Reactivity of interstitial [NiCl 4] 2− complex anions in a MgAl hydrotalcite-like clay towards alkyl bromides in the liquid phase

Abstract

The chloride ligands in [NiCl 4] 2− ions in the interlayers of a MgAl hydrotalcite-like clay (NiClHT) are completely exchanged with bromide in alkyl bromide in the liquid phase. The solvent exerts a very strong effect on the reactivity of interlamellar Cl − anions in NiClHT towards butyl bromide. Thus, all the interstitial Cl − anions of the interlayer [NiCl 4] 2− ions appear as butyl chloride after 15 min in DMF, while in decane or toluene only 52 and 41% of interstitial Cl −, respectively, after 15 min, were found in the organic phase. The use of butanol as a reaction solvent results in complete inhibition of the reaction. [NiCl 4] 2− complex anions in NiClHT are isomorphically transformed into tetrahedral [NiBr 4] 2− by halide exchange with butyl bromide in DMF. NiClHT can be used as a heterogeneous catalyst in the halide exchange between benzyl chloride and butyl bromide in DMF or in toluene.