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Correlation analysis of 31P NMR chemical shifts with substituent effects of phenols

✍ Scribed by Zhi-Hua Jiang; Dimitris S. Argyropoulos; Alessandro Granata


Publisher
John Wiley and Sons
Year
1995
Tongue
English
Weight
690 KB
Volume
33
Category
Article
ISSN
0749-1581

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✦ Synopsis


Over 60 lignin-related model compounds were phosphitylated with 2chloro-4,4,5,5-tetramethyldioxaphospholane, a sterically hindered analogue of 2-chloro-1,3,2-dioxaphospholane used in earlier work, and their 31P chemical shifts were recorded. Excellent resolution between the chemical shifts of phosphitylated carboxylic acids, phenols and aliphatic alcohols was obtained. The correlations of the phosphorus chemical shifts with the chemical environments of lignin-related phenols using the Hammett principles provided an excellent linear relationship between the resonance substituent constant, a: , and the corresponding "P NMR chemical shift values for para-substituted ligninrelated phenols. In addition, a correlation between 31P NMR chemical shifts for ortho-and para-substituted phosphitylated phenols was obtained. A set of empirical parameters that permits the accurate prediction of "P NMR chemical shifts of lignin-related phenolic compounds derivatized with Zchloro-4,4,5,5tetramethyldioxaphospholane was thus obtained.


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