JPS5918398B2 - Process for producing alkyltin trichloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Alkyltin trichloride is an important precursor for producing polyvinyl chloride stabilizers.

Attachment of an alkyl group to a tin atom can be accomplished in various ways. be able to. [Neumann (W, P, Neuma
nn) Author: Die Organische Chemi
edesZinns), Ferdinand Enke Verlag
), stuttgart, 1
967, No. 16-: p. 35].

However, in most cases highly alkylated tin chloride is obtained. This applies in particular to the preparation of alkyltin chlorides from tintetrachloride and alkylaluminum compounds. In this case, a mixture of trialkyltin and tetraalkyltin chloride is formed. In this case, the lower alkylation step is a so-called co-proportional reaction (Knmp
(pages 41-43 of the above-mentioned document).

Alkyltin trichloride can be obtained, for example, by co-proportional reaction of tetraalkyltin and tin tetrachloride: R4Sn+ 3S
nCl4-→4RSnCl3 However, the production of alkyltin trihalides by this method is limited to a few alkyl groups (e.g. vinyl groups), and special solvents (POCl3
/P2O5).

The reason for this difficulty is that the step 5R2SnCl2+ SnCl4−)2RS required for the complete composition
This means that nCl3 can only be realized in special cases.

However, processes have been developed which produce alkyl9tin trichlorides together with dialkyltin or trialkyltin chlorides (see German Patent No. 1,161,893 and British Patent No. 739,883).

Alkyltin trichlorides can be obtained from such mixtures, for example by distillation. However, this process is severely limited by the high boiling point of long-chain alkyltin trichloride and can only be used industrially for the production of short-chain (≦C4) alkyltin trichloride.

A very simple method to produce alkyltin trichloride is to
This is the exchange of the chlorine atom of cl4 with an alkyl group, that is, monoalkylation.

Monoalkylation of Sncl4 using commercially readily available trialkylaluminum has hitherto not been achieved satisfactorily. However, by monoalkylation using alkyl aluminum alkoxide, Snc
Alkyltin trichloride can be produced from L4 [West German Patent Publication No. 2304617, Neumann (
W. P. Neumann): Ann. Chem, Volume 653 (1962)
, p. 163].

However, in this case, trialkylaluminum is limited in terms of economic advantage compared to other alkylating agents in the alkylation reaction. That is, when an alkyl aluminum alkoxide is used, a maximum of two alkyl groups are bonded per aluminum atom. According to West German Patent Publication Nos. 1157617 and 1164407,
Preparation of trialkyltin compounds and dialkyltin compounds or mixtures thereof using alkylaluminum-ether monocomplexes or alkylaluminum-amine monocomplexes with stoichiometric or non-stoichiometric conversions. is possible.

According to this method, the production of monoalkyltin compounds was not previously possible. Later publications [Liebig
sAnn. Chem. ), Volume 653 (1962),
See page 160], in which W. P. Neumann wrote: ``Experiments were conducted to determine whether the reaction of aluminum alkyl with tin tetrachloride proceeds in such a way that various organotin halides can be produced selectively by the following equation. I tried to.

In the case of equations (5) and (6), the objective was indeed satisfactorily achieved when the AlCl3 formed was removed from the reaction mixture under complexation with an ether or an amine. Reaction (7) could not be realized. ] Surprisingly, it has become clear that the above reaction (7) can be realized if the following conditions according to the present invention are simultaneously maintained:
1. Be sure to use a donor complex of an alkyl aluminum compound; 2. Be sure to follow the order: charge the Sncl4, then add the alkyl aluminum mono-donor complex, 3. Stoichiometric ratio SnCl4l mole + al
-R1 equivalent (al-1/3A1), 4.20-70°C,
Maintaining a low temperature, especially between 40°C and 70°C.

The process of the invention for producing alkyltin trichloride by monoalkylating tin tetrachloride comprises initially charging tin tetrachloride with a trialkyltin tetrachloride in the form of a donor monocomplex with an ether or a tertiary amine. It is characterized in that aluminum or alkyl aluminum halide is added in stoichiometric amounts to the monoalkyltin compound and the reaction is carried out at a temperature of 20 to 70°C, preferably 40 to 70°C.

For the process according to the invention, donor monocomplexes of alkyl aluminum compounds are suitable, for example with diethyl ether, di-n-butyl ether, tetrahydrofuran, dioxane, anisole, etc., triethylamine, pyridine or dimethylaniline.

Some donor monocomplexes, such as those with tetrahydrofuran or pyridine, alkylate SnCl4 to give the product mixture RnSnCl4-n (n=1 to 4), which however is always dominated by alkyltin trichloride.

Within the concept of the process according to the invention, di-n-butyl ether complexes with aluminum trialkyls as well as alkylaluminum halides have proven particularly advantageous.

A content of about 90-93% by weight of alkyltin trichloride is obtained. This content can be further increased to 97% when Sncl4 is used as the etheride monocomplex. Next, the method for producing alkyltin trichloride according to the present invention will be described first.
The alkyl aluminum compound is mixed with the desired donor in a manner known per se in a suitable apparatus under protective gas. The alkyl aluminum complex formed is then treated with SnCl4, also under protective gas, or optionally with Sn in a molar ratio such that an alkyl group is distributed on each Sn atom.
a mixture consisting of cl4 and di-n-butyl ether;
Advantageously, SnCl4 is charged to the apparatus and reacted by incorporating the alkyl aluminum monocomplex with good mixing.

Since this is an exothermic process, care is taken to maintain a low temperature during the reaction by good cooling. The best results are achieved if the reaction of the reaction components is carried out at a temperature of 20 to 120'C, preferably 40C. Large amounts of by-products are produced at high temperatures. Furthermore, there is a risk that the 1 donor complex of the aluminum compound will decompose. After the reaction and after-reaction have ended, the reaction mixture is preferably diluted with a suitable solvent and placed in ice water. A suitable solvent is, for example, di-n-butyl ether. If this is added to Sncl4 from the beginning, a dilution with di-n-2-butyl ether results. The later addition of di-n-butyl ether no longer affects the product composition. The ether addition is carried out only for reasons of better work-up of the reaction product.
For example, if the addition of di-n-butyl ether is omitted, 2
Particularly when preparing RSnCl3 with short-chain R, the aqueous phase must be extracted several times, for example with di-n-butyl ether. After phase separation and distillation of the di-n-butyl ether, alkyltin trichloride is obtained, which is mixed with varying amounts of highly alkylated tin chloride or tetraalkyltin chloride. Example 1 SnCl426O. 557 (1 mole)
to (C8Hl7)3A1・(C4H9)20*《171
7 (corresponding to 0.33 mol of tri-n-octylaluminum) is added.

After the addition is complete, the mixture is stirred for about 30 minutes at 40°C, and then di-n-butyl ether 2607 (2 mol) is added at 40-50°C while stirring and cooling. After this addition, stirring is continued for a further 15 minutes without heating or cooling, and the reaction mixture is then poured into 200 ml of ice water with cooling. At this time, the temperature is maintained at a maximum of 50 to 70°C. After phase separation, di-n-
Butyl ether is distilled from the ether phase at low pressure,
C8Hl7sncl3 is obtained as a light to dark brown liquid. The yield is 3227 (90% based on the Sn used). When the sample reacted with C2H5MgCl was analyzed by gas chromatography, it contained 93% by weight of C8Hl7sncl3.

Example 2 In the apparatus described in Example 1, Sncl426O. 5
7 (1 mol) to di-n-butyl ether 26 within 5 minutes.
Add 07 (2 moles).

At this time, the temperature is raised to about 60°C. This reaction mixture contains 4
Since it is fixed at 0 to 50℃, (C8Hl7)3A1・
The after-reaction with (C4H9)20 is carried out at 50 DEG C. and as otherwise described in Example 1.

The yield is 90%; the content of C8Hl7sncl3 detected by gas chromatography is 97%.
Example 3 Sncl4 and (C8H,7)3A1(C4H9)20 are reacted as described in Example 1.

However, di-n-butyl ether is not added.
After hydrolysis of the reaction mixture, the aqueous phase is extracted two to three times with 70 to 100 ml of di-n-butyl ether in each case and the reaction product is isolated as in Example 1. A yield of 90% was obtained; C8 detected by gas chromatography
The content of Hl7sncl3 is 97%.

Claims (1)

[Claims] 1. In producing alkyltin trichloride by monoalkylating tin tetrachloride, tin tetrachloride is charged, and a trialkylaluminum or alkyl halide in the form of a donor complex with an ether or tertiary amine is added to the tin tetrachloride. aluminum,
added in a stoichiometric amount to the monoalkyltin compound,
A method for producing alkyltin trichloride, which is characterized by carrying out the reaction at a temperature of 20 to 70°C.