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D’yachkova, S. G.; Никитина, Е. А.; Гусарова, Н. К.; Албанов, А. И.; Трофимов, Б. А.

doi:10.1023/a:1026147206098

Cited by 11 publications

(14 citation statements)

References 9 publications

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“…As we conclude that the 13 C NMR chemical shifts given in ref 16 are very likely not the ones of 10a, and the chemical shift of the internal standard C 1 70 given in Table 4 might not be correct. However, comparison of the 13 C chemical shifts of similar compounds have indicated that the shift for C 1 is on the order of about 14-15 ppm (9a, ref 71: 14.8 ppm, 12: 14.5 ppm, Et 2 S, ref 72: 14.8 ppm).…”

Section: B a Note On Solvent Effects And Zero-point Vibrationmentioning

confidence: 70%

“…16 Deviations of over 30 ppm occur, which lead the authors to conclude that the synthesis of 10a claimed in ref 16 has not been successful.…”

Section: Discussionmentioning

confidence: 99%

“…17 It is extremely surprising that 11 is reported to be stable without spontaneous isomerization to furnish an aromatic tautomer. Furthermore, the NMR spectroscopic data published 16 for 11 exclude the proposed 4H-1,2,3-triazole structure. Finally, several attempts to reproduce the generation of 10 and 11 from 9 have been unsuccessful.…”

Section: Introductionmentioning

confidence: 96%

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Ab Initio Study of Molecular Properties and Decomposition Products of 1-AzidoalkynesA Challenge for Experimentalists

2007

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In this publication, a characterization of different azidoalkyne compounds using high-level ab initio quantum chemical methods is presented. For this purpose, the molecular structures and the 13C NMR chemical shifts have been calculated at the MP2 and CCSD(T) level of theory and the influence of zero-point vibration as well as the solvent on the chemical shifts are discussed. Furthermore, a comparison of the energy barriers of the decomposition under N2 separation for a set of 1-azidoalkynes with different functional groups has been carried out. The molecular structures and properties of the resultant decomposition products have been investigated. It is remarkable that large deviations of the NMR chemical shifts of ethylthioethynyl azide occur in comparison to the experiment. These deviations are far outside of the error bars. Electron correlation effects are of high importance if an accurate description of the chemical shifts of 1-azidoalkynes shall be obtained. A comparison of the energy barriers of the decomposition under N2 separation of 1-azidoalkynes with different functional groups indicates that the stability of 1-azidoalkynes is not increased by typical donor or acceptor groups but rather by silyl or phenyl substituents. The molecular geometries of the decomposition products indicate that the equilibrium structures are of carbene character. Some of the results presented here are in contradiction to previous experimental publications and cast a new light on some open challenges for experimentalists.

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Section: B a Note On Solvent Effects And Zero-point Vibrationmentioning

confidence: 70%

“…16 Deviations of over 30 ppm occur, which lead the authors to conclude that the synthesis of 10a claimed in ref 16 has not been successful.…”

Section: Discussionmentioning

confidence: 99%

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Ab Initio Study of Molecular Properties and Decomposition Products of 1-AzidoalkynesA Challenge for Experimentalists

2007

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“…As a rule, oxygen-containing acids and based on them mixtures are most commonly used as oxidizing agents: HNO3, HNO3+ H2SO4 etc. As a result of this treatment, depending on the type of an oxidant, carboxylic acids -СООН, carboxylic hydroxy acids -СООН and ОН groups are activated on the surface of the carbon fiber [7]. Carboxyl and hydroxyl groups are formed on the surface in the process of treatment with a mixture of acids HNO3+ H2SO4.…”

mentioning

confidence: 99%

The effect of carbon fabrics modification on the strength of carbon fiber reinforced plastic

Mustafa¹,

Yermakhanova²,

Ismailov³

2019

KIMS/CUMR/MShKP

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This article reviews the study of influence of carbon fabrics modification on the strength of carbon fiber reinforced plastic. Two types of epoxy compound Etal Inject SLM of "cold curing" and Etal Inject-T of "heat curing", nitric acid HNO3 of concentration 60 %, carbon fabric of Toho Tenax/Aksa 3k-1200-200 were used in the study. Comparisons of the strength properties of carbon plastic on these compounds were given. The best result was obtained on Etal Inject-T with tensile strength -1000 MPa and in compression -425 MPa. Carbon fabric modification was carried out by grafting carboxylated groups treated with HNO3 to the carbon fiber surface. The treatment time in acid varied from 0.5 to 6 minutes. The compressive strength by 17 % from 425 MPa to 497 MPa has been established to increase when carbon fiber by HNO3 is modified for from 0.5 min to 2 min, then the strength decreases enlarging the treatment time. The decrease in strength is associated with a supersaturation of the surface of the fibers with carboxyl groups, which were destroyed during heat treatment. Thus, the surface oxidating of carbon fabric is the most effective method of increasing its adhesion to epoxy resin and the strength of carbon fiber. The functional groups formed during the oxidation process allow for a tight cross-linking of the epoxy matrix with carbon fiber. It was previously found that the strength of carbon fiber increases with the modification of epoxy resin with oxidized carbon nanotubes. An assumption is made about a uniform mechanism for strengthening carbon-fiber reinforced plastic due to chemically active functional groups, both on the surface of carbon fiber and on the surface of carbon nanotubes. КӨМІРҰЛПАНЫ ЖЕТІЛДІРУДІҢ КӨМІРПЛАСТИК БЕРІКТІЛІГІНЕ ӘСЕРІ ТУРАЛЫТүйіндеме. Мақалада, көміртекпластик беріктік қасиетіне көміртек матасының модификациясының әсерінің зерттеулері келтірілген. Екі түрлі эпоксидті компаунд -«суық қатайтылған» Этал Инжект SLM және «ыстық қатайтылған» Этал Инжект-Т, 60 % қоюланған азот HNO3 қышқылы, Toho Tenax/Aksa 3к-1200-200 маркалы көміртегі кенеп матасы пайдаланылды. Аталған компаундтардағы көмірпластиктің беріктік қасиеттеріне салыстыру жүргізілді. Ең жоғары нәтиже 1000 МПа созу кезінде және 425 МПа қысу беріктік шектеріндегі Этал Инжект-Т алынды. Көмірұлпаны жетілдіру көміртегі талшықтарының бетіне HNO3 өңделген карбоксилденген топты егу жолымен іске асырылды. Қышқылда өңдеу уақыты 0,5 минуттан 6 минутқа дейінгі аралықта жалғасты. HNO3 көміртегі талшығын 0,5 минуттар 2 минутқа дейін жетілдіру кезінде қысуға беріктілік шегі 17 %-ға, 425 МПа-дан 497 МПа-ға дейін артатыны анықталды, әрмен қарай уақытты арттырған сайын беріктілік төмендей бастайды. Беріктік қасиетінің төмендеуі талшықтардың карбоксилді топтармен қанығуымен байланысты яғни термиялық өндеу кезінде бұзылғандықтан. Осылайша көміртекматаны тотықпен өңдеу үрдісі, эпоксидтті шайырға адгезиясын жақсартып көмірпластиктің беріктігін арта түсіреді. Эпоксидтті матрицасымен көміртек талшықтарды тығыз байланысқа осы белсенді топтар мүмкіндік береді. Эпо...

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“…Des Weiteren sind ähnliche Protokolle unter Metallkatalyse z. [13] In dieser neuen Variante werden phenyl-oder pentylsubstituierte hypervalente Iodoniumalkinyltriflate mit Tetrabutylammoniumazid umgesetzt. Unter leichter Veränderung der Reaktionsbedingungen (niedrigere Temperatur, Base) kann der Zerfall der Azid-Einheit zu 2 a auch verhindert werden.…”

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Vinyl‐ und Alkinyl‐Azide: altbekannte Intermediate im Fokus moderner Synthesemethoden

Jung

Bräse

2012

Angewandte Chemie

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Auf die Schliche gekommen: Während 1‐Azidoalkene schon lange als wichtige Intermediate zur Bildung von vielen Stickstoffheterocyclen bekannt sind, konnte die Existenz der entsprechenden 1‐Azidoalkine für lange Zeit nicht zweifelsfrei bewiesen werden. Die Synthese von 1‐Azidoacetylen, das zum ersten Mal vollständig charakterisiert wurde, erbrachte erst kürzlich den unumstößlichen Beweis für die Existenz dieser Substanzklasse.

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Cited by 11 publications

References 9 publications

Ab Initio Study of Molecular Properties and Decomposition Products of 1-AzidoalkynesA Challenge for Experimentalists

Ab Initio Study of Molecular Properties and Decomposition Products of 1-AzidoalkynesA Challenge for Experimentalists

The effect of carbon fabrics modification on the strength of carbon fiber reinforced plastic

Vinyl‐ und Alkinyl‐Azide: altbekannte Intermediate im Fokus moderner Synthesemethoden

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