DE838000C - Process for the preparation of carboxylic acid esters of aliphatic ªÏ-chloro alcohols - Google Patents

Description

Process for the preparation of carboxylic acid esters of aliphatic w-chloro alcohols It is known to produce carboxylic acid esters of o-chlorobutanol by reacting carboxylic acids with tetrahydrofuran in Gügenwart of hydrogen chloride and expediently with the addition of acidic catalysts. such as zinc chloride or aluminum chloride. the Implementation requires a considerable amount of time and a substantial surplus of tetrahydrofuran.

1's has now been found that the production of (,) - Cliloroalkylesters can be done much more economically if you rely on carboxylic acids or their Anhydrides (,) - Chloral'kanole at temperatures below the boiling point of the cyclic Ether, which can be obtained by splitting off hydrochloric water from the (, t) -chloroalkanol is, in the presence of an acidic catalyst, expediently of hydrogen chloride, act leaves.

Surprisingly, under these conditions, even without one tries to accelerate the implementation by heating or that during the implementation resulting water drives off, an almost complete esterification of the carboxylic acids achieved. This usually saves the use of a water removal device auxiliary liquid used. An advantage of the method is also that the chloral'kanol used is also largely used for ester formation and, if you have it in excess applies, not with regression of the cyclic Ether is consumed. Finally, it is of particular advantage that the Implementation can also be carried out in such vessels that one can, with normal esterifications Cannot use because of the high temperatures applied.

It is particularly useful to use the (»-Chlotalkanol from cyclic ethers of the type of tetrahydrofuran or pentamethylene oxide and To produce hydrogen chloride. @ iän proceeds advantageously in such a way that hydrogen chloride, preferably at least the equimolecular amount, or more preferably an excess from up to 25 to 300/0, dissolves in the cyclic ether below its boiling point and leaves this solution to itself for several hours or a few days. You get then a liquid consisting almost exclusively of the co-chloroalkanol, which, if the hydrogen chloride has been used in excess, without any further addition acidic catalyst can be used directly for the esterification of the carboxylic acid.

The esterification is usually carried out at temperatures below 60 ° carried out. However, it is also possible at temperatures of 30 ° or even at To achieve a very complete esterification at room temperature. Basically can one can also work at temperatures above 60 ° "if one applies increased pressure. In any case, however, a distilling off of the cyclic ether and also of the Water should be avoided.

The starting materials for the present process are both monocarboxylic acids, such as butyric acid and benzoic acid, but especially dicarboxylic acids and their anhydrides, such as maleic acid, succinic acid, adipic acid or phthalic acid, into consideration.

The work-up of the w-Chloral'kanolester itself happens in itself usual way; for example can. one through the crude reaction mixture first Distillation in vacuo of the small amounts of by-products formed, e.g. B. the Free cyclic ether as well as water and unreacted chlorine alcohol, the remaining then crude ester by shaking with aqueous alkalis and washing out with water neutralize and then, if desired, by treating with bleach lighten the color of the ester or convert the ester into a by high vacuum distillation bring pure form. The parts given in the examples below are weighted parts.

Example i One mixes ipity parts of a crude arChlorbutanol that by introducing an excess of hydrogen chloride into tetrahydrofuran Room temperature and standing for 24 hours en $ Lalltem and that noetl 19.8'7e of unconverted gaseous hydrogen chloride edhäk, with 444 parts Phthalic acid aTdhydrid and stir the mixture for 46 55 rounds at 30 °. The thus obtained crude ester is removed from excess hydrogen chloride, the water of reaction and the unreacted chlorobutanol used in excess freed by neutralizing with aqueous sodium hydroxide solution and washing out three times cleaned with water and dried in it. 925 parts of the di-co-chlorobutylphthalic acid ester are obtained in this way, corresponding to a 894 / own yield, calculated on phthalic anhydride. The distilled off Zoo parts of 83% chlorobutanol can again be used for esterification.

Examples 438 parts are set in the manner described in example i Adipic acid with 1017 parts of crude orChlorbutanoi and obtained so in 95% yield 935 parts of adipic acid di-o) chlorobutyl ester.

Claims (2)

PATENT CLAIM: i. Process for the production of carboxylic acid esters aliphatic c) -Chlbralcohols, characterized in that one on carboxylic acids or their anhydrides, co-chloroalkanols, at temperatures below the boiling point of the cyclic ether, which is produced by splitting off hydrogen chloride from the o) -chloroalkanol arises, in the presence of an acidic catalyst, expediently of hydrogen chloride, can act. 2. The method according to claim i, characterized in that one Crude chloroalkanol is blown away, as can be done by dissolving hydrogen chloride; expedient in excess, in a cyefiscary ether, this is tetrahydrofuran and lasts for several hours Residence time of the solution obtained below the boiling point of the cyclic ether receives.