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- Journal of Molecular Catalysis A: Chemical 303():iii (2009)
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- Journal of Molecular Catalysis A: Chemical 303():v-x (2009)
- Theoretical studies of stereoselectivities in the direct organocatalytic Mannich reactions involving ketimine
- Journal of Molecular Catalysis A: Chemical 303():1-8 (2009)
Quantum mechanics calculations have been performed to study the stereoselectivities in the direct Mannich reactions catalyzed by different chiral secondary amine catalysts. The effects of two kinds of catalysts, (S)-1-(2-pyrrolidinylmethyl) pyrrolidine and proline on the diastereoselectivities of the direct Mannich reactions between ketimine and aldehyde have been studied with the aid of the BH and HLYP method. Transition states of the stereochemistry-determining Csingle bondC bond-forming step with the enamine intermediate addition to the ketimine for the subject reactions are reported. These theoretical calculations provide a good explanation for the opposite diastereoselectivities of these two different kinds of catalysts. Calculated and observed diastereomeric ratio and enantiomeric excess values are in good agreement. - Enhanced photocatalytic activity of bismuth molybdates with the preferentially exposed {0 1 0} surface under visible light irradiation
- Journal of Molecular Catalysis A: Chemical 303():9-14 (2009)
In this work, γ-Bi2MoO6 samples with different morphologies and surface structures were prepared via simple solution methods and their photocatalytic degradations of rhodamine-B (RhB) were investigated under visible light irradiation. In spite of their lower BET surface area, we found that the γ-Bi2MoO6 sheets with the preferentially exposed {0 1 0} surface exhibited the greatly enhanced photocatalytic activity. The mechanism study and structural analysis of stoichiometric γ-Bi2MoO6 indicated that the particular reactive surface with much more oxygen defects and in-plane vacancies, derived from the larger distortion of the MoO6 octahedra, play a more important role of the enhanced photocatalytic activity. - Amination of aryl chlorides and fluorides toward the synthesis of aromatic amines by palladium-catalyzed route or transition metal free way: Scopes and limitations
- Journal of Molecular Catalysis A: Chemical 303():15-22 (2009)
This paper presents the application of zeolite (NaY) supported Pd and Cu catalysts in amination reactions of aryl chlorides. Using 0.1 mol% Pd, good yields could be achieved in the coupling of 4-chloroacetohphenone and piperidine after 6 h at 140 °C. In the second part, we demonstrate two different pathways for transition metal free amination of activated aryl chlorides and fluorides, and, respectively, non- and deactivated aryl chlorides. These reactions were performed with excellent yields in short reaction time without any transition metal catalyst under optimized reaction conditions. Activated aryl halides react smoothly using 2.1 equiv. amine without additional base whereas deactivated aryl halides require the use of a strong base (KOtBu) for high conversion. DFT calculations were performed to study the surprising influence of substitutents at the aromatic ring on selectivity in metal free aminations found in this work. - An EPR study of the vanadium species formed upon interaction of vanadyl N and C-capped tris(phenolate) complexes with AlEt3 and AlEt2Cl
- Journal of Molecular Catalysis A: Chemical 303():23-29 (2009)
Reactions of vanadyl N and C-capped tris(phenolate) complexes 1 and 2 (Scheme 1) with AlEt3 and AlEt2Cl, in the absence and in the presence of ethyltrichloroacetate (ETA), were monitored by EPR. It was shown, that vanadium(IV) complexes with proposed structures LNVIV(Et)(AlEt3) and LNVIV(Et)(AlEt2Cl) are formed at the initial stage of interaction of 1 with AlEt3 and AlEt2Cl, respectively (LN are unidentified products of interaction of the initial N-capped ligand and Vdouble bond; length as m-dashO moiety with aluminum alkyls). In the absence of re-activator (ETA), LNVIV(Et)(AlEt3) and LNVIV(Et)(AlEt2Cl) rapidly convert at room temperature to V(III) species, which relatively slowly transform to complexes LNVIIEt2 and LNVII(Et)Cl. Concentration of LNVIV(Et)(AlEt2Cl) dramatically increases in the presence of ETA, that correlates with the increase of the polymerization activity of the catalyst system 1/AlEt2Cl. The complex LNVIV(Et)(AlEt2Cl) can be precursor of the active ! species of polymerization. Similarly, ETA increases concentration of vanadium(IV) complex LCVIV(Et)(AlEt2Cl) in the catalyst system 2/AlEt2Cl (LC are unidentified products of interaction of the initial C-capped ligand and Vdouble bond; length as m-dashO moiety with aluminum alkyls). The complex LCVIV(Et)(AlEt2Cl) can be precursor of the active species of polymerization. - Efficient synthesis of styrene carbonate from CO2 and styrene oxide using zinc catalysts immobilized on soluble imidazolium–styrene copolymers
- Journal of Molecular Catalysis A: Chemical 303():30-34 (2009)
Preparation of zinc catalysts (Zn/PS-IL[X], X = Br−, Cl−, BF4−, and PF6−) supported on imidazolium–styrene copolymers, as well as their catalytic use for the solvent-free synthesis of styrene carbonate from CO2 and styrene oxide, are described. Among the catalysts examined, Zn/PS-IL[Br] was proved to be the most efficient. When used in a homogeneous system during the reaction process, Zn/PS-IL[Br] gave a 97.5% yield of product with a TOF value that can be up to about 3800 h−1. Due to its immiscibility with ethanol, Zn/PS-IL[Br] can be separated like a heterogeneous catalyst through solvent precipitation, and reused at least three times for the reaction without significant loss of activity. - Effects of Pb and Mg doping in Al2O3-supported Pd catalyst on direct oxidative esterification of aldehydes with alcohols to esters
- Journal of Molecular Catalysis A: Chemical 303():35-42 (2009)
An investigation was carried out of oxidative esterification of aldehydes with alcohols and oxygen to corresponding esters over Pb, Mg-doped Al2O3-supported Pd catalyst. This catalyst was prepared by impregnating method and characterized by X-ray diffraction, differential scanning calorimetry, X-ray photoelectron spectroscopy, and transmission electron microscopy. The results showed that Pd atoms with Pb atoms formed bimetallic Pd3Pb crystals, and Mg existed on the support as MgO with electron effect on Pd3Pb crystals. The reactions of aldehyde with alcohol in the presence and absence of oxygen over the doped and undoped Pd catalysts were examined to evaluate the effects of Pb and Mg. It was found that the doping agents Mg had positive effect on reaction rate acceleration only in the presence of oxygen, Pb or the collaboration of Pb and Mg had positive effect on reaction rate acceleration and selectivity enhancement in the presence of oxygen or not. - Carbonylation of aromatic dinitro compounds with carbon monoxide to respective dicarbamates in the presence of the PdCl2/Fe/I2/Py catalytic system
- Journal of Molecular Catalysis A: Chemical 303():43-51 (2009)
The object of this study was the reductive carbonylation of 1,3-dinitrobenzene, 1,4-dinitrobenzene and 2,4-dinitrotoluene to respective dicarbamates in the presence of the PdCl2/Fe/I2/Py catalytic system. By increasing the catalyst amount and extending the carbonylation reaction time a 100% conversion of dinitrobenzene to the corresponding dicarbamates was achieved with a selectivity of 87, 68, and 55%, for 1,4-, 1,3-dinitrobenzene and 2,4-dinitrotoluene, respectively. - Synthesis, spectral, electrochemical and catalytic properties of Cu(II), Ni(II) and Co(II) complexes containing N, O donors
- Journal of Molecular Catalysis A: Chemical 303():52-59 (2009)
Metal(II) chelates of Schiff bases derived from the condensation of multi-substituted aniline with mono- and di-substituted salicylaldehyde have been prepared and characterized by 1H NMR, IR, electronic, EPR, magnetic and cyclic voltammetry measurements. The complexes are of the type M(X-DPMP)2 [(M = Cu(II), Ni(II) or Co(II)), DPMP = 2-[(2,6-diisopropylphenylimino)methyl]phenol, X = Br, Cl, I, BrCl]. The Schiff bases behave as monobasic bidentate ligand in their complexes. The spectral data indicate that the ligand coordinates through the phenolic oxygen and the azomethine nitrogen atoms. The observed A|| values in the Cu(II) complexes indicate a tetrahedrally distorted square planar structure. The cyclic voltammetric redox potential of copper(II) and nickel(II) complexes suggest the existence of irreversible pairs in acetonitrile. Cu(Br-DPMP)2 was found to be an efficient catalyst for cyanosilylation of aldehydes under mild conditions. - Growth of zinc hexacyanoferrate nanocubes and their potential as heterogeneous catalyst for solvent-free oxidation of benzyl alcohol
- Journal of Molecular Catalysis A: Chemical 303():60-64 (2009)
Zinc hexacyanoferrate nanocubes have been synthesized following an extremely simple method and characterized by elemental analysis, thermal analysis, infrared spectroscopic and X-ray diffraction techniques. Field emission scanning electron microscopic image showed that it consisted of sharp cubic particles with size ranging from 83 to 164 nm. Catalytic activity of nanocubic zinc hexacyanoferrate has been studied for solvent-free oxidation of benzyl alcohol using H2O2 as oxidant under the optimum conditions of certain parameters such as benzyl alcohol to H2O2 molar ratio, the amount of catalyst, reaction time and temperature. - Study of phase transformation and catalytic performance on precipitated iron-based catalyst for Fischer–Tropsch synthesis
- Journal of Molecular Catalysis A: Chemical 303():65-71 (2009)
Detailed phase transformation in syngas (H2/CO = 1.2) on a precipitated iron-based catalyst was studied by N2 physisorption, X-ray diffraction (XRD), Mössbauer effect spectroscopy (MES), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy (LRS). Fischer–Tropsch synthesis (FTS) performance of the catalyst was investigated in a slurry-phase continuously stirred tank reactor (STSR). The hematite in the fresh catalyst was reduced initially to magnetite, and then the magnetite in the bulk reached steady state slowly with increasing reduction time. Simultaneously, the Fe3O4 on the surface layers converted gradually to iron carbides, accompanied with the continual increase in the amounts of surface carbonaceous species. In the FTS reaction, the catalytic activity presented an increased trend with gradual carburization of the catalyst by keeping the stability in the bulk Fe3O4, suggesting that the conversion of magnetite to iron carbides in the near-surface region! s provides probably the active sites for FTS. In addition, the chain growth reaction was restrained and the hydrogenation reaction was enhanced with increasing reduction duration. - Aqueous hydroformylation reaction mediated by randomly methylated β-cyclodextrin: How substitution degree influences catalytic activity and selectivity
- Journal of Molecular Catalysis A: Chemical 303():72-77 (2009)
A crude mixture of randomly methylated β-cyclodextrin (RAME-β-CD) has been fractionated by chromatographic column to evaluate the influence of the methylation degree on activity and selectivity of a rhodium/tris(m-sulfonatophenyl)phosphane trisodium salt (TPPTS) catalytic system in hydroformylation of 1-decene. Each sample of methylated β-cyclodextrin (β-CD) was carefully analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and electrospray ionization mass spectrometry (ESI-MS). The catalytic activity was found to gradually increase with the number of methyl groups on the methylated β-CD whereas the chemoselectivity and regioselectivity remained unchanged. - Metathesis co-polymerization as a means of comparing the reactivity of ruthenium initiators in conventional solvents and ionic liquids
- Journal of Molecular Catalysis A: Chemical 303():78-83 (2009)
Ring opened metathesis polymerization was carried out on a number of cyclic olefins using Cl2(PCy3)2Ru[CH(Ph)] and [(η6-p-cymene)(PCy3)RuCl(double bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashCPh2)]OTf in dichloromethane and a range of ionic liquids. Microstructural parameters were determined from the 13C NMR spectra recorded of the polymers. The findings indicate that an increase in activity of both catalysts can occur in certain ionic liquids systems. It was also observed that the activity of [(η6-p-cymene)(PCy3)RuCl(double bond; length as m-dashCdouble bond; length as m-dashCdouble bond; length as m-dashCPh2)]OTf increases upon addition of an excess of phenol. - Room temperature selective oxidation of toluene over vanadium substituted polyoxometalate catalysts
- Journal of Molecular Catalysis A: Chemical 303():84-89 (2009)
Selective oxidation of toluene at room temperature was carried on vanadium containing molybdophosphoric acid supported on niobia catalysts using t-butyl hydrogen peroxide (TBHP) as oxidant. The catalysts were characterized by FT-IR, X-ray diffraction (XRD), 31P MAS NMR, Laser Raman spectroscopy and N2 adsorption. The characterization data reveals the incorporation of vanadium and retention of intact Keggin ion on the support. The catalyst activity is related to the presence of vanadium in Keggin ion. The effect of TBHP–toluene concentration on the conversion and selectivity during toluene oxidation was also studied. A plausible reaction mechanism for the selective formation of benzaldehyde was proposed. The present catalyst is highly active, selective towards benzaldehyde and reusable with out any appreciable loss in activity and selectivity. - Defect of HY as catalyst for selective catalytic reduction of NO in comparison with the pentasil zeolites
- Journal of Molecular Catalysis A: Chemical 303():90-95 (2009)
The specific behavior of HY in some steps that possibly occurred in the selective catalytic reduction of NO by hydrocarbon (HC-SCR) was investigated. Experimental results indicated that the activity of HY for NO oxidation to NO2 was much lower than those of the pentasil zeolites (HZSM-5, HFER and HMOR). In addition, FTIR measurements showed that both nitrosonium ions (NO+) and nitrate species were remarkably produced at 300 °C over the pentasil zeolites and they were highly active towards hydrocarbons at the temperature. On the contrary, no NO+ species could be detected over HY and the nitrate species produced over the zeolite were almost inactive towards reduction at the same reaction condition. It is proposed that the low amount of strong Brönsted acids of HY accounts for the above inferior founctions of the zeolite required by HC-SCR, leading to the low NO reduction activity. - Significant influence of microwave dielectric heating on ionic liquid catalyzed transesterification of ethylene carbonate with methanol
- Journal of Molecular Catalysis A: Chemical 303():96-101 (2009)
This paper reports an energy efficient route for the transesterification of ethylene carbonate (EC) with methanol using ionic liquid (IL) as catalyst through microwave heating. The influence of the reaction parameters such as the microwave irradiation time, power, EC/methanol ratio, and the cation and anion of both 1-alkyl-3-methyl imidazolium and tetraalkyl ammonium salts, was examined under these conditions. Also the heating characteristics of this reaction mixture were examined at various intervals. The coproduction of an equimolar amount of dimethyl carbonate (DMC) and ethylene glycol (EG) were obtained in high yield and better selectivity. Comparative studies were carried out under different reaction conditions with classical heating modes. An induction period observed during conventional reaction can be avoided by microwave dielectric heating. Overall, this study highlights an environmentally benign technology for the production of DMC, a "green reagent", thr! ough microwave irradiation. - Ethylene polymerization and ethylene/1-octene copolymerization using group 4 half-metallocenes containing aryloxo ligands, Cp*MCl2(OAr) [M = Ti, Zr, Hf; Ar = O-2,6-R2C6H3, R = tBu, Ph]—MAO catalyst systems
- Journal of Molecular Catalysis A: Chemical 303():102-109 (2009)
Effect of the centered metal toward the catalytic activity as well as comonomer incorporation has been explored in ethylene (co)polymerization using a series of Cp*MCl2(O-2,6-R2C6H3) [M = Ti (1), Zr (2), Hf (3); R = Ph (a), tBu (b), iPr (c)] in the presence of methylaluminoxane (MAO) cocatalyst. Complexes 2a, 3a,b were prepared and identified, and the structures for 2–3a,b were determined by X-ray crystallography as a distorted tetrahedral geometry around the metal center. The catalytic activity in ethylene polymerization was affected by the centered metal employed [Ti > Zr > Hf]; the complexes containing 2,6-diphenylphenoxy ligand (1–3a) showed higher catalytic activities than the complexes containing 2,6-di-tert-butylphenoxy analogues (1–3b). The molecular weights in the resultant polymers prepared by the Zr and the Hf analogues were lower than those prepared by the Ti–Ph (1a) and the Ti–iPr (1c) analogues. Although the copolymerizations of ethylene with 1-! octene afforded the copolymers with uniform molecular weight distributions (except 1b), both the catalytic activities and the 1-octene incorporation were highly affected by the centered metal employed; the Ti–iPr analogue (1c) seems to be the most suited in terms of both the catalytic activity and the 1-octene incorporation. The attempted copolymerization of ethylene with 2-methyl-1-pentene using 2a,b and 3a—MAO catalysts afforded linear polyethylene. - Synthesis, characterization and ethylene polymerisation of 9,10-phenanthrenequinone-based nickel(II)-α-diimine complexes
- Journal of Molecular Catalysis A: Chemical 303():110-116 (2009)
Two 9,10-phenanthrenequinone-based α-diimine ligands (N,N′Z, N,N′E)-N,N′-(phenanthrene-9,10-diylidene)bis(2,6-dimethylaniline) (1) and (Z)-2,6-dimethyl-N-((E)-10-methylbenzo[f]phenanthro[10,1-bc]azepin-8(14H)-ylidene)aniline (2), were prepared by condensation of 2,6-dimethylaniline and 9,10-phenanthrenequinone in the presence of the TiCl4/1,4-diazabicyclo[2.2.2]octane catalytic system in a one-pot reaction. It was experimentally demonstrated that a reaction temperature increase favors the formation of ligand 2. Nickel dibromide complexes 3 and 4 were synthesized from ligands 1 and 2, respectively, and both showed high productivities as catalysts for polymerisation of ethylene. Complex 3 yielded ultrahigh molecular weight polyethylenes at low temperature (e.g., 1.26 × 106 g/mol at −15 °C), which are significantly higher than those produced by the corresponding 2,3-butanedione- or acenaphthenequinone-based α-diimine nickel complexes. Complex 4 produced polyet! hylenes with relatively lower molecular weights, when compared to 3. It was shown that the catalyst structure and reaction conditions, like the reaction temperature and concentration of activator (MAO), have substantial influence on the polymerisation activities and molecular weights and microstructures of the resulting polymers. - Elucidation of the catalytic cracking pathway for unsaturated mono-, di-, and triacylglycerides on solid acid catalysts
- Journal of Molecular Catalysis A: Chemical 303():117-123 (2009)
Heterogeneous catalytic transformation of lipids to transportation fuels offers a unique opportunity to provide sustainable energy while utilizing the current petroleum refining infrastructure. The reaction chemistry for the heterogeneous catalytic cracking of unsaturated acylglycerides was studied. Mono-, di-, and triolein, which are acylglycerides with oleic acid as the fatty acid constituent, were reacted at 400 °C over H+ZSM-5, faujasite, and silica–alumina catalysts. Reactions were carried out using a pulse-type microreactor utilizing online GC analysis. This technique allowed real time evaluation of reaction products using mass spectrometry and quantitation using a thermal conductivity detector. Selected products of these reactions were further reacted in an effort to elucidate the reaction pathway for producing green fuels from unsaturated lipids. The results indicated the removal of the heteroatom from the oxygenated feedstock by formation of CO and CO2. The! shape-selective zeolite catalysts (i.e. H+ZSM-5 and faujasite) promoted the formation of aromatic compounds as tertiary cracking products. Silica–alumina, an amorphous catalyst, promoted the formation of linear dienes. A reaction scheme has been proposed for the deoxygenation of lipid compounds. These results reveal the potential of using lipid feedstocks for transportation fuels. - Polymerization of terminal alkynes with a triply bonded ditungsten halo-complex
- Journal of Molecular Catalysis A: Chemical 303():124-131 (2009)
In this work are described the reactions of the triply bonded ditungsten face-sharing bioctahedral (fsbo) halides A3[W2(μ-Cl)3Cl6] (A+ = K+ (1), nBu4N+ (2)) and Na[W2(μ-Cl)3Cl4(THF)2]·(THF)3 (3), which contain the (Wtriple bond; length of mdashW)6+ core and have the a′2e′4 electronic configuration, with a range of 1-alkynes (RCtriple bond; length of mdashCH, R = Ph (PA), C7H7 (o-methylphenyl), C7H4F3 (o-trifluoromethylphenyl), nBu, tBu, Me3Si, C10H7 (naphthyl)). At ambient temperature complexes 1 and 2 (THF, CH2Cl2) are inactive towards PA, and when activated with AlCl3 (CH2Cl2) give oligomeric products in low yield. In contrast, compound 3 acts as a highly efficient uni-component initiator for the homogeneous or heterogeneous polymerization of the above alkynes providing polymers with high molecular weight. Small amounts of the cyclotrimers are also formed. The reaction is very fast in CH2Cl2 or in bulk and slower in oxygen-coordinating solvents (THF, Et2O). Th! e conditions dictate the microscopic structure of the polymers formed. The yield is not significantly affected by the bulk of the alkyl substituent. The polymerization of PA was studied in more detail. In THF it is multimodal involving polymerization and equilibration or degradation steps. Direct evidence in support of the metathetical nature of the polymerization has been obtained from the in situ examination of the reaction at various temperatures ranging from −20 to 20 °C by 1H NMR, and the observation of at least two major active species attributed to the tungsten-carbene propagating polymerization centers. - Lewis acid catalysed microwave-assisted synthesis of diaryl sulfones and comparison of associated carbon dioxide emissions
- Journal of Molecular Catalysis A: Chemical 303():132-136 (2009)
Diaryl sulfones were synthesised using a variety of Lewis acid catalysts under microwave activation. Catalysts were used both homogeneously and heterogeneously (K10 montmorillonite clay). The most effective catalyst in terms of yield was found to be iron(III) chloride with a yield of 89%. Supported iron(III) chloride gave a yield of 77%. The highest selectivity to the 4,4′ isomer was obtained using supported bismuth(III) chloride. A series of other diaryl sulfones were synthesised using microwave-assisted Lewis acid catalysis in good yield. The energy used in the reactions was measured and the quantity of carbon dioxide generated per mole of product was compared using microwave and traditional thermal activation (oil bath) methods. Where yields were comparable, microwave-assisted synthesis was shown to produce substantially less carbon dioxide per mole of product. - Characterisation of magnesium carboxylates and their catalytic C–C bond formation reactions
- Journal of Molecular Catalysis A: Chemical 303():137-140 (2009)
Condensation reactions of aromatic aldehydes with acetone for carbon–carbon bond formation are catalysed by magnesium carboxylate complexes. Two magnesium complexes having compositions [(4-NO2-C6H4CO2)2Mg(CH3OH)4] (1) and [(4-CH3-C6H4CO2)2Mg(CH3OH)2(H2O)2] (2) that are catalysts for such reactions are synthesized. They are prepared by reacting metallic magnesium with methanol in the presence of 4-nitrobenzoic acid and 4-methylbenzoic acid, respectively. Structures of 1 and 2 are determined by X-ray crystallography. The catalytic reactions of these two complexes for carbon–carbon bond formation reactions of various aromatic aldehydes with acetone are presented. - Favorable recycling photocatalyst TiO2/CFA: Effects of loading method on the structural property and photocatalytic activity
- Journal of Molecular Catalysis A: Chemical 303():141-147 (2009)
In order to more easily separate TiO2 photocatalyst from the treated wastewater, TiO2 was immobilized on the surface of coal fly ash by employing three kinds of approaches, sol–gel procedure, ambient hydrolysis procedure and hybrid slurry procedure. The effects of loading method on the structural property of TiO2-coated coal fly ash (TiO2/CFA), such as morphology, crystal structure, porous property and ultraviolet-visible absorption were investigated, and the photocatalytic activity of TiO2/CFA was evaluated by the photocatalytic depigmentation and mineralization of methyl orange solution. The results show that TiO2/CFA particles are easy to precipitate and recover from water. The hybrid slurry procedure is a more proper method to immobilize TiO2 on coal fly ash than the other two procedures because the TiO2/CFA sample prepared by hybrid slurry procedure exhibits higher photocatalytic activity and better repeatability. - Application of linear free-energy relationships to perhydrolysis of different carboxylic acids over homogeneous and heterogeneous catalysts
- Journal of Molecular Catalysis A: Chemical 303():148-155 (2009)
This paper describes the application of LFER to understand the mechanism of the perhydrolysis of carboxylic acids over homogeneous and heterogeneous catalysts. Several experiments were carried out with different linear carboxylic acids: formic, acetic, propionic and butyric acids; using sulfuric acid and Amberlite IR-120 as catalyst and different reaction temperatures. From the experiments, the apparent rate constants decrease in the following order: kapp (PFA) > kapp (PAA) > kapp (PPA) > kapp (PBA), in both catalytic system. Furthermore, it was found that this reaction follows Taft and Charton correlations, which implies that the steric effect of the substituent governs that reaction and the mechanism is similar between the different carboxylic acids. Comparison between homogeneous and heterogeneous catalytic system was carried out based on the analysis of the kinetic expression.
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