Kinetics and mechanism of the selective oxidation of primary aliphatic alcohols under phase transfer catalysis

Bijudas, K.; Nair, T. D. Radhakrishnan

doi:10.5267/j.ccl.2013.12.001

Cited by 12 publications

(5 citation statements)

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“…The study of the influence of dielectric constants of solvents forms an important aspect in chemical kinetics in deducing the mechanism of the reaction. The excessive use of quaternary ammonium salts as PT catalyst in our earlier studies prompted us to carry out the preparation of it by applying Menshutkin reaction [23][24][25]. More over very little works have been reported on kinetic and mechanistic studies of quaternization between N,N-Dimethylaniline (DMA) and benzyl chloride (BC) or such systems in polar solvents [26][27][28].…”

Section: -9595mentioning

confidence: 99%

Kinetics of Quaternization Between N, N-Dimethylaniline and Benzyl Chloride in Polar Solvents-a Revisit to Menshutkin Reaction

Bashpa,

Rajendran,

Bijudas

2021

JASR

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This work reports an extension of Menshutkin reaction and involves the studies on kinetics of quaternization reaction between N,N-Dimethylaniline and benzyl chloride in acetone and in other various solvents at 300 K. The progress of the reaction was followed by measuring the conductance of the product formed at regular intervals of time. The effect of [benzyl chloride] and [N,N-Dimethylaniline] on reaction rate was studied under pseudo-first order condition and the rate showed first order dependence on both [benzyl chloride] and [N,N-Dimethylaniline]. The effect of dielectric constant of the medium on reaction rate was studied by employing various solvents such as methyl ethyl ketone, isopropyl alcohol, ethyl alcohol, methyl alcohol and acetonitrile and the rate is found to increase with increase in dielectric constant of the medium. The linear plot with a negative slope on plotting log k2 against 1/D where D is the dielectric constant of the medium indicates the existence of a highly charged or a polar transition state during the progress of the reaction. The quaternization reaction was also carried out at different temperatures so as to compute the various thermodynamic parameters like activation energy, enthalpy of activation, entropy of activation and Gibb’s free energy change. The higher value of activation energy is attributed for a slower reaction which is sterically controlled rather than thermodynamically controlled. The negative value of entropy of activation (ΔS*) indicates some sort of surrendering of disorder in the transition state on its formation which proves that it is highly ordered with sufficient charge separation and polar in character. The product after purification was analysed by melting point and infra-red spectral analysis and is proved to be N-Benzyl-N,N-dimethylphenylmethanaminium chloride. A plausible mechanism in accordance with the obtained experimental results is reported.

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Section: -9595mentioning

confidence: 99%

Kinetics of Quaternization Between N, N-Dimethylaniline and Benzyl Chloride in Polar Solvents-a Revisit to Menshutkin Reaction

Bashpa,

Rajendran,

Bijudas

2021

JASR

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“…[2] Traditionally, synthetic as well as most of the industrial alcohol oxidation processes is carried out in the presence of a stoichiometric amount of hazardous oxidizing agents (HNO 3 , KMnO 4 , CrO 3 , etc.) [3][4][5][6] or expensive metals or metal salts (Au, Pt, Pd, Ru, Ir, Cr, etc.) [7] in halogenated solvents.…”

Section: Introductionmentioning

confidence: 99%

Solvent‐free oxidation of straight‐chain aliphatic primary alcohols by polymer‐grafted vanadium complexes

Kachhap

Chaudhary

Haldar

2021

Applied Organom Chemis

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Oxidovanadium(IV) complexes [VO(tertacac)2] (1), [VO(dipd)2] (2), and [VO(phbd)2] (3) were synthesized by reacting [VO(acac)2] with 2,2,6,6‐tetramethyl‐3,5‐hepatanedione, 1,3‐diphenyl‐1,3‐propanedione, and 1‐phenyl‐1,3‐butanedione, respectively. Imidazole‐modified Merrifield resin was used for the heterogenization of complexes 1–3. During the process of heterogenization, the V4+ center in complex 2 converts into V5+, whereas the other two complexes 1 and 3 remain in the oxidovanadium(IV) state in the polymer matrix. Theoretically, calculated IPA values of 1–3 suggest that 2 is prone to oxidation compared with 1 and 3, which was also supported by the absence of EPR lines in 5. Polymer‐supported complexes Ps‐Im‐[VIVO(tertacac)2] (4), Ps‐Im‐[VVO2(dipd)2] (5), and Ps‐Im‐[VIVO(phbd)2] (6) were applied for the solvent‐free heterogenous oxidation of a series of straight‐chain aliphatic alcohols in the presence of H2O2 at 60°C and showed excellent substrate conversion specially for the alcohols with fewer carbon atoms. Higher reaction temperature improves the substrate conversion significantly for the alcohols containing more carbon atoms such as 1‐pentanol, 1‐hexanol, and 1‐heptanol while using optimized reaction conditions. However, alcohols with fewer carbon atoms seem less affected by reaction temperatures higher than the optimized temperature. A decreasing trend in the selectivity(%) of carboxylic acid was observed with increasing carbon atoms among the examined alcohols, whereas the selectivity towards aldehydes increased. The order of efficiency of the supported catalysts is 4 > 6 > 5 in terms of turnover frequency (TOF) values and substrate conversion, further supported by theoretical calculations.

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“…Various forms of chromate are used in the kinetic studies of the oxidation of benzyl alcohols in aqueous and in other polar solvents [1][2]. But there are very little information regarding the kinetics of corresponding reactions in non polar solvents [3][4][5]. This is because; most of the organic substrates are soluble in non polar solvents while oxidants are soluble only in polar solvents.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Studies on the Selective Oxidation of Benzyl Alcohols in Organic Medium under Phase Transfer Catalysis

Bijudas¹,

Bashpa²,

Nair³

2014

Bull. Chem. React. Eng. Catal.

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Kinetic studies on the oxidation of benzyl alcohol and substituted benzyl alcohols in benzene as the reaction medium have been studied by using potassium dichromate under phase transfer catalysis (PTC). The phase transfer catalysts (PT catalysts) used were tetrabutylammonium bromide (TBAB) and tetrabutylphosphonium bromide (TBPB). Benzyl alcohols were selectively oxidised to corresponding benzaldehydes in good yield (above 90%). The order of reactivity among the studied benzyl alcohols is p-OCH3 > p-CH3 >-H > p-Cl. Plots of log k2 versus Hammett's substituent constant (σ) has been found to be curve in shape and this suggests that there should be a continuous change in transition state with changes in substituent present in the substrate from electron donating to electron withdrawing. A suitable mechanism has been suggested in which the rate determining step involves both C-H bond cleavage and CO bond formations in concerted manner.

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Kinetics and mechanism of the selective oxidation of primary aliphatic alcohols under phase transfer catalysis

Cited by 12 publications

References 12 publications

Kinetics of Quaternization Between N, N-Dimethylaniline and Benzyl Chloride in Polar Solvents-a Revisit to Menshutkin Reaction

Kinetics of Quaternization Between N, N-Dimethylaniline and Benzyl Chloride in Polar Solvents-a Revisit to Menshutkin Reaction

Solvent‐free oxidation of straight‐chain aliphatic primary alcohols by polymer‐grafted vanadium complexes

Kinetic Studies on the Selective Oxidation of Benzyl Alcohols in Organic Medium under Phase Transfer Catalysis

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