DD270916A1 - PROCESS FOR THE PREPARATION OF ORGANOCINNTHIOGLYIC ACID ESTERS - Google Patents

Abstract

The invention relates to a process for the preparation of Organozinnthioglykolsaeureestern as stabilizers for PVC and as catalysts for various organic reactions, by reacting organotin oxides with the alkali-S-alkylthiosulfates of acetic acid esters in an inert solvent in the presence of a phase-active compound, preferably DMF.

Description

Field of application of the invention

The invention relates to a process for the production of organotin thioglycolic acid esters. These compounds have a wide range of applications. Thus, they are suitable as stabilizers for halogenated polymers, in particular PVC, or as catalysts for a variety of organic reactions.

Characteristic of the known technical solutions

The preparation of Organozinnthioglykolf äureestern and their use as stabilizers for polymers has been described many times. (RWWeiss, Organometallic Compounds, Vol. Il p.451-473 (1973), Vol. II Suppl.l p.752-786 [1973], Springer Ver'ag; HVSmith, The Development of Crganotin Stabilizers, The Research Institute Greenford (England) 1959; Primary patents: USP 2648650 (19C-Jj ELWeinberg &EWJohnson; USP 2641588 (1953) WELeistneru WOHKnoepe; USP 2731484 (1956) CEBest; DP 1217609 (1955) H.Fincke et al H.Bohr)

In the art they are represented by reaction of thloglycolic acid esters with organotin oxides or crganotin halides.

(see also Houben Weyl, Vol. 13, S. Thieme Verlag Stuttgart 1971, p. 438 ff.) However, these synthesis variants have significant disadvantages. The main drawback is the need to produce thioglycolic acid esters via thioglycolic acid.

These processes are complex and require the use of environmentally harmful toxic chemicals and also lead to the emission of toxic gases, such as hydrogen sulfide and sulfur dioxide, or wastewater. (Enzyclopedia of Chem. Techn., New York 1955, Vo114, pp. 78-83; Bunte, Bor.7, p.648ff. (1874); Weigang, Hilgetag, Exp. Meth. In Org. Chem. 583ff. (1969); Up.

Patent No. 17564 (19651 et al.)

In addition, a number of possible side reactions, such as the formation of dithiodiglycolic acid, thiodiglycolic acid and polyglycolic acid esters (A.Cook and J. Steel, J. of Pharmacy and Pharmacology 11, p.216-223 [1959] and p.434-441, respectively), are required ) additional technological stages for a complex cleaning with simultaneous significant yield losses. Added to this is the low storage stability of thioglycolic acid.

The esterification with the technically important 2-ethylhexanol to Thioglykolsäureisooktylester then usually only to a 94% product, which still contains significant amounts of unreacted alcohol. This is then difficult to remove from the non-distillable Organozinnthioglykolaten.

Object of the invention

The aim of the invention is the f elective production of org 'iinnthioglykolsäureestern from easily prepared starting compounds.

Explanation of the essence of the invention

The invention has for its object to produce Organozinnthioglykolsäureester from new easily prepared starting materials in one reaction step.

According to the invention, organotin thioglycolic acid esters of the general formula RjSn (SCH ₂ COOR '), ₍

R · »" organo radical, preferably alkyl radical having 1 to 8 carbon atoms

R '= a branched or unbranched alkyl radical,

by reacting organotin oxides, preferably Dialkylzinnoxio ^ n, with alkali S-alkyl thiosulfates of acetic acid esters (Buntesalzessigsäursester) of the general formula

NaO ₃ S ₂ -CH ₂ -C ^.

in an inert aqueous solvent such as toluene, xylene, benzene or benzene in the 2-phase system in the presence of a phase-active compound, preferably dimethylformamide.

For this purpose, the corresponding chloroacetic acid esters are first reacted with equimolar amounts of sodium thiosulfate in a DMF / water mixture. Bunte salt acetic acid esters obtained by other routes are also usable in an OMF / water solution.

Subsequently, the Buntesalzessigsäureester by addition of an inert solvent, preferably toluene and benzene, and stoichiometric amounts of organotin oxide by heating for 2 to 15 hours at 50 to 150 ° C, preferably 70 to 100 ° C, to the desired Organozinnthiogtykolsäureester. It has proved to be particularly advantageous if in the reaction mixture 20 to 150, preferably 50 to 80 wt .-% DMF and 30 to 200Gew .-% water, including water of hydration of thiosulfate, based on the used Buntosalz are included. Further proved the addition of a Sa · "β, especially mineral acids, particularly hydrochloric acid is suitable as a low to achieve high yields and to accelerate the reaction.

After the reaction, the reaction mixture is washed several times with water or a sodium bicarbonate solution, the organic phase is separated off and the solvent is separated off from the product in the usual manner, for example by distillation.

By tJ'eses simple process is obtained in 97-100% yield, the desired Diorganozinndithioglykolsäureester, which can be used without further purification, for example, as stabilizers for chlorine-containing polymers.

Another advantage is the excellent chemical stability of Bunte salt acetic acid both as a mixture with DMF and water as in concentrated form.

embodiments

Example 1a-1d: Dibutyltin dithioglycolic acid isooctyl ester

Example 1 a: 41.5 g (0.2 mol) of isooctyl chloroacetate, 40 g of dimethylformamide, 20 g of water and 49.6 g (0.2 mol) of sodium thiosulphate-5-hydrate are initially charged and reacted with stirring at 70 ° C for 2 hours. Is then added 400g of toluene and 25g (0.1 mole) of dibutyltin oxide and the mixture heated for 15 hours under stirring to 9O ⁰ C. After cooling the batch is mixed with 300 ml Wasssr, the organic phase is separated off and the latter is washed 3 times with in each case 200 ml of water.

Then you narrow in a vacuum.

This leaves 60.2 g (94.1%) of the desired compound.

The analytical identity was confirmed here as in the other examples compared to reference compounds, inter alia, by tin resonance spectroscopy, thin layer chromatography and elemental analysis.

Example 1 b: 41.5 g of isooctyl chloroacetate, 40 g of dimethylformamide, 20 g of water and 49.6 g of sodium thiosulfate-5-hydrate are reacted according to Example 1 a. Then, 400 g of toluene, 25 g of dibutyltin oxide and 3 g of 50% strength sulfuric acid are added and the mixture is stirred for 6 hours at 9O ⁰ C. The work-up is carried out analogously to Example 1 a. 61.5 g (96.1% of theory) of the desired compound remain.

Example 1c: 41.5 g of isooctyl chloroacetate, 40 g of dimethylformamide, 20 g of water and 49.6 g of sodium thiosulfate-5-hydrate are reacted according to Example 1 a. Then you add 400 g toluene, 25.0 g dibutyltin oxide and after 1 hour reaction time still 15g 30% hydrochloric acid added. The mixture is stirred for a total of 4 hours at 90 ° C. The work-up is carried out analogously to Example 1 a

 This gives 62.3 g (97.3% of theory) of the desired compound.

Example H: 41.5 g of chloroacetic acid isooctyl ester, 40 g of dimethylformamide, 20 g of water and 49.6 g of sodium thiosulfate-5-hydrate are reacted according to Example 1 a. Are then added 400g To Jen, 25.0 g of dibutyltin oxide and 24.3 g of 30% strength hydrochloric acid are added and stirred for 2.5 hours at 85 ⁰ C. The work-up ei follows analogously to Example 1 a. This gives 62.4 g (97.5%) of the desired organotin compound.

Example 2: Dibutyl-tin-dithioglycolic acid butyl ester

30.1 g (0.2 mol) of butyl chloroacetate, 40 g of dimethylformamide, 15 g of water and 49.6 g (0.2 mol) of sodium thiosulfate-5-hydra; are presented and reacted for 2 hours at 70 ⁰ C with stirring. Then add 400 g Böruan, 25 g (0.1 mol) of dibutyltin oxide and 24.3 g of 30% hydrochloric acid. The mixture is heated for 2.5 hours with stirring on 7OX. The work-up is carried out analogously to Example 1 a.

This gives 52.0 g of the organotin compound (98.5%).

Example 3: Dibutyltin-dithioglycolic acid ethyl ester

24.5 g (0.2 mol) of ethyl chloroacetate are reacted with 40 g of DMF, 20 g of water and 49.6 g (0.2 mol) of sodium thiosulfate-5 hydrate for 1.5 hours with stirring at 70 ° C now. Subsequently, 400 g of benzene, 25 g of dibutyltin oxide and 12.5 g of 30% pure

Hydrochloric acid and boiled for 4 hours at reflux. The work-up is analogous. 46.6 g (97.1%) of the desired organotin compound are obtained.

Claims (6)

1. A process for preparing organotin thioglycolic acid esters of the general formula R ₂ Sn (SCH ₂ COOFO ₂ , in which R is an organo radical, preferably an alkyl radical having 1 to 8 carbon atoms and R 'is preferably a branched or unbranched alkyl radical, characterized in that organotin oxides with alkali metal S-alkylthiosulfates of acetic acid esters of the general formula NaOsS ₂ -CH ₂ -COOR 'be implemented. 2. The method according to claim 1, characterized in that the reaction is carried out in a water-containing inert solvent in the two-phase system in the presence of a phase-active compound at 50 to 130 ° C. 3. The method according to claim 1 and 2, characterized in that as the phase-active compound preferably dimethylformamide, in amounts of 20 to 150 wt .-%, preferably 50-80%, based on the alkali metal S-alkylthiosulfate of the corresponding acetic acid ester , 4. The method according to claim 1 to 3, characterized in that <hß be used as an inert solvent benzene, toluene, xylene or gasoline. 5. The method according to claim 1 to 4, characterized in that to accelerate the conversion of a mineral acid, preferably hydrochloric acid, is added. 6. The method according to claim 1 to 5, characterized in that the reaction takes place in the temperature range of 50 to 13O ⁰ C.