The Infrared Spectra of N-Substituted Trifluoroacetamides

Diisopropylcyanamide reacts exothermically with trifluoroacetic anhydride to give 2, an equilibrium mixture, in C6D6 solution, of 1:1 adducts, N,N-diisopropyl-N‘,O-bis(trifluoroacetyl)isourea, 2a (10%), and N,N-diisopropyl-N‘,N‘-bis(trifluoroacetyl)urea, 2c (90%), at 27 °C. Compound 2c is a colorless solid, mp 49−51 °C. Thermolysis of 2, at 117 °C, shows first-order kinetics with the intital products being trifluoroacetonitrile, 4, and diisopropylcarbamic trifluoroacetic mixed anhydride, 3. Trifluoroacetonitrile trimerizes to 2,4,6-tris(trifluoromethyl)-1,3,5-triazine, and 3 is thermally labile giving diisopropyltrifluoroacetamide and CO2. In the thermolysis reaction 4 reacts with 2a to give a small amount of 4-(diisopropylamino)-4-(trifluoroacetoxy)-2,6-bis(trifluoromethyl)-4H-1,3,5-oxadiazine, 7. A related compound, 4,4-bis(diisopropylamino)-2,6-bis(trifluoromethyl)-4H-1,3,5-oxadiazine, 8, is formed from 7 and 2c going through a concentration maximum at 4000 s in the kinetic run. Compound 8 thermolytically dissociates to generate 4 and tetraisopropylurea. Compound 2 is a trifluoroacetylating agent with methanol giving methyl trifluoroacetate in 97% yield. Accompanying this reaction is a methanol displacement of diisopropylamine giving a 1.7% yield of methyl-N-(trifluoroacetyl)urethane. Diisopropylcyanamide also reacts exothermically with trifluoromethanesulfonic anhydride to give 2,4,6-tris(diisopropylamino)-1-(trifluoromethanesulfonyl)triazinium trifluoromethanesulfonate, 15, in 96% yield. X-ray crystallographic structure drawing of 15 shows N1 (attached to CF3SO2) is pyramidal while N2, N4, and N6 (all diisopropylamino nitrogens) are sp2-planar. A small amount of O-ethyl-N,N-diisopropyl-N‘-(trifluoromethanesulfonyl)isourea was also recovered, produced by the reaction of the initially formed intermediate, N,N-diisopropyl-N‘,O-bis(trifluoromethanesulfonyl)isourea, with ethanol contaminant in absolute ethyl ether solvent. Treatment of 15 with methanol, in the presence of K2CO3, gave a 90% yield of 2,4,6-tris(diisopropylamino)-1-(trifluoromethanesulfonyl)-4-methoxy-1,4-dihydrotriazine.

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“…The mixed anhydride 3 is also thermally labile and can expel CO 2 to give diisopropyltrifluoroacetamide, 6 .…”

Section: Discussion and Resultsmentioning

confidence: 99%

“…Distillation of the distillation residue, from recovery of 5 , gave 31.7 g (80% yield) of N , N -diisopropyltrifluoroacetamide, 6 : bp 85−90 °C/50 Torr, mp 49−52 °C (lit . mp 52−52.5 °C).…”

Section: Methodsmentioning

confidence: 99%

Formation of Urea, Isourea, and Triazine Derivatives from Diisopropylcyanamide with Trifluoroacetic Anhydride and Trifluoromethanesulfonic Anhydride: Thermal Instability of Urea and Isourea Derivatives

et al. 1997

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“…The melting points were measured in a Gehaka PF1500 Farma equipment at a heating rate of 5 °C min –1 and are corrected (values for the known compounds are given in the literature − ). High-resolution mass spectra (HRMS) were recorded on a high resolution QTof mass spectrometer using electrospray ionization (ESI).…”

Section: Methodsmentioning

confidence: 99%

Infrared Fingerprints of n_N → σ*_NH Hyperconjugation in Hydrazides

et al. 2017

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An earlier study demonstrated that hyperconjugation operates in hydrazides by analyzing the N-H stretching mode in gas phase infrared (IR) spectroscopy, and then observing two very distinct bands corresponding to isolated isomers experiencing or not the n → σ* electron delocalization. The present work reports a chemical method to obtain insight on the hyperconjugation in hydrazide derivatives from solution IR spectroscopy. The analogous amides did not show a ν red-shifted band, as the electron donor orbital in the above hyperconjugative interaction does not exist. In addition, the effect of electron withdrawing groups bonded to a nitrogen atom, namely the trifluoroacetyl and the methanesulfonyl groups, was analyzed on the conformational isomerism and on the ability to induce a stronger hyperconjugation in the resulting compounds.

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“…where R denotes an alkyl group (7,8). This reaction was made quantitative by adding acetic anhydride to the reacting mixture.…”

Section: Methodsmentioning

confidence: 99%

Flow calorimetry of viscous liquids. Volumes and heat capacities of mixtures of N,N-dimethylformamide with N-alkylacetamides

Zegers¹,

Boegschoten²,

Mels³

et al. 1986

Can. J. Chem.

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A sampling device is described which enables the Picker flow heat capacity calorimeter to handle viscous liquids. The necessary constant liquid flow through the calorimetric cell is achieved by an overpressure on the entering liquids, and can be maintained by pressure control. In addition, the device permits automatic measurement of a number of samples. The approach is applied to densities and heat capacities of binary mixtures of dimethylformamide and the viscous liquids N-ethylacetamide, N-n-propylacetamide, and N-n-butylacetamide. The results appear to be accurate enough to establish excess molar heat capacities as well as apparent molar heat capacities.

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The Infrared Spectra of N-Substituted Trifluoroacetamides

Cited by 22 publications

References 0 publications

Formation of Urea, Isourea, and Triazine Derivatives from Diisopropylcyanamide with Trifluoroacetic Anhydride and Trifluoromethanesulfonic Anhydride: Thermal Instability of Urea and Isourea Derivatives

Formation of Urea, Isourea, and Triazine Derivatives from Diisopropylcyanamide with Trifluoroacetic Anhydride and Trifluoromethanesulfonic Anhydride: Thermal Instability of Urea and Isourea Derivatives

Infrared Fingerprints of n_N → σ*_NH Hyperconjugation in Hydrazides

Flow calorimetry of viscous liquids. Volumes and heat capacities of mixtures of N,N-dimethylformamide with N-alkylacetamides

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The Infrared Spectra of N-Substituted Trifluoroacetamides

Cited by 22 publications

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Formation of Urea, Isourea, and Triazine Derivatives from Diisopropylcyanamide with Trifluoroacetic Anhydride and Trifluoromethanesulfonic Anhydride: Thermal Instability of Urea and Isourea Derivatives

Formation of Urea, Isourea, and Triazine Derivatives from Diisopropylcyanamide with Trifluoroacetic Anhydride and Trifluoromethanesulfonic Anhydride: Thermal Instability of Urea and Isourea Derivatives

Infrared Fingerprints of nN → σ*NH Hyperconjugation in Hydrazides

Flow calorimetry of viscous liquids. Volumes and heat capacities of mixtures of N,N-dimethylformamide with N-alkylacetamides

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Infrared Fingerprints of n_N → σ*_NH Hyperconjugation in Hydrazides