Cation-anion combination reactions. 14. Reactions of [p-(dimethylamino)phenyl]tropylium ion with nucleophiles in water and methanol

Ritchie, Calvin D.; Minasz, Richard J.; Kamego, A. A.; Sawada, Minoru

doi:10.1021/ja00453a038

Cited by 34 publications

(25 citation statements)

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“…Note that the half-cell in reaction [16] is quite different from that in reaction [14] used by Edwards. Although very few of the potentials for reaction [I61 have been measured in solution, it was possible to devise a thermodynamic cycle (24.…”

Section: Theories Of Nucleophilic Reactivitymentioning

confidence: 99%

“…The later finding of the difference in mechanism between water reactions and others (10)(11)(12)(13)(14) led to the suggestion (13) that water reactions not be included in the N+ correlations, and that log ko be based on reactions of other nucleophiles. From a purely empirical standpoint, k,,/k, seldom varies outside the range of lo3 to lo5 and is only slightly more poorly behaved than some other relative reactivities which we have encountered in later work (17).…”

Section: T~~-( P -N ( C H~)~) Trityl Cation B~s -(~-N ( C H~)~) Tritymentioning

confidence: 99%

“…[15] in that some reactions required negative values of the parameter A (80). Other authors (81) had expressed doubt about the appropriateness of reaction [14] as a "model process" for nucleophilic reactivity, since the potentials contain a large contribution from the X-X bond energies. The parameter E was then redefined by Edwards (80) as the polarizability of the nucleophile.…”

Section: Theories Of Nucleophilic Reactivitymentioning

confidence: 99%

“…equation, has now been tested for a wide variety of Lewis acid-base reactions (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25). Although it is far from being general, and fails badly in some specific cases without apparent cause, it is probably as good as most of the more complex equations when applied to electrophile-nucleophile combination reactions.…”

Section: Introductionmentioning

confidence: 99%

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Cation–anion combination reactions. 26. A review

Ritchie¹

1986

Can. J. Chem.

196

175

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Rate and equilibrium constants for reactions of carbocations, and a few other electrophiles, with anionic and neutral nucleophiles in several solvents are summarized. Equilibrium constants for such reactions are a measure of the carbon basicities of the nucleophiles, and are discussed in the context of differences in proton and carbon basicities. The factors affecting the kinetic reactivities of nucleophiles are not well understood, even though the reactivity patterns are frequently the same toward widely different electrophiles.

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Section: Theories Of Nucleophilic Reactivitymentioning

confidence: 99%

Section: T~~-( P -N ( C H~)~) Trityl Cation B~s -(~-N ( C H~)~) Tritymentioning

confidence: 99%

Section: Theories Of Nucleophilic Reactivitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cation–anion combination reactions. 26. A review

Ritchie¹

1986

Can. J. Chem.

196

175

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“…The observed rate constants for these reactions, in which the combination step is not always rate-determining, must be "corrected" to account for the relative leaving-group abilities of nucleophiles. We found (5) that a single set of values for these leaving-group abilities could be assigned which led to very good correlations, and which have now been shown to be reasonably related to rate constants for dissociation of cation-amine adducts (6).…”

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confidence: 81%

Problems involved in understanding orders of nucleophilic reactivity

Ritchie

1978

Pure and Applied Chemistry

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-The N+ relationship has been found to have considerable generality for the correlation of rate constants of electrophilenucleophile combination reactions. There are, however, some serious deviations from the relationship, particularly for thiolate anions and for azide ion reactions. Data for a large number of reactions show an absence of selectivity-reactivity relationships and a general absence of observable coulombic effects.Detailed examination of the data by the use of the N+ relationship reveals some examples of apparent steric effects on reactivity which, in the case of secondary amines, cause deviations of up to ca. l log unit. The deviant behavior of thiolate and azide ions do not appear tobe rationalizable by any of the current theories of nucleophilic reactivity.I NTRODUCTI ON A major, perhaps predominant, proportion of the important reactions of Organic Chemistry involve nucleophilic addition or Substitution steps. Thus, the problern of understanding nucleophilic reactivity is one of the central foci of Physical-Organic Chemistry and has a rather lang history. Important early work on this problern includes J. 0. Edwards' recognition of the influence of both basicity and polarizability (l) and A. J. Parker's demonstration of the sometimes overwhelming importance of solvent effects (2). By the late 1960's there appeared to be a general consensus (3) that quantitative correlations of nucleophilic reactivities were unlikely to exist.In our opinion, one of the major stumbling blocks in much of the early work was the failure to distinguish mechanistic types of nucleophilic reactions. Following this belief, we have concentrated our efforts toward the study of reactions in which an electrophile-nucleophile combination step is rate-determining. The simplest example of such reactions is a cationanion combination such as the reaction of tropylium ion with cyanide ion. The large majority of amine reactions with cations, nucleophilic aromatic Substitution reactions in protic solvents, nucleophilic substitution reactions of very reactive esters, and Michael reactions, are other examples.From extensive data on such reactions, obtained principally in our laboratories, those of W. P. Jencks, and those of J. L. Kice, we have shown (4) that rate constants can be correlated by the simple N+ equation:Log k = Log ko + N+ ( l ) in which Log ko is a parameter characteristic of the electrophile and N+ is a parameter characteristic of the nucleophile. In words, the equation states that the relative reactivities of electrophiles are independent of nucleophile and those of nucleophiles are independent of electrophile. There is an obvious implication of the absence of specific interactions between electrophile and nucleophile at the transition states for these reactions.We have also shown that Eq. l applies to the addition step for the reactions of nucleophiles with aryl acetates, N-methylimidazolium acetate, and 2,2,2-trifluoroethylthiol acetate. The observed rate constants for these reactions, in which the combinat...

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Semicarbazide

Belletire¹,

Rauh²

2001

Encyclopedia of Reagents for Organic Synthesis

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Cation-anion combination reactions. 14. Reactions of [p-(dimethylamino)phenyl]tropylium ion with nucleophiles in water and methanol

Cited by 34 publications

References 5 publications

Cation–anion combination reactions. 26. A review

Cation–anion combination reactions. 26. A review

Problems involved in understanding orders of nucleophilic reactivity

Semicarbazide

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