Tributylamine

Abstract: Monodisperse nickel nanoparticles are prepared from the reduction of Ni(acac)2 with borane tributylamine in the presence of oleylamine and oleic acid. Without any special treatment to remove the surfactants, the as-synthesized Ni nanoparticles supported on the Ketjen carbon support exhibit high catalytic activity in hydrogen generation from the hydrolysis of the ammonia−borane (H3NBH3) complex with a total turnover frequency value of 8.8 mol of H2·(mol of Ni)−1·min−1. Such catalysis based on Ni nanoparticles represents a promising step toward the practical development of the H3NBH3 complex as a feasible hydrogen storage medium for fuel cell applications.

Abstract: The development of bimetallic aluminium-salen complexes [{A1-(salen)} 2 O] as catalysts for the synthesis of cyclic carbonates (including the commercially important ethylene and propylene carbonates) from a wide range of terminal epoxides in the presence of tetrabutylammonium bromide as a cocatalyst is reported. The bimetallic structure of one complex was confirmed by X-ray crystallography. The bimetallic complexes displayed exceptionally high catalytic activity and in the presence of tetrabutylammonium bromide could catalyse cyclic carbonate synthesis at atmospheric pressure and room temperature. Catalyst-reuse experiments demonstrated that one bimetallic complex was stable for over 60 reactions, though the tetrabutylammonium bromide decomposed in situ by a retro-Menschutkin reaction to form tributylamine and had to be regularly replaced. The mild reaction conditions allowed a full analysis of the reaction kinetics to be carried out and this showed that the reaction was first order in aluminium complex concentration, first order in epoxide concentration, first order in carbon dioxide concentration (except when used in excess) and unexpectedly second order in tetrabutylammonium bromide concentration. Further kinetic experiments demonstrated that the tributylamine formed in situ was involved in the catalysis and that addition of butyl bromide to reconvert the tributylamine into tetrabutylammonium bromide resulted in inhibition of the reaction. The reaction kinetics also indicated that no kinetic resolution of racemic epoxides was possible with this class of catalysts, even when the catalyst was derived from a chiral salen ligand. However, it was shown that if enantiomerically pure styrene oxide was used as substrate, then enantiomerically pure styrene carbonate was formed. On the basis of the kinetic and other experimental data, a catalytic cycle that explains why the bimetallic complexes display such high catalytic activity has been developed.

Abstract: Diffusion-controlled luminescence quenching of a phosphorescent metal−organic framework built from the Ru(bpy)32+-derived bridging ligand (MOF-1) was studied using a series of amines of different sizes as quenchers. The dynamics of amine diffusion into solvent-filled MOF-1 channels was probed by modeling time-dependent luminescence quenching data, which provide quantitative diffusion coefficients for the amine quenchers. Triethylamine, tripropylamine, and tributylamine were found to follow Fickian diffusion with a diffusivity of (1.1 ± 0.2) × 10−13, (4.8 ± 1.2) × 10−14, and (4.0 ± 0.4) × 10−14 m2/s, respectively. Diisopropylethylamine (DIPEA), on the other hand, was found to be too large to enter the MOF channels. Despite its size, 4-MeOPhNPh2 can enter the MOF channels via a slow, complicated framework/guest intercalation process to result in extensive framework distortion as revealed by powder X-ray diffraction. This work represents the first quantitative study of the dynamics of molecular diffusion int...