Nitration chloride-catalyzed

Figure 5.12 Proposed mechanism for chloride-catalyzed nitration " ...

Wright illustrated the effectiveness of chloride-catalyzed nitration for a number of amines of different basicity. Wright showed that weakly basic amines like iminodiacetonitrile and its dimethyl and tetramethyl derivatives are all nitrated in high yield with nitric acid-acetic anhydride mixtures in the absence of chloride ion. In contrast, the slightly more basic 3,3 -iminodipropionitrile is not appreciably nitrated with acetic anhydride-nitric acid, but the inclusion of a catalytic amount of the hydrochloride salt of the amine base generates the corresponding nitramine in 71 % yield. ... 

The founder of the chloride-catalyzed nitration of amines, G. F. Wright, has extensively reviewed chloride-catalyzed nitration. " Even 50 years later, the importance and success of this method as a route to nitramines is illustrated by the number of examples which can be found in the literature. 

One simple example of chloride-catalyzed nitration is the synthesis of the energetic plasticizer Bu-NENA (34) from the nitration of n-butyl ethanolamine (33) with a mixture of acetic anhydride-nitric acid to which catalytic zinc chloride has been added. ... 

Acetic anhydride-nitric acid mixtures are extensively used for chloride-catalyzed nitrations. Other nitrating agents have been used and involve similar sources of electropositive chlorine for intermediate chloramine formation. 4,10-Dinitro-4,10-diaza-2,6,8,12-tetraoxaisowurtzitane (TEX) (40), an insensitive high performance explosive (VOD 8665 m/s, d = 1.99 g/cm ), is synthesized by treating the dihydrochloride salt of the corresponding amine (39) with strong mixed acid. ... 

The role of dialkylchloramines as intermediates in the chloride-catalyzed nitration of secondary amines is discussed in Section 5.3.1. Wright and co-workers" studied this reaction further and prepared a number of dialkylchloramines by treating secondary amines with aqueous hypochlorous acid (Equation 5.12). Treatment of these dialkylchloramines with nitric acid in acetic anhydride forms the corresponding secondary nitramine, a result consistent with the chloride-catalyzed nitration of amines." ... 

In view of the highly carcinogenic nature of many nitrosamines any experiments involving their isolation must be discouraged, and for this reason, this section has only been written for completeness. This high toxicity is unfortunate because the preparation of nitrosamines from the parent amines is often facile and they provide a route to highly pure nitramines. Other equally useful methods for the synthesis of nitramines, such as the chloride-catalyzed nitration of secondary amines, also suffer from the formation of nitrosamines in appreciable amounts and must also be viewed with caution. 

Nitryl chloride reacts with many organics forming their nitro derivatives. Such Friedel-Crafts nitration is catalyzed by a Lewis acid, such as AICI3. An example is nitration of benzene to nitrobenzene ... 

In order to study this problem, Olah and Lin carried competitive studies of nitration of benzene and toluene with nitry chloride, catalyzed by Lewis acid halides. When carbon tetrachloride or excess aromatics were used as solvent, the data summarized in Table XII were obtained. The data show that the ortho para ratios are smaller than in nitrations with nitio-nium salts. The observed changes point to the fact that the nitrating agents arc the conesponding donor acceptor complexes and not the nitronium ion itself. The lower orthojpara ratios than those obtained in case of NOj, particularly point to bulkier nitrating agents. 

The oxidation of nitrous acid by chlorite to give nitrate and chloride involves uncatalyzed and chloride-catalyzed pathways.The mechanism involves oxygen atom transfer from chlorite to nitrous acid, generating peroxonitrite and hypochlorous acid. The former species isomerizes to nitrate and the latter species oxidizes nitrous acid to nitrate. The Cl"-catalyzed reaction involves oxidation by HOCb". The effect of solvent composition (water-dioxan) on the nitrite-chlorate reaction " is in accord with previous views on the mechanism of this well-studied reaction. 

The U.S. domestic commercial potassium nitrate of the 1990s contains 13.9% N, 44.1% I+O, 0—1.8% Cl, 0.1% acid insoluble, and 0.08% moisture. The material is manufactured by Vicksburg Chemical Co. using a process developed by Southwest Potash Division of AMAX Corp. This process uses highly concentrated nitric acid to catalyze the oxidation of by-product nitrosyl chloride and hydrogen chloride to the mote valuable chlorine (68). The much simplified overall reaction is... 

Manufacture. Historically, ammonium nitrate was manufactured by a double decomposition method using sodium nitrate and either ammonium sulfate or ammonium chloride. Modem commercial processes, however, rely almost exclusively on the neutralization of nitric acid (qv), produced from ammonia through catalyzed oxidation, with ammonia. Manufacturers commonly use onsite ammonia although some ammonium nitrate is made from purchased ammonia. SoHd product used as fertilizer has been the predominant form produced. However, sale of ammonium nitrate as a component in urea—ammonium nitrate Hquid fertilizer has grown to where about half the ammonium nitrate produced is actually marketed as a solution. 

It follows from the above that MPO may catalyze the formation of chlorinated products in media containing chloride ions. Recently, Hazen et al. [172] have shown that the same enzyme catalyzes lipid peroxidation and protein nitration in media containing physiologically relevant levels of nitrite ions. It was found that the interaction of activated monocytes with LDL in the presence of nitrite ions resulted in the nitration of apolipoprotein B-100 tyrosine residues and the generation of lipid peroxidation products 9-hydroxy-10,12-octadecadienoate and 9-hydroxy-10,12-octadecadienoic acid. In this case there might be two mechanisms of MPO catalytic activity. At low rates of nitric oxide flux, the process was inhibited by catalase and MPO inhibitors but not SOD, suggesting the MPO initiation. 

The imidazole complex raras-[Ir(imid)2Cl4]- is stable for days in neutral aqueous solution, and for hours in the presence of added thiocyanate. Addition of silver nitrate precipitates the silver salt of the complex, with no indication of Ag+-catalyzed removal of coordinated chloride. Thus this iridium(III) complex is substitutionally much more inert than its much-studied (because (potentially) anti-tumor) ruthenium(III) analogue (96). 

Fe(III) displacement of Al(III), Ga(III), or In(III) from their respective complexes with these tripodal ligands, have been determined. The M(III)-by-Fe(III) displacement processes are controlled by the ease of dissociation of Al(III), Ga(III), or In(III) Fe(III) may in turn be displaced from these complexes by edta (removal from the two non-equivalent sites gives rise to an appropriate kinetic pattern) (343). Kinetics and mechanism of a catalytic chloride ion effect on the dissociation of model siderophore-hydroxamate iron(III) complexes chloride and, to lesser extents, bromide and nitrate, catalyze ligand dissociation through transient coordination of the added anion to the iron (344). A catechol derivative of desferrioxamine has been found to remove iron from transferrin about 100 times faster than desferrioxamine itself it forms a significantly more stable product with Fe3+ (345). 

If nitration under acidic conditions could only be used for the nitration of the weakest of amine bases its use for the synthesis of secondary nitramines would be severely limited. An important discovery by Wright and co-workers " found that the nitrations of the more basic amines are strongly catalyzed by chloride ion. This is explained by the fact that chloride ion, in the form of anhydrous zinc chloride, the hydrochloride salt of the amine, or dissolved gaseous hydrogen chloride, is a source of electropositive chlorine under the oxidizing conditions of nitration and this can react with the free amine to form an intermediate chloramine. The corresponding chloramines are readily nitrated with the loss of electropositive chlorine and the formation of the secondary nitramine in a catalytic cycle (Equations 5.2, 5.3 and 5.4). The mechanism of this reaction is proposed to involve chlorine acetate as the source of electropositive chlorine but other species may play a role. The success of the reaction appears to be due to the chloramines being weaker bases than the parent amines. 

A reaction in which an electrophile participates in het-erolytic substitution of another molecular entity that supplies both of the bonding electrons. In the case of aromatic electrophilic substitution (AES), one electrophile (typically a proton) is substituted by another electron-deficient species. AES reactions include halogenation (which is often catalyzed by the presence of a Lewis acid salt such as ferric chloride or aluminum chloride), nitration, and so-called Friedel-Crafts acylation and alkylation reactions. On the basis of the extensive literature on AES reactions, one can readily rationalize how this process leads to the synthesis of many substituted aromatic compounds. This is accomplished by considering how the transition states structurally resemble the carbonium ion intermediates in an AES reaction. 

During the dark, polar winter the temperature drops to extremely low values, on the order of-80°C. At these temperatures, water and nitric acid form polar stratospheric clouds. Polar stratospheric clouds are important because chemical reactions in the stratosphere are catalyzed on the surface of the crystals forming these clouds. The chemical primarily responsible for ozone depletion is chlorine. Most of the chlorine in the stratosphere is contained in the compounds hydrogen chloride, HCl, or chlorine nitrate, CIONO. Hydrogen chloride and chlorine nitrate undergo a number of reactions on the surface of the crystals of polar stratospheric clouds. Two important reactions are ... 

Some nitric acid is used for the manufacture of explosives and chemicals, but much is converted on-site to the potentially explosive high nitrogen fertilizer ammonium nitrate (Section 2.11). Ammonia gas from the Haber plant is absorbed in aqueous HN03, and the NH4N03 solution is evaporated to a liquid melt (< 8% H20) for crystallization, but care must be taken to keep the pH of the solution above about 4.5 and to exclude any material (chlorides, organic compounds, metals) that might catalyze the explosive decomposition of NH4N03. It is also wise to keep the melt mass low and to vent it to avoid pressure buildup. The solid product should be stored well away from the main plant. 

Lanthanide(III) triflates catalyze the nitration of a range of simple aromatic compounds (benzene, toluene, biphenyl, m- and p-xylene, naphthalene) in good to excellent yield using stoichiometric quantities of 69% nitric acid.276 Bismuth(III) triflate was found to catalyze sulfonylation of aromatics with aromatic sulfonyl chlorides with similar high efficiency.277... 

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