Using the Colloidal Method to Prepare Au Catalysts for the Alkylation of Aniline by Benzyl Alcohol.

Using the colloidal method, attempts were made to deposit Au NPs on seven different material supports (TiO2, α and γ-Al2O3, HFeO2, CeO2, C, and SiO2). The deposition between 0.8 and 1 wt% of Au NPs can be generally achieved, apart for SiO2 (no deposition) and α-alumina (0.3 wt%). The resultant sizes of the Au NPs were dependent on the nature as well as the surface area of the support. The catalytic activity and selectivity of the supported Au catalysts were then compared in the alkylation of aniline by benzyl alcohol. Correlations were made between the nature of the support, the size of the Au NP, and the H-binding energy. A minimum H-binding energy of 1100 µV K-1 was found to be necessary for high selectivity for the secondary amine. Comparisons of the TEM images of the pre- and post-reaction catalysts also revealed the extent of Au NP agglomeration under the reaction conditions.

Synergistic effect of chloro and sulphonic acid groups on the hydrolysis of microcrystalline cellulose under benign conditions.

The hydrolysis of cellulose catalysed by ionic liquid (IL) immobilized on chloromethyl vinyl benzene (CMVB) with different IL/CMVB ratio was carried out in water as a solvent. The influence of process variables like IL/CMVB ratio in catalyst, temperature and time were investigated in a batch reactor. It was found that 40% IL/CMVB catalyst afforded maximum%TRS and glucose yield 58.5 and 47.9% respectively at 160 °C in 6h reaction time. This can be attributed to the synergistic effect of chloro and sulfonic groups, to dissolve the cellulose by breaking the intra and inter molecular hydrogen bonds and cleave the ß-1, 4 glycosidic bonds respectively. The catalysts synthesized in the laboratory were characterized by FTIR, CHNS and TGA. The catalyst can be recovered three times without any significant loss in activity and characterized by FTIR to show the peaks of chloro and sulfonic groups in the recovered catalyst.

Molecular basis for the affinity and specificity in the binding of five-membered iminocyclitols with glycosidases: an experimental and theoretical synergy.

An unusual substituent dictated complementarity in the inhibition of amino-modified five-membered iminocyclitols toward various glycosidases was reported by us. These intriguing results encouraged us to seek a molecular level explanation for the observation that may facilitate the design of specific iminocyclitol inhibitors against glycosidases of choice. We present here a detailed theoretical account that is substantiated with some new experimental investigations on the molecular origins of the differential affinities of iminocyclitols with various glycosidases. The studies involve docking/scoring, molecular dynamics simulations followed by syntheses of a few novel five-membered iminocyclitols and their in vitro binding assays. Directional hydrogen bonds and snug fit of the ligands are implicated as contributory to the observed selectivities. The observed synergy between the computations and experiment is likely to spur further research in the design of novel iminocyclitols with specific inhibitory activities.

Hydrolysis of microcrystalline cellulose using functionalized Bronsted acidic ionic liquids - A comparative study.

Cellulose conversion to platform chemicals is required to meet the demands of increasing population and modernization of the world. Hydrolysis of microcrystalline cellulose was studied with SO3H, COOH and OH functionalized imidazole based ionic liquid using 1-butyl-3-methylimidazolium chloride [BMIM]Cl as a solvent. The influence of temperature, time, acidity of ionic liquids and catalyst loading was studied on hydrolysis reaction. The maximum %TRS yield 85%, was obtained at 100°C and 90min with 0.2g of SO3H functionalized ionic liquid. UV-vis spectroscopy using 4-nitro aniline as an indicator was performed to find out the Hammett function of ionic liquid and acidity trends are as follows: SO3H>COOH>OH. Density functional theory (DFT) calculations were performed to optimize the ionic liquid and their conjugate bases at B3LYP 6-311G++ (d, p) level using Gaussian 09 program. Theoretical findings are in agreement with the experimental results.