Rearrangements definition

The derivative should be prepared preferably by a general reaction, which under the same experimental conditions would yield a definite derivative with the other individual possibilities. Rearrangements and side reactions should be avoided. 

We can provide an operational definition for the constant by rearranging Equation (14.23) to give... 

It now seems definitely proved that the thiothiophthene (86) rearranged reversibly to a thiophene (87) under the influence of alkali and not to a thiepin derivative, The dimethyl ether of (87) has been oxidized to 4-methylsulfonyl-2-thiophenecarboxylic acid (88)... 

As has been indicated, since there is a ring isotope effect there must be a degree of C-H bond breaking in the transition state of the rate-determining stage. Clearly further work is required in this system before a definitive mechanism can be established for the intramolecular rearrangement. 

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