The Research Of Kumada Cross-Coupling Reaction Catalyzed By Ultrafine Amorphous NiB Alloy

Ultrafine NiB amorphous alloy powder is employed as the catalyst for Kumada cross-coupling reactions for the first time, preliminary results are obtained.The ultrafine NiB amorphous alloy is prepared by improved chemical reduction method. The usual steps containing boronic hydride resolving before addition are simplified by a direct addition of boronic hydride powder into the nickel salt solution. The experimental data show such a simplification has no ill influence on the catalytic activity of NiB amorphous particles for Kumada cross-couplings. During the preparing course, different solvents are selected. Thus, P-1 and P-2 NiB amorphous alloys are prepared from deionized water and industrial alcohol respectively and are applied to Kumada cross-coupling reactions with many kinds of substrates. For the cross-coupling reaction between bromobenzene and n-butylmagnesium chloride, bromobenzene converses fast comparatively when P-l NiB is employed, but the conversion become stable at 56% after 5 hours. When P-2 NiB is employed, the conversion reach 93% after 11 hours, and the amount of the by-product biphenyl is less. The cross-coupling reactions are handled in the presence of NiB and with no aid of ligands.The experimental results show allyl chloride can react with various aryl Grignard reagents with full conversion. The yield of cross-coupling product is beyond 95%. Only trace of homo-coupling product is found. Proparagyl chloride converses completely but with emergence of isomers after interaction with aryl Grignard reagents. A full conversion of benzyl chloride or substituted benzyl chloride is almost achieved in reaction with n-butyl magnesium chloride, above 94%, but the cross-coupling product yield is affected severely by the formation of homo-coupling counterpart. The conversions of aryl halides with alkyl Grignard reagents largely depend on the halide type. Aryl iodides react with the most ease. The order is aryl iodide> aryl bromide> aryl chloride> aryl fluoride. Besides, n-butyl and sec-butyl tosylate that are difficult for oxidative addition can react with phenylmagnesium bromide to form corresponding cross-coupling products. Primary alkyl halide which contains β -hydrogen and is relatively hard to undergo the reaction , n-butyl chloride for instance, can react with aryl Grignard reagents in the presence of NiB alloy as well.In brief, the results illustrate that a great number of substrates and Grignard reagents can participate Kumada cross-coupling reactions with the use of NiB amorphous alloy as catalyst.