ISSN:
0009-2940
Keywords:
Solvatochromism
;
Stilbazolium betaines
;
Steric effects on solvation
;
Alcohols, acidity of
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The hydrogen bond acidity of twenty primary, secondary, and tertiary alkanols has been measured by the solvatochromic method by using three stilbazolium betaines: stilbazolium betaine itself (SB), o-tert-butyl-substituted (TBSB), and o,o'-di-tert-butyl-substituted SB (DTBSB). The spectral differences between two of these betaines and in particular the Δ' values which correspond to SB and DTBSB, have been compared with Reichardt's ET(30) values. Excluding sterically hindered alcohols, both scales are linearly related. For normal alkanols, the Δ' values have been compared with the absorbance of the stretching of the OH band both free and associated with N,N-dimethylacetamide (DMA). There is a linear relationship between Δ' and ln [(Av(OH)associated)/(Av(OH)free)] which proves that Δ' is a measure of the hydrogen-bond donor (HBD) acidity of alcohols. Contrary to some expectations, the effect of alkyl substituents shows a slow attenuation with increasing number of carbon atoms in the chain.
Additional Material:
1 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931261118
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