Definition of an Aliphatic Compound

It contains carbon and hydrogen joined together in chains or rings

Ethylene is an example of an aliphatic compound.
Ethylene is an example of an aliphatic compound. LAGUNA DESIGN / Getty Images

An aliphatic compound is an organic compound containing carbon and hydrogen joined together in straight chains, branched chains, or nonaromatic rings. It is one of two broad classes of hydrocarbons, the other being aromatic compounds.

Open-chain compounds that contain no rings are aliphatic, whether they contain single, double, or triple bonds. In other words, they may be saturated or unsaturated. Some aliphatics are cyclic molecules, but their rings are not as stable as those of aromatic compounds. While hydrogen atoms are most commonly bound to the carbon chain, oxygen, nitrogen, sulfur, or chlorine atoms might also be present.

Aliphatic compounds are also known as aliphatic hydrocarbons or eliphatic compounds.

Examples of Aliphatic Compounds

Ethylene, isooctane, acetylene, propene, propane, squalene, and polyethylene are examples of aliphatic compounds. The simplest aliphatic compound is methane, CH4.

Properties of Aliphatic Compounds

The most significant characteristic of aliphatic compounds is that most of them are flammable. For this reason, aliphatic compounds are often used as fuels. Examples of aliphatic fuels include methane, acetylene, and liquefied natural gas (LNG).

Aliphatic Acids

Aliphatic or eliphatic acids are the acids of nonaromatic hydrocarbons. Examples of aliphatic acids are butyric acid, propionic acid, and acetic acid.