Nucleophilic Displacement Reactions at the Thiol Ester Bond. IV. General Base Catalyzed Hydrolysis of Ethyl Trifluorothiolacetate. Kinetic Evidence for the Formation of a Tetrahedral Intermediate<sup>1</sup>

Fedor, Leo R.; Bruice, Thomas C.

doi:10.1021/ja01096a024

Cited by 53 publications

(37 citation statements)

References 3 publications

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“…The effect of 1.0 mol/dm 3 ionic strength is a 30% depression in k 1 . The magnitude of the effect is similar to that observed in the neutral hydrolyses of CHF 2 CO 2 Et [7], CF 3 COSEt [8], and acetic anhydride [9]. Thus, the k 1 value of Stefanidis and Jencks corrected for the inhibitory salt effect should be 2.7 ϫ 10 Ϫ7 s Ϫ1 .…”

Section: Activation Parameterssupporting

confidence: 66%

Spontaneous hydrolysis of ethyl formate: Isobaric activation parameters

Mata‐Segreda

2000

Int J Chem Kinet

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Ethyl formate undergoes spontaneous autocatalytic hydrolysis via water catalyzed (neutral), as well as hydrogen-ion catalyzed mechanisms. The activation parameters for the neutral reaction are ⌬H ‡ ϭ 91 Ϯ 8 kJ/mol and ⌬S ‡ ϭ Ϫ48 Ϯ 8 J K Ϫ1/mol. This result is in contrast to the values reported in the hydrolyses of the more polar activated haloesters. The specific rate of neutral hydrolysis of ethyl acetate can also be predicted.

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Section: Activation Parameterssupporting

confidence: 66%

Spontaneous hydrolysis of ethyl formate: Isobaric activation parameters

Mata‐Segreda

2000

Int J Chem Kinet

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“…Monomers functionalized with both thiols and thioesters can polymerize into macromolecules (Ura, et al 2009). Reactions coupled to the hydrolysis of thioesters (e.g., formation of phosphoanhydrides via acylphosphate intermediates) can be used to store energy (de Duve 1991;Wächtershäuser 1992). Solid phases functionalized with thiols could be used to concentrate thioesterfunctionalized molecules on surfaces and catalyze reactions (Wächtershäuser 1992).…”

Section: Implications For Thioesters In the Origin Of Lifementioning

confidence: 99%

“…Similar to the case of phosphoanhydrides (e.g., ATP), the hydrolysis of thioesters is relatively slow despite the large thermodynamic favorability of the reaction. Wächtershäuser, de Duve, and others have postulated that thioesters may have played a critical role in early metabolism, primarily as chemical reservoirs of energy (de Duve 1991;Wächtershäuser 1997, 1998;Wächtershäuser 1992). For these theories to have merit, conditions would have needed to exist where constructive reactions of thioesters could compete with hydrolysis to form biologically relevant products, even if only in low yield.…”

Section: Introductionmentioning

confidence: 99%

The Relative Rates of Thiol–Thioester Exchange and Hydrolysis for Alkyl and Aryl Thioalkanoates in Water

Bracher

Snyder

Bohall

et al. 2011

Orig Life Evol Biosph

153

158

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This article reports rate constants for thiol-thioester exchange (k (ex)), and for acid-mediated (k (a)), base-mediated (k (b)), and pH-independent (k (w)) hydrolysis of S-methyl thioacetate and S-phenyl 5-dimethylamino-5-oxo-thiopentanoate-model alkyl and aryl thioalkanoates, respectively-in water. Reactions such as thiol-thioester exchange or aminolysis could have generated molecular complexity on early Earth, but for thioesters to have played important roles in the origin of life, constructive reactions would have needed to compete effectively with hydrolysis under prebiotic conditions. Knowledge of the kinetics of competition between exchange and hydrolysis is also useful in the optimization of systems where exchange is used in applications such as self-assembly or reversible binding. For the alkyl thioester S-methyl thioacetate, which has been synthesized in simulated prebiotic hydrothermal vents, k (a) = 1.5 × 10(-5) M(-1) s(-1), k (b) = 1.6 × 10(-1) M(-1) s(-1), and k (w) = 3.6 × 10(-8) s(-1). At pH 7 and 23°C, the half-life for hydrolysis is 155 days. The second-order rate constant for thiol-thioester exchange between S-methyl thioacetate and 2-sulfonatoethanethiolate is k (ex) = 1.7 M(-1) s(-1). At pH 7 and 23°C, with [R″S(H)] = 1 mM, the half-life of the exchange reaction is 38 h. These results confirm that conditions (pH, temperature, pK (a) of the thiol) exist where prebiotically relevant thioesters can survive hydrolysis in water for long periods of time and rates of thiol-thioester exchange exceed those of hydrolysis by several orders of magnitude.

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“…10-13, 15, 24, 25), thiol esters (14,15), and thionoesters (17)(18)(19) it seenis reasonable to assume that dithioesters hydrolyse via a tetrahedral intermediate. The tetrahedral intermediate for esters and thiolesters is generally thought to be a nionoanion:…”

Section: Tetrclhedral Inter-nzediatementioning

confidence: 99%

“…refs. [4][5][6][7][8][9][10][11][12][13][14][15][16] and a limited amount of work using thionoesters has been reported (17)(18)(19)(20). However, only three reports, none of which contain kinetic analyses, could be found concerning the base catalysed hydrolysis of dithioesters (2 1-23), According to Sakurada (21), the action of aqueous alkali on ethyl dithioacetate leads to the production of dithioacetic acid, however, two other studies (22,23) report that thiol acids are produced by dithioester hydrolysis.…”

Section: Introductionmentioning

confidence: 99%

An investigation of the biphasic kinetics observed during the hydroxide ion-catalyzed hydrolysis of alkyl dithioesters

Storer¹

1983

Can. J. Chem.

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Kinetic evidence is presented for the establishment of an equilibrium, in dilute aqueous alkaline solutions, between alkyl dithioesters and a species I. The species I is formed cither by the extraction of a proton from, or by the addition of an hydroxide ion to, the dithioester. In the former case I would be an anion (probably an enethiolate) formed by the removal of a proton from the α-carbon atom, and in the latter case I would be a stabilized tetrahedral intermediate formed by the addition of an hydroxide ion to the thiocarbonyl carbon atom. It has not been possible, using kinetic evidence alone, to distinguish conclusively between these two possibilities. However, using the available evidence, arguments are presented in favor of I being an enethiolate anion.

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Nucleophilic Displacement Reactions at the Thiol Ester Bond. IV. General Base Catalyzed Hydrolysis of Ethyl Trifluorothiolacetate. Kinetic Evidence for the Formation of a Tetrahedral Intermediate¹

Cited by 53 publications

References 3 publications

Spontaneous hydrolysis of ethyl formate: Isobaric activation parameters

Spontaneous hydrolysis of ethyl formate: Isobaric activation parameters

The Relative Rates of Thiol–Thioester Exchange and Hydrolysis for Alkyl and Aryl Thioalkanoates in Water

An investigation of the biphasic kinetics observed during the hydroxide ion-catalyzed hydrolysis of alkyl dithioesters

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Nucleophilic Displacement Reactions at the Thiol Ester Bond. IV. General Base Catalyzed Hydrolysis of Ethyl Trifluorothiolacetate. Kinetic Evidence for the Formation of a Tetrahedral Intermediate1

Cited by 53 publications

References 3 publications

Spontaneous hydrolysis of ethyl formate: Isobaric activation parameters

Spontaneous hydrolysis of ethyl formate: Isobaric activation parameters

The Relative Rates of Thiol–Thioester Exchange and Hydrolysis for Alkyl and Aryl Thioalkanoates in Water

An investigation of the biphasic kinetics observed during the hydroxide ion-catalyzed hydrolysis of alkyl dithioesters

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Nucleophilic Displacement Reactions at the Thiol Ester Bond. IV. General Base Catalyzed Hydrolysis of Ethyl Trifluorothiolacetate. Kinetic Evidence for the Formation of a Tetrahedral Intermediate¹