Absence of SN1 Involvement in the Solvolysis of Secondary Alkyl Compounds

Murphy, Thomas J.

doi:10.1021/ed086p519

Cited by 7 publications

(4 citation statements)

References 13 publications

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“…Although IrO 2 and RuO 2 are among the best OER catalysts (5,6), a myriad of perovskite (3, 7) and spinel (8) solids have proven to be competent catalysts. In recent years, amorphous metal oxides have also been demonstrated to be excellent OER catalysts (4,9), including when integrated with photoactive electrodes (10)(11)(12). Although an increasing number of amorphous metal oxide catalysts have been reported (4,9,(13)(14)(15)(16)(17), most have been…”

Section: Supplementary Materialsmentioning

confidence: 99%

“…1B) (10). For example, 7-norbornyl substrates are known to undergo S N 1 solvolysis, in contrast to most other secondary systems, by virtue of nonclassical ion formation with attendant steric blockage of backside attack (11,12). The S N 2(e) pathway is expected to be very strained by virtue of nonbonded interactions of the nucleophile and leaving group with the proximate two one-carbon bridges (in the manner of the 7-norbornyl system).…”

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confidence: 99%

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Evidence for a Symmetrical Fluoronium Ion in Solution

Struble

Scerba

Siegler

et al. 2013

Science

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Halonium ions, in which formally positively charged halogens (chlorine, bromine, and iodine) are equivalently attached to two carbon atoms through three-center bonds, are well established in the synthetic chemistry of organochlorides, bromides, and iodides. Mechanistic studies of these ions have generated numerous insights into the origins of stereoselectivity in addition and displacement reactions. However, it has not been clear whether fluorine can form a halonium ion in the same manner. We present chemical and theoretical evidence for the transient generation of a true symmetrical fluoronium ion in solution from an appropriately configured precursor.

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Section: Supplementary Materialsmentioning

confidence: 99%

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confidence: 99%

Evidence for a Symmetrical Fluoronium Ion in Solution

Struble

Scerba

Siegler

et al. 2013

Science

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“…From thermodynamics and the well-known Thomson-Gibbs equation, the surface of crystals can be easily controlled via simply adjusting supersaturation of crystal growth units in the growth medium during the crystal growth process. 16,17,19 The crystal faces with higher surface energy will appear when the supersaturation of the growth units is increased in the medium. Such inference combines both apparent thermodynamic and kinetic factors that governs the crystal growth process, and has been successfully validated by examples ranging from ionic, molecular to metallic crystals.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of NaCl single crystals with defined morphologies as templates for fabricating hollow nano/micro-structures

et al. 2015

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“…It is now apparent that this is true of secondary carbocations too [ 9 , 10 ]. In some (but not all) textbooks one still sees mention of “mixed S N 1 and S N 2” mechanisms involving secondary substrates [ 11 ], due primarily to the early work of the Hughes and Ingold school [ 12 , 13 ], which has since been discredited [ 13 ]. It is now well established that secondary substrates react by an S N 2 process [ 14 ], for instance as shown in Scheme I , although for the example shown [ 15 , 16 ] the specific mechanism given is still speculative.…”

Section: Introductionmentioning

confidence: 99%

A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

Cox

2011

IJMS

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If a species does not have a finite lifetime in the reaction medium, it cannot be a mechanistic intermediate. This principle was first enunciated by Jencks, as the concept of an enforced mechanism. For instance, neither primary nor secondary carbocations have long enough lifetimes to exist in an aqueous medium, so SN1 reactions involving these substrates are not possible, and an SN2 mechanism is enforced. Only tertiary carbocations and those stabilized by resonance (benzyl cations, acylium ions) are stable enough to be reaction intermediates. More importantly, it is now known that neither H3O+ nor HO− exist as such in dilute aqueous solution. Several recent high-level calculations on large proton clusters are unable to localize the positive charge; it is found to be simply “on the cluster” as a whole. The lifetime of any ionized water species is exceedingly short, a few molecular vibrations at most; the best experimental study, using modern IR instrumentation, has the most probable hydrated proton structure as H13O6+, but only an estimated quarter of the protons are present even in this form at any given instant. Thanks to the Grotthuss mechanism of chain transfer along hydrogen bonds, in reality a proton or a hydroxide ion is simply instantly available anywhere it is needed for reaction. Important mechanistic consequences result. Any charged oxygen species (e.g., a tetrahedral intermediate) is also not going to exist long enough to be a reaction intermediate, unless the charge is stabilized in some way, usually by resonance. General acid catalysis is the rule in reactions in concentrated aqueous acids. The Grotthuss mechanism also means that reactions involving neutral water are favored; the solvent is already highly structured, so the entropy involved in bringing several solvent molecules to the reaction center is unimportant. Examples are given.

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Absence of SN1 Involvement in the Solvolysis of Secondary Alkyl Compounds

Abstract: and keywords Full text (PDF)

Cited by 7 publications

References 13 publications

Evidence for a Symmetrical Fluoronium Ion in Solution

Evidence for a Symmetrical Fluoronium Ion in Solution

Synthesis of NaCl single crystals with defined morphologies as templates for fabricating hollow nano/micro-structures

A Greatly Under-Appreciated Fundamental Principle of Physical Organic Chemistry

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