Premium
Exceptionally high decarboxylation rate of a primary aliphatic acyloxy radical determined by radical product yield analysis and quantitative 1 H‐CIDNP spectroscopy
Author(s) -
Fraind Alicia,
Turncliff Ryan,
Fox Teri,
Sodano Justin,
Ryzhkov Lev R.
Publication year - 2011
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1836
Subject(s) - decarboxylation , chemistry , radical , cidnp , yield (engineering) , steric effects , spectroscopy , photochemistry , medicinal chemistry , primary (astronomy) , stereochemistry , organic chemistry , catalysis , astronomy , physics , quantum mechanics , materials science , metallurgy
Symmetrical (RCO 2 CO 2 R; R = XCH 2 CH 2 ) and asymmetrical (RCO 2 CO 2 R′; R = C 9 H 19 CH 2 CH 2 , R′ = CH 3 or m ‐ClC 6 H 4 ) primary diacyl peroxides were thermally decomposed under different conditions to analyze the decarboxylation rates of the thermally generated acyloxy radicals. Quantitative models of the geminate product yields, and qualitative and quantitative 1 H‐CIDNP spectroscopy were used to obtain the decarboxylation rate estimates. Results reported here suggest that, unlike short chain acyloxy radicals such as propanoyloxyl, long chain acyloxy radicals possess the highest decarboxylation rates of all known acyloxy radicals, estimated at (0.5–1.5) × 10 12 s −1 between 80 and 140 °C. Given the nature of the dissociative state of acyloxy radicals, such rates appear to be the result of destabilization of the former by the steric bulk of the long chain substituents. Additionally, the rate of this order of magnitude suggests a nearly concerted decarboxylation of primary diacyl peroxides. Copyright © 2011 John Wiley & Sons, Ltd.