ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The reversible photointerconversion in the above system was investigated in a wide range of temperatures and wavelengths of irradiation. The tetrahydropyrenes are obtainable only photochemically. The unmethylated and the mono-methylated compound are oxidized with iodine quantitatively to 4,5-dihydropyrene, even at -30°. This makes it possible to estimate the absolute concentration of the tetrahydropyrenes, and thereby their molar extinction coefficients and complete electronic absorption spectra. The quantum yields in both directions do not vary appreciably with the temperature, down to -190°. This is the first case in which the photocyclization yield of a cis-stilbenelike compound is not attenuated on cooling, and reflects the special character of highly constrained structures. No emission was observed in solution. 1H-NMR.-spectra of both modifications of the dimethylated compound were taken. They support the structures assumed for both modifications, and also allow an estimate of their relative concentrations.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19740570739
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