and antioxidants (3-tertiary-butyl-4-hydroxyanisole and tertiary-butyl-hydroquinone). A mobile phase of acetonitrile-50 ml aqueous tr-hydroxyisobutyric acid solution (pH 4.5) (2.2 3.4 or 2.4 3.6, v/v) containing 2.5 mM hexadecyltrimethylammonium bromide and a Clg column with a flow rate of 1.0 ml/min and detection at 233 nm were used. This method was found to be very reproducible detection limits ranged from 0.15 to 3.00 p,g. The retention factor (k) of each additive could be affected by the concentrations of hexadecyltrimethylammonium bromide and a-hydroxyisobu-tyric acid and the pH and ratio of mobile phase. The presence of additives in dried roast beef and sugared fruit was determined. The method is suitable for routine analysis of additives in food samples (81). 

Polymerization of hexamethylcyclotrisiloxane with 3-butadienyllithium afforded butadienyl-ended polysiloxane macromonomer,20 [27], Polycondensation of a chiral methyl (3-hydroxyisobutyrate at a temperature higher than 150 °C with Ti(0-nBu)4 afforded directly a biodegradable polyester macromonomer, 21 [28]. 

Of the two diastereoisomers, 168 contains the chiral methyl group in the pro-R position and will lead to a -CH2OH group in the hydroxyisobutyrate, 170, which contains only H. Hence, it remains to analyze 169, to determine whether 3 H is in the pro-R or pro-S position. In the H-decoupled 3H NMR spectrum the product (169 plus 170) obtained from 167 and 168, showed the following signals which had been assigned in the earlier work ... 

C7H1202 5-methyl-4-hexenoic acid 5636-65-7 490.15 42.939 1,2 11558 C7H1204 a-hydroxyisobutyric acid acetate methyl ester 57865-37-9 464.16 40.452 2... 

Leon R, Prazeres DMF, Fernandes P, Molinari F, Cabral JMS. A multiphasic hollow fiber reactor for the whole-ceU bioconversion of 2-methyl-1,3-propanediol to (R)-P-hydroxyisobutyric acid. Biotechnol Prog 2001 17 468-473. 

Commercially available methyl p-hydroxyisobutyrate (16) has been converted to the corresponding halide (17), then either via the silyloxycyclopropane route (A) or via the reductive route (B) to the chiral zinc homoenolate (18 Scheme 28). It is optically stable in ether and has been used for several standard carbon-carbon bond-forming reactions, e.g. carbonyl addition, arylation and acylation. ... 

HIBA 2-Hydroxyisobutyric acid HIBAL 2-Hydroxy-2-methylpropanal HRT Hydraulic retention time LUST Leaking underground storage tank MBR Membrane bioreactor MTBE Methyl tert-butyl ether MPD 2-methyl 1,2-propanediol N Nitrate NA Natural attenuation ND Not determined ns Not specified P Phosphate... 

TBA generated by the oxidation of these two ethers can be further metabolised, first to 2-methyl-1,2-propanediol and then to 2-hydroxyiso-butyrate. These are the major urinary metabolites of MTBE and ETBE, but 2-hydroxyisobutyrate is also measurable in significant amounts in all urine samples from unexposed volunteers (and rats) [11]. This compound is formed endogenously as a product of branch-chained amino-acid degrada-... 

Fig. 3.22. GC separation of keto and hydroxy acids from the urine of a patient with maple syrup urine disease. Top chromatogram, the patient before dietary treatment middle chromatogram, the same patient after two days on a diet bottom chromatogram, a mixture of reference compounds. Peaks 1, lactic acid 2, 2-hydroxyisobutyric acid 3, 2-hydroxybutyric acid 4, pyruvic acid 5, 3-hydroxyisobutyric acid 6, 3-hydroxybutyric acid 7, 2-hydroxyisovaleric acid 8, 2-ketobutyric acid 9, malonic acid (internal standard) 10, 2-methyl-3-hydroxybutyric acid 11, 2-hydroxy-n-valeric acid 12. methylmalonic acid 13, 3-hydroxyisovaleric acid 14a and b, 2-ketoisovaleric acid IS, acetoacetic add 16, 2-hydroxyisocaproic acid 17, 2-hydroxy-3-methylvaleric acid 18a, L-2-keto-3-methylvaleric add 18b, D-2-keto-3-methyl-valeric acid 19, 2-ketoisocaproic acid. Reproduced from [386],...

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