KR880001842B1 - Process for the preparation of ethyl-4,6,6,6-tetrachloro-3,3,-dimethyl hexenoate - Google Patents

Abstract

An ethyl-4,6,6,6-tetrachloro-3,3-dimethyl hexanoate is prepd. by reacting 3,3-dimethyl-4-pentanoic acid (DPA) with 2-4 mol of CCl4 and 0.15-0.25 mol of FeCl2.4H2O in 5-7 mol of ethanol. The DPA is obtained by claisen-rearrangement of phrenol and triethylortho acetate for producing reactants of 3,3-dimethyl pentenoate and phrenyl 3,3-dimethyl-4-pentenoate and then by hydrolysis of the reactants with NaOH or KOH.

Description

Method for preparing ethyl-4,6,6,6, -tetrachloro-3,3-dimethylhexanoate

In the present invention, ethyl-4,6,6,6-tetrachloro-3,3-dimethylhexanenoate (hereinafter referred to as ETDH) required for synthesizing permethrinic acid, which is an acid component such as permethrin and cypermethrin, is used in a pipetroid insecticide. It relates to a manufacturing method of.

Conventionally, ETDH was prepared by adding CCl ₄ to ethyl 3,3-dimethyl- _4- pentenenoate (hereinafter referred to as EDP). The starting material EDP synthesizes triethylortho acetate (TOA) and prenol by a Claisen rearrangement reaction under an acid catalyst, in which prenyl 3,3-dimethyl-4-phene is a byproduct of EDP. Since tennoate (MBDP) is produced, vacuum distillation yields EDP, and the by-product MBDP is trans-esterified with an acid catalyst in excess ethanol and then converted back to EDP by vacuum distillation.

This is expressed as a reaction scheme as follows.

However, in the case of obtaining ETDH as described above, first, since the starting material EDP must be distilled and separated from the by-product MBDP, it is not only costly by distillation but also trans-esterified the separated MBDP to increase the yield. The operation is complicated because the conversion to EDP is performed in two stages of operation.

Second, the yield of the produced ETDH is not only low but also low in purity and should be purified by high vacuum distillation.

Third, it is uneconomical to use excessive TOA (1.3-3.0 equivalents per phenol) to increase the yield of EDP.

The present inventors earnestly researched to solve the above problems, and when 3,3-dimethyl-4-pentenoic acid (hereinafter referred to as DPA) is used as a starting material, CCl ₄ and FeCl ₂ · 4H ₂ O are reacted in ethanol. The present invention was completed in view of the fact that the ester reaction and the CCl ₄ addition reaction occur simultaneously to synthesize the final product ETDH.

DPA of the present invention is obtained by reacting TOA and prenol with a Kreisen potential to obtain a reaction product of EDP and MBDP, and then hydrolyzing with sodium or potassium hydroxide. The DPA thus obtained is of high purity (more than 98% purity) and is used for ETDH reactions without purification.

The method of the present invention is described in detail as follows. In preparing ETDH by reacting prenol and TOA to make a reactant of EDP and MBDP, 1 mole of a reactant having a composition ratio of EDP and MBDP of 4: 1 is added at 1.0-1.5 equivalents of sodium hydroxide or 1.0-1.5 equivalents of potassium hydroxide. Decomposition is performed to synthesize DPA, and this DPA is reacted with CCl ₄ -2-4 equivalents and ferrous chloride and hydrates 0.15-0.25 equivalents in 5-7 equivalents of ethanol to cause simultaneous esterification and addition of CCl ₄ . ETDH synthesis method. This is expressed as a reaction scheme as follows.

The ETDH obtained by the method of the present invention as described above has the following advantages over the conventional method.

First, in the synthesis of EDP, the starting material of prenol is decomposed about 10% by acid as a catalyst, while in the present invention, the amount of prenol is reduced by using 1% or less of xylene as a solvent.

Second, since the starting material DPA can be obtained by hydrolyzing EDP and MBDP, it can be easily obtained in a single process compared to the conventional method of obtaining EDP in two stages, and the purification is not necessary because of high purity.

Third, in order to effectively obtain the conventional EDP, the TOA equivalent ratio to prenol is used in 1.3-3.0 equivalents, while the TOA is used in small amounts in 0.6-0.8 equivalents to obtain the DPA of the present invention.

Fourth, ETDH obtained from EDP can be obtained only by vacuum distillation to obtain high purity ETDH.However, ETDH obtained from DPA as a starting material has high purity (more than 97% purity) and can be used without purification for permethrin synthesis. .

Hereinafter, the method of the present invention will be described in detail by way of examples.

Example 1

0.95.6 g (0.01 mol) of 87% phosphoric acid is added to 95.6 g (1.15 mol) of prenol, 162.23 g (1.00 mol) of TOA and 50 g of xylene, and the reaction temperature is refluxed at 140 ° C. for 5 hours to allow the ethanol to be distilled completely. The reaction was then cooled to room temperature and hydrolyzed with reflux for 30 minutes with the addition of 100.03 g (1.00 mol) of 40% aqueous sodium hydroxide solution, then 120 g of water were added and xylene and prenol were removed by steam distillation. 98g of 50% sulfuric acid was added to the product of the water layer to adjust the pH to 4, and then extracted twice with CCl ₄ 340g and CCl ₄ 171g, respectively. The carbon tetrachloride extracted here was dehydrated with magnesium sulfate, and 230 g (5.00 mol) of ethanol, 39.80 g (0.20 mol) of ferrous chloride and tetrahydrate were added to the filtrate, and the mixture was refluxed for 6 hours, cooled to room temperature, and then cooled to 500 g and 5 Washed with 300 g of aqueous sodium hydroxide solution, dried over magnesium sulfate, and completely removed carbon tetrachloride to obtain 267.3 g of ETDH. The yield of ETDH against TOA is 85%. (More than 97% of purity)

Example 2

A mixture of 128.22 g (1.00 mole) of DPA, 461.52 g (3.00 mole) of carbon tetrachloride, 276.00 g (6.0 mole) of ethanol, and ferric chloride, 39.73 g (0.20 mole) of tetrahydrate was refluxed for 6 hours, followed by 500.00 g of water. Wash with 300.00 g of 50% aqueous sodium hydroxide solution. After dehydration with magnesium sulfate, carbon tetrachloride was completely removed to give 303.69 g of EDTH. The yield is 97.7% (purity 97.7%).

Claims (2)

Reacting with prenol and triethylortho acetate to form a reaction product of 3,3-dimethyl pentenoate and prenyl 3,3-dimethyl-4-pentenoate to yield ethyl-4,6,6,6-tetrachloro-3 In preparing, 3-dimethylhexanoate, this 3,3-dimethyl-4-pentanoic acid is reacted with 2-4 mol of carbon tetrachloride and 0.15-0.25 mol of ferrous chloride. Process for the preparation of ethyl-4,6,6,6-tetrachloro-3,3-dimethylhexanoate for the purpose of treatment. The method of claim 1, wherein 1 mole of the reactant having a composition ratio of 3,3-dimethylpentenoate and prenyl 3,3-dimethyl-4-pentenoate is 4: 1 is sodium hydroxide 1.0-1.5 mol or potassium hydroxide 1.0-. A process for producing 3,3-dimethyl-4-pentenoic acid, characterized in that hydrolysis at 1.5 moles.