Description General description Oxalic acid dihydrate (OAD) crystals are reported to be monoclinic with P21/n space group.[1] The electron density of OAD has been obtained using X-ray diffraction studies under high resolution.[2] Application Oxalic acid dihydrate may be used: • As a catalyst in the preparation of tetrahydroquinoline derivatives via imino Diels-Alder reaction.[3] • As a homogeneous catalyst in the preparation of highly functionalized piperidines via multi-component reaction.[4] • As an oxidant for the formation of triazolinediones from corresponding urazoles and bisurazoles via oxidation.[5] • In the transformation of thiols to nitrosothiols by reacting with sodium nitrite.[6] Packaging 1, 3 kg in poly bottle 10 mg in glass bottle 100, 500 g in poly bottle Legal Information ReagentPlus is a registered trademark of Sigma-Aldrich Co. LLC