ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The pyrolysis kinetics of primary, secondary, and tertiary β-hydroxy ketones have been studied in static seasoned vessels over the pressure range of 21-152 torr and the temperature range of 190°-260°C. These eliminations are homogeneous, unimolecular, and follow a first-order rate law. The rate coefficients are expressed by the following equations: for 1-hydroxy-3-butanone, log k1(s-1) = (12.18 ± 0.39) - (150.0 ± 3.9) kJ mol-1 (2.303RT)-1; for 4-hydroxy-2-pentanone, log k1(s-1) = (11.64 ± 0.28) - (142.1 ± 2.7) kJ mol-1 (2.303RT)-1; and for 4-hydroxy-4-methyl-2-pentanone, log k1(s-1) = (11.36 ± 0.52) - (133.4 ± 4.9) kJ mol-1 (2.303RT)-1. The acid nature of the hydroxyl hydrogen is not determinant in rate enhancement, but important in assistance during elimination. However, methyl substitution at the hydroxyl carbon causes a small but significant increase in rates and, thus, appears to be the limiting factor in a retroaldol type of mechanism in these decompositions. © John Wiley & Sons, Inc.
Additional Material:
6 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550241009
Permalink
