Takashi Abe

Activation of the C-F Bond : Transformation of CF3N=N-into 5-Azidotetrazoles

Considerable attention in recent years has been directed toward the synthesis of energetic heterocyclic compounds including the syntheses and applications of new energetic tetrazole derivatives. Recently, many kinds of energetic tetrazole compounds, some of which contained substituents such as azide groups, were reported. The development of new synthetic routes towards energetic compounds continues to be a topic of significant interest in synthetic chemistry. Many papers have dealt with the preparation of 5-azidotetrazoles. Nearly 70 years ago, 5-azidotetrazole and sodium 5-azidotetrazolate were prepared by the reaction of cyanogen halide (ClCN or BrCN) with sodium or barium azide and acid (Scheme 1). Further detailed investigation on the syntheses and characterizations of 5-azidotetrazoles have been carried out.

Perfluorotetramethylenesulfur difluoride and its derivatives. Perfluoro-1,3-dithietane octafluoride and perfluoro-1,4-dithiane octafluoride

Abstract The fluorination of perfluorotetramethylene sulfide with chlorine monofluoride under controlled conditions results in the formation of both sulfur(IV) and sulfur(VI) compounds as main products. While perfluorotetramethylenesulfur tetrafluoride is very stable to thermolysis and to chemical attack, the hydrolysis of the novel perfluorotetramethylenesulfur difluoride affords perfluorotetramethylene sulfoxide, and its pyrolysis gives perfluro(di-n-butyl)disulfide. Chlorine monofluoride converts perfluorotetramethylene sulfoxide to perfluorotetramethyl-enesulfur oxyfluoride, and perfluorotetramethylene sulfone is obtained quantitatively as a decomposition product in contact with Pyrex glass. Perfluoro-1,3-dithietane octafluoride and perfluoro-1,4-dithiane octafluoride are also formed by the reaction of corresponding perfluorocyclic sulfides with CIF at ambient temperature. Infrared, mass and 19F NMR spectroscopic as well as thermodynamic data are reported.

5-(1,2,3-Triazol-1-yl)tetrazole derivatives of an azidotetrazole via click chemistry.

N-C bonded (non-bridged) 5-(1,2,3-triazol-1-yl)tetrazoles were synthesized by the Cu(I)-catalyzed 1,3-dipolar azide-alkyne cycloaddition click reaction using 5-azido-N-(propan-2-ylidene)-1H-tetrazole (1). For example, the click reaction of 1 in the presence of CuSO(4)5 H(2)O and Na ascorbate at 65-70 degrees C for 48 h in CH(3)CN/H(2)O co-solvent was found to be limited to only terminal alkynes that have electron-withdrawing groups, CF(3)C[triple chemical bond]CH (2 a) and SF(5)C[triple chemical bond]CH (2 b), giving rise to isopropylidene-[5-(4-trifluoromethyl-1,2,3-triazol-1-yl)tetrazol-1-yl]amine (3 a) and isopropylidene-[5-(4-pentafluorosulfanyl-1,2,3-triazol-1-yl)tetrazol-1-yl]amine (3 b) in 47 % and 66 % yields, respectively. When carried out under conditions using CuI and 2,6-lutidine as catalysts at 0 degrees C for 13 h in CHCl(3), the click reaction was versatile toward alkynes even those having electron-donating groups. Properties of new products were determined and compared with those of 1. Heats of formation, detonation pressures, detonation velocities and impact sensitivities are reported for these new 5-(1,2,3-triazol-1-yl)tetrazoles.

Fluorination of perfluoroalkylsulfenyl chlorides, perfluorodialkyl disulfides and perfluorodialkyl sulfides with chlorine monofluoride

Abstract In reactions with perfluoroalkylsulfenyl chlorides (RfSCl; Rf = F3, C2F5, n-C3F7, n-C4F9) and perfluoroalkyl disulfides (RfSSRf′; Rf = Rf′ = CF3, Rf = CF3, Rf′ = C2F5) at 25°, chlorine monofluoride acts primarily as a chlorinating and fluorinating reagent to give the corresponding perfluoroalkylsulfur chloride tetrafluorides, RfSF4Cl, in good yields. However, small amounts of perfluoroalkylsulfur pentafluorides, RfSF5, are also obtained. A mixture of the cis and trans isomers of bis(trifluoromethyl)sulfur tetrafluoride and of trifluoromethyl pentafluoroethylsulfur tetrafluoride has been formed by the reaction of the corresponding bis(perfluoroalkyl) sulfides and chlorine monofluoride. The new perfluoroalkylsulfur chloride tetrafluorides are colorless, unpleasant smelling liquids. The infrared, mass and 19F NMR spectral data, as well as thermodynamic and elementary analysis data, are given for the new compounds.

Disubstituted Azidotetrazoles as Energetic Compounds

Base-catalyzed activation of the C--F bond in the trifluoromethylazo-substituted cyclic and acyclic alkanes provides a route to disubstituted azidotetrazoles. For example, the reaction of 1,2-bis(trifluoromethylazo)ethane with four equivalents of NaN(3) gave the alkyl-bridged bis(5-azido-1H-tetrazol-1-yl)-1,2-dimine, N,N-bis(5-azido-1H-tetrazol-1-yl)-1,2-diiminoethane, in 75 % yield (see scheme).Disubstituted azidotetrazoles are synthesized by the base-catalyzed activation of the C--F bond in the trifluoromethylazo-substituted cyclic and acyclic alkanes. From the reaction of trans-1,4-bis(trifluoromethylazo)cyclohexane with four equivalents of NaN(3), N,N-bis(5-azido-1H-tetrazol-1-yl)-1,4-diiminocyclohexane was formed in good yield. While, from the similar reaction using cis/trans-1,2-bis(trifluoromethylazo)cyclohexane, (5-azido-1H-tetrazol-1-yl)-[6-(5-azido-1H-tetrazol-1-ylimino)cyclohexenyl]amine was formed as the principal product. The structure of these new disubstituted azidotetrazoles was determined by crystal structure analysis as well as NMR and IR spectroscopy. In a similar fashion, from three trifluoromethylazo-substituted acyclic alkanes, corresponding alkyl-bridged N,N-bis(5-azido-1H-tetrazol-1-yl)diiminoalkanes were obtained. For example, from 1,2-bis(trifluoromethylazo)ethane, N,N-bis(5-azido-1H-tetrazol-1-yl)-1,2-diiminoethane was obtained in 75 % yield. Heats of formation, detonation pressures, detonation velocities, and impact sensitivities are reported for these new disubstituted azidotetrazoles.