JPS5944339A - Preparation of 2,3-dihalogeno-3-phenylpropionic acid halide - Google Patents

Abstract

PURPOSE:In halogenating a 2,3-dihalogeno-3-phenylpropionaldehyde, to obtain the titled compound useful as an intermediate mainly for agricultural chemicals industrially advantageously in high yield, by adding a specific azo compound to it. CONSTITUTION:1mol 2,3-dihalogeno-3-phenylpropionaldehyde is halogenated in the presence of 50-500mg, especially 100-200mg azo compound, especially alpha,alpha'- azobisisobutylonitrile shown by the formula I (R are R' are lower alkyl, or cycloalkyl; A is CN, or alkoxycarbonyl) at 30-80 deg.C, preferably 40-60 deg.C, to give a 2,3-dihalogeno-3-phenyl-propionic acid halide shown by the formula II (X is halogen) by a common reactor economically, safely and industrially in high yield.

Description

[Detailed description of the invention] The present invention relates to a method for producing robionic acid halide.

2,3-Dihalogeno-3-phenylpropionic acid halide itself is a known compound, and is mainly useful as an intermediate in the production of agricultural chemicals.

Conventional methods for producing 2,3-dihalogeno-3-phenylpropionic acid halide include 2,3-dihalogeno-3-phenylpropion as represented by the following formula (I) (wherein X is a halogen atom). A photochemical reaction method for converting aldehydes into rogens under light irradiation [Dopobidi]
Akademi Nauk Ukrainskoy R8R Kin
Nries B vol. 1975 A4 pp. 344-346 (1
975): Dopovid+AkademijN
au, kUkraj-ns'koiR8R, KjjnS
er, BVol, 197576.4 P, 344-3
46 (1975)] is known. However, this method (1) is a photochemical reaction, so the equipment is complicated and expensive; (2) the cost is high due to the electricity cost of the light source; and (3) the light source is high voltage, making it highly dangerous. (4) The yield from 2,3-dihalogeno-3-phenylpropionaldehyde was as low as 75% by weight or less, and as a whole, this method was not industrially advantageous.

In view of the above, the present inventors conducted various studies on industrially advantageous production methods for 2,3-dihalogeno-3-phenylpropionic acid halide, and found that the reaction (1) described above is carried out in the presence of an azo compound. discovered that the desired product could be obtained industrially in high yield and completed the present invention.

That is, the present invention provides a method for producing 2,3-dihalogeno-3-phenyl-propionic acid halide by halogenating 2,3-dihalogeno:3-phenylpropionaldehyde. , A represents a cyan group or an alkoxycarbonyl group.2,3-dihalogeno-3-phenyl-
This is a method for producing propionic acid halide.

Chlorine, bromine, etc. are commonly used as halogenating agents in the present invention.

A specific example of the azo compound to be present is CO2C2■1
6 C02C2H5 CN CN CN 0N ON 0N CN 0N CN CN 0N ON etc. One or more types can be mentioned. Especially α,
α'-Azobisisobutyronitrile is preferred.

These azo compounds may be commercially available, or they can be obtained in good yield by obtaining the hydrazo compound from hydrazine sulfate, alkali cyanide, or ketone and then oxidizing it.

This releases radicals and exhibits a catalytic function when 2,3-dino cogeno-3-phenylpropionaldehyde is norogenated.

The present invention carries out the reaction using the above-mentioned raw materials. To explain its implementation mode, first, 2゜3-dihalogeno-3-phenylpropionaldehyde is dissolved in an inert organic solvent, especially a halogenated hydrocarbon. Mix and then allow the azo compound to be present and slowly add more norogen to complete the reaction.

Inert organic solvents that can be used at this time include carbon tetrachloride,
Examples include chloroform, dichloroethane, trichloroethylene, tetrachloroethylene, methylchloroform, monochlorobenzene, and among these, carbon tetrachloride is particularly preferred. There is no particular limit to the amount of 2,3-dihalogeno-3 used, but it is usually used in an amount within a range that does not interfere with the introduction of nitrogen, stirring conditions, temperature conditions, uniform presence of catalyst, etc. -2 to 5 times the volume of phenylpropionaldehyde may be used.

The amount of the azo compound to be present is sufficient to be 50 to 500 mq, preferably 100 to 500 mq, per mole of 2,3-dihalogeno-3-phenylpropionaldehyde.
It is 200 mq. If it is less than 50 mq, the yield of the target product will not be sufficient, and if it exceeds 500 mq, the amount of impurities, typified by impurities, will increase, which is undesirable.

This quantitative relationship is clear from FIG. That is, Figure 1 is a graph showing the yield (%) of the target product, 2,3-dichloro-neely-phenylpropionic acid chloride, for the addition of α,α'-azobisisobutyronitrile. ,
The amount of azo compound is 50 to 500 mq per mole of 2,3-dihalogeno-3-phenylpropionaldehyde.
It can be seen that outside the range, the yield of the target product decreases and impurities increase.

Next, halogen is introduced and the reaction is allowed to proceed gradually, but the amount of halogen used is 2,3-dihalogen-
It is sufficient to use it in an equimolar amount to 3-phenylpropionaldehyde or in a slight excess taking into consideration the amount consumed along with by-product hydrogen halide.

The reaction temperature is suitably 30 to 80°C, preferably 40 to 60°C. This is because if the temperature is lower than 30°C, the start of the reaction will be delayed, and if the temperature is higher than 80°C, by-products will increase and the yield will decrease, which is not desirable. Note that within the above temperature range, it is possible to start the reaction at a high temperature range at the beginning of the reaction and then continue the reaction at a low temperature range without causing a decrease in yield.

The reaction rate is usually slow at the beginning of the reaction, but becomes faster as the radicals of the azo compound are produced in a chain.

Although the reaction time varies depending on the reaction volume, type and amount of solvent, catalyst, temperature, and other operating conditions, it is usually 2.
It is sufficient to react for up to 6 hours.

After the reaction is completed, the solvent is recovered according to a conventional method to obtain the desired product. Thus, according to the present invention, 2.3-dihalogeno-3-phenylpropionic acid halide is produced according to the general reaction according to the present invention. :3-Dihalogeno-:3-phenylpropionaldehyde yield is 94% or more]
-0 In addition, the certain amount of 2,3-dihalogeno-3-phenylpropionic acid halide is 2,3-dihalogeno-3
-Methyl esterification of phenylpropionic acid halide was determined by gas chromatography internal standard method.

The present invention will be specifically explained below with reference to Examples.

Example 1 101.59-(0.50 mol) of 2,3-dichloro-3=phenylpropionaldehyde and carbon tetrachloride were placed in a four-necked flask equipped with a reflux condenser, a temperature side, a chlorine injection tube, and a stirring device. 759 and α.

50 mg of α'-azobisisobutyronitrile was added, and the temperature was raised to 60'C while gradually introducing chlorine.

After about 2 hours, the reaction became faster and the reaction was completed when 42.59 (0.60 mol) of chlorine was introduced after 4 hours.

A portion of this reaction solution was taken out, methyl esterified, and quantitatively determined by gas chromatography internal standard method. As a result, the yield as methyl ester was 945%.

Example 2 In a four-loaf flask equipped with the same apparatus as in Example 1, 2.3
-dichloro-3-phenylpropionaldehyde] 0
], 59 (0.50 mol), carbon tetrachloride 175 g,
and 50 ml of α,α'-azobisisobutyronitrile were charged, and the temperature was raised to 60°C while gradually introducing chlorine. After about 2 hours, after the reaction became rapid, 45°
The temperature was lowered to C and the reaction continued. The total amount of chlorine is 425 liters (060
mol) was introduced, the reaction was complete. As a result of quantitative determination in the same manner as in Example 1, the yield as methyl ester was 955%.
Met.

COMPARATIVE EXAMPLE In a four-loaf flask equipped with the same equipment as in Example 1, 2.3
-dichloro-3-phenylpropionaldehyde 101
．． 5!7 (0.50 mol) and carbon tetrachloride 175f7 were charged. Next, chlorine 4259 was introduced over a period of 4 hours. However, as a result of quantifying the reaction solution using a gas chromatograph, 2,3-dichloro-3-phenylpropionic acid chloride was not obtained.

[Brief explanation of drawings]

FIG. 1 is a graph in which the yield (%) of the target product and the amount of impurities are plotted against the amount of α,α'-azobisinbutyronitrile added. Applicant Nihon Kagaku Kogyo Co., Ltd.

Claims (1)

[Claims] 1)2. : 3-Dihalogeno-3-phenylpropionaldehyde is converted into 2. :3-dino cogeno 3-phenylpropionic acid halide R, 11,
' represents a lower alkyl group or a cycloalkyl group, and A represents a cyan group or an alkoxycarbonyl group. The presence of an azo compound represented by ] indicates a halogen atom. ] A method for producing 2,3-dihalogeno-3-phenyl-propionic acid halide. 2) 50 to 500 m9 of azo compound per mole of 2,3-dihalogeno-3-phenylpropionaldehyde
2. A method for producing 2,3-dino cogeno-3-phenylpropionic acid halide according to claim 1, characterized in that 2,3-dino cogeno 3-phenylpropionic acid halide is present. 3) A method for producing 2°3-dihalogeno-3-phenylpropionic acid halide according to claim 1 or 2, wherein the reaction temperature is 30 to 80°C.