Alcohols

Primary, secondary, and tertiary

Alcohols are then classified into primary, secondary (sec-, s-), and tertiary (tert-, t-), based upon the number of carbon atoms connected to the carbon atom that bears the hydroxylfunctional group. The respective numeric shorthands 1°, 2°, and 3° are sometimes used in informal settings. The primary alcohols have general formulas RCH₂OH. The simplest primary alcohol is methanol (CH₃OH), for which R = H, and the next is ethanol, for which R = CH₃, the methyl group. Secondary alcohols are those of the form RR'CHOH, the simplest of which is 2-propanol (R = R' = CH₃). For the tertiary alcohols, the general form is RR'R"COH. The simplest example is tert-butanol (2-methylpropan-2-ol), for which each of R, R', and R" is CH₃. In these shorthands, R, R', and R" represent substituents, alkyl or other attached, generally organic groups.