Description & warning
2-methylbutane (aka methylbutane or isopentane) is a hydrophobic liquid with a boiling point at just 28°C. Since it is also highly flammable, care has to be taken that it is used under the hood away from fire to avoid accident.
Methylbutane is used in the lab as an intermediate cooling medium. A setup could be: a tissue sample immersed in methylbutane, itself immersed in liquid nitrogen. This type of cooling is more efficient than direct contact of the sample with liquid nitrogen (-196°C) which evaporates upon contact with a warm object. Less heat is transmitted from the sample to the gaseous nitrogen than from the sample to the liquid methylbutane (-160°C).
Biological samples flash frozen for example with a combination of liquid nitrogen and methylbutane can then be used for storage, cryosection, etc.