Functional groups - 3 | Structure and Reactivity

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.