Presence Of Phase Transfer Catalyst Research Articles

Efficient graft-from functionalization of ethylene-propylene-diene rubber (EPDM) dissolved in hexane

A facile and commercially applicable method to modify the polarity of ethylene-propylene-diene rubber (EPDM) by reacting with simple metal salts was described. Firstly, a brominated EPDM was produced by reacting EPDM solution in hexane that was sampled directly from commercial plant with N-bromosuccinimide, and then the brominated EPDM was further reacted with sodium acetate or sodium chlorodifluoroacetate in the presence of phase transfer catalyst to yield the functionalized EPDM. The effectiveness of the functionalization method was demonstrated by estimating contact angle, work of adhesion, and lap shear strength after characterizing the polymers by various spectroscopies.

Influence of various additives on base hydrolysis of chlorine-containing organic impurities in naphtha fractions

Degree of dechlorination of chlorine-containing naphtha fractions in the course of their base hydrolysis in the presence of phase-transfer catalyst and other compounds was studied. The optimal type of the phase-transfer catalyst was determined.

Copper-mediated isotopic exchange between [125I]iodide and bis(triethylammonium) undecahydro-12-iodo-closo-dodecaborate in aqueous media

Derivatives of dodecahydro-closo-dodecaborate(2-) anion were proposed as boron-rich compounds for boron-neutron capture therapy (BNCT) of malignant tumours. Labeling of such tumour-targeting compounds with radioisotopes would facilitate the investigation of their pharmacokinetics and help to optimize patient treatment protocols. Earlier, we reported the feasibility of labeling of closo-dodecaborate(2-) by isotopic exchange in molten acetamide. In this study, the feasibility of low-temperature isotopic exchange in the system [125I]iodide - bis(triethylammonium) undecahydro-12-iodo-closo-dodecaborate was investigated. Our attempts to perform the exchange in solvents such as methylene chloride, acetone and acetonitrile in the presence of phase-transfer catalysts were unsuccessful. However, copper mediated exchange in aqueous media was possible. Isotopic exchange of triethylammonium undecahydro-12-iodo-closo-dodecaborate provided a 90-95% labeling yield after heating for three and half hours at 100 °C.

Exhaustive removal of anions from aqueous waste via nucleophilic displacement reactions in the presence of phase transfer catalysts

Nucleophilic anions such as phenoxide and cyanide dissolved in an aqueous phase were effectively reacted with alkyl halides present in an organic phase containing a phase transfer catalyst. Preliminary data show the concentration of these anions in water decreased from 10,000 ppm to less than 1 ppm in 2–3 h at less than 70 °C. This methodology enables treatment of hazardous anions that are difficult to remove when using a conventional approach.

Synthesis of 2-Amino-5(6)-(4-aminophenyl)benzimidazole Derivatives: II. Reaction of 2-Nitro-4-thiocyanatoaniline with 4-Nitrochlorobenzene

The reaction of 2-nitro-4-thiocyanatoaniline with 4-nitrochlorobenzene in aqueous alkaline medium in the presence of phase-transfer catalyst at 95-100°C was studied with a view to obtain 4-amino-3,4'-dinitrodiphenyl sulfide. Optimal conditions for the synthesis and isolation of the product were found.

Labelling with diethyl-[2-14C]-malonate in solvent-free conditions

A rapid and easy to accomplish solvent-free labelling procedure with diethyl-[2-14C]-malonate in the presence of Phase Transfer Catalyst is reported. Radiochemical preparation by this method shows important advantages over routine methods.

Synthesis, characterization, and reactivity ratio studies on new sulfide copolymers containing ethylbenzene units

Soluble new sulfide copolymers were synthesized readily by the polycondensation of ethylene dibromide (EDB) (or methylene dibromide (MDB)) with styrene dibromide (SDB) and sodium sulfide (Na 2S) in the presence of phase transfer catalyst. The copolymers were characterized by using Fourier transform-infrared, 1H NMR, 13C NMR, gel permeation chromatography, and thermogravimetric analysis (TGA) techniques. The copolymer composition obtained from the 1H NMR spectra led to the determination of reactivity ratios. The analysis of reactivity ratios revealed that both EDB and MDB are more reactive than SDB towards Na 2S, and copolymers formed are random in nature. Furthermore, it also gave an insight on the microstructure of the copolymers that both poly (ethylene sulfide-co-styrene sulfide) (p(ES-co-SS)), and poly(methylene sulfide-co-styrene sulfide) (p(MS-co-SS)) copolymers have more of blocky structure with increase in the concentration of ethylene sulfide (ES) or methylene sulfide (MS) units in the respective copolymers. The TGA was used to find out the thermal stability of these polymers. The XRD data indicated an increase in the amorphous content of the copolymers with an increase in the concentration of styrene sulfide (SS) units and thereby resulting in most of these copolymers being soluble in common organic solvents. The solubility and molecular weight of the polymers formed were dependent on the concentration of SDB taken in the feed.

Catalytic Fluorodechlorination of Polychlorofluorobenzenes with Potassium Fluoride.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Preparation of polymeric sheet porphyrin complexes and their environmentally benignly catalytic activity

The polymeric meso-tetra-(1,5-naphthalene bisulfonyloxo)phenylporphyrin and its complexes (PTNBSOPPM, M=Co, Mn, Fe) have been prepared in the presence of phase-transfer catalyst. Catalyzed by polymeric porphyrin complexes (PTNBSOPPM), styrene can be aerobic oxidized. The main products come from cleavage of double bond is in catalytic oxidation of styrene or α-methyl styrene.

Synthesis and chemical characterization of 2-methoxy-N10-substituted acridones needed to reverse vinblastine resistance in multidrug resistant (MDR) cancer cells

In an attempt to find clinically useful modulators of multidrug resistance (MDR), a series of 19 N10-substituted-2-methoxyacridone analogues has been synthesized. 2-Methoxyacridone and its derivatives (1–19) were synthesized. Compound 1 was prepared by the Ullmann condensation of o-chlorobenzoic acid and p-anisidine followed by cyclization using polyphosphoric acid. This compound undergoes N-alkylation in the presence of phase transfer catalyst (PTC). Stirring of 2-methoxy acridone with 1-bromo-3-chloropropane or 1-bromo-4-chlorobutane in a two-phase system consisting of organic phase (tetrahydrofuran) and 6N potassium hydroxide in the presence of tetrabutylammonium bromide leads to the formation of compounds 2 and 11 in good yield. N-(ω-Chloroalkyl) analogues were found to undergo iodide catalyzed nucleophilic substitution reaction with various secondary amines. Products were characterized by UV, IR, 1H and 13C NMR, mass-spectral data and elemental analysis. The lipophilicity expressed in log10 P and pKa of compounds have been determined. All compounds were examined for their ability to increase the uptake of vinblastine (VLB) in MDR KBChR-8-5 cells and the results showed that the compounds 7, 10, 12, and 15–19 at 100 μM caused a 1.05- to 1.7-fold greater accumulation of vinblastine than did a similar concentration of the standard modulator, verapamil (VRP). However, the effects on VLB uptake were specific because these derivatives had little effect in the parental drug sensitive line KB-3-1. Steady state accumulation of VLB, a substrate for P-glycoprotein (P-gp) mediated efflux, was studied in the MDR cell line KBChR-8-5 in the presence and absence of novel MDR modulators. Results of the efflux experiment showed that VRP and each of the modulators (1–19) significantly inhibited the efflux of VLB, suggesting that they may be competitors for P-gp. From among the compounds examined, 14 except 1, 2, 4, 8, and 11, exhibited greater efflux inhibiting activity than VRP. All the 19 compounds effectively compete with [3H] azidopine for binding to P-gp, pointed out this transport membrane protein as their likely site of action. Cytotoxicity has been determined and the IC50 values lie in the range 8.00–18.50 μM for propyl and 4–15 μM for butyl derivatives against KBChR-8-5 cells suggesting that the antiproliferative activity increases as chain length increases from 3 to 4 carbons at N10-position. Compounds at IC10 were evaluated for their efficacy to modulate the cytotoxicity of VLB in KBChR-8-5 cells and found that the modulators enhanced the cytotoxicity of VLB by 5- to 35-fold. Modulators 12, 14–16, and 19 like VRP, were able to completely reverse the 24-fold resistance of KBChR-8-5 cells to VLB. Examination of the relationship between lipophilicity and antagonism of MDR showed a reasonable correlation suggesting that hydrophobicity is one of the determinants of potency for anti-MDR activity of 2-methoxyacridones.

Catalytic Fluorodechlorination of Polychlorofluorobenzenes with Potassium Fluoride

Fluorodechlorination of polychlorofluorobenzenes with potassium fluoride in the presence of phase-transfer catalysts was investigated. “Onium” catalysts [hexaethylguanidinium chloride, tetra(diethylamino)phosphonium bromide] take part in the stabilization of the intermediate σ-complex. Catalytic role of polyethers (tetraglyme, 18-crown-6) in the fluorodechlorination process is limited to increasing the fluoride ion concentration.

Phase-transfer catalysis and ultrasonic waves II: saponification of vegetable oil

Saponification of oils which is a commercially important heterogeneous reaction, can be speeded up by the application of ultrasound in the presence of phase-transfer catalyst (PTC). This paper focuses on the ability of ultrasound to cause efficient mixing of this liquid–liquid heterogeneous reaction. Castor oil was taken as a model oil and the kinetic of the reaction was followed by the extent of saponification. The hydrolysis of castor oil was carried out with different PTC such as cetyl trimethyl ammonium bromide (CTAB), benzyl triethyl ammonium chloride (BTAC) and tetrabutyl ammonium bromide (TBAB) in aqueous alkaline solution. As hydroxyl anion moves very slowly from aqueous to oil phase, the presence of a PTC is of prime importance. For this purpose, cationic surfactants are selected. The sonication of biphasic system were performed by 20 kHz (simple horn and cup horn) and 900 kHz. It was found that CTAB was better than the two others and this could be related to the molecular structure of the PTCs. The effect of temperature was also studied on the saponification process. By increasing the temperature, the yield was also increased and this could be explained by intermolecular forces, interfacial tension and mass transfer. Saponification of three different vegetable oils shows that the almond oil is saponified easier than the two others and this could be related to their properties such as surface tension, viscosity and density.

Synthesis of Benzyl Esters of Glycyrrhizic Acid in the Presence of Phase-Transfer Catalysts

Benzyl esters of glycyrrhizic acid were synthesized using PhCH2Br in DMSO-CH2Cl2-NaOH in the presence of phase-transfer catalysts, such as tetraalkylammonium salts and 2-methyl-2-propanol.

Rutherford backscattering spectrometry and computer simulation for the in-depth analysis of chemically modified poly(vinylidene fluoride)

The alkaline treatment of poly(vinylidene fluoride) (PVdF), in the presence of phase transfer catalysts (PTCs) has been investigated. Rutherford backscattering spectrometry (RBS) has been used to determine the depth of modification achieved and to provide compositional depth profiles of modified PVdF samples. The complex chemical nature of the modified substrate, and the overlap of the elemental scattering edges within the depths involved (up to 1.4 μm), create RBS spectra which are difficult to interpret. The DataFurnace software has been applied to the data, leading to excellent results. Defluorination and oxygenation of PVdF occurs on treatment with NaOH and PTC. Through the use of samples prepared with the aim of establishing the kinetics of the modification, a mechanism concerning elimination of fluorine followed by oxygenation, is shown to occur. The RBS analysis indicates that the kinetics of the defluorination reaction follows the Case 1 (Fickian) diffusion law, and that the depth of treatment is of the order of 1.4 μm.

ChemInform Abstract: Novel Bifunctional Thiolcarboxylic Acid Esters Useful as Crosslinking Agents for Optical Materials.

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Novel Bifunctional Thiolcarboxylic Acid Esters Useful as Crosslinking Agents for Optical Materials

Novel bifunctional thiolcarboxylic acid esters such as thiodimethacrylates have been prepared in good yield by reaction of dimercaptanes with acid chloride in KOHaq and organic solvent system in the presence of phase transfer catalyst under mild reaction conditions. These bifunctional thiomethacrylates are useful as crosslinking agents having high refractive indices.

Phase-transfer catalyzed allylation of sodium phenoxide in a solid–liquid system

The kinetics for the O-allylation of sodium phenoxide with allyl bromide was investigated in the presence of phase-transfer catalyst in a solid–liquid system. The reaction was carried out in a stirred batch reactor under very mild operating conditions. The role of phase-transfer catalytic intermediate in the solid–liquid system was explored. Effects of various operating variables were performed. When the degree of agitation exceeded 200 rpm, the mass transfer resistance at the solid–liquid interface can be ignored. A kinetic model was proposed for the solid–liquid etherification and the experimental data were well described by the pseudo-first-order equation. The apparent activation energy was also obtained as 60.92 kJ mol −1 for tetra- n-butylammonium bromide (TBAB) as the catalyst. Experimental results also show that C-alkylation of sodium phenoxide with allyl bromide would not occur under the appropriate phase-transfer conditions.

Chlorobenzyl Alcohols from Chlorobenzyl Chlorides via Corresponding Benzoate Esters: Process Development Aspects

Kinetic studies in conversion of benzyl chlorides to corresponding alcohols via the benzoates are presented in this paper. The esterification reaction of 2-chlorobenzyl chloride, 4-chlorobenzyl chloride, 2,4-dichlorobenzyl chloride and benzyl chloride with aqueous sodium benzoate in the presence of phase transfer catalysts was investigated. The parameters studied are stirring speed, catalysts, the catalyst loading, temperature and the concentration of aqueous phase. The esterification reaction follows pseudo-first-order kinetics. The esters, were hydrolysed with and without a phase transfer catalyst to give corresponding benzyl alcohols without involving respective dibenzyl ethers. Material balance for the laboratory batch process of each chlorobenzyl alcohol has also been presented. A recycle strategy presented is shown to be effective in terms of alkali and benzoic acid consumption as the reactants are consumed to near stoichiometric levels.

Poly(triarylamine)s- synthesis and application in electroluminescent devices and photovoltaics

Polymeric triphenyldiamines (p-TPD)s and naphthylphenyldiamines (p-NPD)s were synthesized by Ullmann reaction between bis(N,N-diaryl)amines and aryldiiodides in presence of phase-transfer catalyst, 18-crown-6. The polymers obtained are soluble in THF, CHCl 3 etc and possess Tgs in the range of 206°C to 232°C and form stable and amorphous thin films. The HOMO energy values determined from cyclic voltammetry measurements lie between −5.10 and −5.17 eV with respect to vacuum energy level. The p-TPD and p-NPD are effectively applied as hole transport material in Electroluminescent devices, ITO/p-TPD/Alq 3/Al. A solid-state solar cell, consisting of an inorganic nanocrystalline TiO 2 layer coated on ITO for electron conduction, a surface-adsorbed ruthenium complex dye for light absorption and p-TPD as hole transport layer is also realized. Using appropriate counter electrode such as Au or Pt, quantum efficiencies of up to 0.2% and open circuit voltage of 550mV were realised.

Process Development Aspects of Production of Dibenzyl Ether

To develop an economically viable process for the synthesis of dibenzyl ether, the reaction of benzyl chloride with aqueous sodium hydroxide in the presence of phase-transfer catalysts has been investigated. The effects of agitation speed, catalyst type and concentration, reaction temperature, mole ratio of reactants, concentration of aqueous sodium hydroxide on the conversion of benzyl chloride, and yield of dibenzyl ether have been evaluated. Tributylamine is found to be a suitable catalyst. The reaction is favored by high molar ratio of sodium hydroxide to benzyl chloride. Conversion of benzyl chloride to benzyl alcohol is found to be the rate-controlling step at high sodium hydroxide concentration. Deprotonation of benzyl alcohol at the interphase by aqueous sodium hydroxide is a key step in the formation of dibenzyl ether. The yield of dibenzyl ether is dependent on the concentration of sodium hydroxide in the aqueous phase, the yield being almost 100% at high concentrations of sodium hydroxide. The successful recycle of excess NaOH in the aqueous phase in subsequent batches, without affecting the progress of the reaction, has been demonstrated.