Oxidation of o-toluidine

The orders of reaction in the oxidation of /V,/V-dimcthylanilinc by chromic acid are one and zero, respectively.15 The reaction is catalysed by metal ions such as Cu2+ and Ag+, but retarded by Mn2+ a mechanism is proposed. In contrast, in the chromic acid oxidation of o-toluidine, the reaction is first order in both oxidant and substrate.16... 

Estimated in the oxidation of o-toluidine in 30 mM sodium phosphate [63] buffer pH 7.0... 

A. A. Ensafi and M. Keyvanfard, Kinetic spectrophotometric method for the determination of rhodium by its catalytic effect on the oxidation of o-toluidine blue by periodate in micellar media, Journal of Analytical Chemistry, vol. 58, no. 11, pp. 1060-1064, 2003. 

Suitable mechanisms have been proposed following determination of the kinetic and activation parameters for oxidation of 2-naphthol and cyclic ketones by nicotinium dichromate some a-amino acids by tripropylammonium fluorochromate " distyryl ketone by quinaldinium fluorochromate methanol by benzyltriethylammonium chlorochromate catalysed by 1,10-phenanthroline substituted benzyl alcohols by tetraethylammonium bromochromate L-cysteine by pyridinium bromochromate lactic acid and 3,5-dimethyl-2,6-diaryl piperidin-4-one oximes by pyridinium chlorochromate allyl alcohol by IDC benzophenoxime by bispyridine silver(I) dichromate and alkyl phenyl sulfides by cetyltrimethylammonium dichromate. A non-linear Hammett plot obtained for the oxidation of substituted benzyl alcohols by IDC has been attributed to the operation of substituent effect on two steps of the proposed mechanism. " Kinetic and activation parameters for oxidation of o-toluidine and of A-methyl-2,6-diphenyl piperidin-4-one oxime and its 3-alkyl derivatives by sodium dichromate have been determined and suitable mechanisms have been suggested. Micellar catalysis in the 1,10-phenanthroline-promoted chromic acid oxidation of propanol... 

In a variation of this method, isolation of the ben2hydrol derivative is not required. The methane base undergoes oxidative condensation in the presence of acid with the same or a different arylamine direcdy to the dye. New fuchsine [3248-91 -7] Cl Basic Violet 2 (16), is prepared by condensation of two moles of o-toluidine with formaldehyde in nitrobenzene in the presence of iron salts to give the corresponding substituted diphenylmethane base. This base is also not isolated, but undergoes an oxidative condensation with another mole of o-toluidine to produce the dye. 

Benzisothiazoles are best prepared by oxidative cyclization of o-aminothiobenz-amides (see Section 4.17.9.1.1), reaction of o-toluidines with thionyl chloride (see Section 4.17.9.2.1) or by sulfuration of 2,1-benzisoxazoles (see Section 4.17.10.2). 1,2-Benzisothiazoles can also be prepared from o-disubstituted benzene compounds, cyclodehydration of o-mercaptobenzaldoximes or oxidative cyclization of p-mercaptobenzylamines (see Section 4.17.9.1.1) being the most convenient. Both series of benzo compounds are readily substituted at the 5- and 7-positions by electrophilic reagents. 

Sulfate, CH3.C(5H4.N2.0.S03H wh ndls, hygr, mp - deflgr on heating explodes mildly on impaet readily sol in aeet ae sol in MeOH si sol in ale insol in eth, ehlf, CS2, petr eth, aeet, benz nitrobenz was prepd by passing N oxides thru st soln of o-toluidine in ale to whieh H2SO4 was added dropwise m-(or 3-) Diazonitrotoluene Salts (Ref 2) Borofluoride, CH3.C(5H4.N2.BF4 erysts, dee at 108 ... 

An early procedure which alfords a quick if inefficient route to toluquinone consists in steam distillation of a mixture of o-toluidine, manganese dioxide, and sulfuric acid. The reagent has been used to oxidize pyridoxine (1) to pyridoxal 2f and to oxidize pyridoxamine phosphate (3) to pyridoxal phosphate (4). ... 

Synthesis. Methods of synthesis have changed litde since the synthesis of Basic Red 2. One method starts with o-toluidine [95-53-4], C H9N, which is diazotized and coupled to form amino azotoluene [97-56-3], C14H15N3. Amino azotoluene is reduced to one mole each of o-toluidine and 2,5-diaminotoluene [95-70-5], C7H10N2. Condensation and oxidation with aniline [62-53-3], C HyN, gives the desired dye (13). 

First there is chlorination of nitrogen to yield reactive N-chloro derivatives, which oxidize iodide to iodine in the next step. Finally oxidation of the o-toluidine probably yields colored quinonoid toluidine derivatives. 

Peptides, for example, yield chloramine derivatives on exposure to chlorine gas these derivatives oxidize o-toluidine to a blue semiquinonoid dyestuff in the presence of acetic acid. 

The effects of various metal oxides and salts which promote ignition of amine-red fuming nitric acid systems were examined. Among soluble catalysts, copperQ oxide, ammonium metavanadate, sodium metavanadate, iron(III) chloride (and potassium hexacyanoferrate(II) with o-toluidine) are most effective. Of the insoluble materials, copper(II) oxide, iron(III) oxide, vanadium(V) oxide, potassium chromate, potassium dichromate, potassium hexacyanoferrate(III) and sodium pentacyanonitrosylferrate(II) were effective. 

The entire group of these compounds dates back to the very beginnings of organic dye chemistry. In 1858, E. Verguin in France oxidized a material which he named aniline but which was in actual fact a mixture of aniline, o-toluidine, and p-toluidine. He performed the reaction in nitrobenzene in the presence of tin(IV)chloride or iron(III)chloride and received bluish red fuchsin (120). The process has been industrially exploited since 1859. The central carbon atom is furnished by the CH3 group of p-toluidine, which is initially oxidized to its aldehyde. 

The technical preparation of crystal violet and of its methyl-free parent substance, parafuchsine, almost the oldest of the triphenylmethane dyes, is not so easily explained. As is well known, in this process aniline and p-toluidine are united by oxidation in an acid melt. (In the preparation of fuchsine itself, which contains a methyl group attached to one of the benzene rings, o-toluidine is an additional ingredient.) Although all the phases of this important synthesis have not yet been experimentally established, we may nevertheless explain it on the basis of a dehydrogenation similar to that involved in the formation of malachite green. Moreover, the union of several molecules of base proceeds exactly according to the principle on which indamines are formed (p. 321) (Bucherer). 

A detailed investigation of aniline N-methylation on Cui xZnxFc204 was carried out through in situ FTIR spectroscopy. The reactants (aniline and methanol) and possible products (NMA, DMA and o-toluidine) were adsorbed on the catalysts and analyzed [106,107]. Adsorption of methanol indicated a dissociative chemisorption as methoxy species on catalyst surface at 100°C. As the temperature increased, oxidation of methoxy species to formaldehyde to dioxymethylene to formate species was observed, and above 300°C complete oxidation takes place to CO, CO2 and H2. Indeed methanol alone on Cui xZnxFc204 and Cui.xCoxFc204 behaves in a similar way [79,107]. 

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