Naphtha (petroleum), isomerisation; Low boiling point modified naphtha (A complex combination of hydrocarbons obtained from catalytic isomerisation of straight chain paraffinic C 4 through C 6 hydrocarbons. It consists predominantly of saturated hydrocarbons such as isobutane, isopentane, 2,2- dimethylbutane, 2-methylpentane, and 3-methylpentane.)