DE102016217012A1 - Process for the preparation of high purity monooctyltin trichloride - Google Patents

Abstract

The present invention relates to a process for the preparation of a product comprising: from 94 to 100% p / p, preferably from 97 to 100% p / p, and more preferably from 99 to 100% monooctyltin trichloride based on the total weight of the product , from 0 to 6% p / p, preferably from 0 to 3% p / p, more preferably from 0 to 0.2% dioctyltin dichloride, based on the total weight of the product, from 0 to 6% p / p, preferably from 0 to 3% p / p, and more preferably from 0 to 0.3% trioctyltin chloride based on the total weight of the product, said process comprising the following phases: a) SnCl4 and tetraoctyltin (TTOT) at a temperature between 20 and 60 ° via a redistribution reaction reacting in equimolar amounts, and b) extracting the product obtained in phase a) with an aqueous solution of hydrochloric acid having a concentration of from 3 to 7% and a temperature of between 20 and 80 ° C to produce a product a high Geha lt to win monooctyltin trichloride.

Description

FIELD OF THE INVENTION

The invention relates to a method for the preparation of high purity monooctyltin trichloride. The mercaptan or carboxyl derivatives of the monooctyl trichloride compound find efficient use as stabilizers for polyvinyl chloride.

STATE OF THE ART

It is already known that mixtures of monoalkyltin trichlorides RSnCl ₃ and dialkyltin dichlorides R ₂ SnCl _{2 have} great industrial importance and are used as intermediates for the preparation of thermal stabilizers for PVC.

The organic tin chlorides are usually obtained from a redistribution reaction between tin chloride and tetraalkyl stannate.

Depending on the molecular proportions of the two reagents, it is possible to obtain alkyltin mono-, di- and trichlorides.

The three basic reactions for the synthesis of alkyltin chlorides are represented by the following reactions (1), (2) and (3):

Reaction 1

• 3 R ₄ Sn + SnCl ₄ → 4 R ₃ SnCl

Reaction 2

• R ₄ Sn + SnCl ₄ → 2 R ₂ SnCl ₂

Reaction 3

• R ₄ Sn + 3 SnCl ₄ → 4 RSnCl ₃

Reaction 3 has no industrial feasibility because in the presence of an excess of SnCl ₄ it reacts with the initially formed trialkyltin chloride to give a mixture of monoalkyltin trichloride RSnCl ₃ and dialkyltin dichloride R ₂ SnCl ₂ ; the subsequent reaction of the dialkyltin dichloride R ₂ SnCl ₂ with SnCl ₄ is extremely slow and requires prolonged heating and the use of tuning solvents ( "The Synthesis, Reaction and Structures of Organometallic Compounds" (AG Davies, PJ Smith, Comprehensive Oraganometallic Chemistry, 1982, 11.545-552) , To overcome this problem, it is known to use a reaction involving simultaneous formation of monoalkyltin trichloride RSnCl ₃ and dialkyltin dichloride R ₂ SnCl ₂ (Reaction 4), followed by distillation to increase possibly higher levels of monoalkyl tin chloride achieve:

Reaction 4:

• R ₄ Sn + 2 SnCl ₄ → 2 RSnCl ₃ + R2SnCl ₂

The preparation of mixtures of monoalkyltin trichloride RSnCl ₃ and dialkyltin dichloride R ₂ SnCl ₂ via reaction 4 is carried out with ease and good yield, but requires a distillation process if one wishes to obtain a high content of monoalkyltin trichloride; however, the latter causes loss of the desired product because of the temperature-induced dealkylation. This problem is quite significant if you work with Octylderivaten that require extremely high temperatures and high vacuum during distillation.

Other methods for the preparation of monoalkyltin trichloride provide for a phase of hydrosolation of alkenes in the presence of organometallic transition catalysts in a homogeneous phase, followed by distillation of the mixture as in US8,198,352 described, or the Use of trialkylaluminum by direct alkylation over stannous trichloride (as in US6,846,944 described).

More specifically, among the various octyl derivatives mentioned above as precursors of PVC stabilizers, octyl derivatives are of particular importance. The octyl derivatives are in fact, because of the contact approval with food and the compliance with the pharmacopoeia, the stabilizers used most in the calendering of PVC and are mainly used for the preparation of film for the packaging of medicines and foods.

The PVC stabilizers are generally based on blends of mono / dioctyltin thioglycolate because of the synergistic behavior exhibited by these blends. Recently, the high purity 2-ethylhexyl (MOTE) based monooctyltin thioglycolate stabilizers have been identified as "reprotoxic cat." Due to the classification of the dioctyltin thioglycolate of 2-ethylhexyl (DOTE). 1B ", aroused greater interest in the market. This explains why the development of a process for the preparation of monooctyltin trichloride (MOTCL) in the presence of low levels of dioctyltin dichloride (DOTCL) is also of considerable interest.

Furthermore, the presence of impurities, such as derivatives of trioctyltin chloride (TOTCL) or tetraoctyltin (TTOT), does not prove to be advantageous, since their contribution to performance in the subsequent phase of conversion to PVC stabilizing compounds is zero, and it is therefore convenient to have a process to develop as much as possible to limit their presence. As already explained above, the octyltin chlorides are also generally obtained via a redistribution reaction between tin chloride and tetraoctyl stannate in various stoichiometric ratios. The mixtures thus produced have a Dioctylzinnchlorid content that varies between 99-40% and have a maximum level of 60% Monooctylzinnchlorid on.

Like in US8,198,352 described, a monooctyltin trichloride of higher purity can be obtained via a distillation of the mixture of mono compounds and derivatives. The distillation must be carried out at high temperature (140-155 ° C) and high vacuum (800 Pa). Therefore, in order to achieve a high distillation yield, the stoichiometric ratios in the redistribution phase must be such as to obtain the highest possible percentage of monooctyltin trichloride.

Due to the high temperature, however, the distillation process leads to a degradation of the products, and therefore to low yields and an economically disadvantageous process.

There is therefore a need for an efficient and economically viable process for preparing high purity monooctyic trichloride (MOTCL) in which the presence of the derivatives of dioctyltin chloride (DOTCL), trioctyltin chloride (TOTCL) and tetraoctyltin (TTOT) is controllable and limited.

SUMMARY OF THE INVENTION

• a) SnCl₄ und Tetraoctylzinn (TTOT) bei einer Temperatur zwischen 20 und 60° über eine Umverteilungsreaktion in äquimolaren Mengen reagieren zu lassen, und
• b) das in der Phase a) erzielte Produkt mit einer wässrigen Lösung von Salzsäure zu extrahieren, die eine Konzentration von 3 bis 7% und eine Temperatur zwischen 20 und 80° hat, um ein Produkt mit einem hohen Gehalt an Monooctylzinn-Trichlorid zu erhalten.

The above purpose is achieved by a process for the preparation of a monooctyetine trichloride-containing product comprising:
from 94 to 100% p / p, preferably from 97 to 100% p / p, and more preferably from 99 to 100% monooctyltin trichloride;
from 0 to 6% p / p, preferably from 0 to 3% p / p, and more preferably
from 0 to 0.2% dioctyltin dichloride;
from 0 to 6% p / p, preferably from 0 to 3% p / p, and more preferably
from 0 to 0.3% trioctyltin chloride;
said method comprising the following phases:

• a) reacting SnCl ₄ and tetraoctyltin (TTOT) in equimolar amounts at a temperature between 20 and 60 ° via a redistribution reaction, and
• b) extracting the product obtained in phase a) with an aqueous solution of hydrochloric acid having a concentration of 3 to 7% and a temperature between 20 and 80 ° to obtain a product with a high content of monooctyltin trichloride ,

Surprisingly enough, a process has been discovered which permits the recovery of a high monooctyltin trichloride (MOTCL) without necessarily proceeding from the mixture of monooctyltin trichloride and dioctyltin dichloride (MOTCL-DOTCL) of the prior art. The choice of suitable and inventively stoichiometric ratios and the reaction conditions discovered by the inventors and described herein allow the recovery of a MOTCL of the highest purity, in such a favorable process that it continues to successfully recover and recycle the by-products obtained in the phase b) to convert them into various intermediate products, which may still be usable for the preparation of PVC stabilizers, or into the original TTOT material again. The invention process allows for a favorable MOTCL product, which is efficiently isolated from the other possible redistribution products and, moreover, has the advantage of being usable immediately in the subsequent phase of the preparation of PVC stabilizers.

On the one hand, therefore, if the present invention permits the recovery of high purity MOTCL by a reaction under mild process conditions, the conversion of by-products of the reaction into useful intermediates provides an additional advantage.

Further advantages include the preparation of MOTCL by its extraction in acidic water from the reaction mixture, and the possibility to use this phase directly for the recovery of PVC stabilizers.

By employing the method described herein, the inventors have succeeded in avoiding the use of organic solvents, hazardous reagents (trioctylaluminum) or expensive reagents such as transition metal based catalysts.

DETAILED DESCRIPTION OF THE INVENTION

• a) SnCl₄ und Tetraoctylzinn (TTOT) bei einer Temperatur zwischen 20 und 60° über eine Umverteilungsreaktion in äquimolaren Mengen reagieren zu lassen, und
• b) das in der Phase a) erzielte Produkt mit einer wässrigen Lösung von Salzsäure zu extrahieren, die eine Konzentration von 3 bis 7% und eine Temperatur zwischen 20 und 80° hat, um ein Produkt mit einem hohen Gehalt an Monooctylzinn-Trichlorid zu erhalten.

The present invention therefore relates to a method for the preparation of a product, comprising:
from 94 to 100% p / p, preferably from 97 to 100% p / p, and more preferably from 99 to 100% monooctyltin trichloride, based on the total weight of the product;
from 0 to 6% p / p, preferably from 0 to 3% p / p, and more preferably
from 0 to 0.2% dioctyltin dichloride, based on the total weight of the product;
from 0 to 6% p / p, preferably from 0 to 3% p / p, and more preferably
from 0 to 0.3% trioctyltin chloride, based on the total weight of the product;
said method comprising the following phases:

• a) reacting SnCl ₄ and tetraoctyltin (TTOT) in equimolar amounts at a temperature between 20 and 60 ° via a redistribution reaction, and
• b) extracting the product obtained in phase a) with an aqueous solution of hydrochloric acid having a concentration of 3 to 7% and a temperature between 20 and 80 ° to obtain a product with a high content of monooctyltin trichloride ,

The invention process therefore allows to obtain a product with a high content of monooctyl trichloride, in particular from 94 to 100% p / p, preferably from 97 to 100% p / p, and more preferably from 99 to 100% monooctyltin Trichloride, based on the total weight of the product. Conveniently, the ratio between MOTCL and DOTCL obtainable by the invention method varies between 99: 6 and 110: 0 p / p.

The operational conditions of phase a) are such as to allow preparation of TOTCL and MOTCL in a percentage ratio of typically about 60:40.

In phase b), the concentration of the aqueous hydrochloric acid solution is 3-7%, preferably 4.3-5.6%, and more preferably 4.8-5.2%. The temperature of phase b) is within a margin of from 20 to 80 ° C, preferably from 35 to 65 ° C, and more preferably from 45 to 65 ° C. A leaching with the same aqueous hydrochloric acid solution can be carried out optionally and in a favorable manner after the phase a) and before the extraction phase b).

The invention method conveniently provides for a subsequent phase of the phase b) of the organic phase remaining in the extraction to produce, via further redistribution in the presence of SnCl4, octyltin chlorides useful for the preparation of octyltin derivatives for PVC. Alternatively, it provides for conversion of the residual organic phase to tetraoctyltin, which can be used in the cycle phase a).

Specifically, the acidic aqueous phase resulting from the extraction phase b) contains a MOTCL content between 30% and 50%, a DOTCL content between 0.0% and 0.5%, and a TTOT content between 0.0% and 0.1%.

This phase can be used directly in the synthesis of PVC stabilizers with a high content of monooctyltin. This monooctyltin trichloride can be used, for example, in the aqueous synthesis of the corresponding mercaptan according to the following scheme, and more specifically, according to Example 5: RSnCl _{3 (water)} + 3 R ¹ SH + 3 NaOH → 4 RSn (SR ¹ ) ₃ + 3 H ₂ O + 3 NaCl _(water)

The organic phase deposited after extraction contains a MOTCL content between 0.0% and 10%, a DOTCL content between 0.0% and 5%, a TOTCL content between 75.0% and 100%, and a TOTL Content between 0.0% and 0.5%.

This phase is usefully used in a phase b) subsequent to c) characterized in the treatment of the organic phase resulting from the extraction with SnCl _{4 to} effect a redistribution of the mixtures of DOTCL and MOTCL in variable Held from 60:40 to 99: 1 scored. These mixtures are useful as intermediates for the preparation of conventional tin stabilizers.

Alternatively, the organic phase resulting from the extraction phase b) is advantageously converted again into tetraoctyltin (TTOT), which is used as raw material in phase a) by means of already known alkylation processes with trioctylaluminum or via a Grignard reaction (eg. Journal of Organometallic Chemistry (2004), 689 (13), 2145-2157, Table 2 or Comprehensive Organometallic Chemistry, Part 11 Tin, Chapter 11.3.1, Pergamon Press, 1982 ) could be used.

There now follows some embodiments of the invention and the evaluation of the advantages resulting from the invention process, which are presented here only for an exemplary and non-limiting purpose.

EXPERIMENTAL PART

The analytical results described herein have been obtained by gas chromatographic analysis using a Perkin Elmer Clarus 500 gas chromatograph equipped with a capillary and apolar column type 30m HP11 (100% dimethylpolysiloxane). The method used is suitable for determining the distribution of organic tin compounds expressed in weight percent taking into account the solvent. The pattern dissolved in hexane or diethyl ether was reacted with ethyl magnesium bromide to yield tetra-alkylated species which could be quantitatively detected by gas chromatography.

Example 1, phase a)

Redistribution between TTOT and SnCl ₄

In a four-necked balloon equipped with a thermometer, dropping funnel and condenser and stirred, 147.9 g of SnCl ₄ were added dropwise to 352.1 g of TTOT (a commercial grade containing 8% TOTCL). The dripping has been regulated so that the temperature has held around 50 ° C. After completion of the addition, the mixture was kept at 50 ° C with stirring for two hours. The gas chromatographic analysis of a sample obtained after conversion to an ethyl derivative via a reaction with magnesium bromide has the following Table 1 given composition. Table 1 connection Composition,% MOTCL 37.7 DOTCL 1.80 TTOCL 60.1 Other alkyltin chlorides 0.40

The amount of desired product (MOTCL) was 37.7%, equal to 188 g.

Example 2-4, phase a)

Following the method given in Example 1 and the amounts of reagents given in Table 2, the percentages MOTCL, DOTCL and TOTCL given in Table 2 have been achieved. Board 2 example TTOT SnCl ₄ reaction temperature % % % (G) (G) Phase a) MOTCL phase a) DOTCL phase a) TOTCL phase a) 1 352.1 147.9 50 37.7 1.8 60.1 2 352.1 147.9 50 37.6 2.1 59.9 3 352.1 147.9 40 38.1 0.9 60.6 4 352.1 147.9 40 38.3 0.5 60.8

Example 1, phase b)

Extraction with a hydrochloric acid solution

188 g of a 5% hydrochloric acid aqueous solution were added to the mixture kept under stirring as in the step a1 of Example 1). The addition of the aqueous solution was carried out at a controlled temperature of 35 ° C. The phases were then separated and the acidic aqueous solution was analyzed by gas chromatography. Specifically, after removal of the aqueous phase, the resulting product has been converted to the ethyl derivative via reaction with ethyl magnesium bromide and the following composition given in Table 3 gives: Table 3 connection Composition,% MOTCL 99.9 DOTCL 0.10 TTOCL 0.0 Other alkyltin chlorides 0.0

The amount of desired product recovered from the aqueous extraction (MOTCL) was 167 g.

The remaining organic phase has been analyzed by gas chromatography. Specifically, the organic phase pattern obtained in the phase b), after conversion to an ethyl derivative via a reaction with ethylmagnesium bromide, has been described in U.S. Pat Table 4 given composition: Table 4 connection Composition,% MOTCL 6.2 DOTCL 2.7 TTOCL 90.5 Other alkyltin chlorides 0.60

Example 2-4, phase b)

The products obtained in phase a) of the examples were treated with the reagents indicated in Table 5 and gave the amounts shown in Table 5 below: Table 5 example Concentration% HCl Reaction temperature phase b) % MOTCL aqueous phase b) % DOTCL aqueous phase b) % TOTCL aqueous phase b) % MOTCL organic phase b) % DOTCL organic phase b) TOTCL organic phase b) 1 5 35 99.80 0.1 0.1 6.25 2.7 90.5 2 7 60 99.55 0.3 0.15 8.3 3.1 88.1 3 3 45 99.70 0.2 0.1 8.3 1.3 91.8 4 7 35 99.80 0.1 0.1 6.4 0.7 92.3

Example 5

Phase c)

In a four-necked balloon equipped with a thermometer, dropping funnel and condenser and stirred, 111 g of SnCl _{4 was added to} an amount of 345 g of an organic phase TTOT derived from the phase b) of Example 1. At the end of the addition, the temperature has been brought to 195 ° C. After stirring for three hours, the product was cooled and subjected to gas chromatographic analysis. The product thus obtained comprised 75.7% dioctyltin chloride and 24.3% monooctyltin chloride.

Example 6

Preparation of a PVC stabilizer starting from a high purity octyltin trichloride.

In a four-necked balloon equipped with a thermometer, dropping funnel and condenser and stirred, 316 g of 2-ethylhexylglycolate was added to an amount of 386 g of an acidic aqueous solution containing a high purity monooctyltin chloride prepared as in Example 1. Then, in about 2 hours and maintaining a temperature of 75 ° C, 215 g of an aqueous, 30% NaOH solution was dripped. After two hours of reaction, the product was allowed to cool to 50 ° C and the two phases separated. The aqueous solution was separated and the organic phase was purified by removal of the volatile parts via distillation at 85 ° C and 5000 Pa vacuum. The product was then filtered with filter paper and filtration aids to obtain 422 grams of a MOTE-based PVC stabilization product.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 8198352 [0008]
• US 6846944 [0008]
• US 198352 [0012]

Cited non-patent literature

• "The Synthesis, Reaction and Structures of Organometallic Compounds" (AG Davies, PJ Smith, Comprehensive Oraganometallic Chemistry, 1982, 11.545-552) [0006]
• Journal of Organometallic Chemistry (2004), 689 (13), 2145-2157, Table 2 [0029]
• Comprehensive Organometallic Chemistry, Part 11 Tin, Chapter 11.3.1, Pergamon Press, 1982 [0029]

Claims (7)

A method of preparing a product comprising: from 94 to 100% p / p, preferably from 97 to 100% p / p, and more preferably from 99 to 100% monooctyltin trichloride, based on the total weight of the product; from 0 to 6% p / p, preferably from 0 to 3% p / p, and more preferably from 0 to 0.2% dioctyltin dichloride, based on the total weight of the product; from 0 to 6% p / p, preferably from 0 to 3% p / p, and more preferably from 0 to 0.3% trioctyltin chloride, based on the total weight of the product; said process comprising the following phases: a) reacting SnCl ₄ and tetraoctyltin (TTOT) at equimolar amounts at a temperature of between 20 and 60 ° C via a redistribution reaction; and b) reacting the product obtained in phase a) with an aqueous one Extract solution of hydrochloric acid, which has a concentration of 3 to 7% and a temperature between 20 and 80 ° C to obtain a product with a high content of monooctyltin trichloride. The process of claim 1, wherein the ratio between the monooctyltin chloride and the dioctyltin chloride of the product of phase b) is in the range of 94: 6 to 100: 0. The method according to any one of claims 1-2, wherein in phase a) the concentration of the aqueous hydrochloric acid solution is 4.3 to 5.6%, preferably 4.8 to 5.2%. The process according to any one of claims 1-3, wherein the temperature of the phase b) is in the range of 35 to 65 ° C, preferably 45 to 65 ° C. The process according to any of claims 1-4, wherein the acidic aqueous phase resulting from the extraction phase b) is used directly in the synthesis of PVC stabilizers with a high content of monooctyl derivatives. The process according to any one of claims 1-4, wherein the organic phase resulting from the extraction phase b) is used in a phase c) which comprises treating the organic phase with SnCl ₄ to cause a redistribution reaction to produce mixtures of dioctyltin dichloride and to obtain monooctyltin chloride. The process according to any one of claims 1-4, wherein the temperature of the organic phase resulting from the extraction phase b) is converted back into tetraoctyltin via known processes such as alkylation with trioctylaluminum or via a Grignard reaction.