Title

Comparison of ΔG°Acid (gas phase) and kinetic acidities measured in methanolic sodium methoxide

Document Type

Article

Publication Date

1-1-1998

Abstract

Hydron exchange rates, k (M s ), using methanolic sodium methoxide were compared with ΔG° , (kcal mol ) (gas phase) for 9-phenylfluorene, C H CH(CF ) , m-CF C H CH(CF ) , p-CF C H CHClCF , m-CF C H CHClCF , 3,5-(CF ) C H CHClCF , fluorene and C F H. There is a good linear correlation for p-CF C H CHClCF , m-CF C H CHClCF and 3,5-(CF ) C H CHClCF , with the others falling off the line. The fluorinated benzyl compounds and pentafluorobenzene have near-unity isotope effects and therefore differ from the fluorenyl compounds. Although the acidity and the exchange rates for three of the compounds [9-phenylfluorene, C H CH(CF ) and p-CF C H CHClCF ] are similar, the important proton-transfer step to form a hydrogen-bonded carbanion intermediate and the subsequent breaking of that weak bond to form a free carbanion in methanol differ significantly for the fluoernyl compound compared with the two fluorinated benzylic compounds. © 1998 John Wiley & Sons, Ltd. exc Acid 6 5 3 2 3 6 4 3 2 3 6 4 3 3 6 4 3 3 2 6 3 3 6 5 3 6 2 3 3 6 4 3 3 2 6 3 3 6 5 3 2 3 6 4 3 -1 -1 -1

Publication Name

Journal of Physical Organic Chemistry

Volume Number

11

First Page

614

Last Page

617

Issue Number

8-9

DOI

10.1002/(sici)1099-1395(199808/09)11:8/9<614::aid-poc46>3.0.co;2-8

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