- Raman and infrared spectra, conformational stability, barriers to internal rotation, and ab initio calculations of trifluoroacetyl isocyanate
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The Raman (2500 to 10 cm-1) and infrared (2500 to 30 cm-1) spectra of trifluoroacetyl isocyanate, CF3C(O)NCO, have been recorded for the gas and solid.Additionally, the Raman spectrum of the liquid has been recorded and qualitative depolarization values obtained.The observed bands are assigned on the basis of a more stable cis conformer (isocyanate group cis to the carbonyl bond) and the less stable trans conformer in the fluid phases and only the cis rotamer is present in the solid.From the variable-temperature studies of the infrared spectrum of the sample dissolved in liquified krypton, the conformer pair at 1796 and 1781 cm-1 has been used to determine the ΔH value of 163 +/- 12 cm-1 (466 +/- 34 cal mol-1) which should represent closely the value of ΔH for the gas.The potential function governing conformational interchange has been determined from the asymmetric torsional frequencies and ΔH value.The values of the potential constants are: V1 = 356 +/- 14, V2 = 1865 +/- 60, and V3 = -203 +/- 6 cm-1.Additionally, variable-temperature studies of the Raman spectrum of the liquid give a ΔH of 236 +/- 30 cm-1 (675 +/- 86 cal mol-1).A complete vibrational assignment is proposed for the cis conformer based on infrared band contours, Raman depolarization data, group frequencies, relative intensities, and normal coordinate calculations.Also, several of the fundamentals of the trans conformer have been assigned.The experimental conformational stability, barriers to internal rotation, structural parameters, and fundamental vibrational frequencies are compared with those obtained from ab initio gradient calculations employing the RHF/3-21G, RHF/6-31G* and/or MP2/6-31G* basis sets and to the corresponding quantities obtained for some similar molecules.
- Durig, J. R.,Guirgis, G. A.,Krutules, K. A.
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- Spectroscopy of acyl and carbonyl isocyanates
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The gas phase IR, gas phase UV and solution 13C NMR spectroscopic data for seven carbonyl isocyanates X-CO-NCO and eight acyl isocyanates R-CO-NCO are reported.The IR group frequencies are assigned and substituent-frequency relationships are given for the C=O and NCO stretching frequencies.For carbonyl isocyanates the IR spectra show features of isomeric nonuniformity which are interpreted in terms of cisoid and transoid conformations.For all acyl isocyanates the IR spectra suggest the presence of the cisoid conformation only. ? -> ? and n -> ? transitions are assigned for the gas phase UV spectra and the 13C chemical shifts for the carbonyl and isocyanato carbons are reported.Generalized spectroscopic data, together with theoretical data, indicate a small degree of resonance interaction between the carbonyl and isocyanato groups.
- Klapstein, Dieter,Nau, Werner M.
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- Preparation of fluorinated imides
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A direct method for the preparation of trifluoroacetimides has been extended to the preparation of trifluoroacetyl trifluoracetimide and the new compound trifluoromethylsulfuryl trifluoroacetimide. Points concerning previously reported syntheses of trifluoroacetyl isocyanate have also been clarified.
- Ye,Noftle
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- Acyl and Sulfonyl Isocyanates ib β-Lactam Synthesis
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The preparation of β-lactams from the reactions of several acyl and sulfonyl activated isocyanates with alkenes was studied.Three compounds, (2,2,2-trichloroethoxy)sulfonyl, 2,2,2-trichloroethane sulfonyl, and trifluoroacetyl isocyanates, were shown to be
- Barrett, Anthony G. M.,Betts, Michael J.,Fenwick, Ashley
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p. 169 - 175
(2007/10/02)
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- Trifluoroacetylation and Subsequent Pyrolysis of 2-Amino-2-oxazolines
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Treatment of 2-amino-5-phenyl-2-oxazoline (I) with trifluoroacetic anhydride gave 1,3-bis(2,2,2-trifluoroacetyl)-1-urea (II).Compound II was pyrolyzed at 120 deg C to give 2,2,2-trifluoroacetyl isocyanate (III) and 2,2,2-trifluoro-N-acetamide (IV).Compound II was readily hydrolyzed to give 1-(2,2,2-trifluoroacetyl)-3-urea (VI).Compound VI was pyrolyzed at 230 deg C to give 2,2,2-trifluoroacetamide (VII) and 2,2,2-trifluoro-N-(E)-styrylacetamide (VIII).It was considered that the formation of VIII proceeded through the intermediate 2-(2,2,2-trifluoroacetyloxy)-2-phenylethyl isocyanate (XI) or 1-(2,2,2-trifluoroacetyl)-3-(E)-styrylurea (XII), as shown in Chart 1.Keywords - 2-amino-2-oxazoline; trifluoroacetylation; pyrolysis; 1,3-bis(2,2,2-trifluoroacetyl)-1-alkylurea; O,N-bis(2,2,2-trifluoroacetyl)aminoethanol; 1-(2,2,2-trifluoroacetyl)-3-alkylurea; 1-(2,2,2-trifluoroacetyl)-3-alkenylurea
- Tanaka, Chiaki,Nasu, Keiko,Yamamoto, Noriko,Shibata, Megumi
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p. 3374 - 3376
(2007/10/02)
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- Reactions of Trifluoroacetyl Isocyanate
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Trifluoroacetyl isocyanate (1) can be obtained from trimethylsilyl isocyanate and trifluoroacetyl chloride. 1 reacts with trifluoroacetamide forming N,N'-bis(trifluoroacetyl)urea (2), which can also be obtained from trifluoroacetyl chloride and urea or N,N'-bis(trimethylsilyl)urea, respectively. 1 reacts with ammonia or various amines forming the trifluoroacetylsubstituted ureas 3 - 6, and hydrazine 7.From 1 and trifluoroacetic acid hexafluorodiacetamide (8) could be obtained. 1 reacts with tert-butylalcohol forming tert-butyl (trifluoroacetyl)carbamate (9).From 1 and N,N-dimethylformamide N,N-dimethyl-N'-(trifluoroacetyl)formamidine (10) could be obtained as well as N-(trifluoroacetyl)pyrrole-2-carboxamide (11) from pyrrole.
- Kiemstedt, Wolfgang,Sundermeyer, Wolfgang
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p. 919 - 925
(2007/10/02)
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- N-ALKYLIDENECARBAMOYL ISOCYANATES. REACTIONS WITH PHOSPHORUS CHLORIDES
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In the reactions of alkylidenecarbamoyl isocyanates with phosphorus trichloride, pentachloride, and oxychloride exchange of the isocyanate group by a chlorine atom occurs.In reaction with phosphorus pentachloride 1-methoxy-2,2,2-trifluoroethylidenecarbamoyl isocyanate gives the product from addition of the chlorine at the carbonyl group, i. e., N-(1-methoxy-2,2,2-trifluoroethylidene)-N'-chlorocarbonylcarbonimidoyl chloride.
- Gertsyuk, N. N.,Gorbatenko, V. I.,Samarai, L. I.
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p. 1233 - 1236
(2007/10/02)
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