1 H 614 MAN IS MASTERING HIS MATERIAL WORLD unsaturated compounds and the corresponding saturated compounds produced by hydrogenation are fats. Coal may be hydrogenated to produce gasoline, and this process is now being carried out on a large scale in certain European countries. The Majority of Organic Reactions Are Substitution Reactions. If methane is treated with chlorine under properly controlled conditions, one or more of the hydrogen atoms may be replaced with chlorine atoms. Thus: H H H CI CI ^—c—
C H H COVALENT REACTIONS 615 H H H Glycerol H—C—C—C— OH OH OH Glycerol, known under its common name, glycerine, is used to make nitroglycerine, an explosive. Aldehydes are produced by the oxidation of alcohols in which two atoms of hydrogen are removed. H H HO H—C—C—OH + O —>- H—C—C + H2O H H H H ethyl alcohol acetaldehyde O Formaldehyde H— H is the most common aldehyde. It is used as a disinfectant and preservative and in the manufacture of plastics. Organic acids may be considered to be derivatives of hydrocarbons in which the H is substituted by a carboxyl group, COOH, or as products obtained by the oxidation of aldehydes, thus: HO HO I II I II H—C—C + O — > H—C—C—O— I H I H I H acetic acid (the acid in vinegar) H H H O Acetic acid and butyric acid, H— C — C — C — C —O—H, an acid in rancid butter, are typical organic acids. H H H H H H Such groups of atoms as H— C — C — or H—C— act as units and I H I H I H are therefore called hydrocarbon radicals. They are usually written as C2H5, CHs, etc.