Venugopal Rajendran - Academia.edu (original) (raw)

Papers by Venugopal Rajendran

Indian journal of applied research, 2017

In the present work, kinetics of synthesis of allyl phenyl ether was successfully carried out by ... more In the present work, kinetics of synthesis of allyl phenyl ether was successfully carried out by O-allylation of phenol with allyl bromide using aqueous KOH and catalyzed by a new multi - site phase - transfer catalyst viz., 1,3,5,7-tetrabenzylhexamethylenetetraminium tetrachloride, MPTC under ultrasonic ( 40KH Z , 300W) assisted organic solvent condition. O-allylation of allyl bromide has been achieved by controlling the reaction condition and has been followed using gas chromatogram. The effects of various parameters such as [stirring speed], [catalyst], [KOH], [allyl bromide], volume of water ultrasonic frequency and temperature were studied systematically to understand their influence on the rate of the reaction. The experimental observations are consistent with an interfacial-type process. Further the kinetic results demonstrate clearly, that ultrasonic assisted phase- transfer catalysis significantly increased the reaction rate when compared to conventional method.

In this research work, the convenient synthesis of 1-butoxynaphthalene from cheaply available sta... more In this research work, the convenient synthesis of 1-butoxynaphthalene from cheaply available starting materials under multi-site phase-transfer catalyst viz., 1,4-dibenzyl-1,4-diazoniabicyclo[2.2.2]octane dichloride and assisted by sonication (40 kHz, 300 W) using solution of sodium hydroxide in liquid–liquid biphasic (LL-PTC) system was reported. The reaction is greatly enhanced in the liquid–liquid system, catalyzed by multi-site quaternary ammonium salt (MPTC) and ultrasound irradiation in a batch reactor. The reaction is carried out under pseudo first-order condition and which is sufficient to describe all the results, such as the effects of agitation speed, different ultrasonic frequency, different phase transfer catalysts and the effect of organic solvents, the amount of MPTC, effect of various temperature, concentration of butyl bromide, sodium hydroxide concentrations, on the conversion of butyl bromide and the apparent rate constant (Kapp) were investigated in detail.

Allyl bromides afford the corresponding sulfide derivatives upon treatment with aqueous sodium su... more Allyl bromides afford the corresponding sulfide derivatives upon treatment with aqueous sodium sulfide under multi-site phase-transfer catalysts (MPTC) and ultrasound irradiation conditions. The use of phase-transfer catalysis and sonochemistry has been compared and demonstrated in these nucleophilic substitution reactions. The kinetics of reaction depends on the effect of amount of catalyst, agitation speed, quaternary ammonium salts, amount of sodium sulfide, amount of sodium hydroxide, organic solvents, temperature and frequency of the ultrasound waves on the conversion of allyl bromide was investigated in detail. A kinetic model was built from which a pseudo-first order rate law is sufficient to describe the behavior of the reaction. The observed peculiar phenomena were also explained satisfactorily.

Indian Journal of Chemical Technology

Phase transfer catalysis along with ultrasound technique proved to be useful in various organic h... more Phase transfer catalysis along with ultrasound technique proved to be useful in various organic heterogeneous reactions and recognized as a viable environmentally friendly. The influence of ultrasonic irradiation associated with a new multi site phase transfer catalyst (MPTC) on the synthesis of 1,3-bis(4-nitro phenoxy)benzene from 1,3-dihydroxy benzene with 1chloro-4-nitrobenzene (CNB) under heterogeneous solid-liquid condition using sodium hydroxide as a base at 75 0 C has been studied. The higher conversion of 1-chloro-4-nitrobenzene has been achieved by using the synergistic condition of ultrasonic irradiation (40 kHz, 300W) and multi-site phase transfer catalyst in better efficacy. The reaction rate enhance by decrease the volume of water. The apparent the reaction rate was found to be pseudo-first order kinetics. The apparent rate constant was increased linearly with the increase in the concentration of various parameters multi-site phase transfer catalyst, sodium hydroxide ultrasonic effect, stirring speed and temperature from Arrhenius plot the apparent activation energy (Ea) was also calculated.

Abstract: The ultrasound assisted preparation of 1,4-bis(benzyloxy)benzene from the reaction of b... more Abstract: The ultrasound assisted preparation of 1,4-bis(benzyloxy)benzene from the reaction of benzyl chloride (BC) and hydroquinone was carried out successfully using sodium hydroxide and catalyzed by a multi-site phase-transfer catalyst (MPTC) viz., 1,4-dibenzyl-1,4-diazoniabicyclo[2.2.2] octane dichloride in a solid–liquid reaction condition (SL-PTC). Water is only introduced in a trace quantity to the reaction system to avoid a serious hydration of sodium salt of hydroquinone in the reaction. The reaction is greatly enhanced in the solid–liquid system, catalyzed by multi-site quaternary ammonium salt (MPTC) and ultrasound irradiation (40 kHz, 300 W) in a batch reactor. The reaction mechanism is proposed and verified by examining the experimental evidence. A kinetic model is proposed in which a pseudo first-order rate law is sufficient to describe all the results.

Ultrasonics Sonochemistry, 2007

Journal of Molecular Catalysis A: Chemical, 2008

The kinetics of dichlorocarbene addition to allyl phenyl ether have been studied under phase-tran... more The kinetics of dichlorocarbene addition to allyl phenyl ether have been studied under phase-transfer catalytic conditions using aqueous sodium hydroxide as the base and benzyltriethylammonium bromide as a phase-transfer catalyst. The reaction was carried out at 35 • C under pseudo-first-order conditions by keeping aqueous sodium hydroxide and chloroform in excess and was monitored by GC. The effect of various experimental parameters on the rate of the reaction has been studied and based on the results obtained, a suitable mechanism is proposed.

Journal of Molecular Catalysis A: Chemical, 2007

The kinetics for dichlorocyclopropanation of 1,7-octadiene with an excess of chloroform has been ... more The kinetics for dichlorocyclopropanation of 1,7-octadiene with an excess of chloroform has been studied under phase-transfer catalysts and ultrasound irradiation conditions using aqueous sodium hydroxide as the base. The reaction was carried out at 30 °C and a pseudo-first order rate ...

Page 1. REVISTA ELECTRÓNICA DE PSICOLOGÍA Vol. 1, No. 1, Julio 1997 ISSN 1137-8492 Se ha señalado... more Page 1. REVISTA ELECTRÓNICA DE PSICOLOGÍA Vol. 1, No. 1, Julio 1997 ISSN 1137-8492 Se ha señalado que la cuestión central de una explicación científica es la propuesta de un mecanismo (Maturana, 1995). Pretender ...

Journal of Chromatography B, 2005

An HPLC method was developed to determine the various carotenoids in human serum. A C-30 column a... more An HPLC method was developed to determine the various carotenoids in human serum. A C-30 column and a mobile phase of 100% methanol (A) and 100% methylene chloride (B) with the following gradient elution were used: 90% A and 10% B in the beginning, maintained for 5 min, decreased to 78% A at 15 min, 62% A at 30 min, 52% A at 40 min, 41% A at 50 min, 38% A at 55 min, maintained for 3 min, and returned to 100% A at 65 min. A total of 21 carotenoids, including all-trans forms of lutein, zeaxanthin, alpha-cryptoxanthin, beta-cryptoxanthin, alpha-carotene, beta-carotene and lycopene, as well as their 14 cis-isomers were resolved within 51 min at a flow rate of 1.0 mL/min and detection at 476 nm. all-trans-beta-Carotene was found to be present in highest amount (256.3-864.2 ng/mL), followed by all-trans-lycopene (64.4-569.2 ng/mL), all-trans-lutein (137.9-450.3 ng/mL), all-trans-alpha-cryptoxanthin (55.7-188.2 ng/mL), all-trans-beta-cryptoxanthin (43.1-134.5 ng/mL), all-trans-alpha-carotene (20.0-122.1 ng/mL) and all-trans-zeaxanthin (9.1-21.3 ng/mL). Similar trend was observed for cis-isomers of carotenoids.

In the present work, the reaction between disodium salt of 1,3-dihydroxybenzene (in situ formatio... more In the present work, the reaction between disodium salt of 1,3-dihydroxybenzene (in situ formation) and propargyl bromide was carried out in a solid-liquid biphasic phase transferring catalytic system at 50 °C. Higher selectivity of the bis-derivative (1,3-bis(prop-2-ynyloxy)benzene) was obtained under solid-liquid PTC condion. The conversion of propargyl bromide to more than 99% was achieved in the presence of tetra-n-butylammonium bromide (TBAB) as PTC catalyst. From the experimental evidence, no mono-derivative was observed. Experiments were conducted to increase the conversion of propargyl bromide such as, stirring speed, various PTCs, temperature, various solvents and amount of TBAB loading. All the experiments were conducted to obey pseudo-first order rate law. Apparent activation energy was also determined from the Arrhenius plot.

The ultrasound assisted preparation of 1,4-bis(benzyloxy)benzene from the reaction of benzyl chlo... more The ultrasound assisted preparation of 1,4-bis(benzyloxy)benzene from the reaction of benzyl chloride (BC) and hydroquinone was carried out successfully using sodium hydroxide and catalyzed by a multi-site phase-transfer catalyst (MPTC) viz., 1,4-dibenzyl-1,4-diazoniabicyclo(2.2.2) octane dichloride in a solid-liquid reaction condition (SL-PTC). Water is only introduced in a trace quantity to the reaction system to avoid a serious hydration of sodium salt of hydroquinone in the reaction. The reaction is greatly enhanced in the solid-liquid system, catalyzed by multi-site quaternary ammonium salt (MPTC) and ultrasound irradiation (40 kHz, 300 W) in a batch reactor. The reaction mechanism is proposed and verified by examining the experimental evidence. A kinetic model is proposed in which a pseudo first-order rate law is sufficient to describe all the results.

This work describes the preparation of a new NP multi-site phasetransfer catalyst was obtained fr... more This work describes the preparation of a new NP multi-site phasetransfer catalyst was obtained from the reaction of triphenylphosphine, 1,4-dibromobutane and tributyla mine. Using this new multi-site phase-transfer catalyst the dic hlorocarbene addition reactions were carried out with different alkenes in an alkaline solution/chloroform two phase medium.

Bulletin of Chemical Reaction Engineering & Catalysis, 2016

In this work, the simple, efficient and convenient method to synthesis of 1,4-dithiane from 1,2-d... more In this work, the simple, efficient and convenient method to synthesis of 1,4-dithiane from 1,2-dibromoethane and sodium sulfide under heterogeneous liquid-liquid phase-transfer catalysis (LL-PTC) condition in the presence of ultrasound irradiation (40 kHz, 300W) and multi-site phase-transfer catalyst was reported. The multi-site phase-transfer catalyst namely 1,4-dibenzyl-1,4-diazoniabicyclo[2.2.2]octanium dibromide (MPTC) was successfully prepared and used as a superior catalyst for this synthesis. The combination of both ultrasound and multi-site phase-transfer catalyst are resulted in enhanced reaction rate and efficiency than the individual operations. The reaction was carried out under pseudo-first order condition. The kinetic aspects such as the effect of agitation speeds, ultrasound frequencies, different phase transfer catalysts, various organic solvent, volume of hexane, the amount of prepared MPTC, various temperature, the amount of water, the concentration of 1,2-dibrom...

A new multi-site phase-transfer catalyst (MPTC), viz., N,N’-dioctyl-4,4’-bipyridium dibromide con... more A new multi-site phase-transfer catalyst (MPTC), viz., N,N’-dioctyl-4,4’-bipyridium dibromide containing bi-site was prepared and was also proved by FT-IR, H NMR, C NMR, mass and elemental analysis. The enhancement of C-N peak intensity at 1179 cm was noticed in FT-IR, and the agreement of m/z values, viz., 542.43 bi-site with their theoretical values and the percentage of C, H, N elements noticed in elemental analysis has strongly supported the presence of tri-site MPTC catalysts. Further, the presence of number of active-sites in the catalyst was again confirmed by determining their pseudo-first order rate constant for dichlorocarbene addition to 1,3bis(allyloxy)-5-methylbenzene in the presence of ultrasonic irradiation/mechanical stirring. The comparative study reveals that the kapp determined by the combination of ultrasound and mechanical stirring has shown more activity than by their individual effect. Further, the detailed kinetic study performed with superior di-site MPTC re...

The preparation of 1-isopropoxy- 4-nitrobenzene from the reaction of 1-chloro-4- nitrobenzene (CN... more The preparation of 1-isopropoxy- 4-nitrobenzene from the reaction of 1-chloro-4- nitrobenzene (CNB) and isopropyl alcohol was carried out successfully using potassium hydroxide and catalyzed by a multi-site phase-transfer catalyst (MPTC) viz.,1 ,4-dibenzyl-1,4- diazoniabicyclo(2.2.2)octanium dichloride in a solid-liquid phase-transfer catalysis condition (SL-PTC) under low frequency ultrasound (40 kHz, 300W). Trace of water was added to the reaction system to enhance the rate of the reaction. The advantage of using SL-PTC is to avoid a serious hydration of potassium salt of isopropyl alcohol and the active intermediate. The reaction is greatly enhanced in the solid-liquid system, catalyzed by dual-site quaternary ammonium salt (MPTC) along with ultrasound irradiation (40 kHz, 300W). A pseudo first- order rate law is sufficient to describe the results, such as the effects of agitation speed, kind of phase transfer catalysts and the amount of MPTC, the effect of temperature, the volum...

Ultrasonics Sonochemistry, 2014

In this work, the nitroarylation of imidazole catalyzed by a new novel dual-site phase-transfer c... more In this work, the nitroarylation of imidazole catalyzed by a new novel dual-site phase-transfer catalyst was carried out in an alkaline solution/imidazole in chlorobenzene two-phase medium with ultrasonic irradiation (40 kHz, 300 W). This new synthesized phase-transfer catalyst, N(1),N(6)-diethyl-N(1),N(1),N(6),N(6)-tetraisopropylhexane-1,6-diaminium dichloride (MPTC), which possesses two-site activity, was obtained from the reaction of 1,6-dichlorohexane and N-ethyl-N-isopropylpropane-2-amine. The reaction of imidazole and alkali was carried out at the interface to generate sodium imidazole anion which can further react with MPTC form quaternary ammonium imidazole anion along with ultrasonic irradiation (40 kHz, 300 W). This ion-pair further react with 1-chloro-4-nitrobenzene which is present in the organic phase to produce 1-(4-nitropheny) imidazole. The reaction follows a pseudo first-order rate law. Kinetics of the reactions such as effect of the catalysts, ultrasonic effect, agitation speed, temperature, alkaline concentration, amount of 4-nitrochlorobenzene and the solvent effect on the reaction rate were investigated in detail. Peculiar phenomenon for the dependence of the reaction rate on the amount of MPTC and ultrasonication are explained satisfactorily.

In this paper, we report the reaction of isoamyl alcohol and 1-chloro-4-nitrobenzene was carried ... more In this paper, we report the reaction of isoamyl alcohol and 1-chloro-4-nitrobenzene was carried out in a batch reactor under aqueous-organic biphasic conditions using the techniques like phase transfer catalysis and ultrasound irradiation. Tetrabutylammonium bromide (TBAB) was employed as the phase transfer catalyst. The reaction is greatly enhanced by adding a small quantity of phase-transfer catalyst under ultrasound (28 kHz, 300W). Detailed kinetics of the etherification was investigated. The rate constants were determined by varying the concentration of the catalyst, stirring speed, the concentration of alcohols, temperature, different solvents, concentration of sodium hydroxide, different inorganic salts and different phase transfer catalysts. From the detailed kinetic study, the optimum reaction conditions to produce higher yield of 1-(isopentyloxy)-4-nitrobenzene was obtained. The experimental data were well described by the pseudo-first-order equation. The individual experi...

Manickam Sathiyaraj, Perumal Venkatesh*, Venugopal Rajendran, Mohammadbilal Mohammadiliyas, & Var... more Manickam Sathiyaraj, Perumal Venkatesh*, Venugopal Rajendran, Mohammadbilal Mohammadiliyas, & Varathan Selvaraj aPG & Research, Department of Chemistry, Pachaiyappa’s College, Chennai, Tamil Nadu 600 030, India bPG Department of Chemistry, Pachaiyappa’s College for Men, Kanchipuram, Tamil Nadu 631 501, India cPG Department of Chemistry, Sri Akilandeswari Women’s College,Wandiwash, Tamil Nadu 604 408, India