DE842193C - Process for the production of halogen-containing dicarboxylic acids or their functional Abkoemmlingen - Google Patents

Description

Process for the production of halogen-containing dicarboxylic acids or their functional descendants when exposed to hypohalous acids or from halogen in the presence of water to unsaturated compounds, i.a. even on acrylic acid, there are the corresponding halohydrins, next to them can also when exposed to halogen and water in varying amounts, the corresponding 1) ihalogen compounds are formed by the addition of a 1o1 halogen.

It has now been found that the course of the reaction is different if acrylic acid or such functional derivatives of acrylic acid, e.g. B. acrylic acid esters, acrylic acid amides, acrylic acid salts or acrylonitrile, in which the modified carboxyl group is not changed under the reaction conditions, treated in the presence of a multiple excess of water, based on the unsaturated compound, with a mixture of chlorine or bromine and an inert gas. In addition to the expected halohydrins or dihalogen compounds, dicarboxylic acids or their derivatives, which are apparently formed by the coming together of two molecules of the acrylic compound, surprisingly also arise here. For example, the action of a mixture of chlorine and a diluent gas on an aqueous solution of AcrS-nitrile results in addition to i, 2-dichloropropionitrile and oxychloropropionitrile, a dinitrile with the empirical formula CH Hb C12N2, which probably corresponds to one of the following formulas because in the catalytic hydrogenation, with the exchange of the two chlorine atoms by hydrogen, it is converted into α-methylglutaric acid dinitrile, which in turn can easily be converted into α-methylglutaric acid by saponification in the usual way.

In a corresponding manner, methyl acrylate is obtained from the reaction with a mixture of chlorine and a diluent gas in the presence of water Diesters of the empirical formula C, "H" 0, C1 "also apply after the hydrogenation and saponification gives α-methylglutaric acid. When using acrylic acid itself as the starting material dichloro-a-methylglutaric acid is obtained. In the case of other descendants, the Implementation in the same way. Chlorine is preferably used, but bromine is also suitable.

The implementation conditions are basically the same as for the attachment Conditions applied from hypohalous acids to unsaturated compounds. To determine the ratio of the three reaction products, dihalo addition compound, Halohydrin and dicarboxylic acid or acid derivative, in favor of the latter Moving products and pushing back the formation of other substances will z. B. the chlorine with an inert gas, e.g. B. nitrogen, diluted and appropriate at normal or only moderately elevated temperature, for example up to about 8o ', worked. Furthermore, the unsaturated compound with a multiple amount of water, z. B. with five times the amount or more, diluted.

The easiest way to implement it is by z. B. chlorine, which is diluted with nitrogen, into an aqueous solution or suspension of acrylic acid or the acrylic acid derivative. The method can also, if desired can be carried out in continuous operation.

The separation of the dicarboxylic acids or their derivatives from the others Reaction products are processed in the usual way, for example by distillation, causes, with the by-products in the sense of the present process as the first Fractions are obtained.

The halogen-containing dicarboxylic acids and their derivatives can be used as such or after further chemical reactions as intermediates for various Purposes to be used by the chemical industry.

The parts given in the examples below are parts by weight.

EXAMPLE i A solution of 371 parts of acrylonitrile in 4550 parts of water in a glass tower fitted with a glass frit is used to pass a chlorine-nitrogen mixture in a volume ratio of 3: 1 at 20 'until no more chlorine is absorbed . The deposited 0I is separated, the aqueous portion extracted with ether, combine the ethereal solution with 01 distilled and the whole after drying. This gives 250 parts of α, β-dichloropropionic acid nitrile (bp 18 = 62 to 63 '), 50 parts of oxychloropropionic acid nitrile (bp 8 = 10 3 to 10 7') and 162 parts of a dichlorodicarboxylic acid dinitrile (Kpl = 12o to i35 '), probably dichloromethylglutaric acid dinitrile.

The same compound in addition to dichloro- and oxychloropropiononitrile is obtained if a solution of 371 parts of acrylonitrile in 4450 parts of water is treated at 48 to 50 'with stirring with a chlorine-nitrogen mixture of a volume ratio of 5: 1 to saturation. EXAMPLE 2 A mixture of chlorine and nitrogen in a volume ratio of 3: 1 is passed through an emulsion of 152 parts of methyl acrylate in 1,000 parts of water at 20 'until no more chlorine is absorbed. Working up in the manner described in Example i gives 79 parts of methyl α, β-dichloropropionate (KP, = 35 to 43 °), 46 parts of methyl oxychloropropionate (KP, = 55 to 65 ') and 48 parts of a chlorine-containing dicarboxylic acid ester (Kpa = 100 to 125 '), probably dichloromethylglutaric acid dimethyl ester.

Claims (1)

PATE XTANSPPL CII: Process for the preparation of halogen-containing dicarboxylic acids or their functional derivatives by treating unsaturated compounds of the acrylic acid type with hypohalous acid in the presence of a multiple excess of water, based on the unsaturated starting material, characterized in that acrylic acid or such functional Derivatives of acrylic acid in which the modified carboxyl group is not changed under the reaction conditions are treated in the presence of a multiple excess of water with a mixture of chlorine or bromine and an inert gas and the halogen-containing dicarboxylic acids or their functional derivatives are converted from the reaction mixture obtained in the usual way Way. Attracted publications Beilstein, "Handbuch derorganischen Chemie", 4th ed., Vol. I, p. 398.