Indicate the reaction characteristic of aldehydes.

The most common reactions are nucleophilic addition reactions, which lead to the formation of alcohols, alkenes, diols, cyanohydrins. The main reactions of the carbonyl group are nucleophilic additions to the carbon-oxygen double bond. This addition consists of the addition of a nucleophile and hydrogen through a carbon-oxygen double bond. Due to differences in electronegativity, the carbonyl group is polarized. The carbon atom has a partial positive charge and the oxygen atom has a partially negative charge. Aldehydes are generally more reactive to nucleophilic substitutions than, for example, ketones, due to steric and electronic effects.