Is #"butane"# an homologue of #"butane"#?

1 Answer
Mar 8, 2016

Answer:

I take it your question relates to butane, #n-C_4H_10#, and but-2-ene, #H_3C-CH=CHCH_3#? No they are NOT homologues.

Explanation:

Butane is an alkane, with general formula #C_4H_10#. But-2-ene has general formula #C_4H_8#, and is an olefin, an alkene.

A useful concept to develop is the idea of the degree of unsaturation; each degree of unsaturation corresponds to a DOUBLE BOND or a RING. An carbon chain of #n# carbons thus has #(2n+2)# hydrogen atoms if it is saturated. You can see the relationship between butane, #C_4H_10#, and unsaturated #C_4H_8# (it could be cyclobutane, but here it is butene). The #C_4H_8# formula has 2 hydrogens less than the unsaturated formula, and thus an olefinic bond OR a ring junction MUST be present.