ISSN:
1573-9171
Keywords:
2-alkylthiopropenals
;
Diels–Alder reaction
;
kinetics
;
reaction mechanism
;
2,5-dialkylthio-3,4-dihydro-2H-pyran-2-carbaldehyde
;
IR spectroscopy
;
ab initio calculations
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract The kinetics of 2-alkylthiopropenals cyclodimerization was studied in the temperature range from -7 to +42 °C in heptane and at 20 °C in various solvents. The rate constants for cyclodimerization of 2-alkylthiopropenals are four orders of magnitude higher than those for dimerization of the oxygen-containing analogs, 2-alkoxypropenals, and are independent of the solvent polarity and substituent steric constant. The activation parameters for 2-butylthiopropenal cyclodimerization were estimated. The distribution of electron density in the 2-methoxy- and 2-methylthiopropenals molecules was calculated by the ab initio method. From comparison of the HOMO and LUMO energies for these aldehydes it was concluded that the ratio between the cyclodimerization rates for 2-alkylthio-, 2-ethoxypropenals, and propenal is determined by the HOMO–LUMO gap.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1009507522009
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