Results and Discussion

Photoinduced ether cleavage

Scheme 1: Mechanism of ether bond cleavage

This intramolecular degradation mechanism was proposed by Rivaton and Morel [1]. The primary process is a cleavage of the ether bond leading to a phenyl and a phenoxy radical. This cleavage can occur on two different positions as can be seen in the scheme above. The results for both pathways are summarized in table 1 and figures 1 and 2. The energies of the formed products are summarized in table 2.

Optimized structures can be obtained here:

Cleavage I:  Educt ---> Transition State ---> Product
Cleavage II: Educt ---> Transition State ---> Product

Table 1: Calculated state energies for the ether bond cleavage. Energies given in kJ/mol.
Cleavage I Cleavage II
Educt S0 0.0 0.0
T1 339.1 339.1
S1 424.1 424.1
Transition state S0 233.6 225.0
T1 377.7 318.7
S1 519.3 505.1
Product S0/T1 213.9 204.8
S1 293.3 475.5

Table 2: Calculated UHF-AM1 ground state energies of the products formed in the ether bond cleavage. Energies given in kJ/mol. For structures select here.
Cleavage I: Phenyl- and Phenoxyradical. Cleavage II: Phenyl- and Phenoxyradical.
Cleavage I Cleavage II
Phenylradical 57.1 69.9
Phenoxyradical -218.8 -240.7

Fig. 1: Cleavage I

Fig. 2: Cleavage II

Results Overview
Results 1,5-Hydrogen transfer
P. Gedeck, June 10th 1995