Patented July 4, 1944 UNITED STATES PATENT office PREPARATION OF BETA-AKOxY MONO CARBOXYLCACDs Frederick E. King, Akron, Ohio, assignor to The B. F. Goodrich Company, New corporation of New York . . . York, N. Y., a No Drawing. Application August 5, 1941, Sera No. 405,512 4 Claims. (CL 260-535) This invention relates to a novel process for at least one hydrogen atom on the alpha carbon the preparation of beta-alkoxy derivatives of atom, for example, beta-lactones of saturated monocarboxylic acids, particularly beta-alkoxy aliphatic monocarboxylic acids such as beta-hy derivatives of saturated aliphatic monocarboxylic droxypropionic acid lactone, commonly known as acids such as beta-alkoxy proponic acids, and to 5 hydracrylic acid lactone, beta-hydroxy butyric the conversion of such acids into alkyl esters of acid lactone, alpha-methyl hydracrylic acid lac alpha beta unsaturated monocarboxylic acids tone, beta-hydroxy n-valeric acid actone, beta such as the alkyl esters of acrylic and meth hydroxy alpha-methyl butyric acid lactone, al acrylic acids. - - pharethyl hydracrylic acid lactone, beta-hydroxy In a copending application Serial No. 393,671, 0 isovaleric acid lactone, beta-hydroxy n-caproic filed May 15, 1941, an economical method of pre acid lactone, beta-hydroxy alpha-methyl valeric paring lactones of beta-hydroxy Carboxylic acids acid lactone, beta-methyl beta-ethyl hydracrylic from the reaction of a ketene with a carbonyl acid lactone, alpha-methyl beta-ethylhydracrylic compound such as an aldehyde or ketone has acid lactone, alpha-propyl hydracrylic acid lac been described. The ease with which such lac tone, alpha-butyl hydracrylic acid lactone or the tones are now obtained makes it desirable to use like; beta-lactones of substituted carboxylic acids these compounds as starting materials for the such as beta-phenyl hydracrylic acid lactone, synthesis of other compounds such as unsatu alpha-phenyl hydracrylic acid lactone, beta-chlo rated acids, esters and nitriles all of which are roethyl hydracrylic acid lactone, beta-benzyl hy extremely useful as polymerizable materials in : dracrylic acid lactone, beta-cyclohexyl hydra the production of synthetic rubber, synthetic crylic acid lactone and the like, and other beta resins and the like. lactones of the nature hereinabove set forth. I have now discovered that beta-lactones may The alcohol which is reacted with the lactone be reacted with alcohols to prepare beta-alkoxy may be any monohydric alcohol such as ethyl Carboxylic acids which may then be converted 25 alcohol, methyl alcohol, isopropyl alcohol, propyl into unsaturated carboxylic acid esters by dehy- . alcohol, methyl-ethyl-carbinol, trimethyl-car dration. Thus, unsaturated esters useful in binol, n-amyl alcohol, di-ethyl-carbinol, tert polymerization may conveniently be prepared butyl-carbinol, methyl-n-propyl carbinol, tert. from beta-lactones. Moreover, the beta-alkoxy amyl alcohol, hexyl alcohol, n-heptyl alcohol, n carboxylic acids themselves are useful organic 30 octyl alcohol, lauryl alcohol, myristyl alcohol, compounds, for example, the beta-dodecaneoxy palmityl alcohol, cyclohexanol, benzyl alcohol, or other high molecular weight alkoxy derivatives phenyl ethyl alcohol, ethoxy ethanol, chloro are particularly useful as emulsifying agents. ethyl alcohol, terpineol or the like. w It is quite surprising that beta-lactones yield The preferred compounds to be used in the beta-alkoxy derivatives when treated with alco practice of this invention are the beta-lactones hols since other lactones such as gamma lactones of Saturated aliphatic monocarboxylic acids and yield alkyl esters of hydroxy acids when treated the saturated alkyl alcohols. Accordingly, pre with an alcohol. ferred embodiments of the invention include the The reaction of beta-lactones with alcohols to reaction of hydracrylic acid lactone with methyl, yield beta-alkoxy acids according to this inven 40 ethyl, propyl or butyl alcohol to yield a beta tion proceeds substantially as illustrated by the alkoxy propionic acid and the reaction of alpha following equation: methyl hydracrylic acid lactone with methyl, ethyl, propyl or butyl alcohol to yield an alpha R Ra Rs methyl beta-alkoxy propionic acid, R R. Rs B g4-b-g-oh 45 As mentioned hereinabove, the beta-alkoxy C c4c=0 - ROBI - d h compounds formed by the reaction of a beta -o- k lactone with an alcohol may be dehydrated to give alpha-beta unsaturated esters. This dehy Beta-lactone w Alcohol Beta-alkoxy acid dration may be represented as follows: where R1, R2 and R3 represent hydrogen, alkyl, 50 R R. R. R R. Rs aralkyl, aryl or substituted alkyl, aryl or aralkyl radicals and R4 represents an alkyl, aralkyl or Yo4-i-o-oh se- Yc4 - --OR - O substituted alkyl or aralkyl radical. H. The beta-lactOne employed may be any lactone R of a beta-hydroxy monocarboxylic acid which has As examples of this reaction, beta-methoxy

2 a859,041 proponic acid gives, upon dehydration, methyl the reaction product was then distilled, first at acrylate beta-ethoxy proponic acid gives ethyl atmospheric pressure to remove the excess meth acrylate; alpha-methyl beta-methoxy proponic anol and then at reduced pressure from an Anders acid gives methyl methacrylate and alpha-methy flask, 73 g. (72%) of beta-methoxy propionic beta-ethoxy propionic acid gives ethyl meth acid having the following physical constants were acrylate. obtained: M. P-26 C. to -27 C.; B. Pio The reaction of the beta-lactone with the alco 99-101C.; density at 26 C- -1.099: No 26° hol to yield a beta-alkoxy carboxylic acid is best 166. carried out by refluxing the alcohol. With the lac The chemical constitution of beta-methoxy tone for about 2 to 10 hours at the boiling point O propionic acid was determined by reacting it with of the alcohol. When high boiling alcohols are annonia whereupon a violent reaction occurred used, a suitable solvent such as acetone may be which yielded a product corresponding to the employed as the refluxing medium. Alternatively, formula . a mixture of the alcohol and the lactOne may be CHsO-CHCH.g-ONE heated in an autoclave at a temperature of about 5 50-200 C. if desired, but this method in general If the product had been an ester of a hydroxy produces no better results than are obtained acid, this neutralization reaction would not have simply by refluxing. The reactants may be mixed occurred since no acid group would have been in any desired proportions but highest yields of present, the desired product are obtained when an excess 20 of the alcohol is employed. cample III If it is desired to convert the beta-alkoxy car 26 g. of beta-methoxypropionic acid, obtained boxylic acid formed by the reaction of the beta in Example II were dehydrated by heating in a lactone and an alcohol into an unsaturated ester, distilling flask with 35 g. of concentrated sulfuric this may be accomplished by dehydrating the acid and a trace of copper acetate. Distilation alkoxy compound in any ordinary way such as by 25 yielded a mixture of methyl acrylate and water disting the compound. With a dehydration cata which was partly purified by drying and redis lyst such as sulfuric acid, phosphoric acid, meth tillation. 13.5 g. (B.P. 67-72 C.) of methyl ane sulfonic acid, benzene sulfonic acid or the acrylate Were thus obtained. like or bypassing vapors of the compound over a 30 Eacample IV dehydration catalyst such as silica gel or the like at an elevated temperature of about 200-400 40 g. of beta-methoxypropionic acid were dis C. When carrying out the dehydration it is de tilled from 10 g. of methane sulphonic acid sirable that a substance be present which pre (CH-SO3H) in four portions of 10 g. each. 40 vents the polymerization of the ester formed. g. of crude methyl acrylate and water were ob Suitable substances for this purpose are copper, tained. . ... - copper salts, hydroquinone or other polymeriza Eacample 7 tion inhibitors. In one hour 34 g. of beta-methoxy propionic It is also possible to carry out both of the here acid were passed into a solution of 10 g of meth inabove described reactions in one step. Thus, a 40 ane sulfonic acid and a trace of copper acetate at beta-lactone may be refluxed with an alcohol in 80-200 C. On distillation of the product the the presence of a dehydration catalyst such as yield of methyl acrylate was 67%. sulfuric acid and the mixture then distilled. In , I claim: . this case, an unsaturated ester is produced di 1. The method of preparing a beta-alkoxy rectly from the beta-lactone and the alcohol. monocarboxylic acid which comprises reacting a The following examples will illustrate the prac lactone of a beta-hydroxy monocarboxylic acid, tice of the invention but it is not intended to having at least one hydrogen atom on the alpha limit the invention thereto, for numerous modi Carbon atom, with a monohydric alcohol. fications in the particular compounds and condi 2. The method of preparing a beta-alkoxy ali tions employed will be obvious to those skilled 50 phatic monocarboxylic acid which comprises re in the art. acting a lactOne of a saturated aliphatic beta-hy Eacample I droxy monocarboxylic acid having at least one A mixture of 30 g. of hydraCrylic acid lactOne hydrogen atom on the alpha carbon atom, with an and 90 g. of absolute ethano Was refluxed for 5 alkyl alcohol. . 55 3. The method of preparing beta-methoxypro hours. The reaction product was then distilled pionic acid which comprises reacting beta-hy at reduced pressure. 36 g. (75%) of beta-ethoxy droxy proponic acid lactone with methyl alcohol. propionic acid (B.P.15 mm.-105-115° C.) were 4. The method of preparing beta-ethoxy pro this obtained. pionic acid which comprises reacting beta-hy Eacample II droxy propionic acid lactone with ethyl alcohol. 72 g. of hydracrylic acid lactone and 200 g. of 60 synthetic methanol were refluxed for 6 hours and FREDERICK E. KNG.