Parimal A. Parikh

One-pot synthesis of C8 aldehydes/alcohols from propylene using eco-friendly hydrotalcite supported HRhCO(PPh3)3 catalyst

A multi-functional catalyst [HF/HT] containing a rhodium complex, HRh(CO)(PPh3)3 [HF] and a solid base, hydrotalcite Mg1−xAlx(OH2)x+(CO32−)x/n·mH2O [HT], synthesized by impregnation of [HF] onto the surface of [HT], was investigated for the one-pot synthesis of C8 aldol derivatives (aldehydes or alcohols) from propylene. The catalyst was found to be efficient to carry out hydroformylation, aldol condensation and hydrogenation reactions in one pot. The catalytic activity of [HF/HT(X)] was studied in detail as functions of Mg/Al molar ratio (X) of [HT], amount of [HF] complex and [HT], and reaction temperature. The selectivity for 2-ethylhexanal was observed to increase upon increasing X and amount of [HT]. The highest selectivity for 2-ethylhexanol was observed for [HT] Mg/Al molar ratio of 3.5 at 250 °C. The kinetic profiles of the various products obtained were in agreement with the reaction pathway proposed to understand the role of the [HF/HT] catalyst on the formation of C8 aldol derivatives. Thermal stability of the [HF/HT] catalyst system was also investigated.

Hydroisomerization of Biomass Derived n-Hexadecane Towards Diesel Pool: Effect of Selective Removal External Surface Sites from Pt/ZSM-22

Abstract Influence of dealumination of zeolite ZSM-22 (Si/Al ratio of 45) by treating it with oxalic acid on its catalytic performance in n-hexadecane hydroisomerization reaction was studied. This reaction is an attempt in the direction of green and sustainable source of diesel via improving the cold-flow properties of deoxygenated vegetable oils. Pt (0.5 wt%) on ZSM-22 treated with 1 M oxalic acid afforded highest yields of the mono-branched paraffins. This improved is attributed to selective removal of active sites on external surface of zeolite crystals (responsible for undesired cracking reactions) using the bulkier dealuminating agent, oxalic acid. Thus, pore-mouth key-lock mechanism was brought to play the role to cause high selectivity to mono-branched isomers. Preferential external site deactivation was inferred from mesitylene cracking results. Effects of operating parameters such as temperature, and space velocity on product distribution also were studied. Also, kinetics of the reactions involved too has been in brief reported.

In situ synthesis of nanoclay filled polyethylene using polymer supported metallocene catalyst system

In situ ethylene polymerizations were performed using bis(cyclopentadiene)titanium dichloride supported on polyethersulfone as catalyst. The bis(cyclopentadiene)titanium dichloride supported on polyethersulfone catalyst activity estimated by ethylene polymerization was 360 kgPE/molTi/h. During polymerization the fillers used were montmorillionite nanoclays having surface modifications with 35-45 wt% dimethyl dialkyl(14-18)amine (FA) and 25-30 wt% trimethyl stearyl ammonium (FB). These fillers were pretreated with methylaluminoxine (MAO; cocatalyst) for better dispersion onto the polymer matrix. The formation of polyethylene within the whole matrix was confirmed by FTIR studies. It was found that the nature of nanofiller did not have any remarkable effect on the melting characteristics of the polymer. TGA study indicates that nanoclay FB filled polyethylene has higher thermal stability than nanoclay FA filled polyethylene. The melting temperature of the obtained polyethylenes was 142 oC, which corresponds to that synthesized by the polyether sulfone supported catalyst.

Bioethanol selective oxidation to acetaldehyde over Ag-CeO2: role of metal-support interactions

Bioethanol oxidation was investigated over a Ag/CeO2 catalyst prepared via a wet impregnation method. The prepared catalyst was fully characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The characterization results indicated that a part of silver was inserted into the lattice of CeO2 and it expanded the support lattice. The Ag/CeO2 catalyst was found to outperform the previously reported catalyst systems (acetaldehyde selectivity of 90% and life >36 h) from 200 °C to 350 °C, 5 atm, and gas hourly space velocity of 18u2006000 mL gcat−1 h−1. This study provides a path for the selective oxidation of other biomass-derived compounds.

Microwave Irradiated Acetylation of p-Anisidine: A Step towards Green Chemistry

The present study aims at assessing the effect of microwave irradiation against thermal heat on the production of N-acetyl-p-anisidine by acetylation of p-anisidine. The acetylation of p-anisidine under microwave irradiation produces N-acetyl-p-anisidine in shorter reaction times, which offers a benefit to the laboratories as well as industries. It also eliminates the use of excess solvent. Effects of operating parameters such as reaction time, feed composition, and microwave energy and reaction temperature on selectivity to the desired product have been investigated. The results indicate as high as a 98% conversion of N-acetyl-p-anisidine can be achieved within 12-15 minutes using acetic acid. The use of acetic acid as an acetylating agent against conventionally used acetic anhydride eliminates the handling of explosive acetic anhydride and also the energy intensive distillation step for separation of acetic acid. Organic solvent like acetic anhydride are not only hazardous to the environment, they are also expensive and flammable.

Design, synthesis, characterization, and in vitro antimicrobial action of novel trisubstituted s-triazines

In this article, synthesis of a library of trisubstituted s-triazines, which, in addition to 4-amino-benzonitrile, contain 4-hydroxy-N-methylquinolin-2(1H)-one as well as substituted aliphatic amines condensed to C-6 position of s-triazinyl core is discussed. The newly synthesized analogues were then subjected to determine their efficacy against some bacterial and fungal strains as two gram-positive bacteria (Staphylococcus aureus MTCC 96 and Bacillus cereus MTCC 619), six gram-negative bacteria (Escherichia coli MTCC 739, Pseudomonas aeruginosa MTCC 741, Klebsiella pneumoniae MTCC 109, Salmonella typhi MTCC 733, Proteus vulgaris MTCC 1771, and Shigella flexneria MTCC 1457) and two fungal species (Aspergillus niger MTCC 282 and Candida albicans MTCC 183) with an intent to develop novel class of antimicrobial agents. The results of bioassay showed that some of the newly synthesized s-triazine congeners emerged with noteworthy antimicrobial activity. The structure of final scaffolds has been assigned on the basis of IR, 1H NMR, 13C NMR, mass spectroscopy and elemental analysis.Graphical Abstractxa0