Synthesis of Hydroxypropyl Guar Gum by Phase Transfer Catalysis

HGG (Hydroxypropyl guar gum) was synthesized by phase transfer catalysis for the first time. The effects of alkalinity, phase transfer catalyst, etherification, pH value, temperature, reaction time and stirring speed were investigated. An optimal synthetic reaction technology was established, namely, dose of guar gum is 100 g, propylene oxide 40-50 g, HTAC (hexadecyl trimethyl ammonium chloride ) 1.3-1.7 g, pH value 10-10.5, temperature 45-50℃, and reaction time 3-4 hours. The result shows that the improved HGG has high viscosity. Its dissolution speed, content of insoluble residue, colloid light transparency and stability are apparently superior to guar flour.

One-pot Synthesis of 1-Aryloxyacety l-4-(4'-nitrophenyloxyacetyl)-thiosemicarbazides under Phase Transfer Catalysis and Microwave Irradiation

The 1-aryloxyacetyl-4-(4-nitrophenyloxyacetyl)-thiosemicarbazides (3a-h) are synthe- sized via reaction of 4-nitrophenyloxyacetyl chloride with ammonium thiocyanate and aryloxyacetic hydrazides (2a-h) under phase transfer catalysis and microwave irradiation in excellent yield.

THE REACTION OF AROMATIC ALDEHYDES WITH p-NITROBENZYLLIBUTYLTELLURONIUM BROMIDE BY PHASE TRANSFER CATALYSIS

Under the condition of solid-liquid phase transfer catalysis, olefins were obtained by the reaction of p-nitrobenzyldibutyltelluronium bromide with aromatic aldehyde.Under the condition of liquid-liquid phase transfer catalysis,however,different products were obtained due to the reactivity of different bases or aldehydes.

Synthesis of Cyclopropylamine with Phase Transfer Catalysis

Cyclopropylamine is synthesized with γ butyrolactone and isopropanol by five steps of ring opening esterification, cyclization, hydrolysis, acylation and Hofmann degradation. Cyclization and hydrolysis are key steps in the process, and Phase Transfer Catalysis (PTC) is used in the two steps respectively. In the cyclization reaction, because solid liquid PTC, sodium hydroxide is applied instead of expensive sodium alcoholate, the reaction can be carried out in mild conditions. The optimum re action conditions are as follows: 0.03∶1∶1.5 mole ratio of BTEAC to ester to sodium hydroxide, reacting at 50 ℃ for 2 h with yield of 92%. Hydrolysis of isopropyl cyclopropanecarboxylate is accelerated by liquid liquid PTC, and the order of catalytic activity is BTEAC>BTMAC>CTMAB>TBAB. The results show that the new synthesis method is superior to those from literature and feasible for production with simple routes, mild reaction conditions, cheap materials and total yield of 52.6%.

Synthesis of diethers derived from furoin by phase transfer catalysis under microwave irradiation

A series of new diethers were obtained by alkylation of furoin under microwave irradiation （MWI） in phase transfer catalysis （PTC） conditions. The products of alkyl halides were synthesized in good yields （〉75%） within a few minutes, and the products of dihalides were synthesized in fair yields （about 45%）. The yields are dramatically improved compared to conventional heating under the same conditions, in spite of similar profiles of rising in temperature.

Efficient and Convenient Synthesis of Diethers from Furoin Under Ultrasound and Solid-liquid Phase Transfer Catalysis Conditions

Compounds having an active hydroxy group, such as, acyloins can be easily alkylated by alkyl halides in the presence of a phase transfer catalyst （PTC）. The reaction is usually carried out in the presence of con-centrated aqueous sodium or potassium hydroxide and a phase transfer catalyst, such as, quaternary ammonium salts^[1-3] species, miscible which facilitate the interphase transfer of making reactions between reagents in two im-phases possible. The reaction involves a series of equilibrium and mass-transfer steps.

Synthesis of n-Butyl Acetate by Microwave Irradiation Under the Assistance of Solid-Liquid Phase Transfer Catalysis Without Solvent

Introduction Microwave irradiation has been very widely used in heating, cooking and brewing. Several papers which describe the use of domestic microwave ovens to perform rapid organic synthesis in solution have been published. The high heating efficiency gives rise to remarkable rate of reaction and dramatic reduction of reaction time. Nevertheless, its application seems to be limited to these procedures because of

Application of the Phase Transfer Catalysis in Rare Earth Solvent Extraction

In order to overcome the difficulty in stripping and reduce the equilibrium time in heavy rare earth separation with acidic organophosphorous extractants, the phase transfer catalysis (PTC) technique was introduced to the solvent extraction process, especially applied to the stripping section, which was called phase transfer catalysis stripping (PTCS) process. in the PTCS process, an acidic phosphorous extractant was mixed with another extractant which can transfer hydrogen ion from aqueous phase to organic phase and almost does not extract rare earth ions, so that the stripping efficiency can be improved and the stripping extraction equilibrium be accelerated. The reaction mechanism of the PTCS and the requisite properties for a feasible PTCS catalyst in rare earth extraction were studied. We selected D(2)EHPA as the extractant, Alamine 336 as the PTCS catalyst and mixed rare earth chlorides as the feed to test the PTCS phenomenon. Based on the experimental data, the applicability of PTCS technique in rare earth solvent extraction was discussed.

SYNTHESIS OF DIARYL ETHERS THROUGH PHASE TRANSFER CATALYSIS WITH POTASSIUN FLUORIDE COATED ALUMINA AS A STRONG BASE

Seven diaryl ethers were synthesized with potassium fluoride coated alumina as a strong base and the addition of catalytic amount of PTC. The yield of diaryl ethers with addition of PTC was much higher than that without PTC.A discussion of the catalysis mechanism was given in this paper.

Phase Transfer Catalysis of Henry and Darzens Reactions

We describe in this work the influence of the addition of phase transfer catalyst in heterogeneous medium liquid/liquid on the output of the reactions of Darzens and Henry. It proves that the reaction of Darzens is favoured in the presence of low base such as K2CO3 and Et3N. Phase transfer catalysis is an efficient activation method in Darzens and Henry reactions. Thus, the Ethylene Diammonium Diacetate (EDD) has a comparable catalytic activity has that of quaternary ammonium salts in the reaction of Darzens.

Synthesis of p-nitrophenol under normal pressure with A-1 phase transfer catalysis

p nitrophenol is synthesized using p nitrochlorobenzene and sodium hydroxide with phase transfer catalyst. Several reaction factors, such as catalyst type, the amounts of catalysts and sodium hydroxide, the concentration of sodium hydroxide solution as well as reaction time, affect greatly the yield of p nitrophenol. The optimum reaction conditions are as follows: A 1 used as phase transfer catalyst whose consumption is 6% (mole fraction) of p nitrochlorobenzene; the molar ratio of sodium hydroxide to p nitrochlorobenzene is 3:1; the concentration of sodium hydroxide solution is 50% (mass fraction). Nitrobenzene, whose molar amount is 2.45 times as much as that of p nitrochlorobenzene; reaction time is 7 h at 140 ℃ under normal pressure. The final yield of p nitrophenol is 83.6%.

SYNTHESIS OF 1-O-ACYL-2,3,4-TRI-O-ACETYL-β-D-XYLO-AND ARABINOPYRANOSES BY PHASE TRANSFER CATALYSIS

The acetylated xylo-and arabinopyranosyl esters(1-8) were obtained in high yields with stereoselectivity by phase-transfer catalyzed (PTC) synthesis, and their structures were confirmed by elemental analysis and IR,^(1)H-NMR spectral data.

Kinetics of the Oxidation of Benzhydrols with Permanganate under Phase Transfer Catalysis in Organic Solvents

Kinetic studies of the oxidation of benzhydrol and some of its para-substituted derivatives using phase transferred permanganate in organic solvents that are immiscible with water have been carried out. The products of oxidation were the corresponding benzophenones. Kinetically first order dependence on the concentrations of substrate as well as the oxidant has been observed. The reaction rate was found to decrease with an increase in the dielectric constant of the organic solvent employed. The electronic effects of the substituents were found to be interesting. Both electron withdrawing and electron releasing groups at the para position of benzhydrol increased rate of the oxidation. The effects of different phase transfer catalysts (PTC) were also compared. The activation parameters have been evaluated and a mechanism consistent with the kinetic results has been proposed.

REACTION OF ETHYL N-CYANOMETHYLBENZEHECARBOXIMIDATE WITH ALIPHATIC ALDEHYDES UNDER THE SOLID-LIQUID PHASE TRANSFER CATALYSIS

Ethyl N-cyanomethytbenzenecarboximidate reacted with aliphatic aldehydes under the solid-liquid PTC condition to gire a-ethoxyphenylmethylene- aminoacrylonitrile derivatives and oxazoline derivatives.It is a convenient and new method for synthesis of β,β'-dihyroxy-a-amino acids by hydrolysis of the oxazoline derivatives.

STUDIES ON THE REACTION OF SULFUR,SELENIUM AND TELLURIUM WITH SODIUM HYDROXIDE UNDER PHASE TRANSFER CATALYSIS(Ⅱ).A CONVENIENT METHOD FOR THE SYNTHESIS OF BI(ACYL)DISULFIDES

A simple and general method for the synthesis of bi(acyl)disulfides is reported.Sulfur is allowed to react with sodium hydroxide to give sodium disulfide at 65℃ under PTC,which can react with acyl halides to afford bi(acyl)disulfides in good to excellent isolated yields.The effects of solvents and phase transfer catalysts are discussed.

Ionic liquids as efficient phase-transfer catalysts for the solid base-promoted monoalkylation of diethyl malonate

Ionic liquids （ILs） based on 1,3-dialkylimidazolium and tetraalkylammonium cations were employed as a series of efficient, environmentally benign phase-transfer catalysts （PTCs） for the base-promoted monoalkylation of diethyl malonate. The influence of various heterogeneous bases on yields was studied. Good yields and high selectivity were obtained. Solvent-free, mild reaction condition, short reaction time, and easy purification were the merits of this method. The catalytic system （IL-hase） could also be recycled after the extraction of products with ether.

Asymmetric Phase-transfer Mediated Epoxidation of α, β-Enones Using Dendritic Catalysts Derived from Cinchona Alkaloids

Chiral phase-transfer catalysts, derived from cinchona alkaloids and Fréchet dendritic wedges up to generation two, have been synthesized. These chiral dendritic molecules have been used as PTCs in the epoxidation of α, β-enones, showing a moderate level of asymmetric induction.

Novel Bis-(N-alkyl-N ,N-dimethyl-ammonium) Polyethyleneglycol Ether Salts as Phase Transfer Catalysts in the Condensation of l,4-Diacetyl-2,5-piperazinedione and Aldehydes

Phase transfer catalysis (PTC) has become one of the most extensively used techniques in organic synthesis. The key factor in such processes is the catalyst. There are mainly two kinds of phase transfer catalysts, one is the so called "crown ethers" including macrocyeles, open chain molecules with long chains, bearing heteroatoms at a proper distance, and can chelate inorganic