Methanol is the simplest alcohol, and is a light, volatile, colorless, flammable liquid with a distinctive odor very similar to that of ethanol. At room temperature, it is a polar liquid, and is used as an antifreeze, solvent, fuel, and as a denaturant for ethanol. It is also used for producing biodiesel via transesterification reaction.
About 40% of methanol is converted to formaldehyde, and from there into products as diverse as plastics, plywood, paints, explosives, and permanent press textiles. Methanol is used on a limited basis to fuel internal combustion engines. One of the potential drawbacks of using high concentrations of methanol (and other alcohols, such as ethanol) in fuel is the corrosivity to some metals of methanol, particularly to aluminium. Methanol, although a weak acid, attacks the oxide coating that normally protects the aluminum from corrosion. In addition to direct use as a fuel, methanol (or less commonly, ethanol) is used as a component in the transesterification of triglycerides to yield a form of biodiesel. Other chemical derivatives of methanol include dimethyl ether, which has replaced chlorofluorocarbons as an aerosol spray propellant, and acetic acid. Dimethyl ether (DME) also can be blended with liquified petroleum gas (LPG) for home heating and cooking, and can be used as a diesel replacement for transportation fuel. In some wastewater treatment plants, a small amount of methanol is added to wastewater to provide a carbon food source for the denitrifying bacteria, which convert nitrates to nitrogen to reduce the nitrification of sensitive aquifers. Methanol was used as an automobile coolant antifreeze as well as a denaturing agent in polyacrylamide gel electrophoresis. Methanol is easier to store than hydrogen, burns cleaner than fossil fuels, and is biodegradable.