Branched Chains

In a branched-chain alkane, at least one carbon atom is joined to three or four other carbon atoms, so side chains come off the main chain.The side chains are alkyl groups, with the general formula C_nH_2n+1. The most common are methyl (-CH₃) and ethyl (-C₂H₅).For example, 2-methylpropane, CH₃CH(CH₃)CH₃, has a methyl group on the middle carbon of a propane chain.Branched alkanes still fit the general formula C_nH_2n+2. 2-methylpropane is C₄H₁₀, the same as butane.Branched alkanes are important in petrol because they burn more smoothly in engines than straight-chain alkanes.