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Transesterification of 2-o- benzylglycerol with vinyl acetate by immobilized lipase : study of reaction and deactivation kinetics
Get PDFThe
transesterification
of
2o
-benzylglycerol
with
vinyl
acetate
has
been
studied
in
dichloromethane
using
free
and
immobilized
lipase
from
Pseudomonas
cepacia
with
particular
emphasis
on
the
effect
of
the
pertinent
variables
and
kinetic
aspects
of
the
reaction.
The
activity
of
the
immobilized
lipase
was
found
to
be
maximum
in
the
temperature
range
of
3050
°
C,
and
it
retained
about
one-third
of
the
initial
activity
up
to
the
third
cycle
after
repeated
use.
The
kinetics
of
the
reaction
was
analysed
by
the
so-called
Ping
Pong
Bi
Bi
mechanism,
and
the
model
parameters
were
estimated
by
nonlinear
regression
analysis
using
Marquard’s
technique.
The
immobilized
lipase,
which
had
the
activity
in
general,
3
times
greater
than
that
of
the
free
lipase
was
deactivated
by
both
temperature
and
vinyl
acetate.
The
deactivation
was
found
to
be
insignificant
up
to
a
certain
level
of
vinyl
acetate
concentration
above
which,
however
the
lipase
activity
fell
rapidly.
The
deactivation
kinetics
was
analysed
by
using
a
mathematical
model
which
accounts
for
a
series
type
of
reaction
mechanism
A comparative study of thermal decomposition behaviour of Zn-Cr, Zn-Cr-Al and Zn-Al type layered double hydroxides
Get PDFHydrolysis of ZnO in acidic pH provides a facile route for synthesis of layered double hydroxides
(LDH)bearingZn2+withCr3+andAl3+withouthavingcarbonateionintheinter-layer position.The
thermal decomposition of the prepared LDH show that with the increase of Cr3+ content in the
systemthereisanincreaseinthethermalstability ofthecompounds.IncaseofZn–CrLDHthereis
a non-mass loss transition around 420°C. Segregation of parent LDH structure to a bivalent oxide
and a spineltakesplacein both Zn–Cr and Zn–Al LDH only at temperatures above 550°
Oxidative addition reaction of rhodium(I) carbonyl complexes of the pyridine-aldehyde ligands and their catalytic activity in carbonylation reaction
Get PDFRhodium(I) carbonyl complexes [Rh(CO)2ClL] (1) where L = Py-2-CHO (a), Py-3-CHO (b) and Py-4-CHO (c) have been synthesized
and characterized by elemental analyses, IR, 1H and 13C NMR spectroscopy. The complexes 1 undergo oxidative addition reactions with
different types of electrophiles such as CH3I, C2H5I, C6H5CH2Cl and I2 to yield [Rh(CO)(COCH3)ClIL] (2), [Rh(CO)(COC2H5)ClIL] (3),
[Rh(CO)(COCH2C6H5)Cl2L] (4) and [Rh(CO)ClI2L] (5) complexes, respectively. The kinetic study of the complexes1 with CH3I reveals a
two-stage kinetics and the second-stage reactions are faster than that of the first stage by about 80–100 times. The rate of reaction of 1a is
higherthanthatof1band1c.Thecatalyticactivityofcomplexes1incarbonylationofmethanol,ingeneral,ishigher(TON800–1250)than
that of the well-known species [Rh(CO)2I2]− (TON 650)
ZnCl2-Zn2+ - montmorillonite composite : efficient solid acid catalyst for benzylation of benzene
Get PDFIn-situ generation of metal clusters in the interlamellar spacing of montmorillonite clay and their thermal characterization
Get PDFIntercalated Ni–Ni(CH3COO)2–montmorillonite (I), Ni0–montmorillonite (II), Zn–Zn(CH3COO)2–montmorillonite (III)
and Zn0–montmorillonite (IV) composites have been synthesised and their thermal behaviour is studied by TG, DTG and DTA
substantiated by XRD and TEM. The endothermic DTA peaks of the composites I–IV due to dehydration and dehydroxylation,
in general, occur at lower temperature compared to those of untreated Na–montmorillonite. The phase change of the clay matrix
for the composites I and II takes place at slightly higher temperature compared to Na–montmorillonite, while for the composites
III and IV it occurs at lower temperature. XRD data show that the basal spacing (d0 0 1 value 13.7 A ° ) of the intercalated metal
cluster composite II is higher than that of the composite IV (d0 0 1 value 12.8 A ° ) at about 300 8C revealing intercalated metal
cluster of size 4.1 and 3.2 A ° , respectively. TEM study shows that the particle size of the metals for the composite II is in the range
of about 0–80 nm while for the composite IV, the size range is about 0–30 nm. Therefore, bigger sized metal nanoparticles
(>0.41 nm) are not present in the interlamellar spacing of the cla
Pervaporation aided esterification of carboxylic acids with ethanol catalysed by Porcine pancreatic Lipase
Get PDFFluorescent Pseudomonas influence palisade mesophyll development and spatial root development in Phaseolus vulgaris
Get PDFThree strains of plant growth promoting fluorescent Pseudomonads (HPR6, RRLJ008 and RRLJ134) were studied
for their effect on growth and yield of French bean (Phaseolus vulgaris L.) under field conditions. The effect of
these strains on nature of root development and leaf palisade tube length were also examined. The strains induced
positive response on growth and physiological parameters resulting in higher yield in P. vulgaris. Strain HPR6
produced the most promising results in thickening of leaf palisade layer, spreading of lateral roots and production
of root hairs. The increase in specific leaf weight (SLW), net assimilation rate (NAR) and relative growth rate
(RGR) by these strains were 68%, 152% and 167%, respectively. The growth and yield parameters were also
significantly improved compared to the uninoculated control. Antibiotic resistant mutant strains demonstrated that
these bacteria effectively colonized the rhizosphere of French bean. The results suggest that the strains could be
developed for field application on a large scale
Carbonyl complexes of ruthenium(II) with unsymetrical phosphine- phosphinesulfide ligands of type Ph2P (CH2)nP(S)Ph2 n=1-4
Get PDFReaction of [Ru(CO) 2Cl 2] n with ligands Ph 2P(CH 2)nP(S)Ph 2 (n0/1(a), 2(b), 3(c), 4(d)) in 1:1 molar ratio produces complex cis[Ru(CO)
2Cl 2(PS/S)](1a)(PS/S0/h 2-(P, S) coordinated) and cis-[Ru(CO)2Cl2(P/S)](1b/d)(P/S0/h 1-(P) coordinated), while 1:2
molar ratio yields complex of the type cis-[Ru(CO) 2Cl 2(P/S) 2](2a/d). The complex 2a undergoes partial decarbonylation reaction
inCH 2Cl 2/hexanesolutiontogiveanewchelatedcomplex[Ru(CO)Cl(PS/S) 2]Cl(2a?).AbstractionofhalidewithAgClO 4fromthe
non-chelated complexes 1b/d and 2a/d afford corresponding chelated complexes [Ru(CO) 2Cl(PS/S)](ClO 4)(3b/d) and
[Ru(CO) 2(PS/S) 2](ClO 4)2(4a/d). The molecular structure of the complex 2a? has been determined by single crystal X-ray
diffraction. The ruthenium atom is at the centre of slightly distorted octahedral structure having the two phosphorus atoms of the
twochelatedP,Scoordinatedligandsattrans toeachother,oneCOgroupandClatomcompletingthecoordinationsphere.Other
complexes have been characterized by elemental analysis, IR, 1H and 31P {H} NMR spectroscopy
Lipase catalyzed transesterification of 2-obenzylglycercol with vinyl acetate : solvent effect
Get PDFThe Pseudomonas cepacia lipase catalysed synthesis of (S)-2-o-benzylglycerol-1-acetate by transesterification of 2-o-benzylglycerol
with vinyl acetate was studied in 10 different solvents in order to deduce the solvent effect through an attempt to correlate the initial
reaction rate, selectivity for monoester formation and enantiomeric excess (ee) with such solvent properties as hydrophobicity (log P),
water solubility (log Sw), electron pair acceptance (EN
T ) and donation abilities (DNN
), polarisability and dielectric constant. The initial rate
was found to exhibit reasonable correlation with log P, log Sw, EN
T
+ DNN
, log P/polarisability and dielectric constant. The correlations for
selectivity and ee were also found to be reasonable excepting deviation of data points of certain solvents. Probable explanation for the
deviation has been put forwarded based on established hypothesis. The study revealed, in general that polar solvents favour the initial
reaction rate, selectivity and enantiomeric excess for transesterification of prochiral diol to chiral monoeste
