- Preparation of organogallium compounds from organolithium reagents and gallium chloride. Infrared, magnetic resonance, and mass spectral studies of alkylgallium compounds
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Conditions for the preparation of a series of base-free trialkylgallium compounds in benzene solvent by the exchange reaction of alkyllithium compounds and gallium chloride are described. Optimum conditions which favor formation of the trialkyl involve mixing a benzene solution of an appropriate alkyllithium compound and a benzene solution of gallium chloride in exactly a 3:1 molar ratio, heating of the reaction mixture for 12 hr at 70°, filtration to remove by-product lithium chloride, removal of solvent under vacuum, and vacuum distillation of the product: 3RLi + GaCl3 = 3LiCl + R3Ga, where R = C2H5, n-C3H7, n-C4H9, i-C4H9, s-C4H9, and t-C4H9. Alkylgallium dichlorides and dialkylgallium chlorides are produced when lithium alkyls and gallium chloride are allowed to react in a 1:1 and 2:1 molar ratio, respectively: nRLi + GaCl3 = nLiCl + RnGaCl3-n, where n = 1 and 2. Reaction of an alkyllithium compound and gallium chloride in a molar ratio in excess of 3:1 results in formation of the corresponding lithium tetraalkylgallate: 4n-C3H7Li + GaCl3 = 3LiCl + LiGa(n-C3H7)4. Trivinylgallium tetrahydrofuranate is produced by the reaction of vinyllithium and gallium chloride in 3:1 molar ratio in tetrahydrofuran solvent. Infrared, proton magnetic resonance, and mass spectra of RnGaCl3-n compounds where R = C2H5 to C4H9 isomers and n = 1-3 are reported and discussed. Proton magnetic resonance spectra reveal that the chemical shifts for protons on α-carbon atoms are sensitive to substitution on the gallium. An explanation for these chemical shift data along with molecular association data for RnGaCl3-n. compounds is given. Mass spectroscopy can be used as a convenient, diagnostic tool for the identification of organogallium compounds of this type. Ion abundance data for all compounds are presented and the fragmentation processes believed to give these ions are discussed.
- Kovar, Roger A.,Derr, Henry,Brandau, Duane,Callaway, John Owen
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p. 2809 - 2814
(2007/10/06)
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