HC CN Research Articles

O2-oxidation of cyanomethylene radical: Infrared identification of criegee intermediates syn- and anti-NCC(H)OO

Cyanomethylene radical (HCCN) is an important intermediate in the nitrile chemistry in both the earth’s and the Titan’s atmosphere. Despite that the mechanism for the oxidation of HCCN has been already computationally explored, the key Criegee intermediate, NCC(H)OO, remains unobserved yet. By photolyzing mixtures (1:50:1000) of either HC(N2)CN/O2/N2 (266 nm) or HCCNCO/O2/N2 (193 nm) at 15.0 K, the elusive carbonyl oxides NCC(H)OO, in syn- and anti-conformations, have been generated and characterized with IR spectroscopy. The spectroscopic identification is supported by 18O-labeling experiments and the quantum chemical calculations at the BP86/6-311++G(3df,3pd) level. Upon subsequent UV-light irradiation, both conformers of NCC(H)OO further react with O2 and yield NCC(O)H and O3, whereas, the dioxirane isomer HC(O2)CN, which is lower than syn-NCC(H)OO by 23.7 kcal/mol at the CCSD(T)-F12a/aug-cc-pVTZ//BP86/6-311++G(3df,3pd) level, was not observed experimentally.

Template-Induced High-Crystalline g-C3N4 Nanosheets for Enhanced Photocatalytic H2 Evolution

High-crystalline g-C3N4 nanosheets (HC−CN) with reduced structural defects have been constructed through Ni-foam-induced thermal condensation because Ni-foam not only serves as a template for deposition of the 2D g-C3N4 nanosheets with high surface area to prevent stacking of g-C3N4 nanosheets but also acts as a catalyst to promote the polymerization and crystallization of g-C3N4 via effective dehydrogenation of the −NH2 group. The obtained HC–CN exhibits superior photocatalytic performance for H2 evolution under visible light irradiation (λ > 400 nm), which significantly benefits from the prolonged lifetime of photogenerated charge carriers and the increase of the transfer path within 2D structures of high-crystalline g-C3N4 nanosheets.

The Photochemical and Thermal Decomposition of Azidoacetylene in the Gas Phase, Solid Matrix, and Solutions

AbstractDecomposition of the extremely explosive and unstable parent compound of 1‐azidoalkynes, HCCN3 (azidoacetylene), was studied in the gas phase, solid argon matrix, and solutions. In the gas phase, this azide decomposes quickly at room temperature with a half‐life time (t1/2) of 20 min at an initial pressure (p0) of 0.8 mbar. The decay (p0 = 1.0 mbar) is significantly increased in an atmosphere of O2 with t1/2 of 3 min, in which HC(O)CN was identified as the trapping product of the cyanocarbene intermediate HCCN. Trapping products of this carbene by solvent molecules (CH2Cl2 and CHCl3) were also found during decomposition of the azide in solution, whereas the reaction with a solution of bromine to form dibromoacetonitrile is interpreted as taking place by nucleophilic attack of the alkyne itself. The intermediary formation of triplet HCCN by flash vacuum pyrolysis and photolysis (255 nm) of the azide in the gas phase and in solid argon matrices, respectively, was confirmed by IR spectroscopy and mutual photo‐interconversion of HCCN with isomeric cyclo‐C(H)CN (azirinylidene) and HCNC by selective irradiations at 16 K.

N,N‐dimethylaminoacetylene: (Short Communication)

AbstractN,NDimethylaminoacetylene. HC  CN(CH3)2 has been obtained in about 55% yield by elimination of thiol from the ketene‐N,S‐acetal H2CC (SC4H9)‐(N(CH3)2). The latter compound was synthesized by converting CH3C (O)N‐(CH3)2 into the corresponding thioamide (94% yield) and treating the anion of the thioamide (generated by means of potassium amide) with butyl bromide (85% yield).