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Hexane is an organic compound made of carbon and hydrogen that is most commonly isolated as a byproduct of petroleum and crude oil refinement. At room temperature it is an odorless, colorless liquid, and it has many uses in industry. It is a very popular solvent, for instance, and is often used in industrial cleaners; it is also frequently used to extract oils from vegetables, particularly soybeans. Most vehicle-grade gasoline contains it, too. Though most experts say the compound is non-toxic and presents only low risks to humans and animals, there is still a great deal of controversy in many places when it comes to how often it is included, sometimes without full disclosure, in foods and consumer products.
It is usually considered to be a relatively simple molecule. As the hex- prefix indicates, it has six carbon atoms, which are accompanied by 14 hydrogen atoms giving it the molecular formula C6H14. The carbons are chained in a row, one following the next. Each carbon has at least two hydrogen atoms attached to it except for the first and last carbon, which have three. Due to its exclusive carbon-hydrogen makeup and the fact that it only has single molecular bonds, it can be classified as a straight-chain alkane.
The compound is also easily represented visually. When drawn as a Kekulé structure, it is a line of six carbons, each of which has four line-bonds. Hydrogens surround the central carbon chain so that the condensed structure is written as CH3CH2CH2CH2CH2CH3. It is a simple line with five segments.
This compound is stable at room temperature, and most commonly occurs as a colorless liquid. It has a melting point of roughly -139.54°F (-95.3°C), a boiling point of 154.04°F (67.8°C), and it’s molar mass is 86.18 grams per mole (g/mol). Hexane is also a non-polar molecule, which means that it is not soluble in water.
How It’s Extracted
Hexane occurs in a couple of different places in nature, but is usually most readily available in petroleum deposits. This is often why gasoline contains it in high concentrations. When petroleum and petroleum-containing oils are mined and refined, chemists are often able to isolate the compound, which can then be purified and sold commercially.
Popularity as a Solvent
One of the most popular uses is as an industrial cleaner or degreaser. It is very effective breaking molecules down and separating fats and lipids from other substances. From time to time it may be found in household cleaning products, too, but it is usually most common in solvents designed for use on heavy machinery or in places where a lot of space needs to be cleaned somewhat quickly. The solution isn’t normally very expensive, either, which is often a factor.
In Oil Processing
Many types of plants and vegetables are treated with this chemical in order to extract their oils and proteins for use in other products. Soybeans, peanuts, and corn are some of the most common. The compound is often able to break these foodstuffs down very efficiently, and the oils that result are typically ready to be repackaged and either sold or used in manufactured foods with very little additional treatment.
Other Common Uses
As good as it is at breaking compounds down, hexane can also be good at helping things stick together, particularly when used in conjunction with other non-water soluble compounds. It is often found listed as an ingredient in leather and shoe glue, for instance, and is sometimes used in roofing or tiling adhesives, too.
Controversy and Risks
Hexane is generally believed to be toxic or at least harmful when inhaled, and there have been instances of workplace injury and even death when people have spent long hours each day exposed to its fumes. This is most common in factories where oil extractions, industrial cleaning, or certain manufacturing operations take place. High exposure can cause skin irritation, dizziness, and nausea that progressively worsen over time.
There have also been questions about hexane residues that linger in vegetable oils, particularly when these show up in food products available in the general marketplace. Some health advocates argue that the presence of this chemical is unacceptable and dangerous, while others say that it is benign and shouldn’t be a cause for alarm. In most cases the amounts that actually end up in food are very, very small — but still, not a lot is known about how the compound behaves once ingested. Most of the toxicity studies that have been conducted have focused on inhalation and topical skin exposure.