333. The activation energy of organic reactions. Part IV. Transmission of substituent influences in ester hydrolysis

Tommila, Eero; Hinshelwood, Cyril Norman

doi:10.1039/jr9380001801

Cited by 54 publications

(25 citation statements)

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“…This is what is normally found for A,,-2 ester hydrolysis (e.g. phenyl acetates, p = -0.17 (16); benzyl acetates, p = -0.05 (16)) and can be attributed to the near cancellation of the substituent effects on the two steps in the hydrolysis (12). With these acylals a further factor contributing to the very small p value lies simply in the remoteness of the substituent from the reaction center.…”

Section: Discussionmentioning

confidence: 85%

Mechanisms of Acylal Hydrolysis in Sulfuric Acid Solutions

McClelland¹

1975

Can. J. Chem.

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The acid-catalyzed hydrolysis (in aqueous &So4) of acylals ArOCH20Ac is reported, and compared with that of normal acetate esters. On the basis of r plot behavior and the effects of the aromatic substituents, an A*,-2 ester hydrolysis mechanism is shown to occur in dilute acids, with a changeover to a mechanism analogous to A,,-1 ester hydrolysis (intermediate cation ArOCH2 +) in more concentrated acids, the position of the changeover being dependent on the substituent. Methylene diacetate is also investigated and shown to display the same behavior, with an A-1 mechanism involving an intermediate CH3COOCH2+ becoming important at about 75% &Sod. The relative AA1-1 reactivities for acetates ROAc, R = CH30CH,, tertbutyl, C6H50CH2, C6H5CH2, 4-N0,C6H40CH2, CH3COOCH2, isopropyl, are 6 x lo3, 5 x lo2, 1, 7 x 4 x 1.1 x 1.3 x respectively.ROBERT ALLAN MCCLELLAND. Can. J. Chem. 53,2763Chem. 53, (1975.On rapporte I'hydrolyse acido-catalyse (dans I'acide sulfurique aqueux) d'acylals du type

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Section: Discussionmentioning

confidence: 85%

Mechanisms of Acylal Hydrolysis in Sulfuric Acid Solutions

McClelland¹

1975

Can. J. Chem.

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“…57 This seems to indicate that the nucleophilic character of the OH ligand in the metal complexes studied is similar to that in water.…”

Section: Reaction Between [Re(oh)(co) 3 (N 2 C 2 H 4 )] and Phenyl Acmentioning

confidence: 83%

The Importance of a Conformational Equilibrium on the Reactivity of Molybdenum and Rhenium Hydroxo−Carbonyl Complexes toward Phenyl Acetate: A Theoretical Investigation

2007

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4 )], respectively, was investigated by using the B3LYP density functional theory methodology in conjunction with the PCM-UAHF model to take into account solvent effects. For both complexes, the most favorable reaction mechanism is concerted and takes place, for the first time in the metal-promoted ester hydrolysis, through the addition of the complex O-H bond to the ester single C-O bond. The larger reactivity of the Mo complex experimentally found is explained in terms of the interaction detected in the rate-determining TS between one of the lone pairs of the oxygen atom bearing the phenyl group and the two π-antibonding C-N of the bidentate ligand. Due to the existence of a conformational equilibrium for the Mo complex, its reaction with phenyl acetate can evolve through a rate-determining TS 2.4 kcal mol -1 lower in relative energy than that found for the Re case, thus explaining the ratio between both periods of experimental reaction time.

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“…4), the rate-determining step was confirmed to be TS1(es), with the calculated activation energy +14.45 kcal/mol (exp., +14.6 kcal/mol [47]). While TS2'(es) has a slightly lower energy (= +10.03 kcal/mol) than that (= +10.49 kcal/mol) of TS2(es), the former leads to an unstable intermediate, Ph–C(OH) 2 –OEt, with the energy +8.86 kcal/mol.…”

Section: Resultsmentioning

confidence: 99%

“…The former (ester) reaction has been studied well and its activation energy was reported to be 14.6 kcal/mol [47]. The latter (amide) analogous one ( N , N -dimethyltoluamide, Me–C 6 H 4 –C(C=O)–NMe 2 ) was investigated and the experimental activation free energy was reported to be 27.1 kcal/mol [22].…”

Section: Introductionmentioning

confidence: 99%

Presence or absence of a novel charge-transfer complex in the base-catalyzed hydrolysis of N-ethylbenzamide or ethyl benzoate

Yamabe¹,

Guan²,

Sakaki³

2013

Beilstein J. Org. Chem.

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SummaryReaction paths of base-catalyzed hydrolyses of isoelectronic substrates, Ph–C(=O)–X–Et [X = O (ethyl benzoate) and X = NH (N-ethylbenzamide)], were traced by DFT calculations. To simulate bond interchanges accompanied by proton transfers, a cluster model of Ph–C(=O)–X–Et + OH−(H2O)16 was employed. For X = O, three elementary processes and for X = NH four ones were obtained. The rate-determining step of X = O is the first TS (TS1, the OH− addition step), while that of X = NH is TS2. TS2 of X = NH leads to a novel Mulliken charge-transfer complex, Ph–(OH)(O=)C∙∙∙N(H2)–Et. The superiority or inferiority between the direct nucleophilic process or the general base-catalyzed process for TS1 was examined with the model Ph–C(=O)–X–Et + OH−(H2O)n, n = 3, 5, 8, 12, 16, 24 and 32. The latter process was calculated to be more favorable regardless of the number (n, except n = 3) of water molecules. The counter ion Na+ works unfavorably on the ester hydrolysis, particularly on TS1. A minimal model of TS1 was proposed and was found to be insensitive to n.

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333. The activation energy of organic reactions. Part IV. Transmission of substituent influences in ester hydrolysis

Cited by 54 publications

References 0 publications

Mechanisms of Acylal Hydrolysis in Sulfuric Acid Solutions

Mechanisms of Acylal Hydrolysis in Sulfuric Acid Solutions

The Importance of a Conformational Equilibrium on the Reactivity of Molybdenum and Rhenium Hydroxo−Carbonyl Complexes toward Phenyl Acetate: A Theoretical Investigation

Presence or absence of a novel charge-transfer complex in the base-catalyzed hydrolysis of N-ethylbenzamide or ethyl benzoate

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