Some Derivatives of Cyameluric Acid and Probable Structures of Melam, Melem and Melon

Abstract

Since it has been shown recently that the structure proposed by Pauling and Sturdivant for the cyameluric acid nucleus,11, accounts more satisfactorily for the acidic strength and for the products of hydrolysis2 than any other proposed structure, and because of the prediction made by these authors1 that there should be a group of cyameluric compounds analogous to the cyanuric compounds, attempts have been made to prepare some of these analogs.Cyameluric acid forms a blue-lavender cupric ammonium salt, CuNH4(C6N703)NH3, entirely analogous to that of cyanuric acid,3 CuNH4-(C3N303).NH3. The insoluble cupric ammonium

New Light on an Old Story: Formation of Melam during Thermal Condensation of Melamine

“…[1] Since the 19th century much effort has been devoted to the elucidation of the composition and structure of the pyrolysis products of melamine, which, however, was hampered by conflicting statements with respect to their elemental composition and ways of formation. [24,25,30,31] Whereas the identity of melamine was resolved by the elucidation of its crystal Abstract: We report on the existence and formation of the carbon nitride precursor melam (H 2 N) 2 2 , thereby clarifying one of the last unresolved issues posed by the complex thermal condensation of melamine C 3 N 3 A C H T U N G T R E N N U N G (NH 2 ) 3 . Experimental proof is put forward that melam is a direct condensation product of melamine, but can be detected only in small amounts under special reaction conditions owing to its rapid transformation into melem.…”

“…[24,[25][26][27][28][29] Owing to their prototypic carbon(IV) nitride backbones, resolving the identities of these potential CN x precursors may entail farreaching implications for the structure and formation of g-C 3 N 4 , at the same time shedding light on the historically as well as industrially important thermolysis reaction of melamine.…”

“…The resulting "ditriazinylamine"-type structure model was set out as early as 1886 by Klason [33] and accepted by later investigators. [24,25,34,35] Doubts about the correctness of this proposed structure arose following several unsuccessful attempts to obtain melam by pyrolyzing melamine, the products of which were identified as melem by IR and UV spectroscopy. [27-29, 36, 37] In contrast, May reported on the isolation of melam, melem, and melon as the pyrolysis products of melamine obtained at 633, 673, and 773 K, respectively, based on elemental analysis.…”

Structural Investigation of Graphitic Carbon Nitride via XRD and Neutron Diffraction

“…The first examples of structural investigation date back to the early 20 th century. [5][6][7] Since then two main 2D structures have been suggested: a triazine-based ( Figure 1a) [8][9][10][11] and a tri-s-triazine-based one( Figure 1b) [12][13][14][15] . Many investigations have been carried out in order to confirm which of the two structures could describe g-C 3 N 4 .…”

Poly(triazine imide) with Intercalation of Lithium and Chloride Ions [(C3N3)2(NHxLi1−x)3⋅LiCl]: A Crystalline 2D Carbon Nitride Network

“…[18,19] Due to the amorphous character and undefined composition of melon, its structure was an object of discussion for a long time, which resulted in several structural models based on both heptazine or triazine cores (see Scheme 1), respectively. [18,[20][21][22][23] Recently, a structure solution by combination of several analytical techniques comprising electron diffraction Abstract: Poly(triazine imide) with intercalation of lithium and chloride ions (PTI/Li + Cl À ) was synthesized by temperature-induced condensation of dicyandiamide in a eutectic mixture of lithium chloride and potassium chloride as solvent. By using this ionothermal approach the well-known problem of insufficient crystallinity of carbon nitride (CN) condensation products could be overcome.…”