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- Title
Formation and Characterization of Melam, Melam Hydrate, and a Melam-Melem Adduct.
- Authors
Wirnhier, Eva; Mesch, Maria B.; Senker, Jürgen; Schnick, Wolfgang
- Abstract
Until recently, melam, [C3N3(NH2)2]2NH, has been regarded as a short-lived intermediate in the condensation process of melamine that is only detectable under special reaction conditions owing to its high reactivity. A new synthetic approach has allowed a closer look at the formation and condensation behavior of melam by using elevated ammonia pressure in autoclaves. Whereas the thermal treatment of dicyandiamide at 450 °C and 0.2 MPa ammonia yielded melam in large amounts, prolonged treatment under these conditions (9 days) led to the formation of a melam-melem adduct, thus enabling the first insight into the condensation process of melam into melem. The hydrothermal treatment of melam at 300 °C (24 h) yields melam hydrate, [C3N3(NH2)2]2NH ⋅2 H2O (space group P21/ c; a=676.84(2), b=1220.28(4), c=1394.24(4) pm; β=98.372(2)°; V=1139.28(6)×106 pm3; Z=4), which crystallizes as a layered structure that is composed of almost-planar melam molecules, thereby forming ellipsoidal rosette-like motifs. The resulting voids are filled with four water molecules, thus forming a dense network of hydrogen bonds.
- Publication
Chemistry - A European Journal, 2013, Vol 19, Issue 6, p2041
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201203340