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Chelate and trans effect of P,O donor phosphine ligands on rhodium catalyzed carbonylation of methanol
Get PDFFour 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
Get PDFA 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
Get PDFAlpha-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
Studies on the influence of host plants and effect of chemical stimulants on the feeding behavior in the muga silkworm, Antheraea assamensis
Get PDFThe feeding habits of Antheraea assamensis, Helfer (Lepidoptera: Saturniidae) larvae towards the
leaves of its four different host plants, Persea bombycina King ex. Hook (Laurales: Lauraceae),
Litsea polhantha Jussieu, L. salicifolia Roxburgh ex. Nees and L. citrata Blume, and the
chemical basis of feeding preference were investigated. Nutritional superiority of young and
medium leaves with respect to soluble protein, total phenol and phenylalanine ammonia lyase
activity was observed in the leaves of P. bombycina compared to other host plants. Attraction and
feeding tests with detached leaves and artificial diet with different chemical stimulants revealed
that a mixture of the flavonoids, myrcetin, and 7, 2’, 4’ trimethoxy dihydroxy flavone with sterol
compound β-sitosterol elicited the most biting behavior by A. assamensis larvae. While linalyl
acetate alone attracted larvae towards the leaves of the host plants, a mixture of caryophyllene,
decyl aldehyde and dodecyl aldehyde was found to both attract them to the host leaves and cause
biting behavior. Azaindole was found to deter them from the host plants
Green chemistry approaches to the regioselective synthesis of spiro heterobicyclic rings using iodine as a new and efficient catalyst under solvent-free conditions
Get PDFMycotoxin detection on antibody immobilized conducting polymer supported electrochemically polymerized Acacia gum,
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In-vitro antioxident and free radical scavenging activity of Alternanthera sessilis
Get PDFThe present study was aimed to evaluate the antioxidant activity of A.sessilis
plant extracts in different solvents. The antioxidant activity was studied by
phosphomolybdate method and DPPH method. In phosphomolybdate method
the highest activity was shown by methanolic extract (12.044 mM of ascorbic
acid eqvt/gm of sample). The highest radical scavenging activity by DPPH method
was found in methanol extracts (IC 50 587.093µg/ml). Ferrous chelating activity,
superoxide radical scavenging activity, nitric oxide radical scavenging activity was
found high in acetone, acetone and methanol extracts respectively. Total
Flavonoids and crude phenolics were found to be 0.370 mg/gm dry wt. and
1.529 mg/gm dry wt. respectively. The antioxidant activity increases with
increase in the concentration. This study indicates that A.sessilis is a potential
source of natural antioxidant
Rhodium(I) carbonyl complexes of tetradentate chalcogen functionalized phosphines, [P/(X)(CH2CH2P(X)Ph2)3] {X = O, S, Se}: Synthesis, reactivity and catalytic carbonylation reaction
Get PDFThe reaction of [Rh(CO)2Cl] 2 with 0.5 mol equivalent of the ligands [P0(X)(CH 2eCH 2P(X)Ph 2) 3](P0P 3X 4)
{where X
� O(a), S(b) and Se(c)} affords tetranuclear complexes of the type [Rh 4(CO) 8Cl 4(P0P 3X 4)]
(1ae1c). The complexes 1ae1c have been characterized by elemental analyses, mass spectrometry, IR
and multinuclear NMR spectroscopy, and the ligandsb andc are structurally determined bysingle crystal
X-ray diffraction.1ae1c undergo oxidative addition (OA) reactions with CH3I to generate Rh(III) oxidised
products. Kinetic data for the reaction of 1a and 1b with excess CH 3I indicate a pseudo�01rst order
reaction. The catalytic activity of 1ae1c for the carbonylation of methanol to acetic acid and its ester
show a higher Turn Over Frequency (TOF
� 1349e1748 h �021) compared to the well-known species
[Rh(CO)2I2] �02 (TOF
� 1000 h�021) under the similar experimental conditions. However, 1b and 1c exhibit
lower TOF than 1a, which may be due to the desulfurization and deselinization of the ligands in the
respective complexes under the reaction conditions