NO781716L - PROCEDURE FOR THE PREPARATION OF TIN-ORGANIC COMPOUNDS - Google Patents

Description

Process for the production of organotin compounds.

The present invention relates to a method for producing tetraorganotin compounds from elemental tin.

Organotin compounds can be produced by reaction between tin halides and organometallic compounds such as Grignard reagents. Processes are also described in which organotin compounds are directly produced from elemental tin. Thus describes the applicant's British patent No. 1,115. 646, a process for the preparation of preferably diorganotin dihalides which comprises reacting tin with an aliphatic halide in the presence of a nitrogen, sulfur or phosphorus<1>onium compound with a previously prepared tin(II) halide or organotin halide, and in the optional presence as cocatalyst of a small amount of a metal which may be zinc among many others. US patent no. 3,085,102 describes a similar process, but without the<1>onium compound and pre-prepared halide, but in which the cocatalyst is substantial and preferably magnesium.

US Patent No. 3,547,965 describes the preparation of triorganotin halides by reacting organic halides with an equiatomic mixture of tin and zinc in the presence of an alcohol. US Patent No. 3,561,108 describes the preparation of tetraorganotin compounds by reaction of organic halides in the presence of an onium compound or a Lewis base with tin and an alkali or alkaline earth metal, especially magnesium.

A method for producing tetraorganotin compounds without the use of risky alkali or alkaline earth metal is described in OLS 2,601,497 as a process for producing a tetraorganotin compound which comprises introducing a halide of the formula RX where R is an alkyl group with from. 1 to 4 carbon atoms, and X is chlorine, bromine or iodine, to a heated suspension of metallic material in the form of zinc or tin, or an alloy of tin and zinc, whereby the atomic ratio of zinc to tin is at least 0.5:1 /in a liquid comprising at least one organic quaternary ammonium or phosphonium salt or tertiary sulfonium salt, to obtain a vapor effluent comprising essentially all tetraalkyltin compound produced.

The applicant has now found another process for the production of such tetraorganotin compounds which is also suitable for the production of less volatile tetraorganotin compounds.

The invention thus provides a process for the preparation of tetraorganotin compounds which comprises reacting an organic halide of the formula RX, in which R is

an alkyl group of from 1 to 20 carbon atoms or alkenyl group of from 2 to 20 carbon atoms, and X is chlorine, bromine or iodine, with a heated suspension of zinc in a liquid comprising at least one 'onium salt, which is an organic quaternary ammonium or - phosphonium salt or tertiary sulfonium salt, to obtain a reaction product of the organic halide and zinc and then addition of tin to the reaction product followed by heating to obtain the tetraorganotin compound.

It is assumed that the reaction between the organic halide and zinc occurs so that at least one organic zinc halide and one diorganic zinc compound are formed, although the former is assumed to be the most likely. According to another feature of the invention, a method for the preparation of a tetraorganotin compound is obtained which comprises reacting an organozinc compound which is at least one of an organozinc halide or a diorganozinc compound, in which the organic group R is an alkyl group with 1-20 carbon atoms or an alkenyl group with 2-20. carbon atoms, and the halide X is chlorine, bromine or iodine, with a heated suspension of

tin in a liquid comprising at least one 'onium salt which is an organic quaternary ammonium salt or - phosphonium salt or a tertiary sulphonium salt, to obtain a tetraorganotin compound. Preferably, the organozinc compound is formed in situ by reaction between the organic halide and zinc in the heated suspension in the liquid comprising the onium salt.

Preferably, the organic halide is reacted with zinc in the absence of tin to a degree of reaction of at least 50%, e.g. at least 80%, before tin is added, where the degree of reaction of 80% means that at least 80% of the organozinc compound to be formed has been formed. In a preferred process, the organic halide is introduced into the suspension of zinc in the absence of tin in the liquid comprising the onium salt, and when substantially all of the organic halide has been passed through and the reaction is substantially complete, tin is added and the reaction continued.

The reaction between the reaction product of zinc and organic halide, i.e. the organozinc compound, and the tin can be carried out in the presence of more organic halide regardless of whether the organic halide is free or bound to the suspension.

The organic group in the organic halide can be methyl, ethyl, n- or isopropyl, n-, sec.-, iso- or tert.-butyl, octyl, e.g. n-octyl, vinyl or allyl. The organic halide is preferably an alkyl or alkenyl halide,

each of 3-8 and especially 4-8 carbon atoms. Butyl chloride and octyl chlorides are preferred. A mixture of organic halides can be used to give a mixture of tetraorganotin compounds. The amount of organic halide added,

is usually at least 1, e.g. at least 2 mol/gatom tin, e.g.

1.5-15 such as 2-15 mol, e.g. 2-5 mol and especially 2-2.5 mol/gatom of tin whereby the total amount of organic halide that is added depends on the degree to which the reaction is carried to completion; the amount of organic halide is usually 0.5-2 mol/gatom zinc, e.g. 0.7-1.5 mol. The amount of halide that is added also depends on the amount that remains unreacted and boils off as waste gas. The molar ratio between organic halide and salt can be significant, as ratios above the critical ratio have

a tendency to give organotin products containing significant amounts of triorganotin halide, while conditions below this amount give organotin products containing at least 90% tetraorganotin with less than 10%, e.g. less than 5%,

if at all, triorganotin halide. When the method is used, for the production of organotin compounds comprising

end tetraorganotin, the molar ratio of organic halide to salt is usually from 4:1 to 8:1, such as up to 7:1, preferably 4-6.8:1, e.g. 5-6.7:1.

The liquid containing organic quaternary ammonium or. phosphonium salt or tertiary sulfonium salt, is often kept • at a temperature of 100-300°C, e.g. 150-200°C and preferably 150-220°C. The salt is usually a halide, e.g. a chloride or bromide, especially an iodide, if thus the halide reactant is not itself an iodide, the presence of an iodide in the liquid will be very desirable as the rate of reaction is increased.

The salt is usually a salt of the formula R'4Sy, R14^Y or R'3S~Y, where each of R' is an alkyl group, e.g. with from 1 to 13, especially from 1 to 8 carbon atoms, or an aralkyl group with from 7 to 19 carbon atoms, e.g. an aralkylhydrocarbyl group of from 7 to 19 carbon atoms, such as benzyl, or a cycloalkyl group of from 5 to 7 carbon atoms, e.g. cyclohexyl or an aryl group, e.g. an aromatic hydrocarbyl group of from 6 to 18 carbon atoms, such as a phenyl, tolyl or naphthyl group, and Y is a chloride, bromide or preferably an iodide ion. Examples of salts are tetrabutylammonium and phosphonium halides, benzyltriethylammonium and phosphonium halides, tetraoctylammonium and tetraoctylphosphonium halides, and trioctyl and tributylsulfonium halides. The salt as such, can be mixed with zinc or, can be obtained by reaction in situ between the halide reactant of the formula RX with the corresponding tertiary amine or phosphine or sulfide of the formula R<1>-^, R<1>^? or R'2S' preferably before the addition of zinc. The group R<1> in the quaternary or tertiary salt is preferably the same as R. The salt may be present in an amount of at least 0.01, e.g. at least 0.1 gmol/gatom tin, e.g. 0.1-1.5 or 0.3-1.5 or 0.1-0.8, but preferably 0.3-0.8 or 0.3-0.6 or 0.4-0.8 gmol . The molar amount of organotin product can be of the same order of magnitude as the molar amount of the salt.

The reaction between organic halide and zinc and then the reaction with tin is usually carried out in a dry atmosphere under the exclusion of moisture, especially under an inert gas, e.g. nitrogen.

The solid tin preferably has a maximum dimension

of 5 mm such as 50-1000 ym, especially 50-150 ym; it can be more finely divided in the form of powder or a crushed material, or in sponge form or in the form of plates. The solid zinc becomes

step by step finely divided, e.g. to maximum dimensions of 5 mm, such as 50-1000 ym, especially 50-150 ym, e.g. in the form of powder or crushed material, but can also be present, in the form of granules. The atomic ratio of zinc to tin is usually 0.5:1 to 5:1, preferably 1:1 to 4:1, e.g. 1.5:1 to 3.0:1, and especially 1.5:1 to 2.5:1; stoichiometrically, the reaction suggests a ratio of approx. 2:1. The suspension is usually stirred.

If the melting point of the salt is below the reaction temperature, the molten salt may constitute the necessary liquid phase for the reaction and be the only organic liquid present, if this is preferred. If desired, an organic diluent can be present and should then have a boiling point below the reaction pressure which is significantly higher than the reaction temperature, e.g. at least 50°C higher, and be inert towards the reactants. Examples of such diluents are high-boiling paraffin oils, with a boiling point above 300°C, dodecane, tetradecane or tetralin and polar inert solvents such as dialkyl ethers of diethylene glycol. The diluent is necessary to give a liquid phase, e.g. a solution of the salt if the salt has a melting point higher than the reaction temperature, or if the ratio between sali? and the weight of tin or zinc is insufficient to produce an agitable suspension. The minimum ratio for the salt depends on the form of tin and zinc; less salt can be satisfactorily used with powdered tin or zinc than with tin plates or . zinc granules. Where possible, however, the reaction is carried out in the absence of inert organic liquid diluent. The weight ratio of the liquid phase (ie salt and diluent if present but not including organic halide and organotin compound present) to the weight of zinc is preferably 0.10:1 to 10:1, although higher proportions may used; the ratio is preferably 0.5:1 to 5:1, e.g. 0.5:1 to 2:1.

The organic halide is preferably added to the hot suspension of zinc during the reaction whereby the halide can be released on the surface of the suspension, but is preferably introduced below the surface. The temperature and pressure conditions for the reaction can be such that unreacted organic halides (and in particular essentially all unreacted halides) evaporate and form a gas effluent. In this case, the rate of addition of organic halide is usually not much greater than the reaction rate in order to optimize the reaction, while minimizing the amount of unreacted organic halide in the effluent.

Alternatively, all organic halide can be added in one proportion from the beginning of the reaction, but this is less preferred as the reaction is exothermic.

Simple experiments can be conducted to determine suitable conditions of temperature, pressure and rate of addition to be used for any particular organic halide and salt. As a guide regarding temperature and pressure, suitable conditions for butyl halides are reaction temperatures of 150-250°C, e.g. 150-190°C such as 160-180°C under atmospheric pressure, and for octyl halides temperatures of 150-300°C, preferably 150-250°C, e.g. 150-220°C, under pressure of 10-760 mm Hg, e.g. 150-190°C such as 160-180°C under atmospheric pressure, applicable. Thus, the reaction can preferably be carried out with butyl chloride by adding this during the reaction together with zinc to a liquid above the boiling point of butyl chloride, so that unreacted chloride can evaporate, but the octyl chloride can be added in one portion or during the reaction together with zinc to the liquid below the boiling point of the halide.

The reaction time depends on the nature of the organic group and the halogen in the halide, the reaction temperature, the pressure or the absence of iodine ions in the reaction mixture, the <1>onium catalyst ratio and the degree to which the reaction is brought to completion. The reaction time is reduced with increasing atomic weight of the halogen, a decreasing reaction temperature, the presence of iodine ion, increasing amount of 'onium catalyst. However, total reaction times of 1-24 hours at 150-200°C are often suitable.

After the reaction between zinc and organic halide,

tin is added and the reaction continued at a temperature, usually 130-250°C, e.g. 150-200°C, such as 160-180°C

for at least 0.5 hours, e.g. 0.5-12 hours, such as 0.5-6 hours.

In a particularly preferred embodiment, the invention provides a method in which an organic chloride which is butyl or octyl chloride is fed to a suspension of solid zinc in a molten state with the formula R^NY or R^PY, in which each R' is butyl when butyl chloride is reacted, or octyl when octyl chloride is reacted, and Y is a chlorine, bromide or iodide ion, at 130-200°C, e.g. 160-180°C, to form a reaction product between the organic halide and zinc, after which solid tin is added to the suspension, usually in an atomic ratio of zinc to tin of more than 0.5:1, e.g. 1:1 to 4:1, such as 1.5:1 to 2.5:1, and the molar ratio between salt and tin is 0.1:1 to 1.5:1, e.g. 0.1 to 0.8:1 and especially 0.3 to 0.6:1, and the reaction is carried out at 130-200°C, e.g. 160-200°C to obtain tetrabutyltin or tetraoctyltin.

The reaction between organozinc compound and tin, and preferably also the reaction of alkyl halide with zinc, is usually carried out in an apparatus and under conditions such that gaseous material, if present, is allowed to evaporate from the suspension to form a gaseous effluent, of which at least one proportion usually collected by condensation. Thus, the reaction is usually carried out in an apparatus which is able to condense gas effluents from the reaction. Such effluents may include unreacted organic halide and/or tetraorganotinf compound and/or volatile decomposition products of the organic halide, e.g. alkenes. The unreacted halide in a continuous or a batch process can be fed back for new use, possibly after removal of any tetraorganotin compound, e.g. by fractional distillation.

The procedure for recovery of the tetraorganotin product depends on the boiling point. In the case of tetraorgano-tin compounds with a boiling point below the reaction pressure (usually atmospheric) of less than the reaction temperature, usually 160-200°C, the tin and the organozinc compound or the zinc-containing reaction product are reacted with the collection of organotin as steam effluent; this procedure is very suitable for the production of tetramethyl-, -ethyl- and -propyltin at 160-200°C,

and in the higher part of the temperature scale or under reduced pressure for tetrabutyltin. When the tetraorganotin has a higher boiling point than the reaction temperature under the present pressure, either pressure and/or temperature is changed at the end of the reaction to evaporate the tetraorganotin or the tetraorganotin that remains in the liquid phase; the latter procedure is preferred and suitable for tetraoctyl and tetrabutyltin.

When the reaction is brought to the desired degree of completion, the suspension contains the salt, unreacted tin present and unreacted zinc present, and by-product zinc chloride and tetraorganotin compound (if the temperature is less than the boiling point); it may be in it. substantially free of unreacted organic halide, and may also contain a triorganotin halide. The liquid can be reused when the organotin compound(s) have been removed and when the zinc chloride by-product has also been separated.

The suspension can be worked up by allowing deposition when an upper liquid phase usually separates from a lower suspension phase which also contains unreacted tin and/or zinc. The upper phase comprises the organotin product and, if the reaction was carried out in the absence of a diluent, the bulk of the organotin product. The lower phase comprises the salt, unreacted tin and/or zinc present and zinc chloride by-product. Unreacted organic halide, if present, may be present in both phases,

and can be separated from the organotin product by fractional distillation and can be separated from the lower phase or recycled for use again. The reaction suspension can be separated hot into a liquid organic tin fraction and a lower liquid suspension from which tin and/or zinc residue present can be filtered off; the remaining metal can be mixed with a necessary amount of fresh tin and/or zinc for reuse. Preferably, the reaction suspension in the hot or cold state or the lower phase in the hot or cold state is mixed with an organic solvent to support the filtration step, preferably a solvent capable of decomposition of organozinc compounds present.

Examples of suitable solvents are ketones with 3-6 carbon atoms, e.g. acetone, methyl ethyl ketone and methyl iso-butyl ketone, and alkanols with 1-6 carbon atoms, e.g. methanol, ethanol, propanols or butanols, and the alcoholic solvents are preferably those which best decompose organozinc compounds. The suspension of the total reaction product in the solvent can be extracted with a solvent for the organotin product, e.g. a hydrocarbon, such as a petroleum ether, e.g. one with a boiling point of 40-60°C, 60-80°C or 80-100°C. Evaporation of the extract leaves behind the organotin crude product.

The mixture of 'onium salt and zinc chloride gives a residual liquid and which is separated from unreacted tin and/or zinc,

can itself be separated after evaporation of ketone.or alcohol or both solutions, if these are present, after treatment with aqueous alkali, e.g. an aqueous solution of an alkali metal or alkaline earth metal hydroxide, such as sodium or potassium hydroxide, and the product is extracted with an organic water-immiscible solvent, such as a chlorinated aliphatic hydrocarbon, e.g. with 1-4 carbon atoms, such as chloroform, 1,2-dichloroethane or methylene dichloride, to obtain an organic layer comprising the onium compound and an aqueous phase containing zinc; after which the phases are separated and the onium compound is reconverted to the <1>onium salt, if necessary, and the onium salt is used again. The dissolution of quaternary<1>onium chlorides and hydroxides in organic media is described by Brandstrom et al. in "Acta. Chem. Sean.", 1969, 23, 1215, and subsequent papers.

The organic phase from the first separation of the reaction suspension may consist essentially of the organotin product, or may be a mixture of the organotin product and solvent and/or unreacted organic halide; in the latter case, the solvent and/or the organic halide is distilled off from the organic phase to leave the organotin fraction. The organotin product can be purified by distillation, if it is desired to remove small amounts of salts, solvent and non-

set organic halide. The organotin compound usually comprises at least 50%, e.g. at least 70% and preferably at least 90%, especially at least 95%, such as 95-98% tetraorganotin, while the remainder, if any, is essentially triorganotin halide, wherein in both compounds the organic group is primarily based on the organic group in the organic halides, while mixed products including organic groups of the salt and the hydrocarbons can also be formed.

The tetraorganotin product can be used for the production of triorganotin halide compounds, such as triorganotin chlorides essentially free of di- or monoorganotin compounds by mixing the compound with suitable molar proportions of tin halide, e.g. tin chloride, the corresponding diorgano- and monoorganotin halides can be produced in the same way. The higher the ratio between tetraorganotin and triorganotin halide in the organotin product, the higher the volume efficiency for the plant that produces the organotin product. The organotin halides are used as antifungal compounds or as intermediates for the production of such compounds or stabilizers, e.g. dibutyltin-bis(isooctylthioglycolate), for polymer materials, e.g. PVC. In particular, the tetraalkyltin compounds can be disproportionated with stannous chloride to obtain a

c

2:1 molar mixture of monoalkyltin trihalide and dialkyltin dihalide, usable as an intermediate for the production of stabilizers, e.g. mercaptoester stabilizers for PVC.

The invention shall be illustrated in the following examples: Example 1

To a reaction flask equipped with a stirrer, dropping funnel, thermometer, and an outlet pipe leading to a condenser, was charged 26.16 g or 0.4 g atm of zinc powder, together with 36.9 g or 0.1 mol of tetra-n-butylammonium iodide ..The mixture was heated to 160-180°C to obtain a liquid suspension which was stirred while 46.45 g or 0.5 mol of n-butyl chloride was slowly added over 1 hour while maintaining the temperature at 160-180 °C. Unreacted butyl chloride was evaporated and collected as condensate. After all the butyl chloride was added, 29.67 g or 0.25 gatom of tin powder was added to the suspension and this was stirred and heated to 160-180°C for a further 1 hour. The reaction mixture was allowed to cool, settle to obtain a top layer comprising organotin and a bottom layer containing

end zinc, .tin, zinc chloride and quaternary salt. The top layer of 20.1 g was found by GLC to contain 96% tetrabutyltin

and no tributyltin chloride; the yield of tetrabutyltin was 55.6% (based on the amount of moles of 'onium iodide).

Example 2

The procedure according to e.g. 1 was repeated with them

same amounts of tin and 'onium iodide, but with 52.28 g or 0.8 gatom of zinc powder and 60.12 g or 0.65 mol of butyl chloride, a reaction temperature of 160-180°C and an addition time of butyl chloride in 1.25 hours, and a reaction time after tin was

added in 4 hours. After the reaction mixture had cooled, an upper layer and a bottom layer were obtained as in ex. 1. The layers were separated and the upper layer of 23.3 g was found by analysis to contain 95.3% tetrabutyltin and 0.4% tributyltin chloride, corresponding to a yield of 63.9% tetrabutyltin and 0.3% tributyltin chloride, whereby the yield is expressed on the basis of the number of moles of onium iodide.

Example 3

Example 1 was repeated with the same amount of the same 'onium iodide, but with 39.2 g or 0.6 gatom zinc powder, 35.5 g or 0.3 gatom tin powder and 55.8 g or 0.6 mol n-butyl chloride, with a reaction temperature of 170-180°C, an addition time for butyl chloride of 1.5 hours and a reaction time after addition of the tin of 4 hours, whereby the reaction was allowed to cool.

Methylated spirit (50 ml) was added and the mixture refluxed for 30 min. before cooling and extraction with petroleum ether with a boiling point of 40-60°C (3 x 50 ml) to obtain ether extracts and a lower layer. The ether extracts were evaporated leaving 29.0 g of impure tetrabutyltin containing 98.6% tetrabutyltin, a yield of 83.0% calculated on the weight of the onium salt.

The lower layer was diluted with additional methylated spirit, 100 ml, after which the mixture was filtered and the filtrate evaporated to give a solid residue of 82.6 g containing the onium salt and zinc chloride. The residue was heated to 100°C

and treated with 100 g of an aqueous solution of 24% sodium hydroxide to obtain an aqueous layer of pH 14, after which the reaction mixture was cooled. The reaction mixture was filtered and the solid residue and the filtrate extracted separately with a total of 90 ml of chloroform. The remaining solid was washed with water and extracted with chloroform. The chloroform extracts were combined, dried and evaporated, and a crystalline residue of quaternary compound was obtained in an amount of

31.5 g.'

Eczema Part 4

The procedure according to e.g. 3 was repeated with them

same quantities of zinc dust and tin dust, but with tetraoctyl-ammonium iodide in an amount of 59.3 g or 0.1 mol as 'onium-

iodide, and 89.1 g or 0.6 mol of n-octyl chloride instead of butyl chloride. The dispersion of zinc dust in onium iodide was stirred at 170°C while the octyl chloride was added over 1.25 hours at 175-165°C. At the end of the addition, the octene was distilled off at 175°C/, and then the suspension was cooled to 150°C before the addition of tin followed by stirring for 3.5 hours at 170-175°C. The reaction mixture was cooled to 120°C and methylated spirit in an amount of 50 ml was added. The resulting mixture was cooled, extracted and worked up as in Ex. 3, and 38.2 g of impure organotin compound was obtained which was shown by vapor phase chromatography to contain 9 2.1% tetraoctyltin,

7% cetane and no trioctyltin compounds; whereby the yield of tetraoctyltin was 61.6%, calculated on the onium salt.

The lower layer from the processing was processed further

as described in ex. 3 to separate the components.

The procedure in ex. 4 up to the addition of methyl alcohol, was carried out in a dry atmosphere under the exclusion of moisture and under nitrogen.

Claims (18)

1. Process for producing a tetraorganotin compound, characterized in that it comprises reacting an organic halide with the formula RX where R is an alkyl group with from 1 to 20 carbon atoms or an alkenyl group with from 2 to 20 carbon atoms, and X is a chlorine, bromine or iodine atom, with a heated suspension of zinc in a liquid comprising at least one 'onium salt which is an organic quaternary ammonium or phosphonium salt or tertiary sulphonium salt, to obtain a reaction product of the organic halide and zinc, and then add tin to the reaction product, whereby the atomic ratio of zinc to tin is at least 0.5:1, followed by heating to obtain the tetraorganotin compound. 2. Process for the production of a tetraorganotin compound, characterized in that it comprises reacting an organozinc compound selected from organozinc halide and diorganozinc, in which the organic group R is an alkyl group of from 1 to 20 carbon atoms, or an alkenyl group of from 2 to 20 carbon atoms, and the halide X is a chlorine, bromine or iodine atom, with a heated suspension of tin in a liquid comprising at least one 'onium salt which is a organic quaternary ammonium or phosphonium salt or tertiary sulfonium salt, to obtain the tetraorganotin compound. 3. Method according to claim 2, characterized in that the organozinc compound is formed by reacting an organic halide with the formula RX with a heated suspension of zinc in a liquid comprising an onium salt as stated in claim 2. 4. Method according to claims 1-3, characterized in that the tetraorganotin compound is evaporated and recovered from the gas outlet. 5. Method according to any one of claims 1-3, characterized in that some of the tetraorganotin compound is in the liquid phase and is recovered from the reaction as a liquid organotin fraction. 6. Method according to claim 5, characterized in that the molar ratio between organic halide and onium salt is less than a critical ratio, so that the tetraorganotin compound which is produced contains less than 10% triorganotin halide. 7.. Method according to claim 6, characterized in that the molar ratio between organic halide and onium salt is up to 7:1. 8. Method according to any one of claims 1-7, characterized in that the group R is butyl or octyl and the halide X is chloride. 9. Method according to any one of claims 1-8, characterized in that the atomic ratio between zinc and tin is 1:1 to 4:1, preferably 1.5:1 to 2.5:1. 10. Method according to any one of the preceding claims, characterized in that the molar ratio between salt and tin is 0.1:1 to 1.5:1, preferably 0.1:1 to 0.8:1. 11. Method according to any one of claims 1-10, characterized in that the salt has the formula R'4 NY or R'^Y , where each R' is an alkyl group with from 1 to 13 carbon atoms and preferably the same as R- group h, and Y is a chloride, bromide or iodide, preferably iodide. 12. Method according to any one of claims 1-11, characterized in that the suspension of the only organic liquid is molten quaternary ammonium or phos phonium salt. 13. Method according to any one of claims 1-12, characterized in that an organic chloride which is butyl or octyl chloride is introduced into a suspension of solid zinc in a molten salt with the formula R4 'N" <y> or R4 'P~Y, where each R <1> is butyl when butyl chloride is reacted, or octyl when octyl chloride is reacted, and Y is a chloride, bromide or iodide ion, at 130-200°C, to form an organic halide reaction product and zinc, after which solid tin is added to the suspension in an atomic ratio of zinc to tin of 1:1 to 4:1, whereby the mole ratio of salt to tin is 0.3:1 to 1.5:1, followed by heating to 130- 200°C to obtain tetrabutyltin or tetraoctyltin, whereby at least some is present in the liquid phase. 14. Method according to claim 13, characterized in that the molar ratio between organic chloride and salt is within 4:1 to 7:1. 15. Method according to any one of the preceding claims, characterized in that the reaction is carried out in an apparatus capable of condensing gaseous effluent. 16. Method according to any one of the preceding claims, characterized in that at the end of the reaction, an upper layer comprising a tetraorgano compound and a lower layer is formed, and that the upper layer is separated. 17. Method according to any one of claims 1-15, characterized in that an alcohol is added to the reaction suspension at the end of the reaction and that the organotin product is separated by extraction with a hydrocarbon solvent. 18. Tetraorganotin product, characterized in that it is produced by a method according to any one of the preceding claims.