Phase Transfer Catalytic System Research Articles

Immobilization of quaternary ammonium salts on grafting particle polystyrene/SiO 2 and preliminary study of application performance

Polystyrene (PSt) was grafted on the surface of silica gel particles in the manner of “grafting from” in a solution polymerization system, and grafting particles PSt/SiO 2 was obtained. The chloromethylation reaction of the grafted polystyrene was performed using a novel chloromethylation reagent, 1,4-bis(chloromethyoxy)butane which is un-carcinogenic, and grafting particles CMPS/SiO 2 was gained. Subsequently, grafted CMPS was quaternized (denoted as QPS) using tertiary amine, and finally functional composite-type particles QPS/SiO 2, on which quaternary ammonium groups were immobilized, were prepared. The catalysis activity of the particle QPS/SiO 2 as a triphase catalyst in phase-transfer catalysis systems and its antibacterial activity as a water-insoluble antibacterial material were studied preliminarily. The experimental results show that the particle QPS/SiO 2 exhibits higher catalysis activity as a triphase catalyst for the reaction between benzyl chloride in organic phase and sodium acetate in aqueous phase to form benzyl acetate, and under a mild condition of 60 °C for 7 h of reaction time a conversion of 66% for benzyl chloride can be obtained. The particle QPS/SiO 2 has high antibacterial activity as a water-insoluble antibacterial material against Escherichia coli ( E. coli).

Interfacial tension studies of crown ethers at air/water and hexane/water interfaces

The adsorption of phase transfer catalysts, 18-crown-6 and dicyclohexano-18-crown-6, at the air/water and the hexane/water interfaces were investigated. Interfacial tension σ decreased by increasing concentrations of these compounds and therefore both of these crown ethers are accumulated at interfaces. The variation of σ with concentration for both compounds follows the Szyszkowski equation very well, from which the values of saturated surface densities and interaction parameters have been evaluated. On the basis of occupied surface area of each molecule, the orientation of each of molecules at the air/water and the hexane/water interfaces have been proposed. The present results show that dicyclohexano-18-crown-6 has the higher tendency not only to dissolve into the hexane phase but also to adsorb at the hexane/water interface than 18-crown-6 and that the Starks extraction mechanism was suggested for the present phase transfer catalysis systems.

Synthesis of Ester Derivatives of Brominated Poly(isobutylene-co-isoprene): Solvent-Free Phase Transfer Catalysis

The principles of phase transfer catalysis (PTC) are adapted to facilitate solvent-free nucleophlic substitution reactions of brominated poly(isobutylene-co-isoprene) (BIIR). Catalytic amounts of tetraalkylammonium halides are shown to activate alkali metal carboxylate salts to generate ester derivatives in moderate to high yields without incurring complications associated with ammonium carboxylate salt instability and BIIR dehydrobromination. The structures of a range of new aliphatic and aromatic allylic esters are characterized unambiguously through comparisons with products derived from brominated 2,2,4,8,8-pentamethyl-4-nonene (BPMN), which serves as a model for the reactive functionality found within BIIR. The dynamics of the intrinsic substitution process are examined along with factors that affect the rate and selectivity of phase-partitioned, solvent-free PTC systems.

Kinetics for benzoylation of sodium 4-acetylphenoxide via third-liquid phase in the phase-transfer catalysis

In this research, the kinetics for synthesizing 4-acetylphenyl benzoate (R *COOR) from benzoylation of sodium 4-acetylphenoxide via third-liquid phase-transfer catalysis was investigated. The reaction rate was observed to be strongly dependent on agitation speeds in the third-phase catalytic reaction. By forming the third-liquid phase, the observed reaction can be greatly enhanced to give a product yield of 100% in a duration of 3 min at 20 °C and 200 rpm. If a third-liquid phase was not formed in the liquid–liquid system, the reaction rate is very slow and the product yield is only 2% in 3 min at 20 °C. The reaction conducted in third-liquid phase-transfer catalytic system is faster than that in LLPTC system by 25–28 times. The amount of catalytic intermediate (QOR) in the third-liquid phase was about 50% of the catalyst initially added and kept about 30% of it remained after 1 min, and only small amounts of a catalytic intermediate residing in the organic phase were observed during the reaction using methyl t-butyl ether as the solvent. The concentration of catalytic intermediate slightly decreased with increasing reaction time, while the molar ratio of QOR to benzyl tri- n-butylammonium cation in the third-liquid phase remained almost constant after 1 min and increased with increasing agitation speeds. The experimental results were well described by the pseudo-first-order kinetics. The present work shows an effective method to synthesize 4-acetylphenyl benzoate.

Phase transfer catalytic system with the third liquid phase

Phase transfer catalysis, a technique to bring the reactants in two immiscible phases together by adding a phase transfer agent, has been employed in the production of fine chemicals and pharmaceuticals in the last few decades. The third liquid phase (catalytic phase) may be formed when phase transfer catalysts (PTC), cannot be dissolved in either organic or aqueous phase. The third phase catalytic systems have the following three advantages, that is, (1) high activity (2) repeated use and (3) separation between the organic phase and the aqueous phase. It is expected that simple new processes can be constructed by applying these three advantages.

Synergetic Effect of Tetrabutylammonium Bromide and Polyethylene Glycol as Phase Transfer Catalysts in Third Liquid Phase for Benzyl-n-Butyl Ether Synthesis

This study intends to clarify the forming characteristics of third liquid phase in phase transfer catalytic system in the presence of n-butanol and potassium hydroxide when tetrabutylammonium bromide, polyethylene glycol and their mixture serve as phase transfer catalyst, respectively. At 323 K, the three catalytic systems were applied to yield benzyl-n-butyl ether from benzyl chloride and n-butanol, and they performed distinct reaction activity. Among them, a combination of two kinds of catalyst results in a synergetic effect in reaction activity.

A new type of phase-transfer catalysis via continuous transfer of fluoride anions to the organic phase in the form of potassium difluorotriphenylstannate

Fluorination of alkyl halides and sulfonates is efficiently executed in a liquid–solid phase-transfer catalysis system with Ph3SnF as phase-transfer catalyst acting via continuous formation of lipophilic Ph3SnF2 anions entering the organic phase in the form of the potassium salt.

Rates of Halogen Exchange and Ester Formation by Polyethylene Glycol Catalysts in a Solid-Liquid Phase Transfer Catalytic System

本研究では, 相間移動触媒を無水固液間反応に利用した. 有機相中の塩化ベンジルと固体反応物の臭化カリウムとの固液間ハロゲン交換反応を, 323 Kおよび353 Kで行った. また, 塩化ベンジルと安息香酸ナトリウムとのエステル生成反応も353 Kで行った. 平均分子量の異なる種々のポリエチレングリコールを触媒として用いた. これらの反応を無水で行った場合, ポリエチレングリコールから成る液相が有機液相および固相の間に形成した.無水の場合のハロゲン交換反応の速度は, 水がある場合の18倍となった. さらに, 反応に必要な臭化カリウムの量は, 水がある場合よりもかなり少なくて良かった. 無水の反応速度は, ポリエチレングリコールの平均分子量400で最大となった. これを塩化ベンジルのポリエチレングリコールへの溶解度が分子量の増加とともに増加し, 臭化カリウムは減少することにより説明した.無水の場合のエステル生成反応の速度は, 水がある場合の9倍となり, ポリエチレングリコールの平均分子量200で最大となった.以上の結果から, これら二つの無水固液間反応は, 固体反応物と有機相中の液体反応物がポリエチレングリコールを含む液相に溶解することにより起こると結論した.

Novel fluoride ion mediated synthesis of unsymmetrical siloxanes under phase transfer catalysis conditions

Unsymmetrical siloxanes have been prepared from silanols or hydrosilanes using phase transfer catalytic (PTC) systems Me 3SiN 3–CsF–18-crown-6–toluene or Me 3SiN 3–CsF–18-crown-6–H 2O–toluene, correspondingly. The target unsymmetrical siloxanes were prepared in yields up to 100%. Quantum chemical calculation of mechanism of unsymmetrical siloxanes formation has been performed.

Rate enhancement effect of third liquid phase on dibenzyl ether production in solid–liquid–liquid phase transfer catalytic system

To investigate the effect of polyethylene glycol (PEG) as a phase transfer catalyst (PTC) for a solid–liquid reaction, dibenzyl ether synthesis from benzyl chloride and benzyl alcohol in organic phase by using solid KOH. A third phase containing the catalyst PEG was formed when dodecane was used as an organic phase. Benzyl alcohol reactants and KOH were dissolved into the third phase. PEG, KOH and benzyl alcohol were combined to produce the alcoxide type complex in the third phase. The complex was transferred into the organic phase. Then, the reaction between the complex and benzyl chloride took place in the organic phase. The reaction rate of this system without water was nearly eight times higher than that of the PTC system with water. Furthermore, the amount of KOH could be reduced by this solid (KOH)–liquid (catalyst)–liquid (organic solvent) system. The difference of the reaction rate was explained by the variation of the base strength of the third phase containing the catalyst. The base strength in the system without water was higher than that in the system with water, which results in the higher concentration of the complex.

Synthesis of N‐ and S‐Vinyl Derivatives of Heteroaromatic Compounds Using Phase‐Transfer Catalysis.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Novel Stereoselective Phase Transfer Catalytic Synthesis and Some Applications of ( E )-2-Chlorovinylthioarenes and Hetarenes

A novel two-step method for the preparation of ( E )-2-chlorovinylthioarenes (or hetarenes) from thiols and 1,1,2-trichloroethane in the phase transfer catalytic systems solid K 2 CO 3 /solid KI/18-crown-6/xylene and solid KOH/18-crown-6/toluene has been developed. ( E )-2-chlorovinylthioarenes were isolated in yields up to 98%. Utilization of ( E )-2-chlorovinylthioarenes in the Heck and Stille reactions has been shown.

Formation of a Third Liquid Phase and Its Reuse for Dibenzyl Ether Synthesis in a Tetraalkylammonium Salt Phase Transfer Catalytic System

This paper describes the formation of a third liquid phase in a phase transfer catalytic system in the presence of benzyl alcohol and potassium hydroxide, where dodecane and tetraalkylammonium bromide serve as organic solvent and catalyst, respectively. In this kind of system, a symmetrical ether (dibenzyl ether) was synthesized from benzyl chloride and benzyl alcohol at 323 K. In particular, the investigation demonstrates that the observed reaction rate constant depends on the length of the alkyl group of the catalyst. Tetrabutylammonium bromide exhibits the highest catalytic activity among the catalysts explored. With respect to the reuse of the third liquid phase, the results confirm that there is no decrease in phase transfer catalytic activity in three consecutive runs.

Role of the Omega Phase in the Analysis and Intensification of Solid−Liquid Phase-Transfer-Catalyzed Reactions

Although phase-transfer catalysis (PTC) is a mature discipline, several intricacies of PTC in reactions of industrial importance are not understood or properly modeled. For instance, the effect of the nature and number of phases on the intensification of rates and selectivities has not been investigated in detail. This study deals with the efficacy of the so-called omega phase, which is a small quantity of aqueous phase in a solid reactant−organic liquid reaction involving PTC, in intensification of the rates of the cyanide displacement reaction on p-chlorobenzyl chloride, with special emphasis on the kinetic and modeling aspects. As the reaction proceeds, the process converts itself from a S(reagent)−L(ω)−L(org) into a L(ω)−L(org) PTC system. This paper gives a complete theoretical and experimental analysis of the role of the ω-phase in enhancing the rates of the reaction and the importance of the L(ω)−L(org) PTC system with a phase ratio divergent from that of the normal L(aq)−L(org) PTC system.

Synthesis and Cytotoxicity of Silicon Containing Pyridine and Quinoline Sulfides

Silicon containing pyridine and quinoline sulfides have been prepared using phase transfer catalytic system thiol/alkyl halide / solid KOH/18-crown-6 / toluene. The target S-ethers were isolated in yields up to 81%. The cytotoxicity of the synthesized compounds was studied. Among pyridine sulfides S-[3-(1-methyl- 1-silacyclohexyl)propyl] derivatives 5e and 6e exhibit the highest cytotoxicity. Aliphatic silicon derivatives were considerably less active. 8-[(Trimethylsilylmethyl)thio]quinoline (8a) exhibits the highest activity among quinoline sulfides.

Silacyclic Derivatives of Heteroaromatic Sulfides as SelectiveCholesterol Level Lowering and Vasodilating Agents

Silacyclic derivatives of heteroaromatic sulfides have been prepared by using phase transfer catalytic (PTC) system thiol / silacyclopropyl iodide / solid K2CO3 / 18-crown-6 / toluene. The target sulfides were isolated in yields up to 70 %. The S-derivatives of N-methylimidazolyl, benzoxazolyl and 1,3,4-triazolyl thiols selectively lowered the low density lipoprotein (LDL) level in mice with the high cholesterol diet in nutrition.

Production Rate of Butyiphenyl Ether in Phase Separable Type CSTR by Third Liquid Phase of Phase Transfer Catalytic System.

回分反応器と流通反応器を使って，プロモブタンとフェノールからブチルフェニルエーテルを合成する反応について研究を行った．相聞移動触媒としてポリエチレングリコール（平均分子量3，000），有機溶媒にドデカンを用いたとき，水相の水酸化カリウム濃度が高くなると第3相が形成した．第3相の体積はフエノールを加えると増加したが，塩基強度は減少した．その結果，回分反応器におけるエーテル生成速度はフェノ-ル濃度に対して極大値を持った．相分離型流通式撹拌槽反応器は第3相を効率よく利用できるように工夫した流通反応器である．この反応器では，反応物を直接第3相に供給し，第3相近傍のみ撹拌を行い，生成物のブチルフェニルエーテルを含んだ有機溶媒を連続的に取り出した．反応速度は，流通反応器においてもフエノール濃度に対して回分反応器と同様の傾向を示した．供給したフェノールが完全に消費されたときに定常反応操作を行うことができた．

Application of solid–liquid phase transfer catalysis system for peroxyester synthesis: A kinetic study of hydroperoxides acylation in the presence of solid sodium carbonate

In the research described below, we have developed a convenient and effective method of synthesis of organic peroxyesters to achieve 60–98% yields under extreme mild conditions. The study has been conducted on a model system using a reaction of acylation of 1-methyl-1-phenylethyl hydroperoxide (CHP) by means of butyryl chloride in the presence of solid Na2CO3 and being performed under conditions of phase transfer catalysis (PTC). The effect of the following parameters on the reaction was tested: temperature, Na2CO3 amount, catalyst structure and solvent polarity.

Synthesis of N- and S-Vinyl Derivatives of Heteroaromatic Compounds Using Phase-transfer Catalysis

A method has been developed for the synthesis of N- and S-vinyl derivatives of heteroaromatic compounds from NH heterocycles or their thiols in the phase-transfer catalytic system ClCH2CH2Br-KOH (s)-18-crown-6-toluene. It is shown that it is possible to prepare N,S-divinyl derivatives of 3-mercaptoindole and 2-mercaptobenzimidazole.

Synthesis and cytotoxicity of 3-(hetarylthio)-1-propynyl-(trimethyl)silanes

We have developed a two-step method for synthesis of 3-(hetarylthio)-1-propynyl(trimethyl)silanes from thiols in a phase-transfer catalysis system HCCCH2Br-solid K2CO3-18-crown-6-toluene followed by reaction with n-BuLi-Me3SiCl in ether or THF. We have observed that 3-[1,3-bis(trimethylsilyl)-2-propynyl]thioindole displays high cytotoxicity in HT-1080 and MG-22A tumor cell lines.