A new polymorph of ammonium succinate – serendipity in action

Succinic acid has been known since 1546 and was first chemically identified in the mid‐19th century. In an attempt to prepare a molecular salt of succinic acid with (S)‐(?)‐α‐methylbenzylamine, we have obtained the second polymorph of the monoammonium salt of succinic acid, NH₄⁺·C₄H₅O₄^?. The crystal structure determination proves the structure of the ionic compound and the intimate role of the ammonium ion in the structure, which is compared to the earlier described polymorph.