What is Isopentane?

Isopentane is an organic compound with a variety of uses, ranging from being an ingredient in cosmetics to being a component in a type of geothermal power plant. This solvent is extremely flammable. Its tendency to evaporate makes it useful for dissolving compounds, since it is easily evaporated away. This chemical smells like gasoline and does not dissolve in water, but floats on top of it. It is considered harmful to the environment.

Also known as methylbutane, this compound has a formula of C5H₁₂. It is known as a hydrocarbon, since it contains only carbon and hydrogen atoms. The structure of this compound is CH₃CHCH₂CH₃, with a methyl — CH₃ — group attached to the second carbon. Pentane has the same formula, but has a structure of CH₃CH₂CH₂CH₂CH₃ with no branching. These two compounds are known as structural isomers.

This branching lowers the boiling point of isopentane, compared to pentane. Its boiling point is only 103°F (27.9°C). The flash point of this compound is relatively high, at -68°F (-55°C). This combination of characteristics is responsible for the extreme flammability of the chemical. If there is a fire, one should not spray water on it. That can result in the compound floating to the top of the water, and possibly catching fire again.

Mixed with other compounds, however, isopentane can be quite stable. It is often used in a range of cosmetics, including shaving gel, body wash, and specific types of toothpaste. The manufacture of insulation is another use for this compound.

In laboratories, isopentane is used to make a bath in liquid nitrogen. It is quite common to prepare tissues for storage at -94°F (-70°C) by immersing them in liquid nitrogen. This process of flash freezing preserves such biological samples.

A container of isopentane can be put into a larger container of liquid nitrogen. When the solvent becomes cloudy, it is near freezing. It is then removed from the liquid nitrogen and used to freeze the specimen. It is important to let the solvent evaporate before the sample is stored in a freezer.

Another use of isopentane is in a type of geothermal plant known as a binary cycle power plant. Geothermal plants tap into heat energy deep in the earth and convert it to electricity. This kind of geothermal plant can use cooler reservoirs than other types. This is because the hot water from the geothermal energy heats liquid isopentane and turns it into a gas. This gas then drives a turbine and generator to generate the power plant’s electricity.

The density of isopentane is 0.616 g/ml. Its molecular weight is 72.15 g/mol. It is important to remember that this compound is classified as a lung, skin, and eye irritant.