A<unk>  is a chemical reaction in which two molecules or moieties combine to form one single molecule, together with the loss of a small molecule. When this small molecule is water, it is known as a dehydration reaction; other possible small molecules lost are hydrogen chloride, methanol, or acetic acid.
A<unk>  may be considered as the opposite of a hydrolysis reaction (the cleavage of a chemical entity into two parts by the action of water).
Condensation reaction
Hydrolysis
Exothermic reaction
Chemical modification
Catalytic reforming
Organic reaction
Autoxidation
Polymerization