The Acylation of Aldoximes. VI. The Relative Ease and Mechanism of Conversion of Benzoyl-syn-aldoximes to Nitriles in the Presence of Pyridine and Pyridinium Chloride<sup>1</sup>

Hauser, Charles R.; Vermillion, Gertrude

doi:10.1021/ja01850a017

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“…EXPERIMENTAL 4,4'-Substituted O-benzoylbenzamidoximes 1a-g were obtained by acylation of the corresponding benzamidoximes 9,10 prepared by reactions of the respective benzoni-triles with hydroxylamine in aqueous alcohol. 1 O-Benzoylbenzaldoxime (2) was obtained by acylation of benzaldoxime 11 obtained by reaction of benzaldehyde with hydroxylamine in aqueous sodium acetate. 12 The purity of all the substances synthesized was checked by Table 3.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of the reaction of substitutedO-benzoylbenzamidoximes with sodium methoxide in methanol

Dušek

Kaválek

Štěrba

1999

J. Phys. Org. Chem.

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The kinetics of reaction of substituted O-benzoylbenzamidoximes with sodium methoxide in methanol were studied at 25°C. The only reaction products are substituted benzamidoximes and methyl benzoates. The slope of the dependence of rate constant on sodium methoxide concentration gradually increases, but in the presence of C 18 crown ether the dependence becomes linear and the rate constant is lower than in the absence of the crown ether, which means that the reaction is catalysed by sodium cation. The rate constants of reactions with the ion pair and with methoxide ion were determined with the presumption that the rate-limited step of the catalysed reaction is the reaction of substituted O-benzoylamidoximes with the ion pair of sodium methoxide. The rate constants of the reaction with the ion pair are about 20 times higher than those of the non-catalysed process. The slopes of the dependence of log k of the non-catalysed and catalysed reactions on the pK a of substituted benzamidoximes are 1.05 and 0.94, respectively. These high values indicate the rate-limiting step involving the splitting off of substituted benzamidoxime from the tetrahedral intermediate. On the basis of the relatively high r constant of methanolysis at the benzoyl group substituted derivatives (2.17 and 1.98 for the non-catalysed and catalysed reactions, respectively), it can be presumed that the transition state structure will be close to the tetrahedral intermediate.

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Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of the reaction of substitutedO-benzoylbenzamidoximes with sodium methoxide in methanol

Dušek

Kaválek

Štěrba

1999

J. Phys. Org. Chem.

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p ‐Nitrobenzonitrile

Miller¹

2003

Organic Syntheses

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Potentielle Reaktivatoren der Acetylcholinesterase, 7. Mitt. Ester der Pyridin‐N‐oxid‐carbaldehydoxime und deren quartäre Derivate

Schnekenburger

Heber

1975

Archiv der Pharmazie

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Die Umsetzung von 5 g (0.027 Mol) Alkohol22 rnit 2 g (0.036 Mol) Propionitril nach dem firr IS angegebenen Verfahren ergab 3.1 g (47.8 % d. Th.) 23 als zahflissiges, farbloses 01 vom Sdp., 1R (CHC13): 3435 NH-Val.; 2780 N-CH3; 1670, 1500 Amid Perchlorat: Farblose Kristalle vom Schmp. 145.5' (Athanol/Xther). C 1 4 H~N 2 0 ' H C 1 0 4 (340.8)Ber.: C49.34,H 8.58,N8.22;Gef.: C49.64,H8.51,N8.00. 137-1 39' . (24) 15 g Amid 23 wurden rnit einer Liisung von 50 g KOH in 500 ml Athylenglykol 48 Std. am Ruckflu5 gekocht. Anschhe5end wurde der Ansatz 36 Std. rnit Petrolather perforiert, der Petrolather verdampft und das Amin aus dem Ruckstand als Dihydrochlorid abgetrennt. Die aus dem Salz freigesetzte Base destillierte als dc reines, farbloses 61 vom Sdp.4 91 -92'. Ausbeute: 8.4 g (74.3 % d. Th.). IR (CHC13): 3160 (breit) NH-Val.; 2790 N-CHS Perchlorot: Farblose Kristalle vom Schmp. 189O (Athanol/Xther). CllHzaN2 . HC104 (284.8) -MethyC3-(3-amino-3-methyEbutyl)-piperidinDie Dantellung der Carbonsiiureester 8 bzw. 9 der Pyridin-N-oxid-2(4)-carbaldehydoxime gelingt nach bekannten Verfahren; allerdings miissen beim Essigsaureester 80 sehr schonende B e dingungen eingehalten werden, da sonst das entsprechende Carbonitril entsteht. 8 und 9 reagieren rnit Dimethylsulfat zu den entsprechenden N-Methoxyderivaten. Bei Umsetzung rnit Sulfonsaurechloriden werden sowohl aus den N-Oxiden 4 und 5 als auch aus deren quartaren Derivaten 6 bzw. 7 die betreffenden Carbonitrile erhalten.* Teil der Dissertation D. Heber, Kiel 1971. Schnekenburger und HeberArch. Pharmaz. Esters of Pyridine-N-oxide-carbaldehyde Oximes and of their Quaternary DerivativesCarboxylic acid esters of pyridine-N-oxide-2(4>carbaldehyde oximes are prepared by known methods. For 8a, mild conditions are necessary, the corresponding carbonitrile being formed instead. With dimethyl sulfate, the esters react to give quaternary derivatives. With sulfonic acid chlorides, the carbaldoximes 4 -7 react yielding the corresponding carbonitriles.Einem haufig diskutierten Mechanismus zufolge entstehen bei der Reaktivierung der organophosphat-blockierten Acetylcholinesterase mit Oximen neben dem freien Enzym Phosphordureester 1, die im Falle von R' = H leicht unter Eliminierung zu Carbonitrilen 2 und wenig toxischen Phosphordurediester-Anionen 3 weiter reagie-ren2-' ' 1. 1Nach einer Arbeitshypothese von Hagedorn u. Mitarb.7) verlauft dieser Reaktionsschritt als cyclische 0-Eliminierung; je leichter diese erfolgt, desto giinstiger sollten die Reaktivatoreigenschaften eines Carbaldehydoxims sein. Weil die Tendenz zur Eliminierung auch bei Carbonstiureestern von Carbaldehydoximen deutlich groDer ist als bei den Oximen selbst1'"2), untersuchten wir einige Carbondureester der Pyridin-N-oxid-carbaldehydoxime 4 und 5 auf ihre Eignung als Modelle fur spater darzustellende Oxim-Phosphordureester. Im folgenden wird die Darstellung der Carbondureester 8 -11 der 4 und 5 sowie der entsprechenden quartaren Derivate 6 und 7 beschrieben.

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The Acylation of Aldoximes. VI. The Relative Ease and Mechanism of Conversion of Benzoyl-syn-aldoximes to Nitriles in the Presence of Pyridine and Pyridinium Chloride¹

Cited by 11 publications

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Kinetics and mechanism of the reaction of substitutedO-benzoylbenzamidoximes with sodium methoxide in methanol

Kinetics and mechanism of the reaction of substitutedO-benzoylbenzamidoximes with sodium methoxide in methanol

p ‐Nitrobenzonitrile

Potentielle Reaktivatoren der Acetylcholinesterase, 7. Mitt. Ester der Pyridin‐N‐oxid‐carbaldehydoxime und deren quartäre Derivate

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The Acylation of Aldoximes. VI. The Relative Ease and Mechanism of Conversion of Benzoyl-syn-aldoximes to Nitriles in the Presence of Pyridine and Pyridinium Chloride1

Cited by 11 publications

References 0 publications

Kinetics and mechanism of the reaction of substitutedO-benzoylbenzamidoximes with sodium methoxide in methanol

Kinetics and mechanism of the reaction of substitutedO-benzoylbenzamidoximes with sodium methoxide in methanol

p ‐Nitrobenzonitrile

Potentielle Reaktivatoren der Acetylcholinesterase, 7. Mitt. Ester der Pyridin‐N‐oxid‐carbaldehydoxime und deren quartäre Derivate

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The Acylation of Aldoximes. VI. The Relative Ease and Mechanism of Conversion of Benzoyl-syn-aldoximes to Nitriles in the Presence of Pyridine and Pyridinium Chloride¹