CS273876B1 - Method of 1,1-dichloro-4-methyl-1,3-pentadiene preparation - Google Patents

Abstract

A method of 1,1-dichloro-4-methyl-1,3-pentadiene preparation by dehydrochlorination of 1,1,1,3-tetrachloro-4-methylpentane in an environment of N,N-dimethyl formamide at 130 to 160 degrees C with possible catalysis by lithium chloride. 1,1-Dichloro-4-methyl-1,3-pentadiene is an important intermediate product for production of permethrinic acid and its derived synthetic pyrethroids, which are highly effective insecticides.

Description

The invention relates to a process for the preparation of 1,1-dichloro-4-methyl-1,3-pentadiene by dehydrochlorination

1,1,1,3-tetrachloro-4-methylpentane.

1,1-Oichloro-4-methyl-1,3-pentadiene is an important intermediate in the production of insecticidally active substances called synthetic pyrethroids such as permethrin and cypermethrin. This tonsil is usually produced by condensation of chloral g with butylene by a four-step process including also acetylation, dehydrochlorination and isomerization (Coli. Czech. Chom. Commun. 24, 2230 (1959)). However, this multi-stage process is expensive and is accompanied by a considerable amount of waste.

The aforementioned member may also be prepared in a simpler manner by adding tetrachloromethane to 3-methyl-1-butene to give 1,1,1,3-tetrachloro-4-methylpentane which affords 1,1- dichloro-4-methyl-1,3-pontodiol. Bases such as amines (NSR Pat. No. 2,624,340 (1976)) or alkali metal hydroxides in an aqueous medium (US4 Pat, No. 4 (J7U 404 (1970)) were used as the hydrochloride reagents. 1,1,3-tetrachloro-4-methylpentane can also be carried out catalytically using Lewis acids such as tin tetrachloride (NSR Pat. Appl. 6,751,435 (1970)) or better zinc chloride (Cs. PV 2015-87) Acid-catalyzed dehydrochlorination always results in a certain amount (about 10%) of polymerization of the product under the influence of strong acidic trisodium, which decreases the yield of the product, which is eliminated by the present invention, which yields the desired product in quantitative yield.

The present invention provides a process for the preparation of 1,1-dichloro-4-methyl-1,3-pentadiene by the hydrochlorination of 1,1,1,3-tetrachloro-4-methylpentane in-, Ν-dimethylformamide (DMF) at 130 to 160 ° C, optionally with lithium chloride catalysis.

The starting material, i.e. 1,1,1,3-tetrachloro-4-methylpentane, is readily available by the catalytic reaction of carbon tetrachloride with 3-methyl-1-butene according to U.S. Pat. Certificate No.

257,965, yielding the desired product in almost quantitative yield. The above diene can thus be prepared in a more simple two-step process from readily available raw materials in an almost quantitative yield.

The dehydrochlorination reaction is simple to perform as it is readily carried out at the boiling point of OMP (153 ° C), which is both the solvent and the dehydrochlorination reagent of the reaction and is liberated by hydrogen chloride due to the basic properties of DMF. The dehydrochlorination reaction can be accelerated by the use of a catalyst such as lithium chloride. The most suitable way of isolating the product from the reaction mixture is by steam distillation.

These examples further describe the process for producing 1,1-dichloro-4-methyl-1,3-pentadiene of the invention without limiting or limiting its scope.

Example 1

A mixture of 64.9 g (0.29 mol) of 1,1,1,3-tetrachloro-4-methylpentane and 190 g (2.3 mol) of N, N-dimethylformamide is heated to boiling (149-152 ° C) with stirring. ) under reflux for 17 h, when all 1,1,1,3-tetrachloro-4-methylpentane has reacted. By steam distillation, 42.3 g of 1,1-dichloro-4-methyl-1,3-pentadiene, boiling at 94 DEG C./11.7 kPa, is isolated in a yield of 96.6%.

Example 2

A mixture of 64.9 g (0.29 mol) of 1,1,1,3-tetrachloro-4-methylpentane, 190 g (2.3 mol) of N, N-dimethylformamide and 3.2 g of lithium chloride monohydrate is heated to boiling at 152-153 ° C for 8.5 h while completely reacting 1,1,1,3-tetrachloro-4-methylpentane. In accordance with Example 1, 42.5 g of 1,1-dichloro-4-methyl-1,3-pentadiene were isolated in a yield of 97.1.

Example 3 j A mixture of 64.9 g (0.29 mol) of 1,1,1,3-tetrachloro-4-methylpentane, 63.6 g (0.07 mol) of N, N-dimethylformamide and 12.7 g lithium chloride monohydrate was heated at 130 ° C for 43.5 h / ^'θ'> CS 01 273 876 and 1 h at 160 ° C, the procedure of Example 1 was isolated 42.8 gl, l-dichloro-4-methyl -1,3-pentadiene in 97.9% yield.

Example 4

A mixture of 6.5 g (0.03 mol) of 1,1,1,3-tetrachloro-4-methylpentane and 44 g (0.6 mol) of N, N-dimethylformamide is heated to boiling at 150-153 ° C for a period of time. 20 g. Using the procedure of Example 1, 4.1 g of 1,1-dichloro-4-methyl-1,3-pentadiene is isolated in a yield of 93.6%.

Claims (3)

Process for the preparation of 1,1-dichloro-4-methyl-1,3-pentadiene by dehydrochlorination of 1,1,1,3-tetraohloro-4-methylpentane, characterized in that the dehydrochlorination is carried out by treatment with N, N-dimethylformamide, optionally in presence of lithium chloride by heating the reaction mixture at 130 to 160 ° C. 2. A process according to claim 1, wherein from 3 to 20 molar parts of N, N-dimethylformamide are used per mole of 1,1,1,3-tetrachloro-4-methylpentane. 3. Method according to claims 1 and 2, characterized in that it is applied to 1 wt. % of 1,1,1,3-tetrachloro-4-methylpentane to 0.20 wt. parts of lithium chloride.