Difluoroamine, reaction

Reactions of benzylic a,P-aminoalcohols and a-hydroxyazindines with Olah s reagent provide a highly efficient way to a P-fluoroamines, a-fluoro-azindines, and ot,Y-difluoroamines [dS] (equations 43 and 44)... 

Difluoroamine (fluorimide) was discovered by Kennedy and Colburn as a by-product accompanying tetrafluorohydrazine in the reduction of NF3 by arsenic1 and arsine. It was found to be a product of hydrolysis of fluorinated urea80 and was detected in trace amounts among the products of fluorination of ammonia.8 Reactions to be considered for preparative purposes include the following (1) reduction of tetrafluorohydrazine,4 (2) hydrolysis of difluorourea, (3) protonation of trityldifluoroamine, (4) hydrolysis of difluorosulfamide,7 and (5) hydrolysis of isopropyl difluorocarbamate.8... 

Aziridines behave similarly to epoxides and were used for making aliphatic and steroidal fluoroamines (equations 12 and 13)25, the latter via trans diaxial opening26. Azirines were also treated with HF Py producing a,a -difluoroamines or a-fluorocarbonyl compounds depending on the reaction solvent (equation 14)27. 

The reaction between N2F4 and alkanes, which occurs at higher temperatures and does not give difluoroamine, is referred to later (see Section XVII, A). 

Difluoroamine reacts with primary and secondary amines to give alkanes (32). With imines, a variety of products are obtained depending on the structure of the imine. The three types of compounds obtained are diazirines (I), a-haloazo compounds (II), and a-fluoroalkylidine-hydrazines (III) (138, 139). The reaction of HNF2 with formaldehyde imines or negatively substituted aromatic imines yields diazirines in fair yield as the principal product, whereas with imines derived from aliphatic aldehydes the reaction gives a mixture of the corresponding diazirine derivative and a-fluoroazo compound. 

The difluoroamine radical produced dimerizes to N2F4, the reversible equilibrium resembling that between NOz and N204. The reactivity of the copper, which acts as a defluorinating agent in this reaction, decreases as its surface becomes coated with the involatile fluoride. This difficulty was overcome when it was replaced by arsenic, antimony, or bismuth, the fluorides of which are volatile at the reaction temperature. Conversion of NF3 to N2F4 in these reactions was of the order of 40-60%. There was a similar conversion when the trifluoride was passed over liquid mercury at 320-330°C (91). Alternatively, the trifluoride could be defluorinated by mercury vapor in an electrical discharge (118). 

The presence of difluoroaminomethanol among the products can be accounted for by a reaction of difluoroamine formed in the abstraction reaction with formaldehyde. The latter could result from decomposition of the -CH2OCH3 radical to CH20 and -CH3 (122). 

The addition of N2F4 to unsaturated systems was first studied in detail by Petry and Freeman (235). They found that in most cases vicinal bis(difluoroamines) resulted in good yield. Only with weakly nucleophile olefins, such as tetracyanoethylene, was there no addition. The aliphatic olefins reacted smoothly at about 100°C, the electron-rich olefins reacting more readily than those which were electron-poor. Thus, perfluoropropylene required a temperature of 140°C, whereas dimethyl styrene absorbed N2F4 even at room temperature. Reactions were usually carried out under pressure and in a solvent such as chloroform or chlorobenzene. 

In a jacketed tube reactor, 2.0 ml 30% fuming H2SO4 and 10 ml trichlorofluoromethane were cooled —25°C, 2.0 g difluoroamine condensed into the mixture, warmed to 10 °C to melt the acid layer, and the mixture re-cooled to — 15°C. The product from Step 8 (0.36 mmol) was added, the reaction tube sealed at — 15°C for 3 hours, then quenched in water. The solution was basified with NaHC03 to pH 12 and extracted 4 times with 100 ml CH2CI2. The solute was re-dissolved in CH2CI2, chloroform added, and the mixture concentrated. A precipitate formed and was re-dissolved in acetone, filtered through a medium porosity fritted filter, and the product isolated, mp = 208 °C (explodes). H-and C-NMR data supplied. 

Difluoroamine can be used as a source of NF2 group in numerous reactions, but it is dangerously explosive. 

Preparation. The starting material for the preparation of this reagent is tetra-fluorohydrazine, made by reaction of nitrogen trifluoride with various metals at 375° (I). Conversion into difluoroamine is accomplished by heating tetrufluoro-hydrazine with Ihlophenol In an evacuated bulb yield 74%. ... 

It reacts explosively with H2 in a radical chain reaction.40 It also reacts at 300° with NO and rapid chilling in liquid nitrogen gives the purple nitroso-difluoroamine ONNF2 this is unstable. 

N,N-Difluoroamines. Primary amines can be converted into N,N-difluoro-amines in 50-75% yield by conversion into the Schiff base with benzaldehyde or, preferably, the sodium salt of 4-carboxybenzaldehyde, followed by reaction with fluoroxytrifluoromethane in methanol-methylene chloride. In the absence of methanol the alkyl fluoride is formed preferentially. ... 

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