What are Hydrocarbon Compounds?

Hydrocarbons, as the name suggests, are compounds composed of only hydrogen and carbon atoms. Yet, the sheer diversity of structures and functions that they encompass is nothing short of astonishing.

We will start by exploring the three major types of hydrocarbons: alkanes, alkenes and alkynes, each with its own unique characteristics and reactivity. Alkanes are the simplest of the hydrocarbons, with single carbon-carbon bonds that result in straight or branched chains. Alkenes introduce the concept of double carbon-carbon bonds, lending them a degree of reactivity and structural variation. Finally, alkynes take it a step further with triple carbon-carbon bonds, showcasing even greater reactivity and versatility.

Real-World Examples of Hydrocarbon Compounds

Hydrocarbons are used in a wide variety of applications and on an enormous scale. They are sourced from natural gas and crude oil, the fossil fuel substances taken from underground. These unrefined products are mixtures which are refined in industrial facilities to generate the raw materials used to produce everything from gasoline, to plastics, paints, cosmetics and drugs.

Hydrocarbons are the simplest organic compounds, but they have interesting physiological effects. These effects depend on the size of the hydrocarbon molecules and the part of the body which is exposed to them.

Alkanes of low molar mass—those with from 1 to approximately 10 or so carbon atoms—are gases or light liquids that act as anesthetics. Inhaling these hydrocarbons in gasoline or aerosol propellants for their intoxicating effect is a major health problem that can lead to liver, kidney or brain damage, or to immediate death by asphyxiation by excluding oxygen. Accidental exposure to these fumes is also a danger in certain workplaces.

If swallowed, liquid alkanes do little harm while in the stomach. In the lungs, however, they cause “chemical” pneumonia by dissolving fatlike molecules from cell membranes in the tiny air sacs (alveoli). The lungs then become unable to expel fluids, just as in pneumonia caused by bacteria or viruses. People who swallow gasoline or other liquid alkane mixtures should not be made to vomit, as this increases the chance of getting alkanes into the lungs. (There is no home-treatment antidote for gasoline poisoning; call a poison control center.)

On skin, liquid alkanes with approximately 5–16 carbon atoms per molecule wash away natural skin oils and cause drying and chapping, while heavier liquid alkanes (those with approximately 17 or more carbon atoms per molecule) act as emollients (skin softeners). Such alkane mixtures as mineral oil and petroleum jelly can be applied as a protective barrier. Water and aqueous solutions such as urine will not dissolve such a film, which explains why petroleum jelly is used in diaper ointments. A similar protective barrier is set up in anti-chafing products marketed to athletes.

Alkenes, alkynes and aromatic hydrocarbons are a bit more reactive and have more complex chemical and physiological profiles. Their physical properties are quite similar to alkanes, however, since they are non-polar due to the roughly equivalent electronegativities of carbon and hydrogen.