- Substituted diaryldiazomethanes and diazofluorenes: Structure, reactivity and stability
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The synthesis of several substituted diaryldiazomethanes and diazofluorenes, and an assessment of their structure, reactivity and stability, is reported.
- Davis, Philip J.,Harris, Lawrence,Karim, Aman,Thompson, Amber L.,Gilpin, Martin,Moloney, Mark G.,Pound, Matthew J.,Thompson, Claire
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p. 1553 - 1556
(2011/04/26)
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- SN1 reactions with inverse rate profiles
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Carbocations may accumulate during solvolysis reactions! The fact that fast ionization followed by slow trapping of the carbocation R+ is a characteristic pattern of many solvolysis reactions requires that the generally accepted energy profiles of these reactions be revised.
- Denegri, Bernard,Minegishi, Shinya,Kronja, Olga,Mayr, Herbert
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p. 2302 - 2305
(2007/10/03)
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- A Relationship between Selectivity and Solvent Composition for Nucleophilic Attack on Carbocations in Alcohol-Water Mixtures
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Rate constants and products of solvolyses of p-methoxybenzyl chloride 1, chlorodiphenylmethane 2 (Y = Z = H), chloro(4-chlorophenyl)phenylmethane 2 (Y = H, Z= Cl) and chlorobis(4-chlorophenyl)methane 2 (Y = Z = Cl) are reported in ethanol- and methanol-water mixtures at 25 deg C.Product selectivities (S), defined by: S = / are related to four rate constants for reactions involving one molecule of solvent as nucleophile and another molecule of solvent as general base catalyst (e.g. kwa involves water as nucleophile and alcohol as general base, and kww, kaw and kaa are defined similarly).A linear relationship between 1/S and molar ratios of solvent 1/S = (kwa/kaw)(/) + kww/kaw is derived theoretically and validated experimentally for solvolyses of the above substrates from water up to 70percent alcohol-water-in this range of solvents, the contribution from kaa can be neglected.For solvolyses of p-methoxybenzyl chloride, S is independent of pH between pH 2 and 12, S decreases when acetone is added but increases if acetonitrile is added and for 90percent ethanol-water S increases with added LiCl and LiClO4 and increases further if acetonitrile is also present.
- Bentley, T. William,Ryu, Zoon Ha
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p. 761 - 768
(2007/10/02)
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- An Approach towards Identification of Product Precursors in the Solvolyses of Diarylmethyl p-Nitrobenzoates in Ethanol-Water Solvents
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The product ratios, ether:alcohol, for the solvolyses of the title compounds in ethanol-water solvent mixtures have been measured, and have been compared with ratios of the same products generated from the reactions of the corresponding diaryldiazomethanes in the same solvents.The ratios are similar although not always identical, and disparities are ascribed to solvation differences.The question of 'selectivities' of intermediates towards ethanol and water is addressed, and it is concluded that product ratios can be used as selectivity measures only when a single intermediate yields stable products.The present results thus throw little light on the reality or otherwise of stability-selectivity relationships in the present series.Internal return is suggested as an important component in the unassisted solvolysis of the esters.
- McLennan, Duncan J.,Martin, Peter L.
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p. 1099 - 1106
(2007/10/02)
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