Observation of reactive o-quinodimethanes by flow NMR

The detection of 1,2-dimethylene-1,2-dihydronaphthalene (2) and o-xylylene (1) in the presence of its stable dimers by the technique of flow /sup 1/H NMR is reported. The NMR flow apparatus used for this study was patterned after that of Fyfe; however, the apparatus was designed so that flow rates could be varied by changing the transfer and detector volumes. It was determined by uv-vis spectrometry that 2 is about 100 times less reactive than 1, and it was even possible to obtain the /sup 1/H NMR spectrum of 2 before it dimerizes. The high reactivity of 1 made it impossible to obtain its spectrum in the absence of its dimer. 27 references, 1 figure.