The broad singlet at 4.6 ppm in the 1H-NMR of unknown #7 disappears when the sample is spiked with a trace of acid in D20. The compound is slightly soluble in water (~ 8% by mass) and reacts with HBr to give an alkyl halide. 1C-NMR shows 4 peaks. Write the structure of this compound.

Unknown #8 has a molecular ion region with m/2 152 (M", base) and 151 (94%). The IR spectrum (KBr disc) has a sharp singlet at 3600 cm as well as very strong peaks at 1700, 1600, 1500, 1290, 1275, and 627 cm1. The 1'c-NMR has 191, 152, 147, 130, 127, 115, 109, and 56 ppm. Write the structure of this compound.

The unknown fails to react with PCC in dry CH2Cl but does react with dilute H,SO, to give a mixture of three volatile isomers 18 units lower in mass than the unknown itself; one isomer is the major product, one minor, and one trace in amount. Write the structure of the unknown and the three volatile isomers (indicate major, minor, and trace).