DEI0006592MA - - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

Registration date: November 19, 1952. Advertised on February 2, 1956

GERMAN PATENT OFFICE

Several processes for the preparation of organotin compounds of the type are known from the literature

R ₀ SnX ₆ . .

known, where R is any hydrocarbon radical (alkyl, cycloalkyl, aryl, aralkyl, etc.) and X is an inorganic group (mostly Cl or Br) and where the sum of α and b is 4 and α can vary from 1 to 4.

Dialkyltin dibromides are obtained by the direct action of alkyl bromides on metallic tin at high temperature. Compounds of the R ₄ Sn type are best obtained by reacting SnCl ₄ or SnBr ₄ with Grignard compounds RMgCl or RMgBr or by the action of alkyl halides on a tin-sodium alloy.

The compounds R ₄ Sn can again serve as starting products for the production of compounds with fewer alkyl radicals per tin atom by heating them with SnCl ₄ or SnBr ₄ , mixtures of organic tin compounds with different degrees of substitution being formed, which are produced by fractional distillation or in some other way can be separated.

However, these methods have several disadvantages. In the direct action of alkyl bromides on Tin is obtained almost exclusively from dialkyltin bromide. The manufacture of the other organotin compounds of the type mentioned above is therefore not possible with it.

When tin halides act on compounds of the R ₄ Sn type, one can through

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Applying a correct proportion of the starting materials will mainly allow the reaction to proceed in the desired sense. · To produce tetraalkyltin compounds, however, one must either use the technically not very pleasant reaction with a Grignard compound or use a tin-sodium alloy which requires very special measures for their production and storage. In addition, this alloy is a compound of the composition SnNa, so that when a haloalkyl compound acts on it, three of the four tin atoms present cannot react. If SnNa is used, the maximum yield of R ₄ Sn is therefore only 25%, calculated on the tin present in the alloy.

It has now been found that using a tin-magnesium alloy of the composition Mg ₂ Sn (which may contain an excess of free tin or magnesium) can avoid the disadvantages of the processes known up to now for the production of organotin compounds. By modifying the reaction conditions, it is also possible to obtain compounds with different degrees of substitution as the main product.

The alloy Mg ₂ Sn can be produced by melting tin and magnesium together in the appropriate ratio in the absence of air. The alloy is very brittle after cooling and can easily be ground to a powder that is only slightly sensitive to oxygen and water vapor. You can use the alloy during or after the fusing together catalysts, e.g. B. mercury or mercury salts, add ^

According to the invention, hydrocarbon halides, such as alkyl or aryl halides, act on the tin-magnesium alloy, for which it is often proves expedient to work in certain solvents and with catalysts.

U.S. Patents 2,535,236 and 2,535,237 describe the preparation of tetraalkyl lead by the action of an alkyl halide on the alloy Mg ₂ Pb. However, it could by no means be deduced from this that it would be possible to produce alkyltin compounds _{with the aid of Mg 2 Sn alloys.} If the conditions mentioned in the patents are observed, _{no organotin compounds can be obtained from Mg 2} Sn alloys either. The catalysts effective with Mg ₂ Pb (ether, dimethylaniline, triethylamine, ethyl iodide) are not effective with Mg ₂ Sn alloys. On the other hand, it has been shown that in the present

Description - mentioned _{catalysts effective with Mg 2} Sn alloys, such as mercury and its salts, _{cannot promote the conversion of Mg 2} Pb alloys into alkyl lead compounds. Furthermore, the use of solvents in the reaction with Mg ₂ Pb alloys is not mentioned in the USA patents, while solvents have a great influence in the process according to the invention and are necessary in many cases in order to obtain the desired product. For example, only tetraalkyl lead compounds are formed from Mg ₂ Pb alloys according to the processes of the patents mentioned. According to the process of the present invention, however, alkyl tin compounds of various degrees of alkylation can be obtained as main products from Mg ₂ Sn alloys by changing the reaction conditions. Despite the formal similarity of the starting products, the process according to the invention cannot therefore be derived from the patent specifications mentioned.

In practice, the alkyl bromides are preferred to prepare alkyl tin compounds and run out of alkyl chlorides. The bromides generally react more easily than the chlorides, see above that the use of a catalyst in the bromides generally not, but in the Chlorides is almost always necessary. go

The reaction is preferably carried out at an elevated temperature. Although also at temperatures If a reaction already takes place below 100 °, a higher temperature is preferred in practice between 140 and 170 °, to achieve a quick implementation. Depending on the boiling point the alkyl halide used and the solvent are therefore placed in a pressure vessel work. It is advantageous to stir or stir the finely powdered alloy during the reaction Keep shaking as homogeneously distributed as possible.

The best yield of R ₄ Sn is obtained when starting from almost the theoretical amounts of Mg ₂ Sn alloy and alkyl halide, ie 1 mol of Mg ₂ Sn alloy to 4 mol of alkyl halide. When the amount of alkyl halide is increased, larger amounts of R ₂ SnX _{2 are formed in} addition to R ₄ Sn. Hydrocarbons are preferably used as solvents. Almost no conversion takes place without a solvent.

The invention is explained in more detail by Tables I and II, which describe the reaction of Mg ₂ Sn alloy with ethyl bromide in the presence of cyclohexane as solvent.

Table I.

Mg ₂ Sn-
alloy C ₂ H ₅ Br MoIe-
kular-
mated Cyclo-
hexane Temp. time
length of time (C ₂ H ₅ J ₄ Sn Foreign
(C ₂ H ₆ ) _s SnBr ) today
(C ₂ Hs) ₂ SnBr ₂ Total G G ecm ⁰ C hours 7o Vo Vo % 7th ! 9 i: 4 160 3 IO 2.5 _ 12.5 7th .19 i: 4 40 160 3 61 2.0 6.5 69.5 7th 40 1: 8 . 40 160 3 ■ - 67.0 19.0 86.0 7th 19 ' 1: 4 60 ' 160 3 49 13.0 11.0 73.0

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In addition to the amount, the type of solvent used also has a great influence on the quality and quantitative course of the reaction. This is illustrated in Table II.

Table II

Mg ₂ Sn-
alloy
G C ₂ H ₅ Br
G solvent
20 ecm Temp.
⁰ C time
length of time
hours (C ₂ H ₅ J ₄ Sn
Vo Foreign
(C ₂ H ₅ J ₃ SnBr ) today
(C ₂ H ₅ J ₂ SnBr ₂
Vo Total
Vo tv tv tv tv tv 19th
19th
19th
19th
! 9 Cyclohexane,
benzene
Ligroin
Isooctane
Petroleum ether ....
(Sp. 60 to 8o °) 160
160
160
160
160 co co co co co 55.0
11.0
2.5
4.5
3.5 IO
! 5,
59
37
56 15.O
l6.5
19.0
22.0 65.0 -
41.0
78.0
6O, 5
8l, 5 -

From these tables it is clear that by modifying the solvent and / or the Ratio of the reacting constituents to the formation of tetra- or trialkyl compounds Can promote choice, with considerable yields of dialkyltin compounds can also be obtained.

Mercury salts, e.g. B. mercury bromide and mercury chloride, as well as free mercury have proven to be particularly effective as catalysts. If you use free mercury, it is advantageous to rub it in beforehand with the finely powdered alloy. The amount of catalyst is generally 0.5 to io ° / ₀ of the applied amount by weight of Mg ₂ Sn alloy. Not only the quantitative, but also the qualitative course of the reaction is determined by the amount of catalyst. The effect of the added catalyst is particularly evident when allyl chloride or aryl chloride is used as the starting material. Table III shows reactions of Mg ₂ Sn alloys with ethyl chloride in the presence of cyclohexane as solvent and HgCl ₂ as catalyst. ;

Table III

Mg ₂ Sn-
alloy C ₂ H ₆ Cl MoI-
Relation 8th Cyclo
hexane HgCl ₂ Temp. time
length of time (C ₂ H ₅ J ₄
Sn ' Education
(C ₂ Hs) ₃
SnCl today
(C ₂ H ₅ J ₂
SnCl ₂ Total G G 8th ecm ⁰ C hours % 0 /
/ 0 7o 7th 22nd I. 8th 20th 150 3 _ 7th 22nd I. 8th 20th 0.14 150 3 - - - · - 7th 22nd I. 8th 20th 0.7 150 3 o, 5 20th 18 ■ 38.5 7th 22nd I. 8th 20th 1.4 150 3 10.0 l6 3D 56.0 7th 22nd I. 8th 20th 2.9 150 3 10.0 29 II 50.0 7th 22 ■ I. 20th 5.7 150 3 5.0 32 16 53.0 7th 22nd I. 20th 10.1 150 3 0.5 43 12th 55.5

It has now been shown that it is not absolutely necessary _{to use Mg 2} Sn alloy as a starting product. A reaction is also obtained with a mixture of tin and magnesium, in the above ratio in finely divided form, it also being possible for the mixture to contain a slight excess of tin or magnesium. However, there are certain advantages associated with the use of the alloy Mg _{2 Sn.} Because of its great brittleness, this alloy can be distributed very finely, which greatly promotes a uniform and rapid reaction. Due to its homogeneity, the alloy reacts as a compound Mg ₂ Sn with the alkyl halide, while the mixture of magnesium and tin cannot react homogeneously with the alkyl halide due to the large difference in the specific gravity of its components.

The method according to the invention is described in the nach- no the examples below.

example 1

21 g of Mg ₂ Sn alloy are finely powdered with 2.1 g of mercury and then refluxed with 55 g of ethyl bromide and 80 ecm of cyclohexane for 16 hours. After filtering and washing the residue with cyclohexane, the filtrate is fractionated. This gives 14.8 g of tetraethyltin, equal to a yield of 50% of the theoretical amount calculated _{on the Mg 2 Sn alloy.}

Example 2

21 g of finely powdered Mg ₂ Sn alloy, 55 g of ethyl bromide and 60 ecm of cyclohexane are used during

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3 hours down to a temperature of 160 ° in one Autoclave heated. After filtering, washing the residue with cyclohexane and fractionating, one obtains a yield of 16.3 g of tetraethyltin (55% of the theoretical amount) and 3.6 g of triethyltin bromide (10% of the theoretical amount).

Example 3

21 g of Mg ₂ Sn alloy, 120 g of ethyl bromide and 120 ecm of cyclohexane are heated as in Example 2. A yield of 24 g Triäthylzinnbromid (6y ° / ₀ of the theoretical amount) and 8.1 g Diäthylzinndibromid (i9 ° / ₀ of the theoretical amount) ..

Example 4

In the same way as in Example 2, 21 g of Mg ₂ Sn alloy, 55 g of ethyl bromide and 6 p ecm of petroleum ether (60 to 80 °) are obtained: ig tetraethyl tin (3.5% theoretical amount), 20.1 g triethyl tin bromide ( _{56.0 / 0 of} the theoretical amount) and 9.3 g of diethyltin dibromide (22% of the theoretical amount).

Example 5.

In an autoclave, 21 g of finely powdered Mg ₂ Sn alloy, 65 g of ethyl chloride, 60 ecm of cyclohexane and 1.2 g of HgCl _{3 are} heated to 150 ° for 3 hours. (32% of the theoretical amount) 1.5 g tetraethyltin (5% of the theoretical amount), 9.7 g and 5 g of triethyltin Diäthylzinndichlorid (i6 ° / _0: Filtration, washing of the residue with cyclohexane and fractionation to obtain the following yields theoretical amount).

Example 6

As in Example 2, 21 g of Mg ₂ Sn alloy, 69 g of n-butyl bromide and 60 ecm of cyclohexane are heated to 160 ° for hours. A yield of 21.6 g of tri-n-butyltin bromide (46.5% of the theoretical amount) is obtained. .

Claims (6)

Patent claims: 1. A process for the preparation of organotin compounds of the general formula R ^ SnX ₆ , wherein R is a hydrocarbon radical and X is a halogen atom and α and b are any integers whose sum is 4, characterized in that a hydrocarbon halide on an alloy of Magnesium and tin with the composition Mg ₂ Sn or a corresponding mixture of magnesium and tin, whereby the alloy or mixture can also contain a small excess of tin or magnesium, can act. 2. The method according to claim 1, characterized in that that one uses mercury or mercury salts as catalysts. 3. The method according to claim 1 and 2, characterized in that the reaction is carried out in the presence an organic solvent. Process according to Claim 3, characterized in that a hydrocarbon compound is used used as a solvent. 5. The method according to claim 1 to 4, characterized in that the reaction is at least allows the boiling point of the reaction mixture to take place. 6. The method according to claim 1 to 5, characterized in that one works at temperatures of 140 to 170 ⁰ . . Referred publications:
German Patent No. 508 667;
U.S. Patent Nos. 2,431,038, 2,569,492. © 509 656/58 1.56