Results and Discussion

1,5-Hydrogen transfer

In contrast to the ether bond cleavage, this mechanisms consists of two subsequent steps. In the first step, a hydrogen is transferred from a methyl group to the ipso carbon of the adjacent monomeric unit. The formed biradical can than dissociate in a subsequent reaction to fragments with a quinonemethide and a phenolic structure. The results are summarized in table 3 and displayed in figure 3.

Optimized structures can be obtained here:
Step 1 (Hydrogen Transfer):  I  ---> II(TS) ---> III
Step 2 (Ether cleavage):    III ---> IV(TS) --->  V

Table 1: Calculated state energies for the 1,5-hydrogen transfer and the subsequent ether bond cleavage. Energies given in kJ/mol.
I S0 0.0
T1 339.1
S1 424.1
II (TS) S0 191.2
T1 337.0
S1 485.2
III (Intermediate) S0 134.7
T1 165.3
S1 357.4
IV (TS) S0 188.1
T1 321.3
S1 417.3
V S0 61.6
T1 267.2
S1 422.2

Fig. 3: 1,5-Hydrogen Transfer

Results Overview
Results ether cleavage
P. Gedeck, June 10th 1995