Nitryl chloride, reaction with nitric

A novel, mild system for the direct nitration of calixarenes has been developed using potassium nitrate and aluminum chloride at low temperature. The side products of decomposition formed under conventional conditions are not observed in this system, and the p-nitro-calixarenes are isolated in 75-89% yields.17 Such Friedel-Crafts-type nitration using nitryl chloride and aluminum chloride affords a convenient system for aromatic nitration.18 Nitryl chloride was previously prepared either by the oxidation of nitrosyl chloride or by the reaction of chlorosulfonic acid with nitric acid. However, these procedures are inconvenient and dangerous. Recently, a mixture of sodium nitrate and trimethysilyl chloride (TMSC1) has been developed as a convenient method for the in situ generation of nitryl chloride (Eq. 2.6). 

Critical surveys have shown that the older methods for the preparation of nitryl chloride are inefficient and yield impure products.1-7 Reasonably pure nitryl chloride was first prepared by Schumacher and Sprenger1-3 in 1929 by the reaction of nitrosyl chloride with ozone the preparation from chlorosulfonic acid and nitric acid was reported later.4 Recently, Schmeisser has obtained nitryl chloride from nitrogen(Y) oxide and phosphorus(V) chloride.5 The reaction of chlorosulfonic acid with nitric acid8-10 is probably the most convenient method for preparing large quantities of nitryl chloride of satisfactory purity. 

Nitryl chloride can be prepared from chlorosulphonic acid and anhydrous nitric acid. It combines with halides to form salts such as (N02)SbCl6 which in an ionizing solvent (e.g. liquid SO2) undergo reactions of the type ... 

ACIDE SULFHYDRIQUE (French) (7783-06-4) A highly flammable and reactive gas. Violent reaction with strong oxidizers, metal oxides, metal dusts and powders, bromine penta-fluoride, chlorine trifluoride, chromium trioxide, chromyl chloride, dichlorine oxide, nitrogen trichloride, nitryl hypofluorite, oxygen difluoride, perchloryl fluoride, phospham, phosphorus persulfide, silver fulminate, soda-lime, sodium peroxide. Incompatible with acetaldehyde, chlorine monoxide, chromic acid, chromic anhydride, copper, nitric acid, phenyldiazonium-chloride, sodium. Forms explosive material with benzenediazonium salts. Flow or agitation of substance may generate electrostatic charges due to low conductivity. Attacks many metals. 

Using nitryl chloride as the nitrating agent, which in the laboratory is conveniently prepared by the reaction of nitric acid with chlorosulfuricacid [40], TiCI is found to be the most suitable catalyst. FeCIj, ZrCU. AJCIj Md AlBr3 are also effective but the reactions are more difficult to handle. 

Nitroxanthine is produced is produced as the major nitration product in reactions of 2 -deoxy-guanosine or ca//thymus DNA with nitryl chloride produced by mixing nitrite with hypochlorous acid, and 8-nitroguanidine was a minor product in these reactions (Chen et al. 2001). Formation of 8-nitroxanthine was also detected by xanthine reaction with various reactive nitrogen species, including nitryl chloride, peroxynitrite, nitronium tetra-fluoroborate, and heated nitric and nitrous acids. 

Chlorosulfonic acid reacts with 100% nitric acid (prepared by distillation of concentrated nitric acid and 30% oleum) to give nitryl chloride 6 (Equation 13). Chlorosulfonic acid (one equivalent) is added dropwise to stirred 100% nitric acid at 0 °C, and after half an hour at RT, nitryl chloride distils as a pale yellow liquid (bp —17 to — 18 C). Pure nitryl chloride is a colourless gas and this reaction provides the best synthetic route to the compound. ... 

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