Nitration by acetyl nitrate

The identification of a specific nitrating species can be approached by comparing selectivity with that of nitration under conditions known to involve the nitronium ion. Examination of part B of Table 10.7 shows that the position selectivity exhibited by acetyl nitrate toward toluene and ethylbenzene is not dramatically different from that observed with nitronium ion. The data for i-propylbenzene suggest a lower ortho para ratio for acetyl nitrate nitrations. This could indicate a larger steric factor for nitration by acetyl nitrate. 

The formation of /V-nitroazoles under the effect of sulfuric-nitric mixture is a rather seldom phenomenon [15, 27], since the N-N02 bond is unstable in acids. The most convenient way to (V-nitroindazoles is nitration by acetyl nitrate [15, 27-37],... 

The popularity of the Nef reaction is due in part to the ready availability of nitro compounds. Primary and secondary halides react with sodium nitrite in dimeAyl sulfoxide (DMSO) or dimethylform-amide (DMF) to give useful yields of nitro compounds. Primary amines can be oxidized to nitro compounds with potassium permanganate, m-chloroperbenzoic acitP or ozone. Chlorination of oximes with hypochlorous acid and reduction with magnesium, zinc or hydrogen/lpalladium gives secondary nitro compounds. Stabilized carbanions can be nitrated by treauitent with a nitrate ester, and enol acetates are nitrated by acetyl nitrate to give nitro ketones. ... 

Energetics (in kcal/mol) for the Para and Ortho Electrophilic Nitration by Acetyl Nitrate in the Polymorph B H-Beta Structure at the Acid Site... 

If pure isomers are required, the ortho and meta compounds can be prepared by indirect methods. o-Nitrotoluene can be obtained by treating 2,4-dinitrotoluene with ammonium sulfide followed by diazotization and boiling with ethanol. / -Nitrotoluene can be prepared from -toluidine by acetylation, nitration deacetylation, diazotization, and boiling with ethanol. A fairly pure -nitrotoluene, which has been isolated from the isomeric mixture, can be purified further by repeated crystallization. 

Nitration. Direct nitration of aromatic amines with nitric acid is not a satisfactory method, because the amino group is susceptible to oxidation. The amino group can be protected by acetylation, and the acetylamino derivative is then used in the nitration step. Nitration of acetanilide in sulfuric acid yields the 4-nitro compound that is hydroly2ed to -rutroaruline [100-01-6]. 

However, by protecting the -NHg group by acetylation reaction with acetic anhydride, the nitration reaction can be controlled and the p-nltro derivative can be obtained as the major product. 

D-Manno- D-galsi-heptose. Hexaacetyl-D-manno-D-goZa-heptononitrile was prepared by Miksic and by Brigl, Miihlschlegel and Schinle by acetylation of the free nitrile. It was degraded with methanolic ammonia and silver nitrate, giving D-mannose diacetamide in 34% yield. 

Activated positions (e.g., ZCH2Z compounds) can be nitrated by fuming nitric acid in acetic acid, by acetyl nitrate and an acid catalyst,264 or by alkyl nitrates under alkaline conditions.265 In the latter case it is the carbanionic form of the substrate that is actually nitrated. What is isolated under these alkaline conditions is the conjugate base of the nitro... 

Ref 3) fr p < -20°, bp 147° at 15 mm (dec) in sol in w, benz CSa easily sol in ales, acet, ether NG.Can be prepd by nitrating monoacetin with mixed nitric-sulfuric acid or by acetylation of d initio glycerin. It easily gelatinizes NC at RT, is insensitive to impact but it can be initiated by detonator-Power by Trauzl test 450 cc (Ref 2) and 202 cc(Ref 3) Note According to Naoum(Ref 3) the sample of Vender(Ref 2) probably contained NG... 

Clement and Riviere [59] also reported that cellulose acetate or a mixed ester — a nitrate-acetate — can be obtained by reacting cellulose nitrate with acetic anhydride, acetic acid, and sulphuric acid. According to more recent contributions, e.g. Wolfrom, Bower and Maker [60], the reaction should be performed as follows Cellulose nitrate is dissolved in the cold in a little sulphuric add and acetic anhydride, the surplus of acetic anhydride is then hydrolysed also in the cold, and cellulose acetate is extracted with a suitable solvent, such as chloroform. Other methods of acetylating nitrocellulose consist in reduction, for instance with zinc and hydrogen chloride, which entails denitration of the ester, followed by acetylation with acetic anhydride. All these reactions are carried out in the same vessel. Further, it is possible to synthesize mixed esters, cellulose nitrate-acetates, by subjecting cellulose to the action of a mixture that includes nitric acid, acetic add and acetic anhydride in the presence of sulphuric acid (Kruger [61]). The use of a large amount of nitric acid favours the formation of nitrocellulose only. Mixed esters are formed... 

Protection of the amino group by acetylation, as in acetanilide, therefore usually permits monosubstitution reactions with appropriate electrophilic reagents to proceed smoothly. Thus with bromine, p-bromoacetanilide is the main product the small quantity of the ortho isomer simultaneously formed can be easily eliminated by recrystallisation (Expt 6.67) hydrolysis of p-bromoacetanilide gives p-bromoaniline. Nitration leads similarly to p-nitroacetanilide which can be hydrolysed to p-nitroaniline (Expt 6.68). 

Nitration is widely applicable, can be carried out under a variety of conditions, can usually be stopped cleanly after mononitration, is usually effected by the nitronium ion, can take place on a neutral molecule or a cation, and in many cases can be considered as the standard aromatic electrophilic substitution. However, this last point must be treated with caution. Depending on the reaction conditions and reagents, the mechanism of the reaction does vary, and accompanying reactions such as oxidation (due to the oxidative action of nitric acid), acetoxylation (by acetyl nitrate), and migration of nitro groups following ipso attack (80MI1) can occur. Ipso nitration processes have been extensively studied by Fischer and co-workers. 

Chloro-2-nitroaniline. Primary aromatic amines should be protected by acetylation before nitration to avoid the possibility of accidental diazotization.19 Crotonaldehyde. Ignites in concentrated HN03.2... 

General, Remarks. Primary aromatic amines, whose basic properties are not too strongly reduced by the presence of negative substituents, can often be nitrated smoothly without protecting the amino group by acetylation or the like. The nitration is carried out in the presence of a large amount (at least 10 parts) of concentrated sulfuric acid and at as low a temperature as possible, below 0 in any case. The nitric acid must be entirely free from HNO2. 

The electron-donating ability of an amino group is moderated by acetylation. Only monobromination of acetanilide occurs on reaction with bromine in acetic acid (Scheme 8.5). Acetanilide behaves similarly on nitration. 

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