COMPOSITION OF GRIGNARD COMPOUNDS .5. IN TRIETHYLAMINE SOLUTION

For the first time Grignard compounds have been prepared directly in triethylamine solvent. In some cases side reactions occur during the preparation in triethylamine (quaternary salt formation and dehydrohalogenation); however, the reaction readily produces the desired product in 50-90% yield. The lower solubility of the Grignard compounds in triethylamine (0.1-0.9 m) as compared to diethyl ether (2-4 m) limits somewhat the useful concentration range in which the reagent can be employed. Nevertheless, reaction of the material with a carbonyl compound proceeds smoothly and results in a ratio of addition to reduction product that is significantly lower than that found when the reagent is prepared and reacted in diethyl ether. The composition of Grignard compounds in tertiary amine solvent was shown to be best represented by the equilibrium R2Mg + MgX2 ⇆ 2RMgX. This equilibrium was shown to lie almost completely to the right when X = Cl and Br but not nearly so much to the right when X = I. The redistribution of (CH3)2Mg and (C2H5)2Mg with MgBr2, and MgI2 was shown to take place readily in triethylamine and as the tetramethylethylenediamine complexes in diethyl ether and benzene. © 1968, American Chemical Society. All rights reserved.