CS267890B1 - Method of 1,1-dichloro-4-methyl-1,3-pentadiene production - Google Patents

Abstract

Process for the preparation of 1,1-dichloro-4-methyl-1,3-pentadiene catalytic dehydrochlorination 1,1,1,3-tetrachloro-4-methylpentane with chloride or catalysis zinc oxide or acetate present acetic acid or formic acid at 100-130 ° C. 1,1-Dichloro-4-methyl-1,3-pentadiene is important intermediate in the production of derivatives permethrinic acid di azoacetate procedure. Permethrin esters they are modern, highly efficient insecticides known as synthetic pyrethroids and used in compositions plant protection products.

Description

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

1,1-Dichloro-4-methyl-1,3-pentadiene is an important intermediate in the manufacture of insecticidally active substances called synthetic pyrethroids. This diene is usually produced by the condensation of chloral with isobuytylene in a four-step process, see Farkas et al .: Coll. Czech. Chem. Common. 24, 2230 (1959), including condensation, acetylation, dehydrochlorination and isomerization. However, this process involves the costly elimination of zinc and is accompanied by a considerable amount of waste.

The above diene can also be prepared in a simpler manner by adding carbon tetrachloride to 3-methyl-1-butene to give 1,1,1,3-tetrachloro-4-methylpentane, followed by dehydrochlorination in the liquid phase to give 1.1 l -dichloro-4-methyl-1,3-pentadiene. Amines (NSR Pat. No. 2,624,340 (1976) or alkali metal hydroxides in a non-aqueous medium (U.S. Pat. No. 4,070,404 (1978)) were used as dehydrochlorinating agents.

From an industrial point of view, the most preferred method of dehydrochlorination of 1,1,1,3-tetrachloro-4-methylpentane is the catalytic dehydrochlorination reaction. As the dehydrochlorination catalyst of 1,1,1,3-tetrachloro-4-methylpentane, stannous chloride has been described in NSR Pat. login No. 2,751,435 (1978). However, its disadvantage is the low boiling point (113 ° C) and the high volatility of the dehydrochlorination reaction requiring temperatures of 140 to 170 ° C, which causes the catalyst to be removed from the reaction mixture at the same time as the hydrogen chloride formed. The present invention completely eliminates the above disadvantages and simplifies the whole process.

The above-mentioned disadvantages are eliminated by the process for the catalytic production of 1,1-dichloro-4-methyl-1,3-pentadiene according to the invention, the essence of which is that 1,1,1,3-tetrachloro-4-methylpentane is subjected to a catalytic dehydrochlorination reaction in the presence of chloride. or zinc oxide or acetate in the presence of a solvent by heating the reaction mixture to boiling at 100 to 130 ° C until hydrogen chloride is liberated.

The starting material, i.e. 1,1,1,3-tetrachloro-4-methylpentane, is readily available by catalytic reaction of carbon tetrachloride with 3-methylbutene according to MS. A0 257 965, providing the product in almost quantitative yield. The above diene can thus be prepared more simply by the two-stage catalytic process according to the invention with a minimum amount of waste.

As the dehydrogenation catalyst, it is preferable to use zinc chloride or other zinc compounds with oxygen, or in the form of a salt with an inorganic or organic acid, such as zinc oxide or acetate. These zinc compounds are easily converted in the reaction mixture to zinc chloride, either by the formation of hydrogen chloride or by the addition of a catalytic amount of concentrated hydrochloric acid to the reaction mixture, which results in a shortening of the reaction time.

The dehydrochlorination reaction can be carried out without a solvent, but this requires higher reaction temperatures around 150 to 170 ° C, so it is preferable to use a suitable solvent such as acetic acid or formic acid. In their presence, the dehydrochlorination reaction proceeds more easily even at lower temperatures, usually at 100 to 125 ° C. If formic acid is used as a solvent, it is partially decomposed to water and carbon monoxide during the reaction, but this is not a problem for the dehydrochlorination reaction. The advantage of using acetic acid and formic acid as solvents is the ease of recycling them by distillation from the reaction mixture, which contributes to the economy of the process, since the zinc chloride remaining after the reaction can be reused in the next batch.

The process according to the invention reduces waste to a minimum. Wastes which reach a maximum of 10% by weight per product are usually high-boiling substances formed by the easy polymerization of the above product, i.e. diene, especially in the presence of air. To suppress the polymerization of the diene, especially when isolating it from the reaction mixture, it is therefore convenient to add a polymerization inhibitor such as tert-butylcatechol or hydroquinone monomethyl ether and the like to the reaction system. The most suitable way of isolating the product is vacuum distillation or rectification or steam distillation.

The following examples further describe the process for the preparation of 1,1-dichloro-4-methyl-1,3-pentadiene according to the invention without limiting or limiting its scope.

Example 1

10.3 g of 1,1,1,3-tetrachloro-4-methylpentane, 17 g of acetic acid and 1.5 g of zinc chloride was heated to reflux at 118-120 ⁰ for 6 hours, the hydrogen chloride evolution ceases . The reaction mixture was cooled, diluted with water, the organic layer was separated, and the aqueous layer was extracted with chloroform. 6.2 g of 1,1-dichloro-4-methyl-1,3-pentadiene are isolated from the combined organic phases by distillation under reduced pressure in a yield of 89.2% with a purity of 96% and a heat of 116-119 ° C / 23 kPa.

Example 2

A mixture of 10.3 g of 1,1,1,3-tetrachloro-4-methylpentane, 4 g of acetic acid and 0.7 g of zinc chloride is heated to reflux at 118-125 ° C for 5 hours, at which point the release ceases. hydrogen chloride. According to the method of Example 1, 5.7 g of 1,1-dichloro-4-methyl-1,3-pentadiene are isolated in a yield of 82% with a purity of 95%.

Example 3.

A mixture of 3.9 g of 1,1,1,3-tetrachloro-4-methylpentane, 16 g of acetic acid and 1.4 g of zinc oxide is heated to boiling at 118 DEG-119 DEG C. for 12 hours. 2.0 g of 1,1-dichloro-4-methyl-1,3-pentadiene are isolated in a yield of 76.3%.

Example 4

A mixture of 5.0 g of 1,1,1,3-tetrachloro-4-methylpentane, 4 g of acetic acid, 0.9 g of zinc acetate and 0.1 g of concentrated hydrochloric acid is heated to reflux at 118-120 ° C after for a period of 12 hours at which the release of hydrogen chloride ceases. By the method of Example 1, 2.9 g of 1,1-dichloro-4-methyl-1,3-pentadiene were isolated in a yield of 86.0%.

Example 5

A mixture of 6.5 g of 1,1,1,3-tetrachloro-4-methylpentane, 10 g of 85) formic acid and 1.0 g of zinc chloride is heated to boiling at 100-102 ° C for 15 hours, during which time stops releasing hydrogen chloride. After evaporation of the formic acid, 3.2 g of 1,1-dichloro-4-methyl-1,3-pentadiene are isolated from the reaction mixture by distillation under reduced pressure in a yield of 73.0%.

Claims (1)

OBJECT OF THE INVENTION Process for the preparation of 1,1-dichloro-4-methyl-1,3-pentadiene by catalytic dehydrochlorination of 1,1,1,3-tetrachloro-4-methylpentane, characterized in that the dehydrochlorination is carried out under the catalytic action of zinc chloride or oxide or acetate in an amount of 0, 02 to 0.5 part by weight, per 1 part by weight. 1,1,1,3-tetrachloro-4-methylpentane in the presence of 0.3 to 5 parts by weight of acetic acid or formic acid by heating the reaction mixture to boiling at 100 to 130 ° C until hydrogen chloride is liberated.