DD245434A1 - METHOD FOR PRODUCING PURE DIESTERAL CYLENINE DICHLORIDE - Google Patents

Abstract

The invention relates to a direct conversion of metallic tin-based process for the preparation of Diesteralkylzinndichloriden, which are valuable starting materials for the production of highly effective PVC thermal stabilizers, biocides and polyurethane catalysts. Goals and objects of the invention are, by changing the chemical-technological parameters in the preparation process Diesteralkylzinndichloride the general formula (ROOC CH 2 CH 2) 2 SnCl 2, wherein R is a C1-C12-Alkylrestbedeutet, provide in high purity. According to the invention, diesteralkyltin dichlorides of the above formula are obtained according to the objective, when, following the reaction of metallic tin, hydrochloric acid and an activated olefin of the general formula YCHCH 2 with YCOOH, CN, COOR and RC 1 -C 3 -alkyl carried out in a known manner, the reaction solution is concentrated and the acid concentration of the solution is increased by adding concentrated hydrochloric acid so that the compound bis (2-carboxyethyl) -zinndichlorid precipitates out of this. Bis- (2-carboxyethyl) -zinndichlorid can be isolated in pure form and reacted with alcohol to Diesteralkylzinndichlorid.

Description

Field of application of the invention

The invention relates to a process for the preparation of pure Diesteralkylzinndichloride by direct alkylation of metallic

The Diesteralkylzinndichloride serve primarily as starting materials for the production of highly effective PVC thermal stabilizers, biocides and catalysts for polyurethane production.

Characteristic of the known technical solutions

It is known that by reacting tin, hydrogen chloride and activated olefins Diesteralkylzinndichloride can be synthesized.

For example, DD-EB 125550 is based on such a method.

The general disadvantage of the procedure described therein is that reaction mixtures are obtained which are not suitable for specific fields of application due to the presence of by-products. Although attempts are made to separate off some by-products, in particular inorganic tin compounds, by solvent extraction, the use of organic solvents leads to problems in terms of labor and fire protection, in addition to additional equipment. In addition, energy-intensive systems for the recovery of solvents are required.

Furthermore, it is possible to achieve high conversions and thus relatively pure end products by very long reaction times.

However, this procedure is uneconomical. In addition, only gaseous hydrogen chloride is suitable for such a process. Its application, however, again brings health and safety problems and requires a high expenditure on equipment.

Object of the invention

The object of the invention is to eliminate or largely eliminate the deficiencies inherent in the prior art, which result primarily from the insufficient purity of the diester alkyltin dichlorides.

Explanation of the essence of the invention

The object of the invention is therefore to make the synthesis process for the preparation of Diesteralkylzinndichloriden by Verändemng chemical-technological parameters so that the aforementioned objective is met. According to the invention Diesteralkylzinndichloride the general formula

(ROOCCH ₂ CH ₂ I ₂ SnCl ₂ where

R = C ₁ -C

means

obtained in high purity, if, following the reaction carried out in a known manner of tin, hydrochloric acid and activated olefin of the general formula

Y-CH = CH ₂ ·

Y = CN, COOH, COOR 'and

R '= d-Ca-alkyl,

the reaction solution is concentrated and the acid concentration of the solution is increased by adding concentrated hydrochloric acid so that the compound bis (2-carboxyethyl) -zinndichlorid precipitates out of this. Bis- (2-carboxyethyl) -zinndichlorid can be isolated in pure form and reacted with alcohol to Diesteralkylzinndichlorid.

In the cases Y = CN and COOR 'the complete saponification of the nitrile or ester groups must be carried out after addition of the hydrochloric acid. This is done by boiling with hydrochloric acid. The precipitation of bis (2-carboxyethyl) tin dichloride enables the isolation and separation of inorganic tin compounds and the monoalkyl tin compound carboxyethyltin trichloride. These compounds are dissolved in the aqueous filtrate. Since tin (II) chloride and carboxyethyltin trichloride are intermediates in the preparation of diester alkyltin dichloride, they can be re-reacted with tin, hydrochloric acid and activated olefin and converted to diester alkyltin dichloride.

embodiments

1. 59.4 g of tin granules and 144.1 g of acrylic acid are placed in a 750 ml sulfonation flask equipped with a condenser, stirrer, thermometer and dropping funnel.

At 40 ⁰ C 220g hydrochloric acid (37% strength) are added dropwise with stirring over a period of 8 hours uniformly. After the tin has completely reacted, most of the reaction hydrochloric acid is distilled off. Thereafter, the batch 220 g of concentrated hydrochloric acid are fed. The reaction mixture is stirred for 30 minutes with cooling. A colorless solid separates from the reaction solution and is isolated by filtration. The analytical examination revealed that it is the compound bis (2-carboxyethyl) tin dichloride. The compound has the following analytical data (in brackets calculated values for CI ₂ Sn (CH ₂ CH ₂ COOH) ₂ ):

C: 20.96 (21.46)%; H: 3.32 (3.00)%;

Sn: 34.80 (35.35)%; Cl: 20.73 (21.12)%.

The melting point is 159 ° C, the IR spectrum shows at 1675cm " ¹ the C = O absorption and at 3200cm" ¹ the OH absorption.

By means of complexometric titration it was found that the substance is contaminated only with 0.3% carboxyethyltin trichloride and inorganic tin compounds.

By esterification of bis (2-carboxyethyl) -zinndichlorid with methanol pure bis (2-methoxycarbonylethyl) tin dichloride is obtained.

The melting point of the compound is 132 ^° C. The product has the following analytical data (in brackets calculated values for (CH ₃ OOC CH ₂ CH ₂ J ₂ SnCl ₂ ):

C: 26.10 (26.41)%; H: 3.95 (3.88)%;

Sn: 32.20 (32.63)%; Cl: 20.15 (19.49)%.

2. The procedure is analogous to Example 1 and sets in a 750 ml sulfonating 59.4 g tin granules and 172 g of methyl acrylate before. Within 3 hours at 70 ⁰ C 220 g hydrochloric acid (37%) are added dropwise. Then allowed to react at 7O ⁰ C until the tin is completely reacted. The excess methyl acrylate and most of the reaction hydrochloric acid are then distilled off. The residue is treated with 200 g of concentrated hydrochloric acid and stirred at 100 ⁰ C for 2 hours. Thereafter, the reaction mixture is cooled and stirred for 30 minutes.

Bis- (2-carboxyethyl) -zinndichlorid precipitates as a crystalline solid from the reaction solution and is filtered off. The substance has the following analysis data (in brackets calculated values for CI ₂ Sn (CH ₂ CH ₂ COOH) ₂ ):

C: 21.40 (21.46)%; H: 3.12 (3.00)%;

Sn: 34.72 (35.35)%; Cl: 20.85 (21.12)%.

The product contains only 0.4% by-products of the form of carboxyethyltin trichloride and inorganic tin compounds.

Esterification of the bis- (2-carboxyethyl) -tin dichloride with 2-ethylhexanol gives pure bis- (2-ethylhexoxycarbonylethyl) -tin dichloride, which is obtained as a yellow oil. The compound has the following analytical data (in brackets calculated values for Ii-C ₈ H ₁₇ OOC CH ₂ CH ₂ J ₂ SnCl ₂ ):

C: 46.62 (47.17)%; H: 7.38 (7.56)%;

Sn: 20.79 (21.19)%; Cl: 12.34 (12.66)%.

3. The procedure of Example 1 is repeated and 59.4 g of tin granules and 106 g of acrylonitrile are placed in a 750 ml sulfonating flask. Within 6 hours, 220g of hydrochloric acid (37% strength) are added dropwise at 5O ⁰ C. After about 7-8 hours, the tin has completely reacted. Subsequently, the excess acrylonitrile and most of the reaction hydrochloric acid are distilled off.

The reaction mixture 220 g of concentrated hydrochloric acid are supplied. The mixture is then stirred at 100 ⁰ C for 30 minutes. When the reaction solution is cooled, a mixture of solids which consists of bis (2-carboxyethyl) tin dichloride and ammonium chloride precipitates. This is filtered off with suction and treated with 200 g of butanol. The butanolic solution is boiled on a water separator until no more water of reaction is separated off.

The volatile components of the reaction mixture ¹ are removed after completion of the esterification by vacuum distillation to 100 ° C / 2 Torr. To remove the ammonium chloride, the resulting oily product is filtered. It is pure bis- (2-butoxycarbonylethyl) -zinndichlorid.

The compound has the following analytical data (in brackets calculated values for (C ₄ HgOOC CH ₂ CH ₂ J ₂ SnCl ₂ ):

C: 37.20 (37.54)%; H: 5.72 (5.85)%;

Sn: 26.12 (26.50)%; Cl: 15.52 (15.83)%.

The compound contains 0.3% by-products in the form of 2-butoxycarbonylethyltin trichloride and inorganic tin compounds.

Claims (1)

Erfiiroungsanspruch: 1. A process for the preparation of Diesteralkylzinndichloriden the general formula (ROOCCH ₂ CH ₂ I ₂ SnCl ₂
in which R is a C ₁ -C ₁₂ alkyl group
represents,
by reaction of metallic tin with an activated olefin of the general formula Y - CH = CH ₂ ,
in which Y = COOH, CN or COOR '
and R '= C ₁ -C ₃ -AlkVl means and hydrochloric acid, characterized in that after completion of the reaction, the reaction mixture is concentrated, the acid concentration of the reaction mixture increased by the addition of concentrated hydrochloric acid, saponified if necessary and isolated on cooling the reaction solution precipitating bis (2-carboxyethyl) -zinndichlorid and in a known manner is reacted with alcohol to Diesteralkylzinndichlorid.