- Kinetics and mechanism of the oxidation of substituted benzaldehydes with bis(pyridine)silver permanganate
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The oxidation of thirty-six ortho-, meta- and para-substituted benzaldehydes by bis(pyridine)silver permanganate (BPSP) resulted in the formation of the corresponding benzoic acids. The reaction is first order with respect to both BPSP and aldehydes. The reaction is catalyzed by hydrogen ions. The rate of reaction increases with an increase in the amount of acetic acid in the solvent. The correlation analyses of the rate of oxidation of thirty-six aldehydes were performed in terms of Charton's LDR and LDRS equations. The rate of oxidation of meta- and para-substituted benzaldehydes showed excellent correlation with Charton's LDR equation. The rates of ortho-compounds showed excellent correlation with LDRS equation. The oxidation para-compounds is more susceptible to the delocalization effect. The oxidation of ortho- and meta-compounds exhibited a greater dependence on the field effect. The polar reaction constants are negative indicating an electron-deficient centre in the rate-determining step. A mechanism involving a nucleophilic attack on the carbonyl group by a permanganate-oxygen and a subsequent hydride transfer has been proposed.
- Purohit, Trupti,Banerji, Jayshree,Kotai, Laszlo,Sajo,Banerji,Sharma, Pradeep K.
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p. 1045 - 1052
(2013/01/14)
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- Structure-Reactivity correlation in the oxidation of substituted benzaldehydes by tetraethylammonium chlorochromate
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Oxidation of 36 monosubstituted benzaldehydes by tetraethylammonium chlorochromate in dimethyl sulphoxide, leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to chlorochromate and aldehydes. The reaction is promoted by H+; the H+ dependence has the form kobs = a + b[H+]. The oxidation of duteriated benzaldehyde exhibits substantial primary kinetic isotope effect. The reaction was studied in 19 different organic solvents and the effect of solvent was analyzed using Taft's and Swain's multiparametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraperametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta- substituted compounds, which display a greater dependence on the field effect. The positive value of h suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the orthosubstituents. A suitable mechanism has been proposed.
- Gehlot,Prasadrao,Sharma
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experimental part
p. 1173 - 1178
(2012/01/05)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by morpholinium chlorochromate
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Oxidation of thirty six monosubstituted benzaldehydes by morpholinium chlorochromate (MCC) in dimethylsulphoxide (DMSO), leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to MCC. A Michaelis-Menten type kinetics is observed with respect to benzaldehydes. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form kobs = a + b [H+]. The oxidation of [2H] benzaidehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and meta-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes were correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.
- Choudhary, Anurag,Malani,Agarwal,Sharma,Sharma, Vinita
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experimental part
p. 927 - 935
(2010/07/16)
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- Structure-reactivity correlation in the oxidation of substituted benzaldehydes by 2,2-bipyridinium chlorochromate
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Oxidation of thirty six monosubstituted benzaldchydes by 2,2′-bipyridiniuin chlorochromate (BPCC) in diniethylsulphoxide (DMSO), leads to the formation of corresponding benzoic acids. The reaction is of first order with respect to both BPCC and aldehydes. The reaction is promoted by hydrogen ions; the hydrogen ion dependence has the form kobs= a + b[H+]. The oxidation of [2H]benzaldehyde (PhCDO) exhibited a substantial primary kinetic isotope effect. The reaction was studied in nineteen different organic solvents and the effect of solvent was analysed using Taft's and Swain's multi-parametric equations. The rates of the oxidation of para- and mete-substituted benzaldehydes showed excellent correlation in terms of Charton's triparametric LDR equation, whereas the oxidation of orfAo-substituted benzaldehydes were correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalized effect than is the oxidation of ortho- and mem-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric acceleration by the ortho-substituents. A suitable mechanism has been proposed.
- Sharma, Pradeep K.
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experimental part
p. 1281 - 1288
(2009/12/31)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by tetrabutylammonium tribromide
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The oxidation of thirty-six monosubstituted benzaldehydes by tetrabutylammonium tribromide (TBATB), in aqueous acetic acid solution, leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to both TBATB and aldehydes. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of tetrabutylammonium chloride ions on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the medium. The rates of oxidation of meta- and para-substituted benzaldehydes showed excellent correlations in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzaldehydes correlated well with tetraparametric LDS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect but the oxidation of ortho- and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Chouhan,Sharma, Monica,Sharma, Vinita
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p. 582 - 587
(2008/09/21)
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- Benzoxazines for use in the treatment of parkinson's disease
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Benzoxazines of Formula (I) wherein R1 is C1-C6 alkyl, C2-C6 alkenyl, or (CH2)n phenyl, R2 is C3-C6 alkyl, R3 is hydrogen, halo, hydro
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Page/Page column 3; 5
(2008/06/13)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by benzyltrimethylammonium tribromide
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The oxidation of benzaldehyde and thirty-five monosubstituted benzaldehydes by benzyltrimethylammonium tribromide (BTMAB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids, The reaction is first order with respect to each the benzaldehyde and BTMAB. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of benzyltrimethylammonium chloride on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes are correlated in terms of Charton's triparametric LDR equation whereas the oxidation of ortho-substituted benzaldehydes are correlated with tetraparametric LDRS equation. The oxidation of para- substituted benzaldehydes is more susceptible to the delocalization effect than is the oxidation of ortho-and meta-substituted compounds, which display a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric hindrance by the ortho-substituents.
- Mehla, Satish K.,Kothari, Seema,Banerji, Kalyan K.
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p. 832 - 838
(2007/10/03)
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- Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by pyridinium hydrobromide perbromide
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The oxidation of benzaldehyde and 35 monosubstituted benzaldehydes by pyridinium hydrobromide perbromide (PHPB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to each of the benzaldehydes and PHPB. Addition of pyridinium bromide has no effect on the rate of oxidation. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation whereas those of ortho-substituted benzaldehydes were correlated with a tetraparametric LDRS equation. The oxidations of para- and ortho-substituted benzaldehydes are more susceptible to the delocalization effect while the oxidation of meta-substituted compounds displays a greater dependence on the fi eld effect. The positive value of η suggests the presence of an electron-deficient reaction centre in the rate-determining step. The reaction is subjected to steric hindrance by the ortho substituents.
- Aneja, Meenakshi,Kothari, Seema,Banerji, Kalyan K.
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p. 650 - 656
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by hexamethylenetetramine-bromine
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The oxidation of thirty-six monosubstituted benzaldehydes by hexa-methylenetetramine-bromine (HABR), in aqueous acetic acid solution, leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to HABR. Michaelis-Menten-type kinetics were observed with respect to aldehyde. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of hexamethylenetetramine on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes showed excellent correlations in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes correlated well with tetraparametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect but the oxidation of ortho- and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of γ suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Gangwani,Sharma,Banerji
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p. 615 - 622
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by benzyltrimethylammonium chlorobromate
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The oxidation of 35 monosubstituted benzaldehydes by benzyltrimethylammonium chlorobromate (BTMACB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to both benzaldehyde and BTMACB. The reaction failed to induce the polymerization of acrylonitrile. There is no effect of benzyltrimethylammonium chloride or potassium bromide on the reaction rate. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with an increase in the polarity of the solvent. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes was correlated with the tetraparametric LDRS equation. The oxidation of para- substituted benzaldehydes is more susceptible to the delocalization effect, whereas the oxidation of ortho-and meta-substituted compounds displayed a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining step. The reaction is subjected to steric hindrance by the ortho substituents.
- Raju, V. Sitarama,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 3322 - 3325
(2007/10/03)
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- Kinetics and Mechanism of the Oxidation of Substituted Benzaldehydes by Oxxo(salen)manganese(V) Complexes
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Oxidation of meta- and para-substituted benzaldehydes by substituted oxo(salen)manganese(V) complexes, in acetonitrile, leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to each the aldehyde and the Mn(V) complex. The oxidation of deuteriated benzaldehyde (PhCDO) exhibited the presence of a substantial kinetic isotope effect. The rate of oxidation of the aldehydes by four substituted Mn(V) complexes have been determined. The rates of oxidation of para-substituted benzaldehydes showed an excellent correlation in terms of Taft's ?1 and ?R+ values. The rates of the meta-compounds correlated best with ?1 and ?R0 values. The reaction constants are negative. The rate of reduction of the substituted Mn(V) complexes exhibited an excellent correlation in terms of Hammett equation with positive reaction constants. The reactivity-selectivity principle (RSP) is obeyed in this reaction. The validity of RSP was checked and found genuine by Exner's mathematical procedure. Suitable mechanisms have been discussed.
- Bansal, Varsha,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 2052 - 2074
(2007/10/03)
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- Kinetics and mechanism of the oxidation of substituted benzaldehydes by bis(2,2′-bipyridylyl)copper(II) permanganate
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The oxidation of 35 monosubstituted benzaldehydes by bis(2,2′-bipyridylyl)copper(II) permanganate (BBCP) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to BBCP. Michaelis - Menten-type kinetics were observed with respect to the aldehyde concentrations. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The rates of oxidation of meta- and para-substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation, whereas the oxidation of ortho-substituted benzaldehydes was correlated with the four parametric LDRS equation. The oxidation of para-substituted benzaldehydes is more susceptible to the delocalization effect than is the oxidation of ortho- and meta-substituted compounds which displays a greater dependence on the field effect. The positive value of η suggests the presence of an electron-deficient reaction center in the rate-determining activated complex. The reaction is subjected to steric acceleration when ortho-substituents are present.
- Mohnot, Kavita,Sharma, Pradeep K.,Banerji, Kalyan K.
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p. 1310 - 1314
(2007/10/03)
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- Correlation Analysis of the Reactivity in the Oxidation of Aromatic Aldehydes by N-Bromoacetamide
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The oxidation of thirty two para-, meta- and ortho-substituted benzaldehydes by N-bromoacetamide (NBA), to the corresponding benzoic acid, is first order with respect to the aldehyde, NBA and hydrogen ion.The oxidation of benzaldehyde exhibited a substantial primary kinetic isotope effect (kH/kD = 4.75).Addition of acetamide reduced the rate of oxidation.The postulated oxidising species is (H2OBr)+.The rates of the oxidation of the meta- and para-substituted aldehydes were separately correlated in Taft's and Swain's dual substituent parameter equations.For para-substituted aldehydes, the best correlation was obtained with ?I and ?R+ values, while the meta-substituted compounds correlated best with ?I and ?R0 values.The ortho-substituted aldehydes showed excellent correlation in a triparametric equation of Taft's ?I, ?R+ and Charton's steric parameters.The polar reaction constants have negative values.The reaction is subject to steric hindrance by the ortho-substituents.A mechanism involving transfer of a hydride from the aldehyde to the oxidant, in the rate-determining step, has been proposed.
- Gupta, Anita,Mathur, Sandhya,Banerji, Kalyan K.
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p. 201 - 223
(2007/10/02)
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