Nitric acid treatment, fuming

These precursors are prepared by reaction of fuming nitric acid in excess acetic anhydride at low temperatures with 2-furancarboxaldehyde [98-01-1] (furfural) or its diacetate (16) followed by treatment of an intermediate 2-acetoxy-2,5-dihydrofuran [63848-92-0] with pyridine (17). This process has been improved by the use of concentrated nitric acid (18,19), as well as catalytic amounts of phosphoms pentoxide, trichloride, and oxychloride (20), and sulfuric acid (21). Orthophosphoric acid, -toluenesulfonic acid, arsenic acid, boric acid, and stibonic acid, among others are useful additives for the nitration of furfural with acetyl nitrate. Hydrolysis of 5-nitro-2-furancarboxyaldehyde diacetate [92-55-7] with aqueous mineral acids provides the aldehyde which is suitable for use without additional purification. 

Nitration of pyrazolones and alkoxypyrazoles takes place at the 4-position (or in the para position of the 1-phenyl substituent) (B-76MI40402). Treatment of propyphenazone (296) with fuming nitric acid results in at least 27 products (81AP532), amongst them (297) which was identified by H and C NMR data. 

Preparation of 4,5,6,7-tetrabromobenzotriazole and its tetrachloro analog by direct bromination or chlorination of benzotriazole is described in Section 5.01.7. However, other tetra-substituted benzotriazoles have to be constmcted from a suitably substituted benzene ring. Thus, treatment of pentamethylbenzene 1293 with fuming nitric acid in concentrated sulfuric acid provides 3,4,5,6-tetramethyl-l,2-dinitrobenzene 1294 in 66% yield. Using routine procedures, derivative 1294 is reduced with SnCl2 in aqueous HC1, and the obtained diamine 1295 is subsequently treated with NaNOz (in aq. HC1) to provide 4,5,6,7-tetramcthyl-l //-benzotriazole 1296 (Scheme 216) <2004BMC2617>. 

Theory Selenium is very toxic and its contamination is usually controlled by an absorptiometric method after destruction of the organic compound with fuming nitric acid. The latter converts selenium (Se) as selenous acid (H2Se03), which on subsequent treatment with 3,3 -diaminobenzidinc under controlled experimental parameters, results into the formation of a highly coloured compound known as 3,4-diaminophenylpiazselenol. The latter is consequently extracted with toluene after making the aqueous solution alkaline, and the colour compared with a standard prepared likewise from a known amount of selenium. The various reactions involved may be expressed as follows ... 

Solutions of acetyl nitrate, prepared from fuming nitric acid and acetic anhydride, can react with alkenes to yield a mixture of nitro and nitrate ester products, but the /3-nitroacetate is usually the major product. ° Treatment of cyclohexene with this reagent is reported to yield a mixture of 2-nitrocyclohexanol nitrate, 2-nitrocyclohexanol acetate, 2-nitrocyclohexene and 3-nitrocyclohexene. °/3-Nitroacetates readily undergo elimination to the a-nitroalkenes on heating with potassium bicarbonate. /3-Nitroacetates are also reduced to the nitroalkane on treatment with sodium borohydride in DMSO. ... 

A potential industrial route to potassium dinitromethane (18) involves treatment of methyl malonate (107) with red fuming nitric acid to give methyl Q ,Q -dinitroacetate (108), followed by hydrolysis-decarboxylation with aqueous potassium hydroxide. Dinitromethane is a precursor to 2,2-dinitroethanol and 2,2-dinitro-1,3-propanediol, both of which are useful in addition and esterification reactions for the production of energetic oligomers and plasticizers. 

This unusual process known as the W-method was discovered in Germany by Wolfram and involves the condensation of the potassium salt of sulfamic acid with formaldehyde to form the heterocycle (238) followed by treatment with nitric acid. The extreme sensitivity of (238) to hydrolysis means that nitrolysis has to be conducted under anhydrous conditions using sulfur trioxide or phosphorous pentoxide " dissolved in fuming nitric acid. The yield of RDX from the W-method is 80-90 %. 

Treatment of the isomeric l,3a,4,6a- (220) and 1,3a,6,6a- (91) dibenzotetraazapentalenes with mixed acid or fuming nitric acid forms z-TACOT (225) and y-TACOT (231), respectively. 438 z xaCOT (225) and y-TACOT (231) are highly insensitive to impact and electrostatic charge and exhibit extremely high thermal stability (ignition temperature 494 °C, DTA curve 354 °C). 

Nickel nitrate hexahydrate may be prepared by several methods based on the reaction of dilute nitric acid on nickel powder, nickel oxide or nickel carbonate. The reaction is exothermic and requires controlled cooling during production. The hexahydrate can be dehydrated to anhydrous salt by treatment with fuming nitric acid. 

Nitration of the aromatic ring of (223) occurs at the 7-position. However, its reaction with fuming nitric acid in acetic anhydride followed by treatment with methanol gave the 5-methoxy-4-nitro derivative. This product, on treatment with triethylamine, eliminated nitrous acid from the 3,4-positions. 

Both polonium derivatives are chemically very stable, requiring hot fuming nitric acid for their decomposition. However, they char rapidly under the intense alpha bombardment and attempted analyses with acetyl-acetone labeled with carbon-14 in the 1 and 3 positions were unsuccessful. It is interesting that the corresponding yellow oxide, prepared by treating (VI) with aqueous hydrogen peroxide, reverts to (VI) on treatment with aqueous alkali (12). 

Treatment of dinitroacetonitrile or its Amm salt with fuming nitric acid gave the trinitroacetonitrile described below... 

Dinitroozobenzene, (N02)2 CeH,-N N -C Hj red ndls (from ale) mp 116-9° prepd by reacting yel mercuric oxide with a hot alcoholic soln of 2,4-dinitro-hydrazobenzene. Treatment with fuming nitric acid gives, according to the exptl conditions, either 2,4,4 -trinitro-azoxybenzene or 2,4,4 -trinitro-azobenzene Ref Beil 16, 58... 

Nitrobarbituric acid has been prepared by oxidation of vio-luric acid,1 and by treatment of barbituric acid with fuming nitric acid.2... 

Tri ethyl monosilane. (C2H5)3SiH mw 88.52 colorl liq mp -156.90° bp 107.7°, 108.77° (sep vals) d 0.7318g/cc RI 1.4100. Sol in 95% ethanol insol in w. Prepn is by partial decompn of triethylmonosilylethylether by treatment with diethyl zinc and Na. The silane decomps explosively when reacted with fuming nitric acid... 

Urea may be recognised as a structural feature in the triketo form disconnection then reveals diethyl malonate as the other reagent. The synthesis of barbituric acid is therefore effected (Expt 8.36) by condensation of diethyl malonate with urea in the presence of sodium ethoxide. Barbituric acid undergoes nitration in the 5-position on treatment with fuming nitric acid, and reduction of the nitro derivative (98) yields 5-aminobarbituric acid (99) (uramil). 

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