Chelate and trans effect of P,O donor phosphine ligands on rhodium catalyzed carbonylation of methanol

Four complexes of the type [Rh(CO)Cl(�2-P,O-L)](1a,1b) and [Rh(CO)Cl(�1-P-L)2](2a,2b), where L = Ph2PC6H4-2-OCH3(a) and Ph2PC6H4-2-CH2OCH3(b), have been synthesized by the reaction of [Rh(CO)2Cl]2 with appropriate mol equivalents of the ligands in CH2Cl2. The complexes show single intense �(CO) bands in the range 1965–1989 cm−1 indicating the presence of terminal carbonyl groups. All the complexes have been characterized by elemental analyses, mass spectrometry, IR and multinuclear NMR (1H, 31P and 13C) spectroscopy, and the molecular structure of the ligand b is determined by single crystal X-ray diffraction. The complexes undergo oxidative addition (OA) with excess CH3I to afford Rh(III)-acyl complexes of the type [RhCl(COCH3)I(L)](3a,3b) and [RhCl(COCH3)I(L)2](4a,4b). The kinetic data for the OA reactions with CH3I indicate a first order reaction and also exhibit that the rate of OA for the chelate complexes (1a and 1b) is higher than those of trans-complexes (2a and 2b). The catalytic efficiencies of 1a, 1b, 2a and 2b in carbonylation of methanol exhibit higher Turn Over Frequency (TOF) 689–1808 h−1 than the well-known Monsanto’s species [Rh(CO)2I2]− (TOF = 464–1000 h−1) under similar experimental conditions. The catalytic activities vary in the order as 1a > 1b > 2a > 2

Efficient clay supported Ni0 nanoparticles as heterogeneous catalyst for solvent-free synthesis of Hantzsch polyhydroquinoline

A green and efficient multicomponent one-pot synthesis of Hantzsch polyhydroquinoline was achieved by the condensation of aldehydes, dimedone, ethylacetoacetate and ammonium acetate at room temperature using environmentally benign modified Montmorillonite supported Ni0-nanoparticles as catalyst. The well dispersed Ni0-nanoparticles having a high surface to volume ratio have promising features for the reaction such as easy removal of the catalyst, solvent-free, shorter reaction time, high product yields (about 95%) and easy work up procedure. There is no significant effect of electron withdrawing or donating nature of substituent on aldehydes in the formation of polyhydroquinoline derivatives

Alpha 1 antitrypsin gene: A case-control study in chronic obstructive pulmonary disease

Alpha-1 antitrypsin (AAT) deficiency is an inherited disorder that causes low levels of, or no AAT in the blood. The most common illness in adults with AAT deficiency is lung disease during the third and fourth decades of life. Most commonly, it is associated with chronic obstructive pulmonary disease (COPD). Mutations in the protease inhibitor (PI) gene, located on chromosome 14, are associated with this genetic disorder. The Z protein is due to a single amino acid substitution of 342 glutamine lysine. Although cigarette smoking is the main environmental risk factor, only about 15% of smokers develop clinically significant disease suggesting other influences on disease expression. The study included hospital based age and sex matched 100 cases of COPD and 100 controls without COPD recruited from Christian Medical Centre, Jorhat, Assam. These cases were recruited from February 2009 to December 2009. Subjects were included in the COPD group on the basis of lung function test. DNA extraction was done by DNA extraction kit and amplification for AAT gene was done by site directed mutagenesis polymerase chain reaction (PCR) method as described by Tazellar et al. (1992). We found that smoking was the prior cause of COPD. A1AT deficiency is not prevalent in our population subset but certain other genes could be the attributable factor for COPD

Nanomolar Detection of Glutamate at a Biosensor Based on Screen-Printed Electrodes Modified with Carbon Nanotubes

The flow injection analysis (FIA) of monosodiuml-glutamate (MSG) was performed electrochemically using a biosensor based on screen-printed electrodes containing carbon nanotubes (CNT). The sensor was fabricated by simply adsorbing glutamate oxidase (GlutOx) on the electrode surface. The resulting device displayed excellent electroanalytical properties toward the determination ofl-glutamate in a wide linear range (0.01–10mM) with low detection limit (10 nM, S/N !3), fast response time ( 5 s), and good operational and long-term stability. The CNT-modified screen-printed electrodes have a potential to be of general interest for easy preparation of electrochemical sensors and biosensors relevant for biomedical applications