A theoretical study on the pK_a values of selenium compounds in aqueous solution

Abstract

The pKa values of different kinds of selenium compounds (R-SeH) were investigated by using the ωB97XD method with a SMD model.

Selenium-enriched plant foods: Selenium accumulation, speciation, and health functionality

“…In contrast, Se compounds with higher p K a values, such as SeCys 2 (p K a ∼ 8.07 and 8.94), will be in protonating state and retained very little on anion column chromatography at pH around 5 in the mobile phase ( 49 , 50 ). In contrast, cation exchange chromatography works similarly to anion exchange, except that the stationary phase is negatively charged, which could interact with the positively charged Se compounds ( 51 , 52 ). Furthermore, some other types of chromatography could be applied for Se compound separation.…”

A diselenide additive enables photocatalytic hydroalkoxylation ofgem-difluoroalkenes

“…The excited state photocatalyst PC-I* + [ E 1/2 (PC* + /PC˙) = +1.70 V] 36,37 then oxidizes (BnSe) 2 ( E p = +1.0 V, see ESI†) to generate PC-I˙ and selenyl radical cation 10 , which in turn oxidizes gem -difluoroalkene 6 ( E p = +1.0–1.4 V, see ESI†) to generate radical cation 6 •+ . 28,33–35 The resultant PC-I˙ [ E 1/2 (PC + /PC˙) = –0.97 V] 36,37 reduces selenyl radical 11 to regenerate the ground state PC-I + and form selenolate 12 (p K a calc’d = 6.61 in H 2 O) 45 – direct reduction of (BnSe) 2 is unlikely given its low measured reduction potential ( E p = –1.7 V, see ESI†). Separately, alcohol nucleophile 9 adds to radical cation 6˙ + to form radical oxonium intermediate 13 , an acidic species that can release a proton to form radical intermediate 14 and selenol 15 .…”