Aluminums redistribution with

In addition to the redistributions discussed above which involve exchanges on aluminum atoms only, there is a great deal of literature available on the exchange reactions of aluminum alkyls with halides, oxides, and alkoxides of other elements which undoubtedly are also equilibrium reactions. These, however, have found great interest as methods for the syntheses of organometallic compounds in general 129, 130). It appears that the equilibria in these systems lie almost completely at the side of the alkyl compound of the other element. 

The other commercially important routes to alkyltin chloride intermediates utilize an indirect method having a tetraalkjitin intermediate. Tetraalkyltins are made by transmetaHation of stannic chloride with a metal alkyl where the metal is typicaHy magnesium or aluminum. Subsequent redistribution reactions with additional stannic chloride yield the desired mixture of monoalkyl tin trichloride and dialkyltin dichloride. Both / -butjitin and / -octjitin intermediates are manufactured by one of these schemes. 

Prepa.ra.tlon, Diorganotin dichlorides are the usual precursors for all other diorganotin compounds three primary methods of manufacture are practiced. Dibutyltin dichloride is manufactured by Kocheshkov redistribution from cmde tetrabutyltin and stannic chloride and usually is cataly2ed with a few tenths of a percent aluminum trichloride ... 

The product undergoes a redistribution to produce R4A1C12 and R2A1C14. The reaction of aluminum with HgR2 results in transfer of alkyl groups,... 

The redistribution and cleavage reaction of mixtures of tetramethylgermane and tetrabutylgermane with excess of aluminum chloride give di- as well as trichlorogermanes having mixed alkyl groups. 

These theoretical results discussed in the preceding paragraph are fully consistent with the experimental XPS and UPS data. Indeed, the new features appearing on the C(ls), S(2p), and Al(2p) XPS spectra constitute dear evidence of the charge transfer from aluminum to carbon and sulphur. Other model configurations, where the aluminum atoms are made to interact either only with the sulphur atoms or only with the 0-carbon atoms, are calculated to be much less stable than the Al—C structure described above, and do not result in any electron density redistribution consistent with the XPS results. The inert character of the 0-carbons, and of the adjacent thiophene units, upon reaction of aluminum with a given thiophene unit also is reflected in the spectra, as the major part of the C(ls) and S(2p) contribution remains unshifted when aluminum is deposited... 

The redistribution reaction in lead compounds is straightforward and there are no appreciable side reactions. It is normally carried out commercially in the liquid phase at substantially room temperature. However, a catalyst is required to effect the reaction with lead compounds. A number of catalysts have been patented, but the exact procedure as practiced commercially has never been revealed. Among the effective catalysts are activated alumina and other activated metal oxides, triethyllead chloride, triethyllead iodide, phosphorus trichloride, arsenic trichloride, bismuth trichloride, iron(III)chloride, zirconium(IV)-chloride, tin(IV)chloride, zinc chloride, zinc fluoride, mercury(II)chloride, boron trifluoride, aluminum chloride, aluminum bromide, dimethyl-aluminum chloride, and platinum(IV)chloride 43,70-72,79,80,97,117, 131,31s) A separate catalyst compound is not required for the exchange between R.jPb and R3PbX compounds however, this type of uncatalyzed exchange is rather slow. Again, the products are practically a random mixture. 

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