CS209266B1 - Manufacturing method of alpha-halogen glutaric acid and/or of its dialkyl esters - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of α-haloglutic acid and its dialkyl esters from petrochemical intermediates, in particular ---, -chloroglutaric acid dimethyl ester from low-grade glutaric acid dimethyl esters. From α-bromoglutaric acid, respectively. α-: chloroglutaric and its derivatives, DL-glutamic acid is prepared by ammonolysis, of which L-glutamic acid monosodium salt is widely used in the food industry and is also a valuable essential amino acid for nutritional purposes.

Α-Chloroglutaric acid and its derivatives can be prepared from dihydropyran by chlorination followed by hydrolysis and oxidation. If the oxidation is carried out with dilute nitric acid, then hydrolysis of i and oxidation takes place simultaneously with Japanese pat. No. 32-4562. In a similar manner, with nitric acid or nitrogen oxides, they are simultaneously hydrolyzed! and oxidize polysubstituted pyrans to form α-chloroglutaric acid. No. 32-9308 and 32-9309. However, these processes are multi-stage and, in addition, the production of feedstock is already technically and energy-intensive.

Of interest is the preparation of α-chloro-glutamic acid by chlorination of glutanhydride (U.S. Pat. No. 2,870,167, British Pat. No. 815,906, Canadian Pat. No. 614,079, French Pat. No. 1,188,834). Next, they were sour; α-haloglutaric acid can be prepared from the 3-halocyclopentene. Oxidation of 3-chlorocyclopentene yields either α-hydroxyglutaric acid, α-chloroglutaric acid lactone, α-chloroglutaric acid, or a mixture of these compounds (British Patent No. 843,552). Α-Chloroglutaric acid can also be obtained in relatively low yields by reacting glutaric acid with thionyl chloride via glutaric dichloride and in another chlorine gas treatment under the action of ultraviolet light (Treibs W., Michaelis K .: Chem. Ber. 88, 405 (1955)) .

Chlorination of glutaric acid esters with chlorine, thionyl chloride or sulfuryl chloride is carried out, in particular, in the presence of catalysts such as red phosphorus, phosphorus pentoxide, phosphorus pentoxide, phosphorus pentoxide, phosphorus pentoxide, phosphorous acid, phosphoric acid and other phosphorus compounds (U.S. Pat. No. 2,840,596, British Patent No. 816,648, Japanese Patent No. 36-162, Japanese Patent No. 37-2306).

Α-chlorodicarboxylic acid dialkyl esters! can be prepared from glutaric acid chloride ester by refluxing with sulfuryl chloride and after removing: excess sulfuryl chloride by esterification with al-S cohole (Schwenk E., Papa D .: J. Am. Soc. 70, 3626 (1948). - a-chlororadipic acid ester, the latter two being dicarboxylic acid monoalkyl esters

as starting materials, where the structure of the ester, the more chlorine monoalkyl ester of the dicarboxylic acid, already forms chlorination conditions into the α-position. »

Despite the obvious advantages of several of these procedures, their disadvantage is a lower chlorination selectivity to the α-position and therefore lower yields of α-haloglutaric acid and its dialkyl esters. These problems are, however, sufficiently addressed by the method of the present invention.

According to the invention, a process for the preparation of α-halo-glutaric acid or its dialkyl esters of the general formula is provided

wherein X is chloro or bromo, R 'and R' 'are alkyls having 1 to 5 carbon atoms, wherein R' and R '' are the same or different, from the dialkyl esters of glutaric acid by the action of chlorine or bromine in the presence of a catalyst whereas the chlorination or bromination is carried out under the catalytic effect of antimony or at least one antimony-containing compound at a temperature of 50-160 ° C, whereby the dialkyl ester or the mixture of dialkyl esters is hydrolyzed in the case of the production of α-haloglutaric acid and optionally the individual components are isolated.

The dialkyl ester of a-haloglutaric acid, e.g., α-chloroglutaric acid dimethyl ester, can be readily hydrolyzed to α-chloroglutaric acid, respectively. ammonolysing to glutamic acid. An advantage of the process for the preparation of the dialkyl esters of α-halo-glutaric acid and its dialkyl esters according to the invention is the availability of raw materials for which, for example, by-products of cyclohexane to cyclohexanone oxidation can be used. These can be readily isolated by esterification via glutaric, succinic and adipic acid dimethyl esters and distillation, respectively. rectification of individual esters. Another advantage is the low number of process steps, especially the relatively high halogenation rate, especially the chlorination and the sufficiently high selectivity to the a-position. There is practically no β-chloro derivative present in the crude product, and there are also low amounts of α, α, α, α'-dichloro derivatives and α, α, α'-trichloride dihydrate dialkyl ester. In the case of glutaric dialkyl esters, unless the technical conditions for the isolation or availability of the alcohols, most preferably for chlorination, are dimethyl glutaric acid esters. Because of the length of the alkyls, the possibility of generating more and hence more by-products increases, resulting in a reduction in the selectivity of the desired product, a reduction in yields and a higher consumption of raw materials.

Although halogens, chlorine and bromine can be added in larger quantities continuously, semi-continuously or continuously, but in view of the removal of the reaction heat, in particular the chlorination selectivity to the α-position, chlorine gas or bromine or liquid bromine is continuously added, usually at a rate of 5.10. -3 to 30.10-3 mole per mole of glutaric dialkyl ester per minute. The catalyst concentration in the reaction medium should be in the range of 0.5. 10-3 to 8.10-1 mole, most preferably 1. 10 ~ 2 to 2.10 ~ 2 moles per mole of glutaric dialkyl ester.

In addition to antimony metal, preferably in powder form, the antimony halides can be applied as catalysts. Antimony trichloride, antimony bromide, antimony trichloride are most preferred. Further, antimony oxides, such as antimony trioxide and antimony and antimony oxides, antimony sulfides, especially antimony sulfide. Other antimony compounds, such as antimony trichloride and natural antimony compounds, such as chalkostibite (Cu 2 S 2 Sb 2 O 3), boulangerite (5 PbS. 2 Sb 2 O 3), jamesonite (2 PbS. Sb 2 O 3), ullmanite (NiSbS), and p .

If the production is α-chloroglutaric acid or α-bromoglutaric acid, due to the higher selectivity of halogenation of the dialkyl glutarate ester than glutaric acid itself, the corresponding α-haloglutaric acid ester is hydrolyzed mainly by the action of dilute mineral acids such as hydrochloric acid, acid sulfuric, trihydrogenphosphoric acids, less suitable are organic acids such as formic acid, acetic acid and the like.

The halogenation products of glutaric acid dialkyl esters can be used for practically crude reaction products for some applications, but most often the individual components are isolated, especially dialkyl esters of α-chloro- or α-bromoglutaric acid, most often by distillation under reduced pressure, especially by film distillation, by film distillation using rotating wiped columns and the like. It is more difficult to isolate the individual components by extraction, crystallization at low temperatures. In the case of α-chloro- or α-bromoglutaric acids alone, crystallization is also due to their relatively higher melting point by suitable isolation methods. Unconverted starting materials can be advantageously reused, i.e. recirculated.

Example 1

80 g (0.5 mole) of glutaric acid dimethyl ester (I) having a boiling point of 99 ° C / 1.6 kPa (n2.5 = 1.4235) and 2.28 g (1.10 ~) were weighed into the chlorination reactor. 2 moles of antimony trichloride catalyst. After heating to the desired temperature, chlorine gas was introduced into the mixture to provide high turbulence of the chlorinated feedstock in a special reactor. The degree of conversion was checked continuously by taking liquid samples and measuring their refractive indices. At an optimum refractive index (ηθ = 1.4620), the chlorine feed to the reactor was closed and the liquid product was purged with nitrogen gas. Distillation of the crude product in vacuo gave α-chlorobutaric acid dimethyl ester (II), b.p. 113-114 ° C / 666.6 Pa.

and refractive index ηθ5 = 1.4581. The product was further identified by elemental composition determination, NMR, IR analysis and liquid-gas chromatography.

An overview of the results of the effect of temperature at a constant concentration of 1.10 2 mole of antimony trichloride on the conversion of glutaric acid dimethyl ester and the selectivity of dimethyl alpha-chloroglutarate formation at a chlorine flow rate of 9.7.10 3 mole. mole1 is in Table 1.

Table 1

I - glutaric acid dimethyl ester II - α-chloroglutaric acid dimethyl ester

Under otherwise similar conditions, but without catalyst, substantially less favorable results were obtained as shown in Table 2 below.

Table 2

j

The maximum yield of α-chloroglutaric acid dimethyl ester in the non-catalyzed chlorination reached 30.1% at 180 ° C, while in the catalyzed chlorination it was 78-80% at 90-100 ° C.

Α-Chloroglutaric acid dimethyl ester was isolated on a film evaporator at 66.6 Pa.

Example 2

Under otherwise similar conditions as in Example 1, a series of experiments was carried out in which a constant temperature of 100 [deg.] C. was followed, respectively. 120 ° C and a continuous chlorine flow rate of 9.7. 10 '3 mole. molT1 · min. 1, the effect of the type and concentration of the catalyst system and the reaction time on conversion (I) and selectivity of formation (II). The reactor was charged with 18 g (0.5 mole) of glutaric acid dimethyl ester (I), but varied in type and amount of catalyst system. The results are shown in Table 3.

Table 4

Example 3

The working procedure was similar to that of Example 1, only sh was working at a constant temperature of 100 ± 1 ° C, and the flow rate of chlorine was changed in each experiment. The reactor was charged with 80 g (0.5 mole) of glutaric acid dimethyl ester (I) and 2.28 g of SbCl 3 (1.0 M 2 mol). The results are shown in Tab. 4.

Claims (1)

Original document published without claims.