A cyanohydrin is a chemical unit known as a functional group. In chemistry, a functional group is a distinct unit of atoms that make up part of the structure of larger molecules, but may also exist as separate compounds as well. Functional groups act as a unit during chemical reactions, and will be affected in similar ways during chemical reactions, regardless of the chemical compound they may be part of. Cyanohydrins, some of which are found in nature, are organic compounds, and are important for many industrial applications such as the production of carboxylic and amino acids.
The term cyanohydrin comes from the units that make up such a molecule. Every cyanohydrin is made up of a cyanide group (CN), a hydroxyl group (OH), a carbon atom (C) and two other sub units, which can be hydrogen atoms (H) or either of two chemical groups (R) called alkyls and aryls. For this reason, the general chemical formula of any cyanohydrin is written as R2H(OH)CN.
Ketones and aldehydes, which are two classes of organic molecules, when combined with a cyanide or nitrile, can result in the formation of cyanohydrins. Cyanides and nitriles are chemicals that have either a cyanide group or a nitrile group as part of their chemical structure, both of which contain a hydrogen and a carbon atom, but bonded in different ways. Hydrogen cyanide, one of the most common cyanides, is an extremely toxic chemical. Many people mistakenly assume that cyanide is only one chemical, but in fact there are several cyanides, including sodium cyanide and potassium cyanide, all of which may be used to produce cyanoydrins. Cyanohydrins may be prepared in a number of ways using cyanide or nitrile compounds, sometimes in combination.
Many of the most common cyanohydrins are themselves toxic or otherwise hazardous. Acetone cyanohydrin, which is used in the production of acrylic and other chemicals, such as pesticides, is very dangerous. It is a skin and eye irritant, can be fatal if its fumes are inhaled, and is an explosion hazard as well. Some naturally occurring cyanohydrins such as mandelonitrile and amygdalin are found in very small amounts in the pits of certain stone fruits, such as some plums and apricots. These compounds are not usually found in large enough amounts to be dangerous, but if ingested in quantity, can be harmful or fatal.