The IR spectrum of a compound, X, exhibits a sharp absorption at about 1710 cm -1. Among other peaks located upfield the H-NMR shows a distinct triplit at 9.5ppm. The broadband proton decoupled 13C-NMR shows a singlet peak at 200ppm and three other distinct singlet peaks far upfield. The compound can be easily oxidized with chromic acid. It gives a negative Beilstein test. The coupound has an IHD=1 and does not exhibit optical activity. What is the structure of compound X?