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UNITED STATES PATENT OFFICE GAO ACETA, Edward M

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UNITED STATES PATENT OFFICE GAO ACETA, Edward M Patented Sept. 28, 1943 2,330,570 UNITED STATES PATENT OFFICE GAO ACETA, Edward M. Filachione, Akron, Ohio, assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Application July 31, 1940, serial No. 348,841 11 Claims. (C. 260-615) This invention relates to the preparation of However, the use of a diluent may be omitted, if halo acetals such as the acetals of haloaldehydes. desired. In accordance with the present invention, I have The halogenation may be conducted at room been able to prepare haloacetals by treatment of temperature or above, if desired, but in order to vinyl type esters with halogen such as chlorine improve the yields, however, it is found desirable or bromine in the presence of an alcohol, par to avoid the use of temperatures which are un ticularly an aliphatic alcohol such as ethyl or desirably high and in most cases it is found that methyl alcohol. Similar acetals may be prepared the yield of acetal is improved by conducting the by halogenating the vinyl type esters and treat halogenation at comparatively low temperatures, E. the halogenated product with a suitable alco 10 generally below 10° C., and preferably, below 0°C. ol. Following the halogenation, it is generally The invention is particularly applicable to the found desirable to allow the reaction mixture to treatment of vinyl esters such as vinyl acetate, stand for a suitable period, generally several vinyl propionate, vinyl butyrate, vinyl chlorace hours, in order to permit a more Complete reac tate, vinyl chloropropionate, etc. However, other 5 tion to occur and to insure the production of the esters of the vinyl type may be treated in accord acetal in high yields. During this period cooling ance With my invention. Thus, esters having the of the mixture is found to be unnecessary and, following characteristic structure may be em in general, the mixture is allowed to stand at ployed room temperature, although in some cases the RBI O 20 mixture may be heated. As previously noted, the vinyl ester may be R-(-)-0--R, halogenated prior to the introduction of the al where R1, R2, are hydrogen, or organic radicles, cohol. In such a case, the reaction between the such as methyl, ethyl, propyl, butyl, chloromethyl, halogenated product and the alcohol may be con chloroethyl, bronomethyl, bromopropyl, etc., and ducted at room, temperature or above. R3 is an Organic radicle, such as methyl, ethyl, The acetals may be recovered from the reac chloromethyl, bronomethyl, etc. tion mixtures by convenient methods. In ac The process may be conducted by the addition cordance with the present invention, I have Se of halogen to vinyl acetate or similar ester in the cured an effective separation by adding Water to presence of the desired alcohol. Thus, if methyl 30 the mixture and extracting the acetal layer with or ethyl acetals are desired, the halogenation a water immiscible solvent such as ether, benzene, may be conducted in the presence of methyl or chloroform, etc. Following recovery of the ether ethyl alcohol. Similarly, the acetals of other al extract, the extract may be washed with Water cohols such as propyl, butyl, amyl, hexyl, lauryl, and/or an aqueous alkaline solution such as a benzyl, chloropropyl, chloroethyl, chlorobutyl, 35 solution of sodium bicarbonate to remove acidic bromoethyl, etc., or secondary or tertiary alco Or other water soluble constituents and the Sol hols such as isopropyl alcohol or isobutyl alcohol vent removed by distillation. Subsequently, the or tertiary butyl alcohol may be prepared by. Con acetal may be purified by distillation or by other ducting the halogenation in the presence of the suitable methods. respective alcohol desired. 40 The following examples are illustrative: . If desired, the acetals may be prepared by Eacample I-A solution of 43 g. of dry vinyl means of a two-stage process wherein the corre acetate in 150 cc. of absolute ethyl alcohol was Sponding ester of a 1,2-dihalo alcohol such as an cooled in a closed cooling bath of dry ice in ace a,6-dihalo ethyl ester may be prepared by halo tone. Accompanied by stirring, a stream of dry genation of the vinyl ester and the resulting di 45 chlorine was passed into the solution until 35.5 halo ester may be reacted with alcohols to form g. (A. m.) had been added. The mixture was the corresponding acetal. Thus, vinyl acetate or allowed to warm to room temperature and after similar esters may be halogenated to form the standing overnight, the reaction mixture was corresponding dihalo ethyl acetate and this ester poured into cold water. The ethyl chloroacetal, may be reacted with methyl, ethyl, propyl, or sin 50 which separated, was extracted with ether and ilar alcohol to form the acetal. If desired, suit the ether solution was washed free of acids. Af able diluents such as chloroform, carbon tetra ter drying, the solvent was removed and the chloride, benzene, or other inert diluent which residual ethyl chloroacetal was distilled. In this may be conveniently separated by distillation manner, ethyl chloroacetal was obtained. This from the acetal to be produced may be used. 55 compound (CHaCICH(OCHs)) boiled at 53-54 2 2,880,570 C. under 16 mm. pressure; No. 14171; dao 1,017. Scribed with reference to the specific details of Eacample II.-The process was carried out as in certain embodiments thereof, it is not intended Example, using 86 g. (1 m.) of vinyl acetate dis that such details shall be regarded as limitations Solved in 200 cc. of methanol and 71 g of chlorine. upon the Scope of the invention except insofar as This process resulted in the production of methyl 5 included in the accompanying claims. chloroacetal (CHCCH(OCH3)2) (B. P. 1245 to I claim: 126.5° C. at atmospheric pressure, NDO 1.4150, 1. A method of preparing a halo acetal which d20 1.094). comprises introducing an elemental halogen se Eacample III-Air was passed over the surface lected from the group consisting of bromine and of 12.5 cc. of liquid bromine and the bromine O chlorine into a mixture of vinyl acetate and a laden stream of air was led into a solution of 21.5 monohydric primary alcohol. g. of vinyl acetate in 75 cc. of absolute ethyl alco 2. A method of preparing a halo aceta which hol. During the reaction the mixture was stirred, comprises introducing an elemental halogen se and the temperature was maintained at minus lected from the group consisting of bromine and 10 C. The product of reaction, ethyl bromo 5 chlorine into a mixture of vinyl acetate and a acetal, was isolated in the same manner as de monohydric primary aliphatic alcohol at a ten Scribed for isolating ethyl chloroacetal in Ex perature not above room temperature. ample I. w 3. A method of preparing a halo acetal which The above process resulted in a yield of 33 g. or comprises introducing an elemental halogen se 68% of the theoretical amount of ethyl bromo 20 lected from the group consisting of bromine and acetal, B. P. 62-53 C. at 15 mm. dao 1.276; No chlorine into an essentially organic mixture of 1.4395. vinyl acetate and a primary aliphatic alcohol at Eacample IV.-A solution of 64.5 g. (0.75 mole) a temperature not above room temperature. of vinyl acetate in 150 cc. (3.7 moles) of methyl 4. The method of claim 1 in which the alcohol alcohol was cooled by immersion in an acetone is ethyl alcohol. dry ice cooling bath. To this was added, with 5. The method of claim 1 in which the alcohol . stirring, a solution of 120 g. (0.75 mol) of bromine is methyl alcohol. in 100 cc. of CHCl3. The temperature of the re 6. A method of preparing a halo acetal which action mixture remained below -40° C. during comprises reacting an elemental halogen selected the entire reaction. The product of the reaction, 30 from the group consisting of bromine and chlo methyl bronoacetal, was isolated in the same rine with vinyl acetate and reacting the halo manner as described for ethyl chloroacetal in genation reaction mixture with a monohydric Example I, and a yield of 46% of the theoretical primary alcohol. of methyl bromoacetal which boiled at 48-51 C. 7. A method of preparing a halo acetal which at 18 mm. pressure; d.20 1.467; ND20 1.4475 was comprises reacting an elemental halogen selected obtained. from the group consisting of bromine and chlo Eacample W.-86 g. of vinyl acetate was cooled, rine with vinyl acetate, adding a monohydric the temperature to about minus 10 to 20° C. and primary aliphatic alcohol to form an essentially 72 g. of chlorine was added thereto while the organic reaction mixture and permitting the re mixture was stirred. The resulting reaction mix 40 actants to react. ture was added dropwise to 250 cc. of absolute 8. The process of claim wherein the reaction ethyl alcohol which was stirred as well as cooled takes place at a temperature not above room by ice. After standing overnight, the ethyl temperature. chloroacetal was isolated as in Example I. 9. The process of claim 7 in which the alcohol Eacample VI.-43 g. of vinyl acetate was cooled 45 is ethyl alcohol. to -5° C. and 80 g. of liquid bromine was added 10. The process of claim 7 in which the alco dropwise thereto with stirring. The temperature hol is methyl alcohol. of the reaction mixture remained at 0° C.
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