The Simplest, Isolable, Alkynyl Isocyanate HC≡CNCO: Synthesis and Characterization

Qin, Yuanyuan; Lü, Bo; Rauhut, Guntram; Hagedorn, Manfred; Banert, Klaus; Song, Chao; Chu, Xianxu; Wang, Lina; Zeng, Xiaoqing

doi:10.1002/anie.201911102

Cited by 15 publications

(12 citation statements)

References 50 publications

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“…According to the IR spectrum of the N 2 -matrix-isolated pyrolysis products at 10 K (Figure B), the azide decomposes completely, as evidenced by the absence of its IR bands. Strong IR bands for CH 2 CFNCO ( b , 2248.8/2266.4, 1705.7, 1437.5/1462.0, 1203.0, 915.1/931.5, 839.1/833.4, 827.3, 665.8, 560.0, and 511.4 cm –1 ), HF ( d , 3880.1 cm –1 ), and NCC(H)CO ( c , 3076.7, 2240.2, 2162.8, and 1364.4 cm –1 ) − can be identified, indicating further dissociation of CH 2 CFNCO by the elimination of HF (CH 2 CFNCO → HCCNCO + HF) followed by immediate isomerization of HCCNCO to the cyanoketene isomer under the pyrolysis conditions. This intramolecular isomerization has been previously observed for matrix-isolated HCCNCO under irradiation at 266 nm .…”

Section: Resultsmentioning

confidence: 99%

3-Fluoro-2H-azirine: Generation, Characterization, and Photochemistry

Zhu,

Zeng

2023

J. Phys. Chem. A

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Section: Resultsmentioning

confidence: 99%

3-Fluoro-2H-azirine: Generation, Characterization, and Photochemistry

Zhu,

Zeng

2023

J. Phys. Chem. A

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“…27a is unusual because of its ethyne isocyanate substructure. Alkynyl isocyanates have been previously synthesized and characterized and are relevant to polymer chemistry, atmospheric chemistry, and interstellar chemistry. , Here, we expect 27a to react further and possibly contribute to the formation of other side products.…”

Section: Resultsmentioning

confidence: 99%

Experimental and Computational Mechanistic Study of Carbonazidate-Initiated Cascade Reactions

et al. 2022

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A variety of Huisgen cyclization or nitrene/carbene alkyne cascade reactions with different types of termination were investigated. Accessible nitrene precursors were assessed, and carbonazidates were found to be the only effective initiators. Solvents, terminal alkynyl substituents, and catalysts can all impact the reaction outcome. Study of the mechanism both computationally (by density functional theory) and experimentally revealed relevant intermediates and plausible reaction pathways. Article pubs.acs.org/joc

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“…In recent years, there has been significant experimental research progress on substituted isocyanate molecules including substituents such as, -CN, 1 -ClSO 2 , 2 -CCH, 3,4 CH 3 , 5,6 -Ph, 7,8 -CH 2 CH 2 Cl, 9 -t-Bu, 10 and many more [11][12][13][14] Isocyanic acid (HNCO) is the lowest energy isomer of the HNCO system and the simplest isocyanate, 15,16 an important class of molecules for many diverse chemical contexts. HNCO is an atmospheric pollutant formed via the burning of fossil fuels, cigarette use, and other secondary sources.…”

Section: Introductionmentioning

confidence: 99%

“…[17][18][19][20][21] Many combustion processes are also related to the HNCO species and its derivatives. 7,[22][23][24] Isocyanate molecules are also important interstellar species [4][5][6]25 that are implicated as critical intermediates for prebiotic precursors such as formamide, [26][27][28] thyamine, 29 and urea. 30 One of the reasons isocyanates are so ubiquitous is their diverse and facile reactivity with many organic molecules, 11,17,[31][32][33]33 thus motivating further research into understanding the important features of reactions involving isocyanates.…”

Section: Introductionmentioning

confidence: 99%

Catalyzed Reaction of Isocyanates (RNCO) with Water

Wolf¹,

Vandezande

Schaefer³

2021

Preprint

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The reactions between substituted isocyanates (RNCO) and other small molecules (e.g. water, alcohols, and amines) are of significant industrial importance, particularly for the development of novel polyurethanes and other useful polymers. We present very high level ab initio computations on the HNCO + H 2 O reaction, with results targeting the CCSDT(Q)/CBS//CCSD(T)/cc-pVQZ level of theory. Our results affirm that hydrolysis can occur across both the N− −C and C− −O bonds of HNCO via concerted mechanisms to form carbamate or imidic acid with ∆H 0K barrier heights of 38.5 and 47.5 kcal mol −1 . A total of 24 substituted RNCO + H 2 O reactions were studied.Geometries obtained with a composite method and refined with CCSD(T)/CBS single point energies determine that substituted RNCO species have a significant influence on these barrier heights, with an extreme case like fluorine lowering both barriers by close to 20 kcal mol −1 and most common alkyl substituents lowering both by approximately 4 kcal mol −1 . Natural Bond Oribtal (NBO) analysis provides evidence that the 1 predicted barrier heights are strongly associated with the occupation of the in-plane C−O* orbital of the RNCO reactant. Key autocatalytic mechanisms are considered in the presence of excess water and RNCO species. Additional waters (one or two) are predicted to lower both barriers significantly at the CCSD(T)/aug-cc-pV(T+d)Z level of theory with strongly electron withdrawing RNCO substituents also increasing these effects, similar to the uncatalyzed case. The 298 K Gibbs energies are only marginally lowered by a second catalyst water molecule, indicating that the decreasing ∆H 0K barriers are offset by loss of translational entropy with more than one catalyst water. Two-step 2 RNCO + H 2 O mechanisms are characterized for the formation of carbamate and imidic acid. The second step of these two pathways exhibits the largest barrier and presents no clear pattern with respect to substituent choice. Our results indicate that an additional RNCO molecule might catalyze imidic acid formation but have less influence on the efficiency of carbamate formation. We expect that these results lay a firm foundation for the experimental study of substituted isocyanates and their relationship to the energetic pathways of related systems.

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The Simplest, Isolable, Alkynyl Isocyanate HC≡CNCO: Synthesis and Characterization

Cited by 15 publications

References 50 publications

3-Fluoro-2H-azirine: Generation, Characterization, and Photochemistry

3-Fluoro-2H-azirine: Generation, Characterization, and Photochemistry

Experimental and Computational Mechanistic Study of Carbonazidate-Initiated Cascade Reactions

Catalyzed Reaction of Isocyanates (RNCO) with Water

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