ISSN:
0894-3230
Keywords:
Organic Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
Dipole moments of a series of 2,6-bis(dimethylamino) and 2,6-bis(pyrrolidino) derivatives of 4H-pyran-4-one (2), 4H-thiopyran-4-thione (3), 4H-pyran-4-thione (4) and 4H-thiopyran-4-thione (5) were determined in benzene and dioxane solutions at 25°C. High values of the dipole moments (6·44-8·44 D) and mesomeric moments originated from delocalization of the nitrogen lone pairs into the π-system of the heterocyclic moieties (1·11-3·08 D) indicate a strong polarization of the molecules 2-5 due to a tendency to stabilize pentamethinium and pyrylium (thiopyrylium) ionic structures. The MNDO-calculated electronic distribution in 2-5 compared with that for the parent 4H-pyran(thiopyran)-4-one(thione)s is in line with this conclusion.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/poc.610060902
