https://doi.org/10.1351/goldbook.P04523
A residue from heat treatment and distillation of petroleum fractions. It is solid at room temperature, consists of a complex mixture of numerous predominantly aromatic and alkyl-substituted aromatic
hydrocarbons
, and exhibits a broad softening range instead of a defined melting
temperature.Note:
The hydrogen
The hydrogen
aromaticity
(ratio of aromatic to total hydrogen atoms) varies between 0.3 and 0.6. The aliphatic hydrogen atoms are typically present in alkyl groups
substituted on aromatic rings or as naphthenic hydrogen.