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Updated: Feb 6, 2026

Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
Probing the speciation of quaternary ammonium polybromides by voltammetric tribromide titration
Hyeonjeong Kim1, Dayoung Jung, Jiseon Hwang
1Department of Chemistry, Sungshin W. University, 55 Dobong-ro, 76ga-gil, Gangbuk-gu, Seoul 01133, South Korea. jchae@sungshin.ac.kr.
Abstract:
The speciation of quaternary ammonium polybromides (QBr2n+1) was quantitatively determined by voltammetric tribromide titration on a Pt ultramicroelectrode (UME). The concentration of Br3- in a QBr2n+1-water mixed solution (QBr2n+1-WMS) was electrochemically estimated by measuring the steady state current associated with the electro-reduction of Br3- in a linear sweep voltammogram (LSV). The pBr3- titration curves of QBr2n+1-WMSs show 2-4 plateaus, each of which relates to the formation of QBr2n+1 from Br3- and Br2. The values of pBr3- at these plateaus can be regarded as corrected equilibrium constants of QBr2n+1, K'eq(n), which is Keq(n)/γ±, where γ± is a mean activity coefficient in QBr2n+1-WMS. Based on the estimated K'eq(n), fractional diagrams of QBr2n+1 were obtained, which gave information on QBr2n+1 speciation.
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