Kinetics and Mechanism for the Hydrolysis of Chlorothionoformate and Chlorodithioformate Esters in Water and Aqueous Acetone

. J. Chem. 54,1906Chem. 54, . (1976.The rates of reaction of a series of chlorodithioformate esters with azide ions in 70% aqueous acetone decrease with increasing electron donation to the reaction site. This order is the reverse of that observed for Sxl solvolysis. The entropies of activation are highly negative and the rapid rates of azide attack result from the low activation energies. These results indicate a bimolecular mechanism for azide attack and this is supported by the first-order dependence of the reaction rate on azide concentration. ALAN QUEEN, DAVID M. MCKINNON et ALEXANDER W. BELL. Can. J. Chem. 54.1906. (1976.Les vitesses de rtkction d'une serie d'esters de I'acide chlorodithioformique avec les ions azotures dans I'acCtone aqueux a 70% diminuent avec une augmentation de la densite Clectronique au site de la rCaction. Cet ordre est I'inverse de celui observe pour les rtkctions de solvolyse SN1. Les entropies d'activation sont trks negatives et les vitesses rapides de I'attaque par les ions azotures proviennent d'inergies d'activation faibles. Ces resultats indiquent que les ions azotures attaquent par un mecanisme bimolbulaire et cette conclusion est en accord avec la dependance du premier ordre des vitesses de rtkction sur la concentration des ions azotures.[Traduit par le journal]

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“…The preparation and purification of the chlorodithioformate esters and the preparation of the solvents have been previously described (1).…”

Section: Methodsmentioning

confidence: 99%

The kinetics of the reactions of chlorodithioformate esters with azide ions in 70% aqueous acetone

Queen¹,

McKinnon²,

Bell³

1976

Can. J. Chem.

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“…At 4.8 °C, in 100% H 2 O, it was found that, for the phenyl esters, the chlorothionoformate reacted at almost one-third the rate of the corresponding chlorothioformate ester and the reaction was 55 times slower than that for phenyl chloroformate [69]. …”

Section: Chlorothionoformatesmentioning

confidence: 99%

Influence of Sulfur for Oxygen Substitution in the Solvolytic Reactions of Chloroformate Esters and Related Compounds

D’Souza

Kevill

2014

IJMS

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The replacement of oxygen within a chloroformate ester (ROCOCl) by sulfur can lead to a chlorothioformate (RSCOCl), a chlorothionoformate (ROCSCl), or a chlorodithioformate (RSCSCl). Phenyl chloroformate (PhOCOCl) reacts over the full range of solvents usually included in Grunwald-Winstein equation studies of solvolysis by an addition-elimination (A-E) pathway. At the other extreme, phenyl chlorodithioformate (PhSCSCl) reacts across the range by an ionization pathway. The phenyl chlorothioformate (PhSCOCl) and phenyl chlorothionoformate (PhOCSCl) react at remarkably similar rates in a given solvent and there is a dichotomy of behavior with the A-E pathway favored in solvents such as ethanol-water and the ionization mechanism favored in aqueous solvents rich in fluoroalcohol. Alkyl esters behave similarly but with increased tendency to ionization as the alkyl group goes from 1° to 2° to 3°. N,N-Disubstituted carbamoyl halides favor the ionization pathway as do also the considerably faster reacting thiocarbamoyl chlorides. The tendency towards ionization increases as, within the three contributing structures of the resonance hybrid for the formed cation, the atoms carrying positive charge (other than the central carbon) change from oxygen to sulfur to nitrogen, consistent with the relative stabilities of species with positive charge on these atoms.

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“…It has been shown that there are five factors that influence the nucleofugality of the leaving group, Y Ar [18]. Experimentally, the rate of aminolysis of esters with secondary alicyclic amines in water is found to decrease in the order dithio > thiono > thiol (rate order (1)), whereas for carbonate series the rate of thiono becomes faster than that of dithio compound following rate order (2) [16,17]. …”

Section: Introductionmentioning

confidence: 99%

Theoretical studies on the relative reactivities of aryl thiol, thiono and dithio carbonates and carbamates

Sung

Han

Lee

2007

Journal of Sulfur Chemistry

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RHF, MP2 and DFT calculations were carried out for the unhydrated and explicitly solvated (by five water molecules) putative zwitterionic complexes formed in the aminolysis of oxo {(O, O)} and thio {(O, S), (S, O) and (S, S)} carbonates [MeO−C(=Y)−Y Ar] and carbamates [NH 2 −C(=Y)−Y Ar, where Y and Y are O or S] with ammonia. The reorganization energy of the carbonyl carbon from an sp 2 to an sp 3 center, i.e., the energy needed to form a zwitterionic tetrahedral intermediate, was inversely related to the experimental rate of the aminolysis of carbonates as Y and Y are varied, (O, S) < (O, O) < (S, S) < (S, O). For carbamates the reorganization energy is the highest and the solvation energy is the lowest among ester, carbonate and carbamate series, which is suggestive of the difficulty of zwitterionic intermediate formation and changeover to a concerted mechanism found experimentally for the aminolysis of the carbamates.

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Kinetics and Mechanism for the Hydrolysis of Chlorothionoformate and Chlorodithioformate Esters in Water and Aqueous Acetone

Cited by 33 publications

References 7 publications

The kinetics of the reactions of chlorodithioformate esters with azide ions in 70% aqueous acetone

The kinetics of the reactions of chlorodithioformate esters with azide ions in 70% aqueous acetone

Influence of Sulfur for Oxygen Substitution in the Solvolytic Reactions of Chloroformate Esters and Related Compounds

Theoretical studies on the relative reactivities of aryl thiol, thiono and dithio carbonates and carbamates

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