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Nitrosating

These systems nitrate aromatie eompounds by a proeess of electro-philie substitution, the eharacter of whieh is now understood in some detail ( 6.1). It should be noted, however, that some of them ean eause nitration and various other reactions by less well understood processes. Among sueh nitrations that of nitration via nitrosation is especially important when the aromatic substrate is a reactive one ( 4.3). In reaetion with lithium nitrate in aeetie anhydride, or with fuming nitrie aeid, quinoline gives a small yield of 3-nitroquinoline this untypieal orientation (ef. 10.4.2 ) may be a eonsequenee of nitration following nucleophilic addition. ... [Pg.2]

We are not concerned here with the mechanism of nitrosation, but with the anticatalytic effect of nitrous acid upon nitration, and with the way in which this is superseded with very reactive compounds by an indirect mechanism for nitration. The term nitrous acid indicates all the species in a solution which, after dilution with water, can be estimated as nitrous acid. [Pg.54]

The theory that the catalysed nitration proceeds through nitrosation was supported by the isolation of some />-nitrosophenol from the interrupted nitration of phenol, and from the observation that the ortho.-para ratio (9 91) of strongly catalysed nitration under aqueous conditions was very similar to the corresponding ratio of formation of nitrosophenols in the absence of nitric acid. ... [Pg.57]

The observation of nitration nitrosation for mesitylene is important, for it shows that this reaction depends on the reactivity of the aromatic nucleus rather than on any special properties of phenols or anilines. [Pg.58]

Nitration at the encounter rate and nitrosation As has been seen ( 3.3), the rate of nitration by solutions of nitric acid in nitromethane or sulpholan reaches a limit for activated compounds which is about 300 times the rate for benzene imder the same conditions. Under the conditions of first-order nitration (7-5 % aqueous sulpholan) mesitylene reacts at this limiting rate, and its nitration is not subject to catalysis by nitrous acid thus, mesitylene is nitrated by nitronium ions at the encounter rate, and under these conditions is not subject to nitration via nitrosation. The significance of nitration at the encounter rate for mechanistic studies has been discussed ( 2.5). [Pg.60]

Under the conditions mentioned, i-methylnaphthalene was nitrated appreciably faster than was mesitylene, and the nitration was strongly catalysed by nitrous acid. The mere fact of reaction at a rate greater than the encounter rate demonstrates the incursion of a new mechanism of nitration, and its characteristics identify it as nitration via nitrosation. [Pg.60]

Under the same conditions the even more reactive compounds 1,6-dimethylnaphthalene, phenol, and wt-cresol were nitrated very rapidly by an autocatalytic process [nitrous acid being generated in the way already discussed ( 4.3.3)]. However, by adding urea to the solutions the autocatalytic reaction could be suppressed, and 1,6-dimethyl-naphthalene and phenol were found to be nitrated about 700 times faster than benzene. Again, the barrier of the encounter rate of reaction with nitronium ions was broken, and the occurrence of nitration by the special mechanism, via nitrosation, demonstrated. [Pg.60]

The evidence outlined strongly suggests that nitration via nitrosation accompanies the general mechanism of nitration in these media in the reactions of very reactive compounds.i Proof that phenol, even in solutions prepared from pure nitric acid, underwent nitration by a special mechanism came from examining rates of reaction of phenol and mesi-tylene under zeroth-order conditions. The variation in the initial rates with the concentration of aromatic (fig. 5.2) shows that mesitylene (o-2-0 4 mol 1 ) reacts at the zeroth-order rate, whereas phenol is nitrated considerably faster by a process which is first order in the concentration of aromatic. It is noteworthy that in these solutions the concentration of nitrous acid was below the level of detection (< c. 5 X mol... [Pg.91]

Without further studies little weight can be given to these ideas. In particular there is the possibility that with acetanilide, as with anisole, nitrosation is of some importance, and further with nitrations in sulphuric acid the effect of protonation of the substrate needs quantitative evaluation. The possibility that the latter factor may be important has been recognised, and it may account for the difference between nitration in sulphuric acid and nitration with nitronium tetrafluoroborate. [Pg.96]

Phenol. The change in the orientation of substitution into phenol as a result of the superimposition of nitrosation on nitration is a well-established phenomenon. In aqueous sulphuric acid it leads to a change from the production of 73 % of o-nitrophenol under nitrating... [Pg.96]

Again the uncertainty about the proportion of an observed result which is due to nitration and the proportion which is due to nitrosation exists. Thus, in expt. 11 phenol was being nitrated above the encounter rate and the observed isomer distribution could arise from a combination of nitration by whatever is the usual electrophile with nitration by a new, less reactive electrophile, or with nitrosation, or all three processes could be at work. [Pg.98]

Thus, strong arguments against all of the obvious nitrating species acting alone can be found. However, as has been pointed out, the extent to which ions require solvation by nitric acid molecules in this medium is unknown, and such solvation would influence the apparent order with respect to the stoichiometric nitric acid. The possibility also exists that more than one mechanism of nitration, excluding nitrosation, is operative. [Pg.104]

Butler recently reviewed the diazotization of heterocyclic amines (317). Reactions with nitrous acid yield in most cases N-exocyclic compounds. Since tertiary amines are usually regarded as inen to nitrosation, this... [Pg.65]

Even when deactivated by nitro substitution on C-5, the 2-aminothiazoles still undergo diazotization (35, 338-340). As with carbonyl derivatives (Section III.2.B), competition may occur between N nucleophilic reactivity and nitrosation of the 5-position when it is unsubstituted (341-344). [Pg.67]

The reasons for this apparent polywalent activity toward nitrosation (N ring reaction, N exocyclic reaction, nitrosation on the 5-position) are not... [Pg.67]

Ambident reactivity of the same nucleophilic species toward different nitrosation electrophilic centers. [Pg.68]

Some recent general reviews deal with the mechanism of N-nitrosation in aqueous solution (345), the nitrosation of secondary amines (346). the effect of solvent acidity On diazotization (347) and the reactivity of diazonium salts (1691). Therefore, a complete rationalization of the reactivity of amino azaaromatics would be timelv. [Pg.68]

Nitrosation in the 5-position has been reported with compounds 185 and 186 (Scheme 118) (165, 241). which are then reducible to the 5-aminothiazoles by Zn dust in AcOH. An old report (164) describing the nitrosation product of 2-methylaminothiazole as 2-(N-methylimino)-3-nitroso-2,3-dihydrothiazole (187) (Scheme 118) has been recently corrected by Ref. 314. [Pg.74]

C-5, nitrosation yields 384 (Scheme 219). If alkylisocyanates replace alkylisothiocyanates, the corresponding thioureas (382b) (X = S) are obtained (482). Tertiary ureas 386 are prepared by reaction... [Pg.125]


See other pages where Nitrosating is mentioned: [Pg.50]    [Pg.54]    [Pg.55]    [Pg.57]    [Pg.59]    [Pg.59]    [Pg.94]    [Pg.96]    [Pg.97]    [Pg.97]    [Pg.135]    [Pg.204]    [Pg.205]    [Pg.214]    [Pg.239]    [Pg.239]    [Pg.240]    [Pg.241]    [Pg.242]    [Pg.66]    [Pg.72]   
See also in sourсe #XX -- [ Pg.215 ]




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2 Naphthol nitrosation

3, 5-diamino nitrosation

3- Alkyl-5-acetamidoisothiazoles, nitrosation

Active hydrogen compounds nitrosation

Alkanes nitrosation

Alkyl nitrites, nitrosation

Amides nitrosation

Amides, nitrosated

Amination nitrosation

Amine Amino acids, secondary, nitrosation

Amine nitrosative dealkylation

Amine secondary, nitrosation

Amine tertiary, nitrosative dealkylation

Amines nitrosation

Amino acids nitrosation

Aminopyrine nitrosation

Amylene nitrosate

Anions nitrosation

Apparatus for nitrosation with methyl nitrite

Arylamines nitrosation

Ascorbic acid nitrosation inhibition

Azides via nitrosation of hydrazines and hydrazides

Barton esters nitrosation

Carbazole, nitrosation

Cobalt nitrosation

Cresols, nitrosation

Cysteine, nitrosation

Dealkylation, nitrosative

Dealkylation, nitrosative, tertiary

Decarboxylative nitrosation

Determination of Dissolved Lignin by the Modified Pearl-Benson (Nitrosation) Method

Dimethylamine nitrosation

Dinitrogen tetroxide in nitrosation

Electrophilic aromatic nitrosation

Electrophilic nitrosation

Endogenous nitrosation

Enolates Nitrosation with nitroso compounds

Enolates nitrosation

Enols Nitrosation with nitrites

Enols nitrosation

Ethyl nitrite, nitrosation

Glucose nitrosation

Guanidines, nitrosation

Halogenation, nitrosation, and nitration

Herbicide nitrosation

Imidazo thiazoles, nitrosation

Imidazoles nitrosation

In nitrosation

Indole nitrosation

Isoamyl nitrite, nitrosation with

Ketones nitrosation

Methylamine nitrosation

Methylaniline, nitrosation

Methylene groups, nitrosation

Methylene groups, nitrosation oxidation

N-Nitrosation

N2O3 Nitrosative Stress

NITROSATED NYLON

Nitration Nitrosating agent

Nitration Nitrosation

Nitration and Nitrosation

Nitration via nitrosation

Nitric Oxide Reduction, Oxidation, and Mechanisms of Nitrosation

Nitric acid nitrosation

Nitrites nitrosation

Nitronic acids, nitrosation

Nitroprusside Nitrosation

Nitrosated heme

Nitrosates

Nitrosates

Nitrosating agent

Nitrosating potential

Nitrosation

Nitrosation

Nitrosation Nitrosodimethylaniline

Nitrosation alkenes

Nitrosation and diazotization

Nitrosation application

Nitrosation by nitrosyl halides

Nitrosation by positive nitrosating agents

Nitrosation cleavage

Nitrosation compounds

Nitrosation indoles

Nitrosation inhibition

Nitrosation isotope effects

Nitrosation mechanism

Nitrosation nitric oxide

Nitrosation nitrite/nitrate addition

Nitrosation of Alkylamines

Nitrosation of Arylamines

Nitrosation of N-methyl-/>-toluenesulfonamide

Nitrosation of amines

Nitrosation of amino acids

Nitrosation of aromatic amines

Nitrosation of dimethylamine

Nitrosation of dimethylaniline

Nitrosation of ethyl N-methylcarbamate

Nitrosation of ethyl acetoacetate

Nitrosation of ethyl malonate

Nitrosation of guanidines

Nitrosation of hydroxylamine

Nitrosation of ketones

Nitrosation of ketones s. a-Isonitrosoketones

Nitrosation of methyl ethyl ketone

Nitrosation of methylaniline

Nitrosation of methylurea

Nitrosation of oxime

Nitrosation of phenols

Nitrosation of phenols and tertiary amines

Nitrosation of primary amines

Nitrosation of propiophenone

Nitrosation of pyrimidines

Nitrosation of pyrrole

Nitrosation of secondary

Nitrosation of secondary amines

Nitrosation on carbon

Nitrosation posttranslational

Nitrosation primary aliphatic amines

Nitrosation primary aromatic amines

Nitrosation processing

Nitrosation pyrazolones

Nitrosation pyrimidine

Nitrosation pyrimidines, activated

Nitrosation reaction

Nitrosation side-reactions during

Nitrosation tertiary amines

Nitrosation with Nitrite Esters

Nitrosation with metal nitrosyl complexes

Nitrosation with nitrite ions

Nitrosation, by nitrosyl chloride

Nitrosation, fundamentals

Nitrosation, hydrolytic

Nitrosation, nitration through

Nitrosation, of 6-aminouracil

Nitrosation, of enols

Nitrosation-oxidation

Nitrosation-oxidation rearrangement

Nitrosations

Nitrosative cyclization

Nitrosative dealkylation of tertiary

Nitrosative dealkylation of tertiary amines

Nitrosative stress

Nitrosative stress oxygen/nitrogen

Nitrosic acid

Nitrosyl tnfluoroacetate electrophilic nitrosation

Nitrous Acid and Nitrosation

Nitrous acid Nitrosation

Oxidative/nitrosative stress

Oxidative/nitrosative stress Reactive oxygen species

Oximes N-nitrosation

Oximinomalononitrile, from nitrosation

Oximinomalononitrile, from nitrosation of malononitrile

Oximinomalononitrile, from nitrosation reduction with aluminum amalgam

Pentyl nitrite nitrosation with

Peptides, nitrosation

Phenol nitrosation

Photochemical nitrosation

Piperazine nitrosation

Potential, nitrosation

Precursors nitrosating agents

Proline, nitrosation

Protein nitrosation

Pyrazole nitrosation

Pyrazolin-5-ones nitrosation

Pyrrole nitrosation

Pyrrolidine nitrosation

Reductive nitrosation

Resorcinol, Nitrosation

Ring nitrosation

S-Nitrosoproteins Functional Effects of Posttranslational Nitrosation

S-nitrosation

Sulphides, 5-nitrosation

Temperature effect, nitrosation

Thiazole 2- -, nitrosation

Toluene nitrosation

Tyrosine nitration, and nitrosation

Tyrosine nitrosation

Ureas nitrosation

Waters, nitrosation

Xylenes, nitrosation

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