Synchronous Disrotatory Motion

Fig. 8. Two-dimensional potential energy surface and static reaction path for the synchronous disrotatory motion of the terminal methylene groups. 2 a represents the value of the carbon ring angle. The abcissa gives the common absolute value of both rotational angles 9 = Sj = -02. TS denotes the position of a transition state. The energies are in kcal/mol...

Five different values of have been studied, namely 61, 62,63, 64 and 65 kcal/mol. For tot = 61 kcal/mol, the only available chatmel is the synchronous conrotatory motion (transition state at 59.8 kcal/mol). For > 62 kcal/mol, the rotation of a single group (transition state at 61.6 kcal/mol) and the concerted disrotatory motion (transition state at 61.9 kcal/mol) both become feasible motions, at least in principle. For each value of jEtot, j rot has been varied stepwise from 2 to 50 kcal/mol, with a step of 2 kcal/mol. In addition, for given values of E o and has been varied from 45° (conrotatory motion, ie. antisymmetric vibra-... 

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