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Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid
Published on: November 15, 2017
Reaction of tetramethylpiperidine N-oxides with persistent triplet diphenylcarbenes
Jun-ichi Nakajima1, Katsuyuki Hirai, Hideo Tomioka
1Chemistry Department for Materials, Faculty of Engineering, Mie University, Tsu, Mie 514-8507, Japan.
Abstract:
Persistent triplet diphenylcarbenes with considerable stability have been shown to be trapped by tetramethylpiperidine N-oxides (TEMPOs) to give the corresponding benzophenones as major products along with tetramethylpiperidine, which indicates that the reaction pattern is essentially identical with that observed for parent triplet diphenylcarbene. The absolute rate constants for the quenching reaction were measured by a laser flash photolysis technique and compared with those for quenching by other typical triplet carbene quenchers. The results showed that the reactivity of TEMPOs toward triplet carbenes was lower than that of oxygen but higher than that of 1,4-cyclohexadiene. The advantages of TEMPOs as a triplet carbene quencher as opposed to the other quenchers are discussed, and TEMPOs are shown to be very convenient reagents to estimate the reactivity of triplet carbenes.
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