When levulinic acid was hydrogenated at high pressure over a nickel catalyst at 220°C, a s...

When levulinic acid was hydrogenated at high pressure over a nickel catalyst at 220°C, a single product, C5H8O2, was isolated in 94% yield. This compound lacks hydroxyl absorption in its IR spectrum and does not immediately liberate carbon dioxide on being shaken with sodium bicarbonate. What is a reasonable structure for the compound?