Catalytic reductions, nitric acid with

Hydroxylamine sulfate is produced by direct hydrogen reduction of nitric oxide over platinum catalyst in the presence of sulfuric acid. Only 0.9 kg ammonium sulfate is produced per kilogram of caprolactam, but at the expense of hydrogen consumption (11). A concentrated nitric oxide stream is obtained by catalytic oxidation of ammonia with oxygen. Steam is used as a diluent in order to avoid operating within the explosive limits for the system. The oxidation is followed by condensation of the steam. The net reaction is... 

Nitric oxide is the simplest thermally stable odd-electron molecule known and, accordingly, its electronic structure and reaction chemistry have been very extensively studied. The compound is an intermediate in the production of nitric acid and is prepared industrially by the catalytic oxidation of ammonia (p. 466). On the laboratory scale it can be synthesized from aqueous solution by the mild reduction of acidified nitrites with iodide or ferrocyanide or by the disproportionation of nitrous acid in the presence of dilute sulfuric acid ... 

Nitric acid synthesis, platinum-group metal catalysts in, 19 621 Nitric acid wet spinning process, 11 189 Nitric oxide (NO), 13 791-792. See also Nitrogen oxides (NOJ affinity for ruthenium, 19 638—639 air pollutant, 1 789, 796 cardioprotection role, 5 188 catalyst poison, 5 257t chemistry of, 13 443—444 control of, 26 691—692 effect on ozone depletion, 17 785 mechanism of action in muscle cells, 5 109, 112-113 oxidation of, 17 181 in photochemical smog, 1 789, 790 reduction with catalytic aerogels, l 763t, 764... 

Initial halogenation of the oxime can use chlorine, hypobromite, bromine, or A-bromoacetamide. " Oxidation of the a-halonitrosoalkane can be achieved with nitric acid, nitric acid-hydrogen peroxide, " atmospheric oxygen, ozone, or a peroxyacid. Reduction of thea-halonitroalkaneis achieved with sodium borohydride or by catalytic hydrogenation, although potassium hydroxide in ethanol has been used for the conversion. 

F. T. Austen said that hydrogen burns with an intense white flame in the vapour of nitric aoid. H. Gall and W. Manohot said that the catalytic reduction of nitric acid in aq. soln. in the presence of spongy platinum yields ammonia and nitrous aoid. If water be gradually added to the fuming acid, the reddish-brown colour changes... 

Selective Catalytic Reduction (SCR) is normally used in new nitric acid plants. In this process ammonia reacts with nitric oxide and nitrogen dioxide but only to a lesser extent with oxygen to selectively reduce the NOx compounds to N2. The reactions are shown below97,104 ... 

II. 5).204,205 Unsupported iridium catalysts have been prepared by reducing an iridium oxide of Adams type at 165°C under a stream of hydrogen206 or by reducing iridium hydroxide, prepared by addition of lithium hydroxide to an aqueous solution of irid-ium(III) chloride, at 80-90°C and 8 MPa H2.204 Unsupported and supported iridium catalysts may also be prepared by reduction of iridium(IV) chloride with sodium boro-hydride.207 It is noted that the catalytic activity of deactivated iridium can be almost completely regenerated by treatment with concentrated nitric acid.205... 

Compound 10b has been treated with a solution of the nitrating mixture made from acetic anhydride and nitric acid in dioxane affording nitro derivative 10c, with not very high yields. The catalytic reduction of nitro derivative 10c, carried out with hydrazine in ethanol in the presence of palladium on calcium carbonate, affords compound lOd. The guanidino group at C-5 has be i introduced by reaction of compound lOd with ( anamide in solution of hydrochloric acid affording the objective molecule 10. 

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