Multi-site Phase Transfer Catalyst Research Articles

Synthesis of 4-(benzyloxy)biphenyl under a multi-site phase-transfer catalyst along with ultrasonication – A kinetic study

In this present study, the synthesis of 4-(benzyloxy)biphenyl has been successfully carried out using 4-phenylphenol and benzyl chloride in the presence of ultrasonic power (40 kHz, 300W) along with synthesized multi - site phase - transfer catalyst viz., N1,N2-dibenzyl-N1,N1,N2,N2-tetramethylethane-1,2-diaminium dibromide (MPTC). The pseudo first-order kinetic equation has been applied to describe the organic reaction. The various kinetic parameters on the preparation of 4-(benzyloxy)biphenyl has been carried out under ultrasonic frequency condition and synthesized multi - site phase transfer catalyst. Sonication has resulted in better selectivity, high yield, avoids the use of the high temperature, side products and reduces the time consumption. The activation energy (Ea) has been calculated from the experimental results.

Kinetic study of synergistic effect of multi-site phase transfer catalysis and ultrasound irradiation for the synthesis of 1, 3-bis (4-nitrophenoxy) benzene

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 1-chloro-4-nitrobenzene (CNB) under heterogeneous solid-liquid condition using sodium hydroxide as a base at 750C 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.

Synthesis of 1-butoxy-4-tert-butylbenzene under The Effect of Multi-site Phase Transfer Catalysis System – A Kinetic Study

Phase transfer catalysis technique proved to be a useful method for synthesizing various organic compounds under heterogeneous reactions and recognized as a viable environmentally friendly. The influence of a new multi site phase transfer catalyst (MPTC) is the synthesis of 1-butoxy-4-tertbutylbenzene from 4-tert-butylphenol with 1-bromobutane (BB) under heterogeneous solid-liquid condition using potassium hydroxide as a base at 60 °C. The higher conversion of 1-bromobutane was achieved by using the synergistic condition of multi-site phase transfer catalyst in better efficacy. The reaction rate enhanced by decreases 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, such as: MPTC, temperature, potassium hydroxide, and stirring speed. The activation energy (Ea) was also calculated through the Arrhenius plot. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Enhanced catalytic activity of new di-site onium salt in the kinetics of α-Tolunitrile monoalkylation

In this study, we investigate in detail the catalytic efficiency of 1,4-bis-(ethylmethyleneammounium chloride)-2,5- dimethoxy benzene, BEMACDB (multi-site phase transfer catalyst) by observing the pseudo-first order kinetics of mono-alkylation of α-Tolunitrile (ATN). The formation of product was monitored by GC. The comparative study of catalytic efficiency of the new catalysts with single-site salts reveals higher catalytic activity for new catalysts under varying experimental conditions ([BEMACDB], [Base], [ATN], Stirring Speed and Temperature). By understanding the kinetics of mono-alkyaltion, we further establish the experimental parameters that influence reaction conditions. With the support of kinetic data we establish the suitable mechanism for monoalklation of ATN. The catalyst shows consistent catalytic activity in the C-alkylation of ATN in different experimental conditions.

A Kinetic Study on the Synthesis of N-arylation of Indole Under Synergetic Effect of Multi-Site Phase Transfer Catalysis System

Background:Phase transfer catalysis technique is recognized as an attractive method for synthesizing several organic compounds under heterogeneous reaction.Methods:In this study, the effect of Multi-site Phase-Transfer Catalyst (MPTC) was tested during the synthesis of 1-(4-nitrophenyl)-1-indole from 1-chloro-4-nitrobenzene (CNB) and indole in a heterogeneous solid-liquid condition using sodium hydroxide at 50°C.Results:In a synergetic condition, in the presence of MPTC the conversion of 1-chloro-4- nitrobenzeneyield was increased, which is proved the efficacy of this catalyst. In addition, the rate of this reaction was also enhanced by the change in volume of water.Conclusion:The apparent reaction rate was found to be of pseudo-first-order kinetics. MPTC is a promising tool for many organic reactions. Therefore, increase the rate constant can be achieved by various parameters, such as temperature, MPTC, sodium hydroxide, and stirring speed.

Influence of ultrasound on multi-site phase transfer catalyzed polymerization of N-vinyl carbazole in two phase system

Carbazole—containing motifs are of most desired materials because of its wide range of applications due to π- extended systems, molecular and optical properties was easily tunable via diverse structural modifications. Herein, we reported an efficient and facile polymerization of N-vinyl carbazole (NVK) using multi-site phase transfer catalyst with and without ultrasound condition. The rate of polymerization (Rp) was effectively improved with ultrasound in short time on compare with silent condition. Role of different parameters such as variation of frequency, monomer, initiator, catalyst and temperature, solvents, aqueous and pH on the rate of polymerization of NVK was explored under silent and ultrasound condition (45 kHz/550 W). Activation energy of polymerization was supported for an enhancement of rate under ultrasound condition. From the experimental results, an appropriate kinetic model and role of various parameters in polymerization reaction was discussed. The obtained poly (N-vinyl carbazole) was confirmed and characterized by FT-IR, 1H NMR, TGA and XRD techniques.

Synergetic effect of multi-site phase transfer catalysis system mediated free radical polymerization of acrylonitrile – a kinetic study

In this work, the kinetics and mechanism of free radical polymerization of acrylonitrile (AN) using potassium peroxydisulphate (PDS-K2S2O8) as a water soluble initiator in the presence of synthesized 4,4'-dihexadecyl-1,1'-bipyridine diiumdichloride (DHBPDDC) as multi-site phase-transfer catalyst (MPTC) has been investigated. The polymerization reaction were carried out under nitrogen atmosphere and unstirred condition at constant temperature 60+1°C in ethyl acetate/water biphasic medium. The effects of variation of monomer(AN), initiator(PDS) and catalyst(MPTC) solvent polarity and temperature on the rate of polymerisation (Rp) were ascertained. The order with respect to monomer(acrylonitrile) was found to be unity. The order with respect to initiator and catalyst was found to be 0.51, 0.48 respectively. However, an increase in the polarity of the solvent has slightly increased the rate of polymerization value (Rp). Based on the results obtained, a suitable kinetic mechanism scheme has been proposed to account for the experimental observations and its significance was discussed. The other thermodynamic parameters such as entropy of activation ((∆S#), enthalpy of activation (∆H#) and free energy of activation (∆G#) have been calculated.

Comparative investigation on radical polymerization of methyl and ethyl methacrylate under multi-site phase-transfer catalytic conditions

Methyl and ethyl methacrylate was polymerized in heterogeneous system with the help of newly synthesized multi-site phase-transfer catalyst and using water-soluble initiator at 60 ± 1 °C under unstirred inert atmospheric condition. Polymer yield was increased with increasing molar concentrations of monomer, initiator, catalyst and temperature. Polymerization follows first-order kinetics with respect to monomer and half-order with respect to catalyst and initiator, respectively. PTC has myriads of applications in the synthesis of various organic and polymeric materials because of its fast reaction and high yield in short period of time. Without addition of PTC, polymerization did not occur; this indicates that catalyst plays the pivotal role on initiation of polymerization. It extracts the reactive radical anion from aqueous phase and transfers to the organic phase where acrylates were polymerized. Polymerization reactivity of methyl and ethyl methacrylate under PTC conditions was studied by various parameters. The activation energy (Ea) and other thermodynamic parameters were calculated. The Ea value supports the reactivity of acrylates. The results obtained from this investigation were used for inferring the radical mechanism of phase-transfer-catalyzed polymerization. The obtained polymers were analyzed by spectral and thermal analyses.

Multi-site phase transfer catalyzed radical polymerization of methyl methacrylate in mixed aqueous\u2013organic medium: a kinetic study

This work establishes the kinetics of radical polymerization of methyl methacrylate in an aqueous–organic two-phase system using 1,4-bis (triethylmethylammonium) benzene dichloride (TEMABDC) as multi-site phase transfer catalyst and potassium peroxydisulphate (K2S2O8) as water-soluble initiator at 60 ± 1 °C under nitrogen atmosphere. The role of concentrations of monomer, initiator, catalyst, acid and ionic strength, temperature and volume fraction of aqueous phase on the rate of polymerization (Rp) was investigated. The rate of polymerization (Rp); Rp α [MMA]0.64, [TEMABDC]1.24 and [K2S2O8]1.50. The rate of polymerization increases with an increase in the concentration of monomer, initiator, catalyst and temperature. A generalized reaction model was developed to explain the phase transfer catalyzed polymerization reaction. Based on the kinetic results, radical mechanism has been derived. The activation energy and other thermodynamic parameters were calculated. The FT-IR spectroscopy validates a band of 1732 cm−1 of ester group of the obtained polymer. The viscosity average molecular weight of the PMMA was found 1.6955 × 104 g/mol.

New quaternary phosphonium salt as multi-site phase-transfer catalyst for various alkylation reactions

The present work describes the C-alkylation reactions of fluorene and curcumin catalyzed by a new phosphonium salt, benzene-1,3,5-triyltris(methylene))tris(triphenylphosphonium)bromide, as a multi-site phase-transfer catalyst (MPTC). The catalytic efficiencies were found to be quite effective for di- and tetra-alkylation reactions with very excellent yields under mild base and low concentrations of the catalyst. The synthesized MPTC 3 have privileged catalytic activity compared to commercially available single-site phase-transfer catalysts.

Kinetic study on the synthesis of 1,4-dithiane under ultrasound and multi-site phase-transfer catalyst in liquid-liquid PTC condition

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-dibromoethane, on the conversion of 1,2-dibromoethane and the apparent rate constant (K app ) were investigated in detail. The suitable mechanism has been proposed for reaction system.

Synthesis and characterization of new multi-site phase transfer catalyst and its catalytic efficiency in dichlorocarbene addition to (R)-Carvone

A new multi-site phase transfer catalyst (MPTC) was synthesized from 1,4-dibromo-2,3,5,6-tetramethylbenzene that contain 12 active sites per molecule. The MPTC was thoroughly characterized by different spectral techniques, viz., FT-IR, NMR, MALDI-TOF Mass spectroscopic techniques and elemental analysis. The catalytic efficiency was demonstrated by dichlorocarbene addition to (R)-carvone. The MPTC's catalytic efficiency was compared with the commercially available, single site, phase transfer catalysts (PTCs) by monitoring the disappearance of (R)-carvone using gas chromatography. Among these PTCs the newly synthesized MPTC shows higher activity than the four-site, six-site, and commercially available single site PTCs. Further, new MPTC catalyst was selected for thorough kinetic study for the dichlorocarbene addition to (R)-carvone. Furthermore, the experimental parameters such as concentrations of substrate, catalyst, NaOH, stirring speed, and temperature has been found to play a significant role in the reaction rate. Based on the obtained results suitable mechanism was proposed.

Dichlorocarbene Addition of N-Vinylimidazole under Ultrasound Assisted a New Multi-Site Phase-Transfer Catalyst - A Kinetic Study

The kinetics for dichlorocyclopropanation of N-vinylimidazole with an excess of chloroform has been studied under multi-site phase-transfer catalyst and ultrasound irradiation conditions using aqueous sodium hydroxide as the base. The reaction was carried out at 40°C and a pseudo-first order rate is used to describe the reaction rate at high alkaline concentration (>30 wt.%). Kinetics of the reaction including the effects of the reaction conditions on the conversion of N-vinylimidazole was investigated. A rational explanation was made for a peculiar phenomenon that the conversion of N-vinylimidazole was increased and then decreased with an increase in the amount of sodium hydroxide and the kapp value increases with increasing other kinetic parameters that is the amount of multi-site phase-transfer catalyst, viz., N,N’-dihexyl-4,4’-bipyridinium dibromide, concentration of substrate, ultrasonication, stirring speed, temperature, etc.

Kinetic Investigation of Nitroarylation of Pyrrole with 1-Chloro-4- Nitrobenzene Using a New Multi-Site Phase-Transfer Catalyst under Ultrasonic Condition

In the present research work, the solid-liquid reaction was successfully carried out in the new synthesized multisite phase-transfer catalyst, namely i.e., 1,3,5-tribenzyl-1,3,5-triethyl-1,3,5-triazinane-1,3,5-triium trichloride(MPTC), and sonication (40 kHz, 300 W) to produce the desired product namely 1-(4-nitropheny) pyrrole from pyrrole and 4-nitrochlorobenzene. The selectivity of N-arylation product was obtained under sonication and MPTC. The combination of ultrasound and MPTC resulted in better efficacy as compared to the individual operations. The apparent reaction rate is greatly enhanced and observed to obey the pseudo-first order kinetics. The kapp value increases with increasing kinetic parameters that is the amount of [MPTC], [substrate], ultrasonication, stirring speed, temperature, etc.

Sonication effect on the reaction of 4-bromo-1-methylbenzene with sodium sulfide in liquid–liquid multi-site phase-transfer catalysis condition – Kinetic study

The synthesis of di-p-tolylsulfane from the reaction of 4-bromo-1-methylbenzene (BMB) with sodium sulfide was carried out using a multi-site phase-transfer catalyst (MPTC) viz., 1,4-dihexyl-1,4-diazoniabicyclo[2.2.2]octanium dibromide and ultrasonic irradiation in a liquid–liquid reaction condition. The overall reaction rate is greatly enhanced when catalyzed by multi-site phase-transfer catalyst (MPTC) combined with sonication (40kHz, 300W) in a batch reactor than catalyzed by MPTC without sonication. Effects on the reaction due to various operating conditions, such as agitation speed, different ultrasound frequencies, different phase-transfer catalysts, different organic solvents, the amount of MPTC, temperature, amount of sodium sulfide, effect of sodium hydroxide, volume of n-hexane and the concentration of 4-bromo-1-methylbenzene. The reaction obeys a pseudo first-order rate law and a suitable mechanism was proposed based on the experimental observation.

Highly Enantioselective Asymmetric Michael Addition Reactions with New Chiral Multisite Phase-Transfer Catalysts

Highly enantioselective Michael addition reactions of diethyl malonate to various chalcones have been achieved under mild chiral multisite phase-transfer reaction conditions by the successful utilization of 2,4,6-(triscinchoniummethyl)phenyl-1,3,5-triazines as new chiral quaternary ammonium catalysts. This simple asymmetric Michael addition process was found to be quite effective and to obtain Michael adducts with very good yields and enantiomeric excesses.

Synthesis of new polymer-supported multi-site phase transfer catalysts and their catalysis for the C-alkylation of 1-indanone in association with ultrasound: A kinetic study

Three different types of polymer supported multi-site phase transfer catalysts having two, four and six active sites are synthesized by simple routes. The available number of active sites in each catalyst was established based on the results derived from various microscopic and spectroscopic techniques. Similarly, the catalytic ability of each catalyst was studied by determining their pseudo-first order rate constants for C-alkylation of 1-indanone. The comparative catalytic study reveals that the kobs determined under the influence of combination of ultrasound and mechanical stirring showed five and three fold increase in the activity compared to the individual effect. Similarly, the catalytic efficiency was found to be in the order: six-site > four-site > two-site > single-site irrespective of individual effect of ultrasound/mechanical stirring or both, thus confirming the availability of active sites in each catalyst. Furthermore, the detailed kinetics of C-alkylation of 1-indanone was conducted using the superior six-site PSBTTMACEMPE catalyst by varying stirring speed, [substrate], [catalyst], [NaOH], and temperature. Based on the observed kinetic results and activation energy, a suitable mechanism was proposed.

Effect of ultrasound in the free radical polymerization of acrylonitrile under a new multi-site phase-transfer catalyst – A kinetic study

The kinetics of polymerization of acrylonitrile (AN) was carried out under heterogeneous condition using a new multi-site phase-transfer catalyst (MPTC), viz., N,N′-dihexyl-4,4′-bipyridinium dibromide in the presence of water soluble initiator, potassium peroxydisulphate (PDS) under chlorobenzene/water two phase system assisted by ultrasound irradiation at constant temperature 60+1°C under nitrogen atmosphere. The rate of polymerization increases with an increasing the concentrations of AN, MPTC and PDS. The order with respect to [AN], [MPTC], and [PDS] were found to be 1.01, 1.03 and 0.52, respectively. Based on the observed results a suitable mechanism has been proposed to account for the experimental observations followed by a discussion on its significance.

Ultrasound assisted arylation of benzyl alcohol with 4-nitrochlorobenzene under a new multi-site phase-transfer catalyst in solid–liquid condition

The ultrasound assisted preparation of 1-(benzyloxy)-4-nitrobenzene from the reaction of 4-chloronitrobenzene (CNB) and benzyl alcohol was carried out successfully using potassium hydroxide and catalyzed by a new multi-site phase-transfer catalyst (MPTC) viz., 1,3,5-triethyl-1,3,5-trihexyl-1,3,5-triazinane-1,3,5-triium trichloride in a solid–liquid reaction condition (SL-MPTC). The advantage of using SL-MPTC is to avoid a serious hydration of potassium salt of benzyl alcohol in the reaction between 4-chloronitrobenzene (CNB) and benzyl alcohol. The reaction is greatly enhanced in the solid–liquid system, catalyzed by multi-site quaternary ammonium salt (MPTC) and ultrasound irradiation (40kHz, 300W) in a batch reactor, it shows that the overall reaction greatly enhanced with ultrasound irradiation than without ultrasound. 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 the results, such as the effects of agitation speed, ultrasound, different phase transfer catalysts and the effect of organic solvents, the amount of newly prepared MPTC, the effect of temperature, the amount of water, the concentration of 4-chloronitrobenzene (CNB) and potassium hydroxide concentrations. The apparent rate constant (kapp) were investigated in detail. Rational explanations to account for the phenomena on the results were made.

Ultrasonic assisted dimeric cinchona based chiral phase transfer catalysts for highly enanatioselective synthesis of epoxidation of α,β-unsaturated ketones

New types of bis-quaternary ammonium bromide as chiral multisite phase transfer catalysts derived from cinchona alkaloids have been developed and evaluated for the enantioselective epoxidation of chalcones in the presence of lower concentrations of various oxidants, bases and ultrasonic irradiation conditions.