Structure, names and properties
A monohydric alcohol contains one hydroxyl group, –OH, attached to a saturated carbon atom. For a simple saturated open-chain member the general formula may be written CnH2n+1OH. The carbon chain is chosen as the parent, numbered so that –OH receives the lowest possible locant, and the alkane ending is replaced by -ol: methanol, ethanol, propan-1-ol and propan-2-ol. Alcohols may be primary, secondary or tertiary according to how many carbon groups are bonded to the carbon carrying –OH.
The O–H and C–O bonds are polar. Alcohol molecules form hydrogen bonds with one another, so their boiling points are higher than those of similar-sized alkanes. The lower members mix well with water because the hydroxyl group forms hydrogen bonds with water. Solubility decreases as the nonpolar carbon chain grows.