Fluorenyllithium-Lewis Base Complexes

Dixon, Joseph A.; Gwinner, Paul; Lini, David C.

doi:10.1021/ja01084a037

Cited by 80 publications

(18 citation statements)

References 2 publications

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“…3 that there is no real discrepancy between the 'H NMR results and those obtained with other methods. As expected, the direct effect on the 5-membered ring protons (1,3) and (2) is much larger than that on the 6-membered ring protons (4,7) and (5,6). In other words, in the contact ion pair the counter ion is localised above the 5-membered ring.…”

Section: Resul'is and Discussionsupporting

confidence: 82%

The alkali cation effect on the ¹H NMR chemical shifts of the indenyl carbanion

Gooijer¹,

Velthorst²

1979

Org. Magn. Reson.

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The complex character of the temperature dependence of the 'H N M R chemical shifts of indenyl-lithium and -sodium in dimethoxyethane is explained. It is shown that the cation causes a polarisation of the C-H bonds and thus inflnenees the proton shifts of the anion, both directly by i t s electric field along the bonds (the direct effect) and induectly via its effect on tEe Ir-electron distribution (the indirect effect). The indirect effect is inferred from uC NMR chemical shift data. By subtracting the temperature dependent contribution of the indirect effect from the experimental 'H data, the direct effect is visualised. It appears that information on ion pairs obtained by 'H and "C NMR on the one hand and optical spectroscopy on the other hand is complementary. Apparently, aggregation of ion pairs does not seriously affect the chemical shift data.

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Section: Resul'is and Discussionsupporting

confidence: 82%

The alkali cation effect on the ¹H NMR chemical shifts of the indenyl carbanion

Gooijer¹,

Velthorst²

1979

Org. Magn. Reson.

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“…1). The spectra showed signals based on FlK9–11 in addition to those due to fluorene and the t ‐BuO group, and they suggested that there was equilibrium, as illustrated in Scheme . The sample temperature was elevated stepwise from 0 to 55 °C to obtain further information on the reaction.…”

Section: Resultsmentioning

confidence: 98%

Synthesis of fluorenylpotassium species with potassium t‐butoxide (t‐BuOK) and its use for anionic polymerization

Nakagawa

Tanaka

Yade

et al. 2005

J. Polym. Sci. A Polym. Chem.

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“…In most cases 2,6-lutidine was included in the rate samples to trap HBr; in no instance was there evidence that it had any influence on the solvolysis rate constant. 6 Calculated using an £a value of 20.3 kcal/mol, as evaluated from solvolysis rate constants reported at other temperatures; 5* = -19eu. = Calculated using £a = 18.9 kcal/mol; AS* = -22 eu.…”

Section: Methodsmentioning

confidence: 99%

Solvent system ethanol-2,2,2-trifluoroethanol as a medium for solvolytic displacement

Roza¹,

Andrews²,

Keefer³

1973

J. Am. Chem. Soc.

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AppendixAH i °(g) has been measured for trimethyl orthoformate;11 for trimethyl orthoacetate, AHt°{g) was calculated using the bond-bond interaction scheme of Pihlaja.12 The standard entropies of the gaseous ortho esters were estimated using the standard entropies of the corresponding hydrocarbons and the correction factor proposed by Stull, et al,13 (it was assumed that this factor should be applied for each oxygen14). S°(g) for methyl acetate was estimated from the value of (11) K.

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Fluorenyllithium-Lewis Base Complexes

Cited by 80 publications

References 2 publications

The alkali cation effect on the ¹H NMR chemical shifts of the indenyl carbanion

The alkali cation effect on the ¹H NMR chemical shifts of the indenyl carbanion

Synthesis of fluorenylpotassium species with potassium t‐butoxide (t‐BuOK) and its use for anionic polymerization

Solvent system ethanol-2,2,2-trifluoroethanol as a medium for solvolytic displacement

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Fluorenyllithium-Lewis Base Complexes

Cited by 80 publications

References 2 publications

The alkali cation effect on the 1H NMR chemical shifts of the indenyl carbanion

The alkali cation effect on the 1H NMR chemical shifts of the indenyl carbanion

Synthesis of fluorenylpotassium species with potassium t‐butoxide (t‐BuOK) and its use for anionic polymerization

Solvent system ethanol-2,2,2-trifluoroethanol as a medium for solvolytic displacement

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The alkali cation effect on the ¹H NMR chemical shifts of the indenyl carbanion

The alkali cation effect on the ¹H NMR chemical shifts of the indenyl carbanion