Functional groups - 3 | Structure and Reactivity

Organic Chemistry 1 - Functional groups - 3

A is an alkane with formula C6H12 with only secondary carbons.
B is an ether with formula C4H8O with no trigonal planar carbon.
C is a thiol with formula C4H10S, which is not primary.
D is a ketone with 5 carbons and at least one of them is tertiary.
Draw A, B, C and D.