Basic methanolysis of N-aryl-N-phenylbenzamides

Broxton, Trevor J.; Deady, Leslie W.; Rowe, Jeffrey E.

doi:10.1021/jo01300a028

Cited by 4 publications

(2 citation statements)

References 3 publications

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“…Thus, the pK a of the primary amino group of 2 should be nearly 8 -9. The values of pK a of NH 3 , C 6 H 5 NH 2 , CH 3 CONH 2 , and CF 3 CONHC 6 H 5 are 35 [22], 27 [10], 15.4 [19], and 9.5 [23], respectively. In view of these results it seems that the pK a of 9 CONH 9 group of AZIM should be Ͻ 4.…”

Section: Mechanistic Speculationsmentioning

confidence: 99%

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Kinetic study on acid-base catalyzed hydrolysis of azimsulfuron, a sulfonylurea herbicide

Khan

Bakar

Yin

1999

Int. J. Chem. Kinet.

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Pseudo-first-order rate constants (k obs ) for hydrolysis of a sulfonylurea herbicide, azimsulfuron, AZIM, {N-[[(4,6-dimethoxy-2-pyrimidinyl)amino]carbony]-1-methyl-4-(2-methyl-2H-tetrazol-5-yl)-1H-pyrazole-5-sulfonamide} (AZS) follow an empirical relationship:] 2 within the [NaOH] range of 0.1-2.0 M at different temperatures ranging from 40 to 55ЊC. The contribution of ␣ 3 [ Ϫ OH] 2 term is small compared with ␣ 2 [ Ϫ OH] term and this turns out to be zero at 60ЊC. Pseudo-first-order rate constants (k obs ) for hydrolysis of AZS within the [H ϩ ] range from 2.5 ϫ 10 Ϫ6 to 1.4 M follow the relationship: k obswhere pK a ϭ 4.37 at 50ЊC. The value of ␤ 1 is nearly 25 times larger than that of ␣ 1 . The rate of alkaline hydrolysis of AZIM is weakly sensitive to ionic strength.

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Section: Mechanistic Speculationsmentioning

confidence: 99%

“…It is difficult to ascertain whether 9 SO 2 NH 2 or 9 NH 2 is better leaving group because the pK a of C 6 H 5 SO 2 NH 2 , C 6 H 5 NH 2 , and 3 at 50ЊC are 10.11 [9], 27 [10], and 8.4 [11], respectively.…”

Section: Product Characterizationmentioning

confidence: 99%

Kinetic study on acid-base catalyzed hydrolysis of azimsulfuron, a sulfonylurea herbicide

Khan

Bakar

Yin

1999

Int. J. Chem. Kinet.

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ChemInform Abstract: BASIC METHANOLYSIS OF N‐ARYL‐N‐PHENYLBENZAMIDES

Broxton¹,

Deady²,

Rowe³

1980

Chemischer Informationsdienst

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Trifunctional Metal Ion-Catalyzed Solvolysis: Cu(II)-Promoted Methanolysis of N,N-bis(2-picolyl) Benzamides Involves Unusual Lewis Acid Activation of Substrate, Delivery of Coordinated Nucleophile, Powerful Assistance of the Leaving Group Departure

et al. 2012

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The methanolyses of Cu(II) complexes of a series of N,N-bis(2-picolyl) benzamides (4a-g) bearing substituents X on the aromatic ring were studied under (s)(s)pH-controlled conditions at 25 °C. The active form of the complexes at neutral (s)(s)pH has a stoichiometry of 4:Cu(II):((-)OCH(3))(HOCH(3)) and decomposes unimolecularly with a rate constant k(x). A Hammett plot of log(k(x)) vs σ(x) values has a ρ(x) of 0.80 ± 0.05. Solvent deuterium kinetic isotope effects of 1.12 and 1.20 were determined for decomposition of the 4-nitro and 4-methoxy derivatives, 4b:Cu(II):((-)OCH(3))(HOCH(3)) and 4g:Cu(II):((-)OCH(3))(HOCH(3)), in the plateau region of the (s)(s)pH/log(k(x)) profiles in both CH(3)OH and CH(3)OD. Activation parameters for decomposition of these complexes are ΔH(++) = 19.1 and 21.3 kcal mol(-1) respectively and ΔS(++) = -5.1 and -2 cal K(-1) mol(-1). Density functional theory (DFT) calculations for the reactions of the Cu(II):((-)OCH(3))(HOCH(3)) complexes of 4a,b and g (4a, X = 3,5-dinitro) were conducted to probe the relative transition state energies and geometries of the different states. The experimental and computational data support a mechanism where the metal ion is coordinated to the N,N-bis(2-picolyl) amide unit and positioned so that it permits delivery of a coordinated Cu(II):((-)OCH(3)) nucleophile to the C═O in the rate-limiting transition state (TS) of the reaction. This proceeds to a tetrahedral intermediate INT, occupying a shallow minimum on the free energy surface with the Cu(II) coordinated to both the methoxide and the amidic N. Breakdown of INT is a virtually barrierless process, involving a Cu(II)-assisted departure of the bis(2-picolyl)amide anion. The analysis of the data points to a trifunctional role for the metal ion in the solvolysis mechanism where it activates intramolecular nucleophilic attack on the C═O group by coordination to an amidic N in the first step of the reaction and subsequently assists leaving group departure in the second step. The catalysis is very large; compared with the second order rate constant for methoxide attack on 4b, the computed reaction of CH3O(-) and 4b:Cu(II):(HOCH(3))(2) is accelerated by roughly 2.0 × 10(16) times.

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Basic methanolysis of N-aryl-N-phenylbenzamides

Cited by 4 publications

References 3 publications

Kinetic study on acid-base catalyzed hydrolysis of azimsulfuron, a sulfonylurea herbicide

Kinetic study on acid-base catalyzed hydrolysis of azimsulfuron, a sulfonylurea herbicide

ChemInform Abstract: BASIC METHANOLYSIS OF N‐ARYL‐N‐PHENYLBENZAMIDES

Trifunctional Metal Ion-Catalyzed Solvolysis: Cu(II)-Promoted Methanolysis of N,N-bis(2-picolyl) Benzamides Involves Unusual Lewis Acid Activation of Substrate, Delivery of Coordinated Nucleophile, Powerful Assistance of the Leaving Group Departure

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