Question

What feature in its structural formula indicates whether a hydrocarbon is an alkane, alkene, alkyne, or aromatic compound?

Answer 1

The following features decide the kind of hydrocarbon

1. The general molecuar formula of alkane will be: CnH2n + 2 where n = number of carbons.

They will lack any pi bond.

2. The general molecuar formula of alkene will be: CnH2n where n = number of carbons.

They will have single pi bond between any two carbons.

3 The general molecuar formula of alkyne will be: CnH2n -2 where n = number of carbons.

They will have two pi bonds between two carbon atoms

4. An aromatic hydrocarbon is unsaturated and instead of being in a straight line is in a ring format. Aromatic compounds will be

a) Planar

b) will have a cyclic pi electron conjugated system

c) They will have 4n+2 pi electrons in the cycic cloud, where n = 1,2,3,4...etc [Huckel's rule]