ISSN:
0009-2940
Keywords:
[6]Paracyclophanes
;
Dewar isomers
;
Prismane isomers
;
Photo valence isomerization
;
Quantum yields
;
Activation energy
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Irradiation in the wavelength range of λ = 270 - 320 nm of 8,9-bis(N-cyclohexylcarbamoyloxymethyl)-[6]paracyclophane(1b) in dilute fluid solutions produces the 1,4-Dewar isomer 2b in a quantum yield of 2.8% while the quantum yield of the rearomatization is 19% in heptane at room temperature. A photostationary equilibrium may be attained which depends strongly on the wavelength of irradiation. At λ = 290 nm 76% of the [6]paracyclophane isomer 1b is obtained whereas at λ = 310 nm 83% of the Dewar isomer 2b is formed in ethanol. The thermal back reaction 2b → 1b follows the Arrhenius law (Ea = 95.9 ± 4.0 kJ/mol, lg A = 10.6 ± 0.4 in heptane). By irradiating 1b with λ 〈 270 nm the prismane isomer 3b is formed via the Dewar isomer 2b.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911240821
