Mechanistic studies in strongly basic media. Part III. Bifluorenylidene formation from 9-bromo-9,9′-bifluorenyl

Abstract

9-Bromo-9,9′-bifluorenyl undergoes E2 elimination in t-butyl alcohol solution containing hydroxide, methoxide, or t-butoxide ions, or piperidine to form bifluorenylidene. Comparison of the rate with that for elimination of deuterium bromide from 9-bromo-9′-deutero-9,9′-bifluorenyl leads to k_H/k_D values greater than predicted from the difference of zero-point vibrational energy for the stretching of the tertiary C–H and C–D bonds in the halides. An earlier conclusion concerning the mechanism of conversion of 9-bromofluorene into bifluorenylidene in basic media has been confirmed.