Some Reactions of Cyameluric Chloride

117

By studying the thermal condensation of melamine, we have identified three solid molecular adducts consisting of melamine C(3)N(3)(NH(2))(3) and melem C(6)N(7)(NH(2))(3) in differing molar ratios. We solved the crystal structure of 2 C(3)N(3)(NH(2))(3)C(6)N(7)(NH(2))(3) (1; C2/c; a=21.526(4), b=12.595(3), c=6.8483(14) A; beta=94.80(3) degrees ; Z=4; V=1850.2(7) A(3)), C(3)N(3)(NH(2))(3)C(6)N(7)(NH(2))(3) (2; Pcca; a=7.3280(2), b=7.4842(2), c=24.9167(8) A; Z=4; V=1366.54(7) A(3)), and C(3)N(3)(NH(2))(3)3 C(6)N(7)(NH(2))(3) (3; C2/c; a=14.370(3), b=25.809(5), c=8.1560(16) A; beta=94.62(3) degrees ; Z=4; V=3015.0(10) A(3)) by using single-crystal XRD. All syntheses were carried out in sealed glass ampoules starting from melamine. By variation of the reaction conditions in terms of temperature, pressure, and the presence of ammonia-binding metals (europium) we gained a detailed insight into the occurrence of the three adduct phases during the thermal condensation process of melamine leading to melem. A rational bulk synthesis allowed us to realize adduct phases as well as phase separation into melamine and melem under equilibrium conditions. A solid-state NMR spectroscopic investigation of adduct 1 was conducted.

Section: Introductionmentioning

confidence: 99%

Melamine–Melem Adduct Phases: Investigating the Thermal Condensation of Melamine

Sattler

Pagano

Zeuner

et al. 2009

117

“…The thio-and selenocyamelurates were synthesized by heating cyameluric chloride with an excess of the respectivet hiol or selenol in mesitylene (Scheme1). Cyameluric chloride was synthesized in accordance with al iterature procedure [6] and purified by sublimation.T he products wereo btained in moderate yields (54-69 %) as white (1,3)o ry ellow solids (2,4,5,6,7). These compounds were heatedi nH 2 Oa nd monitored by IR spectroscopy,which provedt heir stabilitya gainst hydrolysis.…”

Section: Synthesismentioning

confidence: 99%

“…[1] Furthermore, s-heptazines have been proposeda sh alogen-free flame retardants, [2] OLED materials, [3,4] and as MOF linkers. [5] Melem (C 6 N 7 (NH 2 ) 3 )a nd cyameluric chloride (C 6 N 7 Cl 3 ) [6] represent two key compounds for the synthesis of new s-heptazine compounds, such as different melem derivatives, [7][8][9][10] cyameluric acid derivatives, [11,12,13] and triaryl-s-heptazines. [5] In contrastt o the well-exploredc hemistry of s-triazines (C 3 N 3 RR'R''), the diversity of s-heptazine derivatives reported to date is still very limited.…”

Section: Introductionmentioning

confidence: 99%

Arylthio‐ and Arylseleno‐Substituted s‐Heptazines

Posern

Böhme

Wagler

et al. 2017

In contrast to numerous thio- and selenocyanuric acid derivatives, sulfur- or selenium-containing s-heptazines have not been reported so far. Thio- and selenocyameluric acid esters were obtained by substitution reactions of s-heptazine chloride C N Cl with aromatic thiols and selenophenol; the resultant white or yellow solids were stable in air. They were comprehensively characterized by elemental analysis, H, C NMR, and IR spectroscopy. The thiocyameluric acid phenyl ester (1, C N (S(C H )) ) and the corresponding selenium compound (7) formed co-crystals with mesitylene, which were analyzed by single-crystal X-ray diffraction. Both structures showed unusually large channels of ≈12 Å diameter. The thermal stability was measured by TGA (thermogravimetric analysis), and the flame retardancy of compound 1 was tested in PP by carrying out limiting oxygen index (LOI) measurements, which gave promising results. Quantum chemical calculations of the title compounds were performed to explain the observed properties and structural characteristics.

“…[19] Cyameluric acid is almosti nsoluble in most organic solvents and shows al ow reactivity.T herefore, the synthesis of organic cyameluric acid esters usually requires cyameluric chloride, which is in turn obtained from potassium cyamelurate as a typical starting material. [20] Triphenylcyameluratew as described by Schroeder and Kober [20] and single crystals could be obtained later by sublimation. [21] In previous work we described triaryl-and trialkylthiocyamelurates as sulfur analogues.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Thiocyameluric Acid C₆N₇S₃H₃, Its Reaction to Alkali Metal Thiocyamelurates and Organic Tris(dithio)cyamelurates

Posern

Höhne

Böhme

et al. 2019

Thiocyameluric acidC 6 N 7 S 3 H 3 ,the tri-thio analogue of cyameluric acid, is ak ey compound for the synthesis of new s-heptazine (tri-s-triazine) derivatives. Here, two different routes for the synthesis of thiocyamelurica cid and its reaction to tris(aryldithio)-and tris(alkyldithio)cyamelurates C 6 N 7 (SSR) 3 are reported as well as transformation to alkali metal thiocyamelurates M 3 [C 6 N 7 S 3 ], M= Na, K. Thesec ompoundsw ere characterisedb yF TIR, Raman, solution 13 Ca nd 1 HNMR spectroscopies, thermal gravimetric analysis( TGA) and elementala nalysis. The three (de)protonation steps of thiocyamelurica cid were investigated by acid-base titration followed via UV/Vis absorptions pectroscopy.W hile it was not possible to determine the three pK a values, it could be postulated that the acid strength probably increases in the following order:cyanuric acid (C 3 N 3 O 3 H 3 ) < thiocyanuric acid (C 3 N 3 S 3 H 3 ) < cyameluric acid (C 6 N 7 O 3 H 3 ) < thiocyameluric acid (C 6 N 7 S 3 H 3 ). Single crystalso fN a 3 [C 6 N 7 S 3 ]·10 H 2 Oa nd K 3 [C 6 N 7 S 3 ]·6 H 2 Ow ere obtained and the structures analyzed by single crystal X-ray diffraction. Additionally,q uantum chemicalc alculationsw ere performed to get insights into the electronic structure of thiocyameluric acid and to clarify the thiol-thione tautomerism.B ased on ac omparison of calculated and measuredv ibrational spectra it can be concluded that thiocyamelurica cid and the di-and mono-protonated anionsexist in the thione form.Scheme1.Principalstructures of the s-triazine derived cyanurates [C 3 N 3 O 3 ] 3À ,a nd the s-heptazine derived cyamelurates [C 6 N 7 O 3 ] 3À and their thio analogues. For ab etterc omparisonw ith cyameluricacid andcyamelurates we named 2,5,8-trimeracpto-tri-s-triazine and its derivatives thiocyameluric acid, thiocyameluratesa nd the disulfidesa re named dithiocyamelurates.[a] C.Supporting Information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.org/10.