4452-08-8Relevant articles and documents
The Simplest, Isolable, Alkynyl Isocyanate HC≡CNCO: Synthesis and Characterization
Qin, Yuanyuan,Lu, Bo,Rauhut, Guntram,Hagedorn, Manfred,Banert, Klaus,Song, Chao,Chu, Xianxu,Wang, Lina,Zeng, Xiaoqing
supporting information, p. 17277 - 17281 (2019/11/11)
Alkynyl isocyanates have been postulated as highly reactive intermediates in synthetic chemistry. Herein, the parent molecule HC≡CNCO is isolated for the first time. In sharp contrast to the previously reported short lifetime (ca. 15 s) at room temperature, we found that HC≡CNCO has a lifetime of 55 h in the gas phase (2 mbar, 300 K) with a melting point of ?79.5 °C and vaporization enthalpy (ΔHvap) of 23.1(1) kJ mol?1. Apart from the IR (gas, solid, and matrix), 1H and 13C NMR, and UV/Vis spectroscopic characterization, its photoisomerization with a acylnitrene HC≡CC(O)N and cyanoketene NCC(H)CO has been observed.
Cyanoketene and Iminopropadienones
Moloney, Daniel W. J.,Wong, Ming Wah,Flammang, Robert,Wentrup, Curt
, p. 4240 - 4247 (2007/10/03)
Cyanoketene (8) is generated in high yields on flash vacuum thermolysis (FVT) of suitably substituted Meldrum's acid derivatives (5-[(alkylamino)(methylthio or alkylamino)methylene]-2,2-dimethyl-1,3-dioxane-4,6-diones) (3e-j), and also on FVT of cyanoacetic acid derivatives 9e,f,g,j,k,m. The major reaction pathway from 3 proceeds via ketenimines 6 and (alkylimino)propadienones 7, the latter undergoing a retro-ene reaction to 8. A minor pathway is via imidoylketenes 4e,h and oxoketenimines 5e,h, which undergo retro-ene reactions to 9. All intermediates were characterized by Ar matrix FTIR and tandem mass spectrometry (collisional activation MS). Trapping of 4, 5, and 8 with nucleophiles is also reported. The preference of 1,3-X shifts over 1,5-H shifts in imidoylketenes 12 (X = SMe or NMe2) is corroborated by the calculated activation barriers. Neat cyanoketene is highly reactive, reacting at or below 80 K, and this is attributed to the availability of a low-lying ketene LUMO. The IR spectrum of cyanoketene (Ar, 14 K) is dominated by two absorptions at 2163 (s; C=C=O) and 2239 (w; CN) cm-1 in excellent agreement with density functional (B3-LYP/6-31G*) and ab initio (QCISD/6-31G*) calculations.
Pyrolysis of aminonitriles, cyanohydrazones, and cyanoacetamides. Part II. Elimination reactions of arylacetylhydrazone, arylcyanoacetylhydrazone, and substituted cyanoacetamides
Al-Awadi,Elnagdi,Mathew,Abdel Khalik
, p. 749 - 754 (2007/10/03)
Rates of pyrolytic reactions of arylacetyldydrazone and arylcyanoacetylhydrazone (1-4) of the general formula GCH2CONHN=CHAr (G = H,CN) have been measured. The increase in the acidity of the hydrogen atom involved in the six-centered elimination process suggested for these reactions causes a significant increase in rates and thus appears to be the limiting factor in these pyrolytic reactions. The implication of this conclusion for the pyrolytic reactions of substituted cyanoacetamides (5-8), NCCH2CONHAr are considered. The mechanism of pyrolytic reactions of compounds (5-8) appears to proceed through a 4-membered cyclic transition state.
Pyrolysis of amino nitriles, cyanohydrazones, and cyanoacetamides. Part I. Elimination reaction of 1-arylmethyleneamino-1,2-dihydro-4, 6-dimethyl-2-oxopyridine-3-carbonitriles and substituted benzaldehyde cyanoacetylhydrazones
Al-Awadi,Elnagdi,Mathew,El-Gamry,Abdel Khalik
, p. 741 - 748 (2007/10/03)
Pyrolysis of the Schiff bases of 1-arylmethyleneamino-1,2-dihydro-4, 6-dimethyl-2-oxopyridine-3-carbonitriles (1-5) has been studied. These compounds eliminate via a six-membered transition state to produce substituted benzonitriles and 2-hydroxy-4,6-dimethylpyridine-3-carbonitrile. These eliminations are unimolecular first-order reactions. The kinetic data gave a good correlation with σ0 values of the substituents on the aryl group with ρ = 0.83 at 520 K. Utilization of the pyrolytic reaction in synthesis of various benzonitriles is considered, and mechanistic information has been obtained by comparing the kinetic data and product analysis of the Schiff bases with their open-chain substituted benzaldehyde cyanoacetylhydrazones (6-9) analogues.
Phosphoric anhydride in the synthesis of monosubstituted ketenes and related dimers
Zavlin, P. M.,Efremov, D. A.,Essentseva, N. S.,Tebby, J. C.
, p. 529 - 532 (2007/10/03)
Monosubstituted ketenes and related condensation products, including phosphorylated, were obtained by the action of phosphoric anhydride on ethyl esters of monosubstituted acetic and malonic acids.
The Phosphorylation of Organic Compounds by Phosphoric Anhydride. Part 3. Synthesis of Monosubstituted Ketenes in the Reaction of Esters with Phosphoric Anhydride and cyclotrimerization of these Ketenes
Efremov, Dimitry A.,Zavlin, Pavel M.,Essentseva, Nataly S.,Tebby, John C.
, p. 3163 - 3168 (2007/10/02)
Monosubstituted ketenes 1 have been synthesized from substituted acetic esters 2 by elimination of alcohol under the action of phosphoric anhydride.The ketenes undergo cyclotrimerization to give substituted phloroglucinols (1,3,5-trihydroxybenzenes) 3 and their phosphorylated derivatives.
