Патент USA US3028330код для вставки
United States Patent Free 3,028,320 Patented Apr. 3, 1962 2 1 The electrolyte mixture usually contains from 5-95 per cent of the alkali metal aluminum methyl compound. 3,028,320 MANUFACTURE OF TIN ALKYL COMPOUNDS Best results are obtained using a concentration of the Paul Kohetz and Richard C. Pinkerton, Baton Rouge, La., alkali metal aluminum methyl compound of from 10-75 assignors to Ethyl Corporation, New York, N.Y., a cor- 5 mole percent. A preferred concentration of the alkali poration of Delaware metal aluminum methyl compound in the electrolyte mix No Drawing, Filed Feb. 1, 1960, Ser. No. 5,672 ture is from about 20—-65 mole percent. In general, the 4 Claims. (Cl. 204—59) electrolyte mixture should have a melting point below about 150° C. for manufacture of alkyl tin compounds This invention relates to the manufacture of tin ongano compounds and more particularly to the manufacture of 10 and the most preferred electrolytes have melting points tin tetraorgano compounds and especially tin tetraal-kyl below about 100° C. The pure sodium aluminum tetra methyl, for example, has a melting point in excess of compounds, such as tin tetraethyl. 240° C. but the addition of relatively small quantities of Tin alkyl compounds are highly useful as intermediates the sodium or potassium aluminum tetraethyl, or higher in making stabilizers for polymeric materials, such as vinyl chloride or for stabilising components for liquid 15 organo compounds, sharply reduces the melting point of the mixture. chlorinated hydrocarbon compounds such as are used The above process involves exceptionally simple tech in transformer dielectric liquids or the like. Heretofore, niques and apparatus and provides high yields of the tin the accepted method for making tin alkyl compounds, alkyl compounds, in essence, directly from tin, hydrogen, such as tetrabutyl tin, has been the reaction of stannic chloride by the Grignard process, i.e., reacting the stannic 20 and ole?n. The tin metal is converted at the anode to tin organo compounds and the electrolyte, in the manufacture chloride with butyl magnesium chloride to form tetrabutyl of such products, can be regenerated, either periodically tin according to the following equation: or continuously, by reaction with an ole?n and hydrogen. The process is capable of extremely high production ca Sodium tin alloys have been proposed for manufacture of 25 pacities because it can be operated at high current densi tetraalk-yl tins by reacting with lower alkyl chlorides, but ties, and this is practical because of the very high con this type of process is relatively ine?icient in that a pre ductivity of the complex electrolyte. The process can be ponderant proportion of the tin metal originally fed, as conducted at these high current densities at temperatures alloy, is released as elemental metal and must be recovered well below the thermal decomposition temperature of the and recycled. Accordingly, a signi?cant need has existed 30 tin alkyl products. This good conductivity also materially for an eifective and economical process for the production reduces the problem of heat removal from the cell. A of tin hydrocarbon compounds. particularly surprising feature of this invention is that the tin alkyl products contain only minor proportions of It is accordingly an object of this invention to provide an improved process for the manufacture of tin tetra~ methyl groups when the electrolyte contains R groups in organo compounds and especially tin alkyl compounds, 35 addition to the methyl groups, but instead the methyl such as tin tetraethyl. Another object is to provide an groups are recovered as aluminum-containing compounds electrolytic process capable of producing substantial quan tities of tin alkyl compounds in a relatively small elec which can be readily converted to the complex alkali metal aluminum methyl compound and recycled to the trolytic cell. Still another object is a process in which the electrolytic cell. The aluminum-methyl by-prouct (with tin alkyl products can be readily separated from the elec- 40 out alkali metal) has a materially lower boiling point than trolyte and by-products by simple and economical tech the tin alkyl compound and thus can be readily separated niques and in which the by-product can be regenerated and from the tin organo product. Essential functions of the returned to the cell. alkali metal aluminum methyl compound, in other words, These and other objects of the invention are obtained are to provide high conductivity to the system and at the if the electrolyte contains an alkali metal aluminum 45 same time form an aluminum-containing by-product which methyl compound and especially an alkali metal alumi- q can be readily separated from the tin organo product. As num tetraalkyl in which at least one of the alkyl ‘groups is will be seen from the following discussion, through regen a methyl group. An especially desirable electrolyte for eration of the alkali metal aluminum alkyl, the only raw carrying out the process of this invention comprises a - materials necessary for this process are metallic tin, ole?n mixture or complex of an alkali metal aluminum methyl 50 and hydrogen. When using the mixed electrolyte, the compound with an alkali metal aluminum tetraalkyl or aluminum methyl compound is formed in from 5-30 per tetraaryl, the organo groups of the latter compound con cent of the total product and in some cases up to about 50 taining from 2 to about 12 carbon atoms. - percent and can be recovered as a second product or con More speci?cally the process for manufacture of the verted back to the alkali metal-containing compound for tin alkyl compounds in accordance with this invention 55 reuse in the process. comprises passing an electrolyzing current from a tin The reaction of the present process can be illustrated, anode through an electrolyte comprising an alkali metal using the mixed electroltye, as follows: aluminum tetraorgano compound having the formula MAlMei 60 wherein M is an alkali metal, R is selected from the group wherein M, Me, and R are as de?ned above. The alumi num trialkyl can be separated from the tin tetraorgano from 2 to 12 carbon atoms, and x is an integer of from 1 compound by distillation or by chemical means. In addi to 4 inclusive. An especially preferred embodiment of tion, some methyl-containing aluminum compounds are this invention relates to the manufacture of tin alkyl prod- 65 formed which may, under certain conditions, react with ucts using a mixed complex having, in addition to the alkali the AlR3 to form mixed organo compounds. A suitable consisting of alkyl and aryl groups, each group containing metal aluminum methyl compound, another alkali metal chemical method of recovering the tin organo products aluminum compound in which all of the organo groups and regenerating the aluminum compound is to react the contain from 2 to 12 carbon atoms. A11 especially pre aluminum compound with an alkali metal boron com ferred electrolyte contains more than one alkali metal, e.g. 70 pound in accordance with the following equation: both sodium and potassium or sodium and lithium or all three metals. A1R3 + BRa 3,028,320 4 3 sodium boron tetraethyl at a temperature of 100° C. to 01' produce the corresponding sodium aluminum alkyls and the corresponding alkyl boron compounds. The latter The complex can then be regenerated by the following are gases at reaction temperature and can be readily sep arated from the mixture. The sodium aluminum tetra equations: alkyl complex is readily separated from the tin alkyl products by ?ltration and can thereafter be recycled to As discussed above, it is convenient to carry out the electrolysis of this invention using an electrolyte con taining both an alkali metal aluminum tetramethyl and an alkali metal aluminum tetraalkyl in which the alkyl contains at least 2 carbon atoms. It is to be recognized the electrolytic cell. The tin hydrocarbon product liquid from the fore going example consistcd of predominant quantities of tin tetraethyl, with minor quantities of tin alkyl compounds that the electrolyte can contain two or more methyl-con smaller proportion of tin alkyl compounds of ditin types, taining compounds, such as sodium aluminum methyl tri e.g. hexaethyl ditin. ethyl, sodium aluminum dimethyl diethyl and sodium 15 Example 11 Example I is repeated except that 25 mole percent of potassium metal is added to the electrolyte to displace having appreciable methyl radicals therein and an even aluminum trimethylethyl, and especially mixed com pounds of two or more alkali metals. The present process can be carried out over an ex the corresponding amount of sodium metal. In this electrolysis the current density in amperes/sq. cm. is The upper temperature at the anode is 20 greater and the anode ef?ciency is of the same order of ceedingly Wide temperature range, generally from 0 to about 200° C. sometimes limited by the decomposition temperature of magnitude. ‘the tin tetraorgano product. Accordingly, with tin tetra ethyl as a predominant product component, it is usually desirable to maintain the temperature below about 100 Example III Example I is repeated except that the electrolyte con 25 sisted of 3 moles of sodium aluminum tetraethyl and 1 to 110° C. mole of sodium aluminum tetrarnethyl. Comparable anode ef?ciency and current density are experienced. Such solvents can be either miscible or non-miscible with Example IV the electrolyte. Typical examples of suitable extractants 30 Example III is repeated except that 10 mole percent are aliphatic and aromatic hydrocarbon liquids. Excel potassium is added to displace a corresponding quantity lent results are obtained with such extractants as kerosene of sodium, providing an electrolyte containing both so and mineral oil used in a concentration of from about 25 In some cases it is desirable to use a solvent for the tin organo compound, directly in the electrolysis cell. to 75 percent of the tin tetraorgano product formed. ium and potassium. In this instance, a higher anode e?iciency is achieved at a comparable current density. Normally, the electrolysis is conducted at or near at The following tabulated examples are carried out in a mospheric pressure. However, a pressure of inert gas 35 similar fashion to Example I. The product in each in stance is a tin alkylproduct liquid, predominating in the tetraalkyl corresponding to the longer alkyl group present in the electrolyte mixture. In addition to the principal fect distillation of the tin organo compound and/or the aluminum compound from the cell during the electrolysis. 4O component of the product, minor components present in clude the dialkyl tin compounds and some small propor The following are typical examples of the process of such as nitrogen can be employed when desired, especial ly to assure an oxygen and moisture-free system. In some cases, it is desirable to employ a reduced pressure to ef this invention, all parts being given in parts by weight. tion of di-tin compounds, illustrated by hexaethyl distan nane. The alkyl groups in the tin organometallic products are predominantly the higher alkyl groups, but a small A closed cell was provided with an annular copper 45 proportion of methyl radicals occur, of from 5 to 25 per cent‘ of the total alkyl rgoups. In Example VIII, how cathode and an axially positioned tin anode. To this cell ever, all the alkyl groups in the product are methyl was added an electrolyte containing equimo-lar propor radicals. tions of sodium aluminum tetramethyl and sodium alumi Example I Solvent or Extractant Example MAlMe; MAlRl N 0. MAlMe4/ MAIR; Proportion- Temper ature, Product~major mole based on tin- ° 0. component ratio KAlM ____ __ KAl(i-pr)t _________ __ Type organo product, percent 8 160 Tin tetraisopropyl. NaAlMe4_ ____ NaAl(OsH5)4___ 0. 1 180 Tin tetraphenyl. LiAlMe; ____ __ 0. 3 40 5 100 The tetramethyl. 2 125 Tin tetraethyl. N aAl(CsH11)4_ _ _ RbA1Me4__-__ NaAl(OH3)4. NaAlMel~ _ ___ CsAlEtl ____ __ Tin tetraoctyl. i-pr=isopropyl. num tetraethyl. CsH5=phenyL The cell was heated to a temperature Example X of approximately 100° C. and a 3.8 volt potential was 65 Example I is repeated except that the electrolyte con ‘applied across the electrodes. The current density in sists of sodium aluminum tetrarnethyl, potassium alumi amperes/sq. cm. Was 0.25. The anode e?iciency was ap num tetraethyl, and lithium aluminum tetraethyl in equi proximately 80 percent. Tin alkyl compounds were pro duced at the anode and formed a separate phase from molecular proportions. In addition, mineral oil (80 Weight percent of the tin alkyl product) is employed in the electrolyte. The product was drained by gravity from 70 the electrolyte as an extractant to aid in the removal of the the cell. Sodium metal was deposited at the cathode dur ing the electrolysis and this was also removed as a liq uid from the cell. The methyl and ethyl aluminum by tin alkyl product. The alkali metal aluminum methyl compounds can be prepared in one of several ways. A convenient process involves the displacement reaction of the elemental alkali products, mixed with the tin alkyl product compounds andminm” quémities of electrolyte, are then reacted with 75 metal with aluminum trimethyl forming the correspond 3,028,320 6 5 ing alkali metal tetramcthyl. These compounds can also be prepared by the addition reaction of aluminum tri methyl and alkali metal alkyl compounds, or contrari wise, aluminum trialkyls with sodium methyl. A par ticularly suitable method for the mixed alkyl compounds 5 is the reaction of an ole?n, e.g. ethylene with an alkali stituted benzene and naphthalene compounds. In some cases the ethers can be used, especially the glycol ethers, such as ethylene glycol dialkyl ethcrs, diethylene glycol dialkyl ethers and triethylene glycol dialkyl ethers, where in the alkyl group contains from 1-6 carbon atoms. We claim: metal aluminum alkyl hydride. Likewise, the complex 1. A process for the manufacture of tetraethyltin which comprises passing an electric current through an anode methyl compound can be made by reaction of an alkyl containing tin and an electrolyte containing equimolar halide with an alkali metal and trimethyl aluminum. The alkali metal aluminum tetraorgano compound '10 proportions of sodium aluminum tetramethyl and sodium aluminum tetraethyl at a temperature of about 100° C. (the organo group containing 2 or more carbon atoms) and a current density of 0.25 amperes per square cen can be made by analogous processes. That is, the alkali timeter. metal can be reacted directly with the aluminum trior 2. A process for the manufacture of tetrahydrocarbon gano compound, e.g. sodium reacts with triethyl a1umi~ num to form sodium aluminum tetraethyl and metallic 15 tin compounds, the hydrocarbon radicals thereof pre dominating in radicals of at least two carbon atoms, aluminum. Likewise, sodium ethyl and other alkali comprising passing an electric current through an electro metal organo compounds will react directly with the alu lyte and a tin containing anode, said electrolyte consisting minum triorgano compound to form the complex as an essentially of alkali metal aluminum tetrahydrocarbon, addition product. The corresponding organo halides will also react with the alkali metal and aluminum triorgano 20 the hydrocarbon radicals in said electrolyte including from 5 to 95 percent methyl groups. compound to form the complex, for example, sodium re 3. A process for the manufacture of tetraalkyl tin acts with ethyl chloride and aluminum triethyl to ‘form comprising forming an electrolyte from an alkali metal sodium aluminum tetraethyl. A particularly desirable aluminum tetramethyl and alkali metal aluminum tetra method of preparing the alkyl complexes is the process discussed above with reference to regeneration of the 25 ethyl, the alkali metal aluminum tetramethyl being in proportions of from about 5 to 95 mole percent, and trialkyl aluminum electrolyte. Trialkyl aluminums, e.g. charging to an electrolytic zone, and electrolyzing by trimethyl aluminum or triethyl aluminum, will react with passing an electric current therethrough and through a tin an alkali metal hydride such as sodium hydride to form the corresponding complex hydride, e.g. sodium alumi anode in contact therewith and'forming thereby tetra num triethyl hydride, which can thereafter be reacted 30 alkyl tin, wherein the alkyl groups thereof predominate in non-metal groups, and removing said tetraalkyl tin with a suitable ole?n, as discussed above, forming sodium from the electrolysis zone. aluminum tetraethyl. All of the above preparation re 4. The process of claim 3 wherein the alkali metals of actions can be carried out at temperatures from about 0° the electrolyte compounds are different. C. to about 150° C. Normally, solvents are not employed in the electrol— 35 ysis system of this invention since they tend to reduce the conductivity of the electrolyte. However, when they are desired for certain purposes, such as to provide a more ?uid medium, it is best to employ hydrocarbons, especially aromatic hydrocarbons which are unreactive 40 References Cited in the ?le of this patent UNITED STATES PATENTS 2,849,349 Ziegler et al. .._.__- _____ __ Aug. 26, 1958 214,834 Australia ____________ __ Apr. 24, 1958 FOREIGN PATENTS with the reactants, products and electrolyte. Particularly suitable solvents are toluene, the xylenes and other sub i. am.