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The present work introduces the favorable synthesis of porous functionalized nanomaterials with excellent surface area, porosity, and high CO2 capture ability to facilitate cyclizative reactions by...

An efficient synthesis of primary carbamates and N-substituted ureas is explored with a newly developed heterogeneous polymer supported iron catalyst in the presence of a sustainable carbonylation source. The Merrifield anchored iron(II)-anthra catalyst [FeII(Anthra-Merf)] was synthesized by functionalization of Merrifield polymer followed by grafting of iron metal. The catalyst [FeII(Anthra-Merf)] was characterized by several techniques, like SEM, EDAX, TGA, PXRD, XPS, FTIR, CHN, AAS and UV-Vis analysis. The designed polymer embedded [FeII(Anthra-Merf)] complex is a remarkably successful catalyst for the synthesis of primary organic carbamates and N-substituted ureas by using safe carbonylation agent urea with different derivatives of alcohols and amines, respectively. The reported catalyst is a potential candidate towards contributing a satisfactory yield of isolated products under suitable reaction conditions. The catalyst is recyclable and almost non-leaching in nature after six runs with an insignificant drop in catalytic activity. Thus we found an economical and viable catalyst [FeII(Anthra-Merf)] for primary carbamates and N-substituted urea synthesis under moderate reaction conditions.

Surfactant is a special kind of amphiphilic compound composed of water-loving and hating parts. The remarkable physical properties like interfacial tension, wettability, emulsifying and dispersing ability make the surfactant accessible for numerous applications from laboratory to commercial products. In recent years, the commercial applications of surfactant have led to greater relevance on account of the environmental concerns and market pressures of this compound. The utility of surfactants in global market increases steadily since its formulation with several beneficial aspects in pharmaceutical, detergent, cosmetic, paint, food science, gas hydrate, nanotechnology, petroleum recovery, bioremediation, chemical transformation and drug delivery. This review briefly discusses the applied aspect of surfactants in diverse area as well as catalytic effect of micelle in organic reactions from the recent literature survey. The trend of increasing use of bioderived surfactants in the modern field of research is also considered in this report. The recent advancement of surfactant-based organic transformations has been emphasized with the role of surfactant aggregates in course of different organic reactions.

A new heterogeneous polymer supported solid phase oxovanadium(IV) catalyst was synthesized successfully. The designed catalyst furnished excellent results in the oxidation reactions of various aromatic alkanes, e.g. toluene, para-xylene, mesitylene. The polymer supported vanadium complex was proved also an efficient catalyst for the oxidation of aromatic alkenes, like substituted styrenes, trans-stilbene, etc. under mild reaction conditions. The supported catalyst was nicely elucidated by SEM-EDAX, TGA, FT-IR and UV–Vis spectral analysis. The catalytic activity was tested in the presence of an environment-friendly oxidant, 30% aqueous H2O2 during the oxidation of broad range of substrates. Another important fact is that the designed oxovanadium(IV) catalyst is heterogeneous in nature. Moreover, the newly synthesized oxovanadium(IV) complex exhibited a notable recoverability and it could be recycled up to six runs devoid of any prominent reduction in catalytic behavior.

Chemical fixation of CO2 into the organic molecules is very challenging from the perspective of greenhouse gas consumption and manufacturing of chemicals with C1 backbone. The process was developed with the synthesis of an efficient polystyrene functionalized Magnesium-anthranilic acid complex (Mg@PS-anthra). The catalytic system was successfully explored as a heterogeneous catalyst for the synthesis of cyclic carbonates by CO2 fixation at atmospheric pressure and Knoevenagel condensation reaction under room temperature solvent free condition. The material was thoroughly characterized by diffuse reflectance UV-vis, FTIR spectroscopy, thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and powder X-ray diffraction (PXRD) techniques. The catalytic pathway has been investigated for the cyclo-addition reaction of epoxides using atmospheric CO2 accompanied by the Knoevenagel condensation reaction with a variety of different aldehydes over cost effective environmental friendly Mg-catalyst. This is attributed to its high catalytic activity, recovery simplicity and excellent five times recycling efficiency; without any substantial decrease in catalytic performance.

In this existing work, an efficient polymer-supported palladium catalyst, a furfurylamine-functionalized Merrifield complex of palladium [Pd@(Merf-FA)], was synthesized and characterized, showing excellent catalytic activity towards in situ carbonylation reactions using carbon monoxide surrogates like formic acid and chloroform. Herein, we examined the catalytic activity of the Pd@(Merf-FA) catalyst for the formylation of aryl iodides and carbonylative Suzuki–Miyaura coupling reactions. The Pd@(Merf-FA) catalyst was systematically characterized by several techniques like HRTEM, elemental mapping, PXRD, TGA-DTA, FESEM, UV-vis, EDAX, CHN and AAS analysis. The catalyst is highly recyclable, able to be recycled up to six times without showing any significant decrease in catalytic activity. The [Pd@(Merf-FA)] catalyst proved to be more efficient compared to the corresponding homogeneous palladium catalyst. In addition, the leaching experiment of the synthesized catalyst was studied, which showed that negligible leaching of metal occurred from the polymeric support.

This work represents an efficient and unique phosphine-free approach for the polystyrene embedded Schiff-base palladium catalyzed diaryl urea synthesis and Suzuki-Miyaura cross-coupling reaction by reductive carbonylation process. The careful instrumental investigations with FE-SEM, TEM, EDAX, TGA, UV–Vis, FTIR, AAS, and elemental analysis precisely characterized the developed heterogeneous catalyst. Reaction parameters, like catalytic natures, starting materials, reaction environment, and solvent were examined sequentially. The present work has been adequately addressed to account for the generation and characterization of a new polymer bound Pd-catalyst and using it in the synthesis of diaryl ureas and diaryl ketones, with no substantial decay of catalytic activity.

A new and interesting heterogeneous iron-anchored naphthyl-azo catalyst (PS-Fe-NAPA) has been designed using aminopolystyrene and 2-nitrosonaphthol followed by loading iron in the naphthyl-azo complex. The prepared polymer supported material has been well characterized by FE-SEM, EDAX, TGA analysis, UV–Vis, FTIR, AAS, and elemental analysis. Iron-anchored naphthyl-azo complex exhibited excellent catalytic activity for the selective oxidation of toluene and substituted toluenes containing inactive benzylic C–H bonds in presence of mild oxidant hydrogen peroxide. Additionally, PS-Fe-NAPA complex is highly recyclable up-to six times without loss of its significant catalytic efficiency.

Different spectroscopic methods have been applied to investigate the chromic acid oxidation of acetaldehyde in aqueous media, catalysed by surfactants. Three representative heteroaromatic nitrogen base promoters, 2-picolinic acid (PA), 2,2’-bipyridine (bpy) and 1,10-phenanthroline (phen), have been associated along with surfactants as promoters to the kinetic study. Comparative studies of unpromoted and promoted reactions invoked that 2,2’-bipyridine produced maximum rate enhancement. The mechanism of the reaction path has been proposed with the help of kinetic results and spectroscopic studies. The observed net enhancement of rate effects has been explained with scientific manipulations and data obtained. The combination of TX-100 and1,10-phenanthroline is found to be most effective for acetaldehyde oxidation. Chromium(VI) oxidation of acetaldehyde in aqueous micellar media has been carried out. Micellar catalysis by TX-100 in association with a ‘phen’ promoter increases the rate of the reaction almost 60 fold. The combination of TX-100 and ‘phen’ is the most suitable one for chromic acid oxidation of acetaldehyde to acetic acid in aqueous media.

Surfactants are classified on the basis of the nature of the hydrophilic groups. Surfactant micelle represents a tiny template or nanoreactor which is generally used for preparing nano-structured materials of desired sizes and shapes with required functionalities. In this present investigation chromic acid oxidation of 1.3-propanediol (1.3-PDO) to 3-hydroxy propionaldehyde (3-HPA) was carried out by using four representative promoters: picolinic acid (PA), 2.3-pyridine dicarboxylic acid (2.3 diPA), 2.2′-bipyridine (bipy) and 1.10-phenanthroline (phen) in presence and absence of surfactants sodium dodecylsulphate (SDS), N-cetylpyridinium chloride (CPC) and Triton-X-100 (TX-100). Reactions were performed under pseudo-first-order condition: [1.3-PDO]T ≫ [Cr(VI)]T in aqueous media at 30 °C temperature. Different combinations were performed to select the suitable combination of promoter and micellar catalyst for this oxidation. Based on the kinetic results, combination of TX-100 and phen was found to be the most suitable one for this oxidation. The mechanisms of both unpromoted and promoted reaction paths were proposed. The product was confirmed by 2.4-DNP test followed by FTIR spectroscopy of the hydrazone derivative.

Aldol condensation is an important synthetic method widely used in organic synthesis. Development of catalytic methods that avoids the production of stoichiometric by-products while maintaining high levels of control available from stoichiometric processes provides an atom-economical alternative for these important transformations. Indeed, numerous catalysts for the aldol reaction have been reported in recent years, including enzymes, catalytic antibodies, organometals, organocatalysts, and small molecules. The direct aldol reaction is the most important reaction employed by synthetic chemists and is common in nature. Recently, various Lewis acids have been examined as catalysts for aldol reactions, but aldol condensation in a micellar medium has not been studied in detail so far. Because of stronger environmental concerns, organic reactions in green media, especially in water, have attracted more attention. It is believed that micelles act as nano reactors to enhance the reaction rates and give v...

The short chain straight fatty acid, valeric or pentanoic acid is chemically significant for its huge applications in variety of industrial target compounds including plasticizers, lubricants, biodegradable solvents, perfumery and pharmaceuticals. Synthesis of valeric acid has been achieved by the cerium(IV) oxidation of a straight C 5 chain valeraldehyde which is a precursor of organic compounds. Ce(IV) is selected as an alternative oxidizing agent in place of higher valent metals. The oxidation kinetics of valeraldehyde has been investigated under pseudo-first-order conditions in acidic medium at 30 °C. Several transition metal salts: Cr(III), Mn(II), Cu(II), Ir(III) and Ru(III) have been introduced to observe their effect on reaction rate 6 . Three different representative non-functional surfactants: Cetyltrimethylammonium bromide (CTAB; cationic), Sodium dodecylsulphate (SDS; anionic) and 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS; zwitterionic) catalyze the reaction significantly. Ir(III) and Ru(III) enhance the oxidation rate in the presence and absence of surfactant. Cr(III), Mn(II) and Cu(II) interestingly inhibit the reaction rate. CMC values of the surfactants have been determined by spectrofluorometry and conductometry. The oxidized product valeric acid has been characterized by NMR and FTIR spectroscopy. Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) experiments support the aggregation of surfactants Ru(III) in association with CTAB micellar catalyst that exhibited a dramatic ~ 330 fold rate enhancement compared to the uncatalyzed reaction path.

A kinetic study of homogeneously micelle-catalyzed, hetero-aromatic N-base (2-picolinic acid, 2,2′-bipyridine and 1,10-phenanthroline)-promoted oxidation of 2-propenol by chromium(VI) in sulfuric acid medium was carried out at 303 K. The pseudo first-order rate constant (k obs) of the oxidation reaction is directly proportional to [H+] and [promoters], which indicates that the reaction is first order with respect to H+ and promoters. The reaction was conducted at four different temperatures from which the activation parameters were calculated. Proton nuclear magnetic resonance (1H-NMR) studies were performed to detect the location of reactant molecules in nanometer-sized micelles. From the observed kinetic results, a suitable mechanism consistent with the rate law has been proposed. The micelles produced a catalytic effect in the entire range of sodium dodecylsulphate (SDS) concentrations used, and the effect is explained by pseudo-phase ion exchange. The combination of 2,2′-bipyridine (bipy) and SDS exhibited a 15-fold rate enhancement of Cr(VI) oxidation of 2-propenol to 2-propenal. Ultraviolet-visible (UV-Vis) spectrum of reaction mixture for the Cr(VI) oxidation of 2-propenol with varying solution colour at different reaction times. Right: Location of reactant molecule in the micellar pseudophase region.

Chromic acid oxidation of 2-butanol to 2-butanone has been carried out by using three representative promoters: picolinic acid, quinolinic acid (2,3 PDA), and dipicolinic acid (2,6 PDA) in the presence and absence of surfactants (SDS, CPC, TX-100). Various combinations have been studied to select the most suitable combination of promoter and micellar catalyst for this oxidation. Reactions were done under kinetic condition [2-butanol]T ≫ [Cr(VI)]T in aqueous media at room temperature. The pseudo-first-order rate constant k obs and half-life of all the reactions were determined. Based on the kinetic results, the combination of SDS and 2,3 PDA was found to be the most efficient for this oxidation. The mechanisms of both unpromoted and promoted reaction paths have been proposed. The product is confirmed by 2,4-DNP test, I.R., and 1H NMR spectroscopy. The anionic surfactant sodium dodecyl sulphate (SDS) accelerates the rate whereas no appreciable change in rate was observed in case of cationic surfactants, CPC, and neutral surfactants, TX-100.

Kinetics of cerium(IV) oxidation of aliphatic alcohols: ethanol, propanol, propan-2-ol, 1-butanol and 2-butanol were studied at 30 °C in the presence and absence of surfactants in acidic medium. The reaction was studied under pseudo-first-order conditions, [alcohol] T ≫ [Ce(IV)] T . Ir(III)-salt used as catalyst had a significant effect on reaction rate. Cationic surfactant CPC ( N -cetylpyridinium chloride) inhibits the reaction rate but zwitterionic surfactant CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) catalyzes the oxidation reaction significantly. CMC value of CHAPS was determined by a spectrofluorometer. The reaction rate increased with increase in the acid concentration of the medium. NMR and FTIR spectra confirmed the oxidized products. The aggregation of surfactants in the reaction condition was studied through Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). Dynamic light scattering (DLS) was used to characterize the shape changes of the aggregates. The variations of the reaction rates for the different alcohols in the presence of surfactants and metal ion catalyst are discussed qualitatively in terms of Berezin's model, nature of surfactants, and charge of surfactants. Ir(III) in association with CHAPS micellar catalyst exhibited ~ 500–2000 fold rate enhancements compared to the uncatalyzed reaction path.

In aqueous acidic media, picolinic acid, 2,3-dipicolinic acid, and 2,6-dipicolinic acid promoted Cr(VI) oxidation of lactose to lactobionic acid has been carried out at room temperature. A possible reaction mechanism, which is based on the kinetic results and the product analysis, has been proposed. The anionic surfactant sodium dodecyl sulphate (SDS) and nonionic surfactant Triton-X-100 (TX-100) accelerate the process while the cationic surfactant N-cetylpyridinium chloride (CPC) retards the reaction.

The kinetics of oxidation of methanol by quinquivalent vanadium in aqueous sulfuric acid medium has been studied at 313 K under pseudo-first-order condition by UV–vis spectrophotometry. Nonfunctional sodium dodecyl sulfate (SDS) surfactant solution was used as a microheterogeneous micellar catalyst. The reaction rate and selectivity strongly depend on the chosen surfactant, and in some cases also on the surfactant concentration. The critical micelle concentration (CMC) values of the SDS surfactant in aqueous medium as well as in the presence of the substrate methanol were determined by the conductivity method, matching well with the kinetically determined CMC value. SDS was found to be an excellent catalyst for oxidation of methanol by vanadium(V) in aqueous sulfuric acid medium, leading to the corresponding oxidized product (formaldehyde), which was detected by 1H nuclear magnetic resonance (NMR). The micellar catalysis by SDS is due to strong binding of the cationic oxidant with the anionic surfactant. Formation of aggregates by the catalytic surfactant was studied using optical microscopy, and the change in shape and size of the aggregates in the reaction condition was studied by using scanning electron microscopy and the dynamic light scattering method. Mechanisms for this oxidation reaction in aqueous medium as well as with micellar catalyst are proposed, being completely supported by our experimental results.

The kinetics of oxidation of formaldehyde by pentavalent vanadium in 3.0 mol dm−3 H2SO4, at 313 K, under pseudo first-order conditions [Formaldehyde]T ≫ [V(V)]T, have been studied by UV–visible spectrophotometry. Two representative non-functional surfactants (sodium dodecyl sulfate, SDS, and polyoxyethylene octyl phenyl ether, TX-100), at concentrations above and below their critical micelle concentrations (CMC), were used as micro-heterogeneous catalysts in this oxidation. The reaction rate and selectivity strongly depend on the surfactant used, and sometimes on surfactant concentration also. The CMC for both surfactants in aqueous media were determined by spectrofluorimetry, from the sharp change in fluorescence intensity. In contrast with TX-100, SDS was an excellent catalyst of oxidation of formaldehyde by vanadium(V) in aqueous micellar media, leading to the corresponding oxidation product. Formic acid was detected by 1H NMR spectroscopy. Formation of aggregates by the catalytic surfactants under the reaction conditions was studied by scanning electron microscopy. Dynamic light scattering was used to characterize shape changes during oxidation, by monitoring changes in the hydrodynamic diameter (D h = 2R h, where R h is hydrodynamic radius) of aggregates. A mechanism proposed for this micelle-catalysed slow oxidation reaction was entirely supported by our experimental results.

Kinetic data for oxidation of D-sorbitol to glucose by hexavalent chromium in aqueous medium and aqueous surfactant medium (SDS, TX-100) have been reported. Effect of promoter such as PA, bipy and phenanthroline on the reaction has been investigated. The reaction is performed under pseudo first order condition with an excess of substrate over the oxidant. The reaction is first order with respect to substrate and oxidant. The micelles have a catalytic effect on the reaction. Combination of phen and TX-100 produces almost twelve times increase in rate of oxidation.

The kinetics and mechanism of the Ru(III) and Ir(III) catalyzed oxidation reaction of p-chlorobenzaldehyde by ceric(IV) have been studied spectrophotometrically at constant ionic strength of 2.0 mol dm− 3 in the presence and absence of the cationic surfactant N-cetylpyridinium chloride (CPC) at 30 °C. The oxidized product p-chlorobenzoic acid was confirmed by the 1H NMR, HR Mass and FTIR spectral analysis. Dramatic rate enhancements have been observed in the oxidation of p-chlorobenzaldehyde by ceric(IV) in the presence of metal ions Ru(III) and Ir(III). The rate of oxidation in the presence of catalyst Ru(III) is much faster than in the Ir(III) catalyzed reaction in micellar media. The observed micellar effect is explained on the basis of reverse CPC micelle formation. This phenomenon was identified with the help of UV Spectra and Scanning Electron Microscopy (SEM) images. The presence of CPC micelles at a certain concentration may increase the effective concentration of the reactant in the hydrophobic part and resulting enhancement of the rate. The substrate undergoes effective collision with the expected positive reactive species Ce(SO4)2 + resulting enhancement of the rate. The enhanced local concentration of reactants in the interfacial region of CPC reverse micelle increases the observed rate. The Ru(III) catalyzed oxidation rate has been found to increase up to 5000 fold in micellar media compared to aqueous media. Ru(III) in combination with CPC is the most effective and suitable catalyst for the catalytic oxidation of p-chlorobenzaldehyde to p-chlorobenzoic acid.

Acetone, the simplest ketone of abundant useful is produced from 2-propanol by oxidation with hexavalent Cr(VI) sluggishly under pseudo 1st order reaction condition. The rate is enhanced considerably using Ru(III) metal salt solution at ppm level as a catalyst. Additional rate enhancement, is obtained in SDS micellar media, is reflected in rapid reduction of peak height of absorbance curve of the oxidant Cr(VI) at λmax = 440 nm. The product, acetone is confirmed by IR spectrum of 2, 4- DNP derivative and 1H NMR study of acetone.

Oxidation of propanol by chromic acid produces propionaldehyde under kinetic condition [propanol]T ≫ [Cr(VI)]T. This oxidation reaction is performed also in presence of micellar catalysts (anionic, cationic and neutral) and hetero-aromatic nitrogen bases promoters (picolinic acid, 2,2′-bipyridine, 1,10-phenanthroline) in aqueous media. The product is confirmed by 2,4-DNP test and 1H NMR spectroscopy. Anionic surfactant sodium dodecyl sulphate (SDS), neutral surfactant triton X-100 (TX-100) accelerated the reaction both in presence and absence of promoters whereas cationic surfactant N-cetyl pyridinium chloride (CPC) inhibited the reaction. Combination of SDS and bipy is found to be the most efficient for this oxidation.

In the present investigation, kinetic studies of oxidation of formic acid with and without catalyst and promoter in aqueous acid media were studied under the pseudo-first order conditions (formic acid)T >>(Cr(VI))T at room temperature. In the 1,10-phenanthroline (phen) promoted path, the cationic Cr(VI) phen complex is the main active oxidant species under- goes a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition through several steps leading to the products CO2 and H2 along with the Cr(III) phen complex. The anionic surfactant (i.e., sodium dodecyl sulfate, SDS) and neutral surfactant (i.e., Triton X-100, TX-100) act as catalyst and the reaction undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Whereas the cat- ionic surfactant (i.e., N-cetyl pyridinium chloride, CPC) acts as an inhibitor restricts the reaction to aqueous phase. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the sur- factants and reactants. The neutral surfactant TX-100 has been observed as the suitable micellar catalyst for the phen pro- moted chromic acid oxidation of formic acid.

Chromic acid oxidation of tartaric acid in aqueous acid media produces glycolaldehyde very sluggishly at room temperature. Suitable combination of promoter (2,2′-bipyridine and 1,10-phenanthroline) and micellar catalyst (sodium dodecyl sulphate, cetylpyridinium chloride, triton X-100) enhances the rate of reaction to almost 14-fold. Observation showed that anionic surfactant (SDS) and nonionic surfactant (TX-100) accelerates the process but cationic surfactant (CPC) retards the reaction. The efficient combination for the production of glycolaldehyde from tartaric acid is found to be 1,10-phenanthroline and SDS.

The micellar catalyzed 2,2′-bipyridine (bipy)-promoted oxidation of glycerol to glyceraldehyde by chromic acid is investigated under the criteria [glycerol]T ≫ [Cr(VI)]T at 30 °C. The critical micellar concentrations values of the three representative surfactants, N-cetylpyridinium chloride (CPC), sodium dodecyl sulphate (SDS), and TX-100, are determined by conductometric and spectrophotometric methods. The oxidized product glyceraldehyde is identified by 2,4-DNP test and FTIR spectral measurement. The pseudo-first-order rate constants (k obs, s−1) are calculated from the slope of plots of ln(A 450) versus time (t) which are linear. From these plots, the kinetic parameter k eff values are calculated and the k eff value of SDS-catalyzed bipy-promoted reaction path was found to be highest among all the combinations. In the bipy-promoted oxidation path, Cr(VI)–bipy complex is the main active oxidant which undergoes attack by the substrate to form the product. The active oxidant Cr(VI)–bipy complex reacts with glycerol to form a ternary complex which undergoes redox decomposition in a rate-limiting step. Here, the anionic surfactant SDS and the neutral surfactant TX-100 both catalyze the reaction in the presence of bipy, whereas the cationic surfactant CPC and neutral surfactant TX-100 inhibit the reaction in the absence of bipy. SDS is found to be the most suitable micellar catalyst for the bipy-promoted chromic acid oxidation of glycerol.

Oxidation kinetics of formaldehyde by Ce(IV) in aqueous medium in the presence of surfactants has been carried out to observe the micellar effect on rate. The oxidation kinetics was studied by UV–VIS spectrophotometry. Three catalysts Cu(II), Cr(III), and Ag(I) are used. Both Cr(III) and Ag(I) are active catalysts for the formaldehyde oxidation in the presence and absence of anionic surfactants, but Cu(II) is not an effective catalyst in this reaction. There are no roles of hetero-aromatic N -bases: picolinic acid (PA), 2,2′-bipyridine (bipy) and 1,10-phenanthroline (phen) as rate enhancement agents rather they inhibit the oxidation reaction. The presence of micelles was found to accelerate the reaction rate and this effect has been explained by the partitioning of the reactants in micelle and also by considering the hydrophobic and electrostatic interactions between the surfactants and reactants. The effect of sodium dodecyl sulfate (SDS) on the rate also indicate that Ce(SO 4 ) 2 + was the main reactive form of cerium(IV). The main product formic acid was identified by the NMR spectroscopy and spot test. The probable mechanism is proposed and rate constants are calculated. The combination of Cr(III) and SDS is the most suitable combination for the conversion of formaldehyde to formic acid.

Oxidation of p-anisaldehyde by chromic acid produces p-anisic acid under kinetic condition [p-anisaldehyde]T≫[Cr(VI)]T. This oxidation reaction is performed also in presence of micellar catalysts in aqueous media at room temperature. The progress of the reaction is monitored spectrophotometrically by following the decay of Cr(VI) at 450 nm wavelength. The product is confirmed by 1H NMR spectroscopy. Anionic surfactant sodium dodecyl sulfate (SDS) accelerated the reaction almost three-fold compared to uncatalyzed path, whereas cationic surfactant N-cetylpyridinium chloride (CPC) and neutral surfactant triton-X-100 (TX-100) inhibited the reaction.

The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation.

Oxidation of organic molecule by metal is very important. Selective oxidants require non aqueous media, which is toxic and hazardous. L-methionine is oxidized to industrially important methyl thiol in micellar media by chromic acid. The overall reaction follows a first order dependency on substrate and hexavalent chromium and second order dependency on hydrogen ion. Here, reverse micelle formation is observed. TX-100 increases the rate where as SDS retards the rate of oxidation.

The effect of the promoter and micellar catalyst on chromic acid on the oxidation of ethanol in aqueous acid media has been studied. Picolinic acid (PA), 1,10-phenanthroline (phen), and 2,2′-bipyridine (bipy) are used as promoters. Sodium dodecyl sulfate (SDS), cetyl pyridinium chloride (CPC), and Triton-X-100 (TX-100) are tested as micellar catalysts. Hexavelent chromium is an active species in the absence of the promoter. In the presence of the heteroaromatic nitrogen bases used as the promoter, Cr(VI)–PA, Cr(VI)–bipy, and Cr(VI)–phen complexes have been proposed as the active oxidants. The time taken for completion of the reaction using different combinations of promoter and micellar catalysts are different. Although the rate is highest (12.5 times) in TX-100 in the absence of the promoter, it is observed that the rate is almost 737 times faster for the combination of SDS and bipy compared to the unpromoted and uncatalyzed path. CPC inhibits the oxidation process. The observed acceleration and retardation of the rate of oxidation process has been explained on the basis of partitioning of the reactants in the micellar and aqueous phase. © 2013 Wiley Periodicals, Inc. Int J Chem Kinet 45: 175–186, 2013

Oxidation of propan-2-ol to acetone was carried out in aqueous media at room temperature. The effect of promoter (PA, bpy, phen), micellar catalyst (SDS, CPC, TX-100) and their combination has been studied. The reactions were performed under the condition [Propan-2-ol]T ≫ [Cr(VI)]T at 30 °C. Then kobs and half life of all the reaction were determined to identify which promoter and which combination are the most effective for this oxidation. Among the promoters phen accelerates the reaction most in aqueous media. In absence of promoters anionic surfactant SDS increases the rate more effectively than neutral surfactant TX-100. CPC retards the rate in comparison to aqueous media. The rate of the oxidation is highest in presence of the combination of bpy and SDS.

Ethers have been synthesized by the different protocols such as Williamson ether synthesis, the Mitsunobu reaction, bimolecular dehydration, the Ullmann method, a transition metal-free coupling reaction between aliphatic alcohols and unsymmetric diaryliodonium salts, room temperature ionic liquid promoted synthesis, Cu(II) catalyzed synthesis, microwave assisted synthesis, and synthesis under solvent free micellar conditions. A good number of homogeneous Bronsted acids and Lewis acid based transition metals have also been reported as catalysts in the etherification of alcohols. The above mentioned pathway has exhibited some drawbacks including their deactivation through decomposition caused by the water formed during the course of the reaction. In many cases these methods also reveal the accumulation of a significant amount of acid at the end of the reaction due to the hydrolysis of Lewis acid catalysts such as metal oxides, which upon neutralization give a considerable amount of salts. A literature survey shows some reports on the use of phase transfer and polymer and clay supported catalysts for the synthesis of symmetrical and unsymmetrical ethers. To a synthetic chemist, an aqueous micellar solution is a good choice as a reaction medium for synthesizing several organic compounds. Micellar conditions are a new direction of study for ether synthesis as they are simple, efficient, economical and environmentally friendly.

Aldol condensation is an important synthetic method widely used in organic synthesis. Development of catalytic methods that avoids the production of stoichiometric by-products while maintaining high levels of control available from stoichiometric processes provides an atom-economical alternative for these important transformations. Indeed, numerous catalysts for the aldol reaction have been reported in recent years, including enzymes, catalytic antibodies, organometals, organocatalysts, and small molecules. The direct aldol reaction is the most important reaction employed by synthetic chemists and is common in nature. Recently, various Lewis acids have been examined as catalysts for aldol reactions, but aldol condensation in a micellar medium has not been studied in detail so far. Because of stronger environmental concerns, organic reactions in green media, especially in water, have attracted more attention. It is believed that micelles act as nano reactors to enhance the reaction rates and give v...

Under pseudo-first order conditions, the monomeric species of Cr(VI) was found to be kinetically active in the absence of phenanthroline (phen) whereas in the phenpromoted path, the Cr(VI)-phen complex undergoes a nucleophilic attack by etane-1,2-diol to form a ternary complex which subsequently experience a redox decomposition leading to hydroxy ethanal and Cr(III)-phen com

The regioselective hydroformylation reactions of long chain olefins catalyzed by different unmodified and modified Co-based, Rh-based catalysts are summarized. The mechanism of homogeneous hydroformylation reactions using Co-based/Rh-based catalysts (unmodified) showed inhibition of reaction rate due to higher partial pressure of CO and also caused difficulty in separating catalysts from the product mixture. Hydroformylation reactions in biphasic medium using water soluble catalysts (Rh, Co, Ru/TPPTS) with an effective surfactant, cetyltrimethylammonium bromide (CTAB), are discussed. The homogeneous biphasic systems are not applicable for long chain olefins due to their low solubility in aqueous phase.

In aqueous media 1,10-phenanthroline (phen) promoted chromic acid oxidation of propan-2-ol produces propan-2-one (acetone). Acetone is separated from the mixture by fractional distillation. The effect of an anionic surfactant (SDS) and a neutral surfactant (TX-100) on the unpromoted and phen-promoted path have been studied. The catalytic effects of micelles have been explained by considering the preferential partitioning of reactants between the micellar and aqueous phases. The reaction becomes much faster when phen and TX-100 are combined together.

Chromic acid oxidation of dl-mandelic acid in the presence and absence of different promoters has been studied in aqueous media under the kinetic conditions [mandelic acid]T ≫ [Cr(VI)]T and [promoter]T ≫ [Cr(VI)]T at 30 °C. The promoters used in this oxidation reaction, picolinic acid (PA), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), are strong chelating ligands which form complexes with most transition metal ions. The reaction is first-order with regard to [H+], [mandelic acid]T, and [Cr(VI)]T and also has first-order dependence on [promoter]T. HCrO4 − was found to be kinetically active in the absence of promoters; in the presence of promoters the Cr(VI)–promoter complexes were believed to be the active oxidants. In this path the Cr(VI)-promoter complex in each case undergoes nucleophilic attack by the mandelic acid to form a ternary complex which subsequently undergoes redox decomposition involving 3e transfer as the rate-determining step. Among the three promoters oxidation is much faster with 1,10-phenanthroline.

Under pseudo-first-order conditions, monomeric Cr(VI) was found to be kinetically active in the absence of picolinic acid (PA), whereas in the PA-promoted path, the Cr(VI)–PA complex undergoes nucleophilic attack by the substrate to form a ternary complex which subsequently experiences redox decomposition, leading to glyceraldehydes and Cr(IV)–PA complex. The uncatalyzed path shows a second-order dependence on [H+], whereas the PA-catalyzed path shows zero-order dependence on [H+]. Both the uncatalyzed and PA-catalyzed path show a first-order dependence on [glycerol]T and [Cr(VI)]T. The PA-catalyzed path is first order in [PA]T. All these observations remain unaltered in the presence of externally added surfactants. The effect of the cationic surfactant cetyl pyridinium chloride (CPC) and anionic surfactant sodium dodecyl sulfate (SDS) on the PA-catalyzed path have been studied. CPC inhibits, whereas SDS accelerates the reaction. Here, SDS is a catalyst for glyceraldehydes production and at the same time ...

The kinetics and mechanism of Cr(VI) oxidation of ethanol in the presence and absence of 1,10-phenanthroline in aqueous acid media have been carried out. Monomeric species of Cr(VI) are kinetically active in the absence of phen, while in the phen catalyzed path, the Cr(VI)-phen complex has been suggested as the active oxidant. In the catalyzed path, the Cr(VI)-phen complex participates in the oxidation of ethanol and ultimately is converted into the Cr(III)-phen complex. In the uncatalyzed path, the Cr(VI)-substrate ester experiences an acid catalyzed redox decomposition in the rate-determining step. The uncatalyzed path shows a second-order dependence on [H+], while the phen catalyzed path shows a first-order dependence on [H+]. Both the uncatalyzed and phen-catalyzed paths show first-order dependence on [ethanol]T and [Cr(VI)]T. The phen-catalyzed path is first order in [phen]T. These observations remain unaltered in the presence of externally added surfactants. CPC inhibits the reactions while SDS cata...

In aqueous acidic media, picolinic acid, 2,2′-bipyridine and 1,10-phenanthroline promoted Cr(VI) oxidation of 1-butanol produces 1-butanal. 1-butanal is separated from mixture by fractional distillation. The anionic surfactant (SDS) and neutral surfactant (TX-100) accelerate the process while the cationic surfactant (CPC) retards the reaction. Combination of bipy and SDS is the best choice for chromic acid oxidation of 1-butanol to 1-butanal in aqueous media.

Picolinic acid, 2,2′-bipyridine and 1,10-phenanthroline promoted Cr(VI) oxidation of d -galactose to d -galactonic acid in three representative aqueous micellar media has been studied. The anionic surfactant (SDS) accelerated the rate of reaction while the cationic surfactant (CPC) and neutral surfactant (TX-100) retarded the reaction rate. Combination of bipy and SDS is the best choice for chromic acid oxidation of d -galactose to d -galactonic acid in aqueous media although 1,10-phenanthroline is best promoter in absence of micellar catalyst.

Vanadium(V) oxidation of ethanol follows a first order dependency on the concentration of ethanol, vanadium(V), H+ and HSO4 –. These observations remain unaltered in the presence of externally added surfactants. The effect of the cationic surfactant (i.e., N-cetylpyridinium chloride [CPC]), anionic surfactant (i.e., sodium dodecyl sulphate [SDS]) and neutral surfactant (i.e., Triton X-100 [TX-100]) has been studied. CPC inhibits the reactions, whereas SDS and TX-100 accelerate the reaction to different extents. Observed effects have been justified by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and TX-100 can be used as catalysts in the production of acetaldehyde from ethanol.

The chromic acid oxidation of formaldehyde in micellar solution of sodium dodecyl sulphate (SDS)/TX-100 at room temperature has been investigated under pseudo first-order condition. Heterocyclic bases such as picolinic acid (PA), 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen) have been employed which acts as a promoter. The rate of this oxidation reaction increased 50 times by combination of bipy and SDS micelle compared to rate in pure aqueous media. Here, we can avoid hazardous organic solvents, high pressure and temperature which are required for conventional preparation of formic acid. The catalytic effect of SDS/TX-100 micelle has been explained.

Chromic acid oxidation of D-mannitol to mannose has been studied in aqueous media. The effect of promoter (PA, phen and bpy), micellar catalyst (SDS, TX-100 and CPC) and their combination is studied. All the reactions were performed under the condition [D-mannitol]T ≫ [Cr(VI)]T. All the promoters accelerate the reaction rate and the rate is highest in presence of phen. In absence of a promoter the anionic surfactant SDS increases the rate followed by Triton TX-100. The cationic surfactant CPC retards the reaction in comparison to the reaction in aqueous media. Although phen is the best promoter in absence of any surfactant the catalyst combination of bpy and SDS produce a maximum rate enhancement.