Kinetic analysis, partial melting

Polycrystalline samples of these racemates were irradiated, and the diastereomeric dimers were isolated and submitted to a careful mass-spectrometric analysis. The values of r were deduced from the ratios of the intensities of peaks corresponding to doubly deuteriated (55), partially deuteriated (RS + SR), and non-deuteriated dimers (RR). Parallel investigations of the dependence of r on temperature and time of irradiation have shown that no differential kinetic effect is operative in the dimerization of (RR) [or (55)] with respect to (RS). By applying this method to monomer (2) rapidly cooled from the melt we obtained values of r = I, suggesting a totally random distribution of the enantiomers along the polymerization axis. ... 

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