Substituent effects on the basic methanolysis of a series of substituted N-Methyl-p-toluanilides

1980 ◽  
Vol 33 (4) ◽  
pp. 903 ◽  
Author(s):  
TJ Broxton ◽  
NW Duddy
Keyword(s):  
Substituent Effects ◽  
Bond Breaking ◽  
Straight Line ◽  
Breaking Mechanism ◽  
Basic Hydrolysis ◽  
Line P ◽  
Hydrolysis Of

The rate of basic methanolysis of a series of substituted N-methyl-p- toluanilides (1) has been measured at 373 K. A Hammett plot of these results resulted in a straight line (p 3.1, r 0.998) indicative of reaction by solvent-assisted bond breaking (mechanism B) throughout the series. The relevance of these results to previous results for the basic hydrolysis of N-methyl-p-toluanilides (I) and basic methanolysis of N-methylbenzanilides (2) is discussed.

Micellar catalysis of the basic hydrolysis of anilides. III. α-Substituted N-methyl-N-p-nitrophenylacetamides

1980 ◽  
Vol 33 (8) ◽  
pp. 1771 ◽  
Author(s):  
TJ Broxton ◽  
NW Duddy
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Substituent Effects ◽  
Micellar Catalysis ◽  
Single Parameter ◽  
Parameter Analysis ◽  
Basic Hydrolysis ◽  
Presence And Absence ◽  
Hydrolysis Of ◽  
Acetic Acids

The basic hydrolysis of a number of α-substituted N-methyl-N-p- nitrophenylacetamides has been studied both in the presence and absence of micelles of cetyltrimethylammonium bromide (ctab). Unlike the related p-nitrophenyl esters of a-substituted acetic acids, no evidence for the operation of the E1cb mechanism in the basic hydrolysis has been detected. Reasons for the differences between the amides and esters are discussed. Substituent effects on the hydrolysis of the amides have been studied both by single-parameter and dual-parameter analysis.

Basic hydrolysis of some N-phenylcarbamates and basic methanolysis of some N-phenylacetamides containing an ortho nitro substituent

1984 ◽  
Vol 37 (10) ◽  
pp. 2005
Author(s):  
TJ Broxton
Keyword(s):  
Induction Period ◽  
Nitro Group ◽  
Resonance Effect ◽  
Kinetic Studies ◽  
Bond Breaking ◽  
Hydroxide Ion ◽  
Tetrahedral Intermediate ◽  
Group Reaction ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

Kinetic studies of the basic methanolysis of N-(2-nitropheny1)acetamides indicate that unlike the 4-nitro isomer, no change of mechanism occurs on inclusion of an N-methyl group. Reaction occurs with rate-determining C-N bond breaking for both the N-H and N-methyl compounds. Basic hydrolysis of some methyl N-(2-nitropheny1)carbamates occurred by the BAC2 mechanism and the tetrahedral intermediate formed during the hydrolysis decomposed with preferential C-O bond breaking. This is in contrast to the basic hydrolysis of methyl N-methyl-N-4-nitrophenyl- carbamate, which has previously been shown to occur with preferential C-N bond breaking. For the hydrolysis of methyl N-methyl-N-(2-nitrophenyl)carbamate, an induction period in amine production was detected at 0.45 M hydroxide ion. This was interpreted to mean that the tetrahedral intermediate breaks down by loss of methoxide ion. At 0.93 M hydroxide ion, however, no induction period in amine production was observed. The possibility of reaction through a dianionic intermediate was raised to explain this observation. The amide ion (2-NO2C6H4NMe-) is a poorer leaving group than its 4-nitro isomer. This is explained by steric crowding in the 2-nitro compound, resulting in twisting of the nitro group out of the plane of the benzene ring and a consequent reduction in the electron-withdrawing resonance effect of the 2-nitro group compared to the 4-nitro group.

Micellar catalysis of organic reactions. XII. Basic hydrolysis of some alkyl and aryl N-(4-Nitrophenyl)carbamates

1984 ◽  
Vol 37 (1) ◽  
pp. 47 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Kinetic Studies ◽  
Micellar Catalysis ◽  
Organic Reactions ◽  
Bond Breaking ◽  
Tetrahedral Intermediate ◽  
Stable Product ◽  
Methyl Derivatives ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

The basic hydrolysis of a number of alkyl and aryl N-(4-nitrophenyl)carbamates in the presence and absence of micelles of cetyltrimethylammonium bromide (ctab) are reported. In water the stable product at 26�C was N-(4-nitrophenyl)carbamate ion (3). At higher temperatures this carbamate ion slowly decomposed to 4-nitroaniline. In ctab the decarboxylation of the N-(4-nitrophenyl)carbamate ion was strongly catalysed (× 45) and thus the observed final product even at 26�C was 4-nitroaniline. Kinetic studies in water and in ctab were consistent with decomposition of the methyl carbamate (la) by a BAC2 mechanism and the 2,2,2-trifluoroethyl carbamate (lc) by an E1cB mechanism. The extent of ionization of the substrate carbamates to nitranion (4) was enhanced in ctab as was the rate of spontaneous decomposition of the nitranion. This is in contrast to other E1cB reactions reported in the literature, for which the rate of spontaneous decomposition of the carbanion was inhibited by ctab. For compounds reacting by the BAC2 mechanism, the tetrahedral intermediate (2) partitioned in favour of C-OR bond breaking rather than C-N bond breaking observed previously for some N-methyl derivatives.

Basic hydrolysis of some alkyl and phenyl N-Aryl-N-methylcarbamates

1983 ◽  
Vol 36 (11) ◽  
pp. 2203 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Rate Constants ◽  
Cetyltrimethylammonium Bromide ◽  
Ester Hydrolysis ◽  
Micellar Catalysis ◽  
Bond Breaking ◽  
Methyl Ethyl ◽  
Hydroxide Ion ◽  
Tetrahedral Intermediate ◽  
Basic Hydrolysis ◽  
Hydrolysis Of

Rate constants for the basic hydrolysis of methyl, ethyl and phenyl N-aryl-N-methylcarbamates in the presence and absence of micelles of cetyltrimethylammonium bromide are reported. Hammett plots for the methyl and ethyl carbamates were curved, and this is explained by consideration of the competition between C-N and C-OR bond breaking for decomposition of the tetrahedral intermediate. In one case (p-nitro-substituted), rate-determining formation of the tetrahedral intermediate is suggested, whereas for other compounds rate-determining C-N bond breaking or C-OR bond breaking is proposed. Micellar catalysis for each of the reactions is reported, and large catalysis (× 50) was observed for compounds where C-N bond breaking was kinetically significant. This is compared with results in the literature for amide and ester hydrolysis. Whereas, for ester hydrolysis, loss of alkoxide ion from the tetrahedral intermediate is favoured over loss of hydroxide ion, in carbamate hydrolysis, loss of hydroxide ion is favoured. A possible reason for this reversal of nucleofugicity of OH- and OR- is proposed.

Substituent Effects on the Micelle-Catalysed and Uncatalysed Basic Hydrolysis of a Series of Substituted N-Methyl-p-toluanilides

1979 ◽  
Vol 32 (8) ◽  
pp. 1717 ◽  
Author(s):  
TJ Broxton ◽  
NW Duddy
Keyword(s):  
Substituent Effects ◽  
Cationic Micelles ◽  
Mechanism Of Reaction ◽  
Rate Of Reaction ◽  
Hammett Correlation ◽  
Rate Of Hydrolysis ◽  
Linear Plot ◽  
Basic Hydrolysis ◽  
Hydrolysis Of ◽  
Reaction In Water

The rate of hydrolysis of a series of substituted N-methyl-p-toluanilides has been measured in water and in the presence of cationic micelles [cetyltrimethylammonium bromide (ctab)]. A Hammett correlation of the rates of hydrolysis gave a curved Hammett plot for the reaction in water (k2,W) but a linear plot for the rate of reaction at optimal concentrations of ctab (k2,max) and for derived rate constants within the micelle (k2,m) These results are discussed in terms of the mechanism of reaction, and for two compounds a micelle-induced change of mechanism is indicated.

A FACILE SYNTHESIS AND REACTIONS OF AMINO SELENOLO[2,3-b]PYRIDINE CARBOXYLATE

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed
Keyword(s):  
Biological Activity ◽  
Carbonyl Compounds ◽  
Mass Spectra ◽  
The Other ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
High Biological Activity ◽  
Basic Hydrolysis ◽  
Pyridine Carboxylate ◽  
Hydrolysis Of

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.

Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous Bu4NBr

2009 ◽  
Vol 74 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Vilve Nummert ◽  
Mare Piirsalu ◽  
Signe Vahur ◽  
Oksana Travnikova ◽  
Ilmar A. Koppel
Keyword(s):  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Pure Water ◽  
Substituent Effects ◽  
Benzoic Acids ◽  
Resonance Effects ◽  
The Media ◽  
Substituted Benzoic Acids ◽  
Hydrolysis Of ◽  
Ortho Substituent

The second-order rate constants k (in dm3 mol–1 s–1) for alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids, X-C6H4CO2C6H5, have been measured spectrophotometrically in aqueous 0.5 and 2.25 M Bu4NBr at 25 °C. The substituent effects for para and meta derivatives were described using the Hammett relationship. For the ortho derivatives the Charton equation was used. For ortho-substituted esters two steric scales were involved: the EsB and the Charton steric (υ) constants. When going from pure water to aqueous 0.5 and 2.25 M Bu4NBr, the meta and para polar effects, the ortho inductive and resonance effects in alkaline hydrolysis of phenyl esters of substituted benzoic acids, became stronger nearly to the same extent as found for alkaline hydrolysis of C6H5CO2C6H4-X. The steric term of ortho-substituted esters was almost independent of the media considered. The rate constants of alkaline hydrolysis of ortho-, meta- and para-substituted phenyl benzoates (X-C6H4CO2C6H5, C6H5CO2C6H4-X) and alkyl benzoates, C6H5CO2R, in water, 0.5 and 2.25 M Bu4NBr were correlated with the corresponding IR stretching frequencies of carbonyl group, (ΔνCO)X.

Kinetic Study of Hydrolysis of Benzoates. Part XXVI. Variation of the Substituent Effect with Solvent in Alkaline Hydrolysis of Substituted Alkyl Benzoates

2006 ◽  
Vol 71 (11-12) ◽  
pp. 1557-1570 ◽  
Author(s):  
Vilve Nummert ◽  
Mare Piirsalu ◽  
Ilmar A. Koppel
Keyword(s):  
Kinetic Study ◽  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Substituent Effect ◽  
Substituent Effects ◽  
Alkyl Substituent ◽  
Solvent Parameters ◽  
Substituent Constants ◽  
Hydrolysis Of ◽  
Main Factor

The second-order rate constants k2 (dm3 mol-1 s-1) for the alkaline hydrolysis of substituted alkyl benzoates C6H5CO2R have been measured spectrophotometrically in aqueous 0.5 M Bu4NBr at 50 and 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH, CH2C6H5, CH2CH2Cl, CH2CH2OCH3, CH2CH3) and in aqueous 5.3 M NaClO4 at 25 °C (R = CH3, CH2Cl, CH2CN, CH2C≡CH). The dependence of the alkyl substituent effects on different solvent parameters was studied using the following equations:      ∆ log k = c0 + c1σI + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆EσI + c7∆YσI + c8∆PσI     ∆ log k = c0 + c1σ* + c2EsB + c3∆E + c4∆Y + c5∆P + c6∆Eσ* + c7∆Yσ* + c8∆Pσ* .  ∆ log k = log kR - log kCH3. σI and σ* are the Taft inductive and polar substituent constants. E, Y and P are the solvent electrophilicity, polarity and polarizability parameters, respectively. In the data treatment ∆E = ES - EH2O , ∆Y = YS - YH2O , ∆P = PS - PH2O were used. The solvent electrophilicity, E, was found to be the main factor responsible for changes in alkyl substituent effects with medium. When σI constants were used, variation of the polar term of alkyl substituents with the solvent electrophilicity E was found to be similar to that observed earlier for meta and para substituents, but twice less when σ* constants were used. The steric term for alkyl substituents was approximately independent of the solvent parameters.

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