Synthesis of Epoxide Compounds

Carbon papers (TGP-H-090) were purchased from Toray Industries, Inc (Tokyo, Japan). Potassium bromide (KBr, 99%), potassium chloride (KCl, 99.5%), potassium iodide (KI, 99%), sodium hydroxide (NaOH, 96%), nitric acid (HNO₃, 65-68%), silver nitrate (AgNO₃, 99.8%) and hydrochloric acid (HCl, 36-38%) were all purchased from Sinopharm Chemical Reagent Co. Ltd. (Shanghai, China). PO (99.7%), propylene bromohydrin (75%), ethylene oxide (99.5%), 1,2-butylene oxide (99%), isobutylene oxide (97%), 1,2-epoxyoctane (97%), cyclopentene oxide (97%), and styrene oxide (97%) were purchased from Aladdin Co. Ltd. (Shanghai, China). 4,4-dimethyl-4-silapentane−1-sulfonic acid (DSS), dimethyl sulfoxide-d₆ (DMSO-d₆, 99.9 atom% D), and Nafion 115 membrane were purchased from Sigma-Aldrich. The deionized (DI) water with a resistivity of 18.2 MΩ cm was provided by a Millipore Milli-Q grade. All of the chemicals were used without any further purification.