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Abstract

This work reports on synthesis of high yield (92%) of isosadeuteriobenzopinacol (benzopinacol-d20) via photo-reductive dimerization of benzophenone-d10. The latter compound was obtained using an improved method to achieve a material with high isotopic purity (> 99%). This material can be served for calibration of mass spectrometric assays. In this study, it was also observed that benzophenone-d10 reacts faster than its natural abundance counterpart. However, elucidating the origin of this phenomenon will require additional work.

From Incident Light to Persistent and Regenerable Radicals of Urea-Assembled Benzophenone Frameworks: A Structural Investigation

“…Usually upon ketyl radical formation in solution, BP reacts to form dimers and the sample must be resynthesized. , Indeed, irradiation of 2 or 3 in acetonitrile (∼1 mg/mL) for 24 h showed loss of all starting material resonances in the 1 H NMR (Figures S37–38). In contrast, urea assembly orients the BPs in a geometry that appears to prevent dimerization as no changes were observed by 1 H-NMR or X-ray diffraction .…”

“…10 From the T 1 state, BP can undergo phosphorescence, 10 nonradiative decay, 11 intermolecular energy transfer, or abstraction of a neighboring hydrogen to form a ketyl radical, 12 which commonly leads to dimerization. 13,14 Early studies of triplettriplet energy transfer in mixed BP/naphthalene glasses displayed phosphorescence of naphthalene after BP excitation. 15 Later, triplet excited BP ( 3 BP) was shown to undergo electron transfer with neighboring BPs via π-type or n-type self-quenching mechanisms.…”

“…BP is an efficient triplet sensitizer that rapidly undergoes intersystem crossing from an S 1 to T 2 and ultimately T 1 state . From the T 1 state, BP can undergo phosphorescence, non-radiative decay, intermolecular energy transfer, or abstraction of a neighboring hydrogen to form a ketyl radical, which commonly leads to dimerization. , Early studies of triplet-triplet energy transfer in mixed BP/naphthalene glasses displayed phosphorescence of naphthalene after BP excitation . Later, triplet excited BP ( 3 BP) was shown to undergo electron transfer with neighboring BPs via π-type or n-type self-quenching mechanisms. , The π-type self-quenching occurs when the lone electron in the π* orbital of 3 BP is donated to the empty π* orbital of a neighboring ground state BP.…”