Cross-Linked Polyvinylpyridine Supported Zinc Borohydride as a Highly Chemoselective Reducing Agent

Aldehydes are reduced in ethanol under reflux condition in high yelds. This reagent absolutely discriminates aldehydes from ketones.     

Borohydride Exchange Resin,a New Reducing Agent for Reductive Amination

A system consisting of tosyl chloride-dimethyl formamide-pyridine was found to ensure oxidation of poly(vinyl alcohol) and some molecular alcohols.     

Solid Phase Derivatizations in HPLC: Borohydride/Silica Reductions for Carbonyl Compounds

Abstract

Sodium borohydride adsorbed onto silica gel has now been utilized for on-line, pre-and post-analytical column chemical derivatizations via reductions of various organic carbonyl compounds. These on-line reactions have been performed using normal phase HPLC conditions, involving conventional silica gel packings, organic mobile phases, and commercially available HPLC equipment and instrumentation. This approach for on-line HPLC derivatizations has been evaluated for a large number of organic carbonyl compounds, at a variety of temperatures for aldehydes and ketones. The overall rates of such carbonyl reductions via sodium borohydride/silica are sufficiently different as a function of temperature of the reaction to permit for compound/class identifications. Analyte identification can be both qualitative and quantitative, even wherein an analyte co-elutes with a non-carbonyl compound. In-house prepared borohydride/silica gel reactors can be characterized via standard iodine titration procedures along with inductively coupled plasma (ICP) elemental boron analysis. These normal phase derivatization approaches have been applied to certain standard vitamins, and to cinnamaldehyde found in a commercial spice product. Such approaches to on-line HPLC derivatizations     

Sodium Borohydride: Tartaric Acid. A Novel and Facile Reducing Agent for Cyclic Ketones

The utility of a sodium acyloxyborohydride, derived from sodium borohydride and tartaric acid, in stereoselective reductions of cyclic ketones is demonstrated.     

A Facile Synthesis of Unsymmetrical Sulfides Under Phase Transfer Conditions

An efficient synthesis of unsynmetrical sulfides (3) is described by reacting S-alkylisothiouroniu″ salts (1) with alkyl halides (2) under liquid-liquid phase transfer catalyst conditions.     

A Convenient Synthesis of the Symmetrical bis-Sulfides Under Phase Transfer Conditions

Phase transfer catalysis has been found to be effective for the preparation of symmetrical bis-sulfides (4) in high yields by a one-pot proudure which consists of generating the thiolate ions from s-alkylisothiouronium salys (2) and then reacting with alkyl halides (3).     

Synthesis of Diarylselenides and Diarylsulfides Under Phase Transfer Conditions

Diarylselenides and diarylsulfides are synthesized from the corresponding diaryldiselenide and diaryldisulfide by reduction with aminoiminomethanesulfinic acid, and reaction with activated aryl halides under phase transfer conditions. The reactions yields vary from good to excellent.     

A Facile Method for the Syntheses of Dialkyl Disulfides from Sulfur Under Phase Transfer Conditions

A convenient reaction of alkyl halides with sulfur in alkaline medium has been found to afford disulfides in good to excellent isolated yield under phase transfer conditions.     

New Phase Transfer Agent for Dye： Application for Hyperbranched Poly （ester-amine）

Hydrophilic hyperbranched poly(ester-amine) (HPEA) synthesized from diethanolamine and methyl acrylate was used as phase transfer agent for the first time to transfer methyl orange(MO) from water into chloroform. This process was quantified by UV-Vis spectra. A possible mechanism was put forward based on the formation of amphiphilic aggregates.     

Reaction of Dichlorocarbene with Substituted Cyclopentadienones Under Phase Transfer Conditions

The cycloaddition reactions involving dichlorocarbene generated under phase transfer conditions have been studied extensively in the past few years due to the simplicity of the procedure involved.¹ The facile formation of dichlorocyclopropanes provides an easy entry to functionalised aromatics and expanded carbocyclic compounds.² The dichlorocarbene generated under phase transfer conditions is capable of adding even to electron deficient olefins. We describe here the cyclo-addition reaction of dichlorocarbene to tetrasubstituted cyclopentadienones.     

Acylation of Phosphorus Substituted Ch-Acids Under Phase Transfer Catalysis Conditions

Abstract.

Acylation of phosphoryl- and thiophosphoryl acetonitriles under phase transfer catalysis (PTC) conditions leads in high yields to C-acylated products existing as Z-isomers of the corresponding enol forms. They are stabilized by strong intramolecular H-bonds. On the contrary, acylation of phosphorylacetone proceeds mainly at the oxygene atom and gives Z and E enolacetate. Phosphorus trichloride was used as an acylating agent under PTC conditions. S-Alkyldichlorophosphites were obtained by the reaction with mercaptanes. Alcohols react with PCl₃ in the presence of sodium carbonate to result in dialkylphosphites.     

Poly-n-(Pyrazine)Zinc Borohydride as a New Stable,Efficient and Selective Reducing Agent

Coordination polymer of unstable zinc borohydride and pyrazine is prepared and used as an stable, efficient and selective bench top reducing agent for a variety of organic compounds.     

Zirconium Borohydride - a Versatile Reducing Agent for the Reduction of Electrophilic and Nucleophilic Substrates

Zirconium borohydride, a potential reducing agent, reduces acids, esters, imines to the corresponding alcohols and secondary amines in good yield at room temperature within two hours. This facile reducing property was taken advantage off in the synthesis of pheromones and some novel chiral precursors for asymmetric synthesis.     

Borohydride Reductions in Dichloromethane: A Convenient,Environmentally Compatible Procedure for the Methylation of Amines

The combination of zinc chloride and sodium borohydride in dichloromethane is used to effect reductive aminations of formaldehyde with a variety of primary and secondary amines containing potentially acid-sensitive functional groups in good to excellent yields.     

Hydroxide Ion Initiated Reactions Under Phase Transfer Catalysis Conditions: Mechanism and Implications. New Synthetic Methods (62)

The development of Phase Transfer Catalysis (PTC) represents a major step forward in the employment of many organic reactions and renders them very convenient and useful processes. These reactions involve the application of nucleophiles in general, anions and bases in particular, in reactions carried out in a water-organic solvent system. They can be performed both in the laboratory and on an industrial scale. The ease of application of PTC processes is the main reason for their increasing utilization in industry. An outstanding achievement of this technique is the employment of aqueous bases in reactions which traditionally would otherwise require a strong base in a nonaqueous medium. The classical procedures that require severe anhydrous conditions, expensive solvents and dangerous bases such as metal hydrides and organometallic reagents are now replaced by aqueous solutions of, e.g., sodium or potassium hydroxides (PTC/OH processes). In contrast to the extensive synthetic applications of PTC/OH systems, the detailed mechanisms of these processes have been the subject of a great deal of controversy and various mechanisms have been suggested. However, it would seem that our knowledge concerning the mechanistic aspects of such reactions has now reached the stage where it can be used to advantage in synthesis planning. A better understanding of the various factors which influence the reaction would undoubtedly help to optimize PTC/OH processes such as to enable higher yields in shorter reaction times at lower temperatures. The importance of, inter alia, the catalyst will be pointed out and it is highly recommended that such catalysts be always available in the laboratory, for the range of organic reactions that they can efficiently, conveniently and safely catalyze is vast indeed.     

Dihalocyclopropanation of Phenylthio or Butylthiocycloalkenes Under Phase Transfer Conditions. Opening of Cyclopropanes Under Microwave Irradiation

Dihalocarbenes (X=C1,Br) generated under phase transfer conditions added to phenylthio or butylthiocylcloalkenes give corresponding 1,1-dihalo-2-thiobutyl or thiophenyl-cyclopropanes. The ring opening of dichlorophenylthiocyclopropanes (2a, 2b, 2c) was obtained by using silver tetrafluoborate on alumina under microwave irradiation.     

A Novel Montmorillonite - KMnO4 System for the Oxidation of Alkenes Under Triphase Conditions

A very simple oxidation of alkenes to dicarboxylic acids using H-montmorillonite-K MnO₄ system has been described for the first time.     

Ni Nanoparticles Supported Montmorillonite Clay for Selective Catalytic Transfer Hydrodeoxygenation of Vanillin into 2-Methoxy-4-methylphenol

The targeted catalytic transfer hydrodeoxygenation (CTHDO) of vanillin (VAN) to 2-methoxy-4-methylphenol (MMP) holds promise as a noteworthy subject in the domain of bio-oil utilization, offering potential as a future biofuel and finding versatile use in fragrances and pharmaceutical industry. In this study, stable, cost-effective Ni nanoparticles supported on montmorillonite (MMT) clay was synthesized for eco-friendly, alcohol-mediated CTHDO of VAN to MMP. The Ni(10 %)/MMT catalyst achieved >99 % VAN conversion and 95.2 % MMP selectivity using isopropanol (IPA) as a solvent and hydrogen donor. Characterization encompassing PXRD, SEM, TEM, and XPS confirmed successful Ni integration onto MMT. NH₃-TPD, pyridine-IR, and H₂-TPR analysis evaluated catalyst surface acidity and reducibility. The synergy between surface-modulated acidity of MMT and Ni nanoparticles collectively facilitated IPA and VAN activation, driving CTHDO performance. The Ni(10 %)/MMT catalyst displayed sustained activity over five recycles. Its exceptional stability and performance underscore its potential as an eco-friendly, sustainable, non-noble transition metal-based catalyst for the hydrogenating lignin bio-oil model compounds, contributing to greener catalytic advancements.