6.1. CLASSIFICATION
There are three main types of hydrocarbons, depending on the nature of carboncarbon bonds in a molecule:
• Saturated hydrocarbons that contain single C-C bonds only;
• Unsaturated hydrocarbons containing multiple carbon-carbon bonds: a double bond (or bonds), a triple bond (or bonds), or their combination. Single C-C bonds may be also present, of course;
• Aromatic hydrocarbons that are related in structure to benzene (Sec. 3.2). The first two types are sometimes referred to as aliphatic compounds (from the Greek aleiphas - fat), i. e. compounds of a nonaromatic series.
Hydrocarbons vary considerably in their chemical properties that depend on the nature of the carbon-carbon bonds. This is true also for compounds with various functional groups because hydrocarbons represent a framework of organic molecules.