In chemistry, hexahydro-1,3,5-triazine is a class of heterocyclic compounds with the formula (CH2NR)3. Known as aldehyde ammonias, these compounds characteristically crystallize with water. They are reduced derivatives of 1,3,5-triazine, which have the formula (CHN)3, a family of aromatic heterocycles.
They are also called triazacyclohexanes or TACH's, but this acronym is also applied to cis,cis-1,3,5-triaminocyclohexane.