Reactivity-selectivity correlations. 4. The .alpha. effect in SN2 reactions at sp3 carbon. The reactions of hydrogen peroxide anion with methyl phenyl sulfates

Buncel, Erwin; Wilson, H.K.; Chuaqui, Claudio

doi:10.1021/ja00382a025

Cited by 69 publications

(41 citation statements)

References 3 publications

(4 reference statements)

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“…Also, the Pnuc values for water and methanol are very similar, showing a relative lack of solvent effects in this system. The a effect in the present work is consistent with the a effect for methyl transfers to H02-from the p-nitrophenylsulfate ion (5.7-1 1 .O) (23). The large Pnuc values are associated with very small a effects.…”

Section: Discussionsupporting

confidence: 79%

“…The large Pnuc values are associated with very small a effects. We can estimate the Pnuc for the phenolate anions by using the known rate constants (Table 1) (23) for methyl transfer to H02-. In that report the authors argued that an increased Pnuc showed that there was an anti-Hammond character in the behavior of the transition state (TS) (i.e., the TS was more covalently bound than for normal nucleophiles).…”

Section: Discussionmentioning

confidence: 99%

“…It is strongest at unsaturated sites, such as the carbonyl group (lg, 13), but small a effects are also found at the benzylic group (2), and in displacement of p-nitrophenylsulfate ions from methyl groups by hydrazine and H02-anion (3,23).…”

Section: Introductionmentioning

confidence: 99%

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Reactivity patterns of N-methylbenzhydroxamates. I. Studies of methyl transfer between N-methylbenzhydroxamates and arenesulfonates

Fountain¹,

Fountain²,

Michaels³

et al. 1991

Can. J. Chem.

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. Can. J. Chem. 69,798 (1991).The rates of methyl transfer between benzohydroxamates and sulfonates show large Pnuc values (ca. 0.8) indicating much charge transfer to the C atom, similar to the results of N,N-dialkylaminofluorene anions. A small a effect shows that even in methyl substrates, with certain leaving groups, the effect is displayed. Investigation of the PI, shows that from the leaving group side of the reaction it is a normal SN2 reaction. Correlation of the reactivity with computed gas phase ionization potentials shows that desolvation of anions is probably not important. These results suggest an a-effect model that explains the larger size of the effect at carbonyl groups in terms of greater solvation of the charge transferred to the 0 atom. anions N,N-dialkylaminofluor&nes. Un faible effet a montre que, m&me avec des substrats mCthyles de certains nuclCofuges, on peut observer cet effet. Une Ctude du PI, montre que, par rapport au groupement nuclCofuge, il s'agit d'une reaction SN2 normale.Une corrClation de la rCactivitt avec les potentiels d'ionisation en phase gazeuse calculks montre que la dksolvatation des anions n'est probablement pas importante. Ces rCsultats suggkrent un modkle d'effet a qui explique l'importance plus grande de l'effet au niveau des groupements carbonyles en termes de plus grande solvatation de la charge qui est transfkrke i l'atome d'oxygkne.Mots clis : effet a , courbe de Bransted, potentiels d'ionisation, voltamktrie cyclique, PI,, P,,,, AMl, E4.[Traduit par la rCdaction]

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Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

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Reactivity patterns of N-methylbenzhydroxamates. I. Studies of methyl transfer between N-methylbenzhydroxamates and arenesulfonates

Fountain¹,

Fountain²,

Michaels³

et al. 1991

Can. J. Chem.

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“…Among the following three major factors responsible for the a-effect, namely, (I) destabilization of the ground state of the a-nucleophile by repulsion between the adjacent lone electron pairs (5), (2) stabilization of the transition state by the extra pair of electrons, and (3) reduced solvation of the a-nucleophile by the adjacent lone electron pair, the last two factors have been fairly well substantiated by both theoretical (6)(7)(8)(9) and experimental studies (10)(11)(12)(13). Stabilization of the transition state by the a-nucleophile, namely the second factor, has recently been considered quite important and possibly the major factor for the enhanced reactivity in the nucleophilic attack of the a-nucleophile on the electropositive reacting center, especially in solution.…”

mentioning

confidence: 81%

Importance of repulsion of lone electron pairs in the enhanced reactivity of 1,8-naphthyridine and the large α-effect of hydrazine in the aminolyses of p-toluenesulfonyl chloride

Ōae¹,

Kadoma²

1986

Can. J. Chem.

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SHIGERU OAE and YOSHIHITO KADOMA. Can. J. Chem. 64, 1184 (1986.The rates of aminolyses of p-toluenesulfonyl chloride with primary and tertiary amines have been determined both in acetonitrile and in ethanol. The Bronsted plots of log k, , again pKac values of amines (except hydrazine and 1,8-naphthyridine in acetonitrile) gave a good correlation when the aminolyses were carried out in acetonitrile. In ethanol, however, although Bronsted plots with all tertiary amines show a good correlation, less basic hydrazine shows a higher reactivity than n-butylamine. The abnormal rate enhancement found with hydrazine is undoubtedly due to the a-effect, while that with 1,8-naphthyridine in acetonitrile is considered to be due to the repulsion of two lone electron pairs on the two nitrogen atoms in 1,8-naphthyridine.

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“…1 Current technology for the detoxification of these compounds focuses primarily on the hydrolysis of phosphorus-heteroatom bonds, either with hydroxide ion or with another nucleophile that ultimately exchanges with hydroxide in water. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Sometimes, however, this hydrolysis does not proceed to afford exclusively less toxic products, as in the case of the nerve agent VX. 17 An alternative approach to detoxification is 'hydrolysis' of the P-C bond [i.e.…”

Section: Introductionmentioning

confidence: 99%

Ab initio calculations on P?C bond cleavage in phosphoranyl radicals: implications for the biodegradation of organophosphonate derivatives

Lim

Cramer

1998

J. Phys. Org. Chem.

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Barrier heights for P-C bond homolysis in P-hydroxy-P-methyl-P,P-dioxophosphoranyl and P,P,Ptrihydroxy-P-methylphosphoranyl were calculated using well correlated levels of electronic structure theory. The best estimate for the difference in barriers between the two indicates that homolysis is more facile for P,P,P-trihydroxy-Pmethylphosphoranyl by roughly 9 kcal mol À1 . This result suggests that bacterial pathways leading to P-C bond cleavage in organophosphonate derivatives will preferentially proceed via initial one-electron reduction of substrates rather than oxidation.

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Reactivity-selectivity correlations. 4. The .alpha. effect in SN2 reactions at sp3 carbon. The reactions of hydrogen peroxide anion with methyl phenyl sulfates

Cited by 69 publications

References 3 publications

Reactivity patterns of N-methylbenzhydroxamates. I. Studies of methyl transfer between N-methylbenzhydroxamates and arenesulfonates

Reactivity patterns of N-methylbenzhydroxamates. I. Studies of methyl transfer between N-methylbenzhydroxamates and arenesulfonates

Importance of repulsion of lone electron pairs in the enhanced reactivity of 1,8-naphthyridine and the large α-effect of hydrazine in the aminolyses of p-toluenesulfonyl chloride

Ab initio calculations on P?C bond cleavage in phosphoranyl radicals: implications for the biodegradation of organophosphonate derivatives

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