Two isomers having molecular formula C4H6O are both symmetrical in structure . In their infrared spectra , neither isomer when in dilute solution in CCl4(used because it is nonpolar ) has absorption in the 3600 cm-1 region. Isomer a has absorption bands in the 2900 cm-1 region and at 1780 cm-1 . Propose a structure for A and two possible structure for B ?

Compound C is asymmetric , has molecular formula C5H10O , and contains two methyl groups and a 3 functional group . It has a broad infrared absorption band in the 3200-3550 cm-1 region and no absorption in the 1620-1680 cm-1 region

a) Propose a structural for C
b) Is your suggested structure capable of stereoisomerism ? If so, draw the stereoisomer's using the wedge-dashed wedge method .

The 1620-1680 cm-1 band is a carbonyl stretch (C=O). The 3200-3550 band is a CH stretch.

Your compound has a carbonyl in it, so it's not an alcohol: C-OH, or an ether, C-O-C. It has to be either a ketone, R-CO-R, or an aldehyde, R-CO. To decide, check your tables and see where aldehydes and ketones absorb (they're shifted a bit). Also, you can figure out whether you have double bonds by the C/H ratio.

Look at the information I gave you for your previous problem. The very high 1780 cm-1 band is a certain type of CO bond.