Chemistry of difluoraminocarbonyl chloride. New route to perfluorourea

Abstract

Improved yields of NF,C(0)C1 are obtained by short-term (4-6 hr) photolysis of N2F4 with oxalyl chloride. Reactions of NF2C(0)C1 with AgCN, AgNCS, AgNCO, Hg(SCF3)2 and Hg(ON(CF3)2)2 give the new difluoraminocarbonyl pseudohalides NF2C(0)CN, NF2C(0)NCS, NF2C(0)NC0, NF2C(0)SCF3, and NF2C(0)0N(CF3)2. With excess of either Ag20 at 0°or HgO at -78°, NF2C(0)C1 is converted to (NF2)2CO and C02 in nearly quantitative yield. Chlorocarbonyl fluorosulfate results when NF,C(0)C1 is mixed with S206F2 or BrOS02F.This work concerns a modified preparation2,3 of difluoraminocarbonyl chloride, NF2C(0)C1, and some of its chemistry on which a preliminary report has recently appeared.4 It is now possible to prepare the compound in amounts which make studying its chemistry feasible. Only with AgNCS and Hg(ON(CF3)2)2 does NF2C(0)C1 undergo metathetical reactions at or below 25°. With AgCN, Ag-NCO, and Hg(SCF3)2, higher temperatures, longer reaction times, and, in some cases, recycling of unreacted NF2C(0)C1 are necessary to ensure yields greater than 50%. It is likely that perfluorourea arises via decarboxylation of an unstable symmetrical anhydride intermediate formed when NF2C(0)C1 reacts with either HgO or Ag20. This provides a facile, much less hazardous route to (NF2)2CO than the original method of pyrolyzing KOCN2Fs ,2'5 Reactions of NF2C(0)C1 with several other silver, mercury, and alkali metal salts which do not result in new compounds are also described.Surprisingly, both peroxydisulfuryl difluoride, S206F2, and bromine fluorosulfate, BrOS02F, form chlorocarbonyl fluorosulfate, C1C(0)0S02F,6 at 25°with NF2C(0)C1.Other methods for preparing C1C(0)0S02F, as well as some of its reaction chemistry, are detailed below. Experimental SectionCaution! Nitrogen-fluorine-containing compounds are strong oxidizing agents and should be handled with proper shielding and other safety precautions. Although we experienced no difficulty in handling these materials, it should be reported that the analyst was injured when a sample of NF2C(0)NCO exploded in his hand. These difluoraminocarbonyl compounds are very sensitive to hydrolysis and can be handled successfully only under highly anhydrous conditions.Starting Materials. Most reagents used are available from standard chemical supply houses. AgNCO,7 Hg(ON(CF3)2)2,8Hg(SCF3V (CF3)2NOH,10 HgfOSOjF),,1 11 S206F2,12 Br0S02F,13 and (CF3)2C=NLi14 were synthesized via literature methods.

Conformational and Structural Determination of F2NC(O)F and F2NC(O)NCO. A Joint Experimental and Theoretical Study

“…To our knowledge, no detailed vibrational studies on NF 2 C(O)F nor NF 2 C(O)NCO have been performed. Although the IR spectra were reported previously, , they have been only used as purity criteria, without any band assignments. Moreover, no reports of the Raman spectrum of difluoroaminocarbonyl compounds exist in the literature.…”

“…4 F 2 NC(O)NCO was obtained by reacting NF 2 C(O)F with excess of dry AgNCO following the method reported elsewhere. 6 Both compounds were purified by trap-to-trap distillation and the final purity was checked by IR and 19 F NMR spectroscopy.…”

“…NF 2 C(O)F was synthesized by irradiation of a mixture of N 2 F 4 and carbon monoxide according to the method reported by Fraser and Shreeve . F 2 NC(O)NCO was obtained by reacting NF 2 C(O)F with excess of dry AgNCO following the method reported elsewhere . Both compounds were purified by trap-to-trap distillation and the final purity was checked by IR and 19 F NMR spectroscopy.…”

“…The chemistry of F 2 NC(O)F was further extended by the same authors . Subsequently, pseudohalide derivatives NF 2 C(O)X (X = CN, NCO, NCS, and SCF 3 ) were prepared by reacting F 2 NC(O)Cl with silver or mercury salts …”

“…5 Subsequently, pseudohalide derivatives NF 2 C(O)X (X ) CN, NCO, NCS, and SCF 3 ) were prepared by reacting F 2 NC(O)Cl with silver or mercury salts. 6 The synthetic interest in difluoramines attracted considerable attention, including the preparation of poly(difluoroamino)alkanes, difluoroaminoalkanols, and diazirines from aldehydes, ketones, alkynes, alkenes, ethers, and imines. 7 Difluoramines are also good candidates as energetic materials in rocket propellant and explosives formulations.…”