3576-88-3Relevant academic research and scientific papers
Ammelinium Sulfate Monohydrate and Ammelinium Sulfate Cyanuric Acid – Synthesis and Structural Characterization
Kessler, Fabian K.,Schnick, Wolfgang
, p. 848 - 856 (2019)
Two ionic carbon nitride type compounds containing the ammelinium cation, ammelinium sulfate cyanuric acid (6C3N5H6O+·3SO4 2–·1?C3N3H3O3·H2O) (1) and ammelinium sulfate monohydrate (2C3N5H6O+·SO4 2–·H2O) (2) were synthesized through hydrolysis of melam (C6N11H9) in diluted sulfuric acid. 1 crystallizes in hexagonal space group P63 (no. 173) with lattice parameters of a = 14.642(3), c = 13.113(4), and Z = 2. The structure is comprised of protonated ammelinium ions and neutral cyanuric acid molecules, which form a layered structure, as well as sulfate ions that span through these layers. 2 crystallizes in the triclinic space group P1 with lattice parameters of a = 7.404(3), b = 9.673(4), c = 10.040(4), α = 91.098(15), β = 109.884(10), γ = 92.567(13), and Z = 2. As for 1, the ammelinium rings form layers with the sulfate ions located in between. In both structures, no extended hydrogen bond networks between the respective triazine-based molecules are formed. Instead, single molecules or small building blocks occur isolated and interact primarily with sulfate anions. Compound 1, which was obtained phase pure, was further investigated by FTIR spectroscopy, solid-state NMR spectroscopy and powder X-ray diffractometry.
New light on an old story: Formation of melam during thermal condensation of melamine
Lotsch, Bettina V.,Schnick, Wolfgang
, p. 4956 - 4968 (2007)
We report on the existence and formation of the carbon nitride precursor melam (H2N)2(C3N3)NH-(C 3N3)(NH2)2, thereby clarifying one of the last unresolved issues posed by the complex thermal condensation of melamine C3N3(NH2)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. The coexistence of melamine and melem during thermal condensation yields two adduct phases with distinct compositions [C3N3(NH2)3] 2[C6N7-(NH2)3] and [C3N3(NH2)3][C6N 7-(NH2)3]2. They may be considered as co-crystallizates of melamine and melem and can be isolated as intermediates between 590 and 650 K prior to the formation of single-phase melem C 6N7(NH2)3. Melam (C2/c, a = 1811.0(4), b = 1086.7(2), c = 1398.4(3) pm, β= 96.31(3)°, V= 2735.3(9) × 106 pm3, T=130 K) adopts a ditriazinylamine-type structure with a twisted conformation about the bridging NH moiety and transforms into melem around 640 K. Two compounds deriving from melam have been synthesized by solution and solid-state reactions. The salt melamium diperchlorate C6N11H11(ClO4) 2·2H2O (C2/c, a = 1747.8(4), b = 1148.2(2), c = 993.6(2) pm, β= 118.79(3)°, V= 1747.4(6)×106 pm 3, T=130K) crystallizes as a dihydrate and exhibits a doubly protonated, planar melam core. In the neutral complex Zn[C6N 11H9]Cl2 (P21/c, a = 743.00(15), b = 2233.2(5), c = 762.5(2) pm, β = 99.86(3)°, V= 1246.5(4) × 106 pm3, T=200K), melam acts as a symmetrically bent bidentate ligand, which is coordinated to the Lewis acid Zn-site through two ring nitrogen atoms.
Formation and characterization of melam, melam hydrate, and a melam-melem adduct
Wirnhier, Eva,Mesch, Maria B.,Senker, Juergen,Schnick, Wolfgang
, p. 2041 - 2049 (2013)
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 P2 1/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. Copyright
From Heptazines to Triazines – On the Formation of Poly(triazine imide)
Kessler, Fabian K.,Schnick, Wolfgang
, p. 857 - 862 (2019/05/24)
Poly(triazine imide), a 2D extended carbon nitride network compound that is obtained from ionothermal synthesis in LiCl/KCl or LiBr/KBr salt melt has been known for over a decade. We now have investigated the formation process of this material starting from various triazine- and heptazine-based precursors as well as the differences between ionothermal and conventional synthesis via thermal condensation. Independent of chosen starting material, melem (triamino-s-heptazine) is initially formed from the starting material as the imminent precursor to poly(triazine imide). We elucidate the impact of various different carbon nitride precursor compounds on the formation process, propose a mechanism for the back reaction of heptazines to triazines, and rationalize the occurring processes.
Novel carbon nitride composites with improved visible light absorption synthesized in ZnCl2-based salt melts
Fettkenhauer, Christian,Weber, Jens,Antonietti, Markus,Dontsova, Dariya
, p. 40803 - 40811 (2015/02/19)
Poly(triazine imide)-based carbon nitride materials with BET surface areas up to 200 m2g-1were synthesized in ZnCl2containing salt melts without the use of hard templates. We found that the composition, structural order, optical properties and morphology of the products can be adjusted by careful selection of synthesis parameters. The nature of the salt eutectic and precursor concentration in the melt have an especially large influence, with ZnCl2being a reactive solvent. This novel synthesis route provides access to easily processable materials with improved optical absorption in the visible range that can be used as composite photocatalysts, CO2adsorbents or nanocomposite fillers. This journal is
PROCESS FOR THE PREPARATION OF CONDENSATION PRODUCTS OF MELAMINE
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Page/Page column 10-11, (2012/10/18)
The invention relates to a process for the purification of a melamine condensation product, comprising the steps of a) making a diluted slurry of a reaction product mixture comprising the melamine condensation product in a solution of a base in water with a pH of at least 9, b) keeping the diluted slurry for a period of at least 1 hour, c) concentrating the diluted slurry, thereby obtaining a concentrated slurry and an eluent, and d) washing the concentrated slurry by diluting the concentrated slurry with aqueous liquid and repeating step c, wherein the washing is performed by counterflow washing wherein eluents of downstream concentration steps are used to wash the slurry in upstream concentration steps.
Generation of melamine polymer condensates upon hypergolic ignition of dicyanamide ionic liquids
Chingin, Konstantin,Perry, Richard H.,Chambreau, Steven D.,Vaghjiani, Ghanshyam L.,Zare, Richard N.
experimental part, p. 8634 - 8637 (2011/11/07)
The reaction of dicyanamide ionic liquids with nitric acid results in hypergolic ignition and the formation of a stable precipitate. The precipitate consists of cyclic triazines, including melamine and its polymers, such as melam and melem (see scheme). This study introduces a novel approach to the synthesis of cyclic azines without resorting to high temperatures and pressures. Copyright
