Dimethylaniline, oxidation

In an attempt to address the PCET versus HAT issue, Shearer, Karlin, and coworkers investigated the mechanism of dimethylaniline oxidations by [ Cu(MePy2) 2(02)] + (10, Figure 12). Here, the complexes are not pure peroxo or bis-/u.-oxo complexes, but instead are mixtures. The R -para pyridyl ligand donor substituent produces more of the bis-/u.-oxo tautomer as the R group is made more electron donating (7-30% bis-/u.-oxo). Based upon comparisons of both infra- vs intermolecular KIEs and KIE profiles of para-substituted dimethylaniline oxidations (R-DMA, Figure 12), it was determined that both PCET and HAT reactions occur. For the more easily oxidizable R-DMAs, a PCET reaction is preferred, while for the more difficult to oxidize R-DMAs a HAT pathway is favored. Also, it was observed that the more bis-/tr-oxo isomer that is in solution, the more likely it is that a HAT reaction will occur. 

An easy route to amine oxides is the oxidation of tertiary amines with /n-chloroperoxybenzoic acid in chloroform solution at 0-5 °C for 3 h. Trimethylamine oxide, tribenzylamine oxide, and dimethylaniline oxide are obtained in 96, 96, and 94% yields, respectively [320],... 

Dimethylaniline was first investigated by Hildebrandt (164), using rabbits, and he reported that this compound probably first was oxidized to dimethylaniline oxide which then rearranged to dimethylaminophenol. 

Coloured oxidation products, (a) Dissolve a few small crystals of triphenylamine in i ml. of cone. H2SO4 (cf. footnote, p. 376). Add 2 drops of cone. HNO3 to about 10 ml. of water, mix, and add i drop of this diluted HNO3 to the triphenylamine solution an intense greenish-blue coloration is produced. Dimethylaniline when treated in this way turns a deep dichromate colour. 

A AlI lation. A number of methods are available for preparation of A/-alkyl and A[,A/-dialkyl derivatives of aromatic amines. Passing a mixture of aniline and methanol over a copper—zinc oxide catalyst at 250°C and 101 kPa (1 atm) reportedly gives /V-methylaniline [100-61-8] in 96% yield (1). Heating aniline with methanol under pressure or with excess methanol produces /V, /V-dimethylaniline [121 -69-7] (2,3). 

The central carbon atom is derived from an aromatic aldehyde or a substance capable of generating an aldehyde during the course of the condensation. Malachite green is prepared by heating benzaldehyde under reflux with a slight excess of dimethyl aniline in aqueous acid (Fig. 2). The reaction mass is made alkaline and the excess dimethylaniline is removed by steam distillation. The resulting leuco base is oxidized with freshly prepared lead dioxide to the carbinol base, and the lead is removed by precipitation as the sulfate. Subsequent treatment of the carbinol base with acid produces the dye, which can be isolated as the chloride, the oxalate [2437-29-8] or the zinc chloride double salt [79118-82-4]. 

Benziodoxol 1782 can be readily converted by Me3SiCN 18 into HMDSO 7 and 1-cyanobenziodoxol 1783, which oxidizes N,N-dimethylaniline in 96% yield into N-cya-... 

Reaction of N,N-dimethylaniline with 1-cyanobenziodoxol 1783 to afford N-methyl-N-cyanomethylaniline 1784 in 97% yield has been discussed in Section 12.1 [31]. Analogously, oxidation of dimethylaniline with iodosobenzene and trimethylsilyl azide 19 at 0°C in CDCI3 gives the azido compound 2040 in 95% yield, iodobenzene, and HMDSO 7 [194, 195] (Scheme 12.56). Likewise, the nucleophilic catalyst 4-dimethylaminopyridine (DMAP) is oxidized, in 95% yield, to the azide 2041, which is too sensitive toward hydrolysis to 4-N-methylaminopyri-dine to enable isolation [194, 195]. Amides such as 2042, in combination with tri-... 

The oxidation of N, A-dimethylaniline by aerated, ethanolic cupric chloride to give a mixture of products including methyl and crystal violets is simple second-order when an excess of amine is used Presumably Cu(I) is re-oxidised by dissolved oxygen, for otherwise the observed linearity of log [residual amine] versus time plots would not be found as Cu(II) disappears. Under nitrogen the kinetics are complex, but a new optical absorption (472 and 1007 nm) appears immediately on mixing the reactants. This absorption decays whilst a new one at 740 nm develops. The latter absorption originates from a 1 1 complex formulated... 

When we allowed pentafluorophenyl-lithium to decompose in ether in the presence of an excess of N, ZV-dimethy laniline we obtained the compounds (92) 70, X = F), (94), the latter as the major compound, and a product which was shown to be (97). That this latter compound did not arise by metallation of 2V,lV-dimethylaniline followed by addition to tetrafluorobenzyne was shown by quenching the reaction mixture with deuterium oxide. No deuterium incorporation was detected. The compound (97) provides a rare example of a product derived by a Stevens rearrangement in which aryl migration has occurred b>. 

Although diselenonium-, ditelluronium- and mixed sulfonium-selenonium dications can exhibit either oxidative or electrophilic properties in reactions with nucleophiles, substitution at the onium chalcogen atom is more typical.96 Owing to the increased stability of heavier dichalcogenium-dications, they react only with highly activated substrates such as aniline and tV,A-dimethylaniline, while no reaction is observed with phenol and diphenylamine.113 Reactions of ditelluronium dications with activated aromatics are also not known (Scheme 44).114... 

One of numerous examples of LOX-catalyzed cooxidation reactions is the oxidation and demethylation of amino derivatives of aromatic compounds. Oxidation of such compounds as 4-aminobiphenyl, a component of tobacco smoke, phenothiazine tranquillizers, and others is supposed to be the origin of their damaging effects including reproductive toxicity. Thus, LOX-catalyzed cooxidation of phenothiazine derivatives with hydrogen peroxide resulted in the formation of cation radicals [40]. Soybean LOX and human term placenta LOX catalyzed the free radical-mediated cooxidation of 4-aminobiphenyl to toxic intermediates [41]. It has been suggested that demethylation of aminopyrine by soybean LOX is mediated by the cation radicals and neutral radicals [42]. Similarly, soybean and human term placenta LOXs catalyzed N-demethylation of phenothiazines [43] and derivatives of A,A-dimethylaniline [44] and the formation of glutathione conjugate from ethacrynic acid and p-aminophenol [45,46],... 

It is prepared by air oxidation of dimethylaniline in the presence of phenol and copper salts as well as sodium chloride. The reaction product consists of tetra- to hexamethylated pararosanilines (see 119, p. 541) ... 

Another route proceeds via bis(dimethylaminophenyl)methane, which is synthesized from dimethylaniline and formaldehyde. The thus prepared intermediate may be oxidized to form the hydrol and then reacted again with dimethylaniline to afford the leuco base, which is finally oxidized to yield 127 ... 

Methylene blue is also produced by the oxidation of dimethyl-p-phenylenediamine without the addition of dimethylaniline, and was discovered in this way by Caro in 1876. In explanation of this modification it is considered that the intermediate product (not isolated) at stage II is probably converted into the substance IV, in which the other ring is quinonoid, by replacement of the NH-group by... 

Triphenylamine (TPA), AWW W -tetramethyl-p-phenylenediamine (TMPD) and dimethylaniline (DMA) have been popular substrates for reaction under pulse radiolysis conditions. One of the earlier reports dealt with the formation of the radical cation of TMPD by reaction (k = 3 x 108 M 1 s 1) with the peroxy radical derived from oxidation of methylene chloride (CHCI2O2) by pulse radiolysis26. DMA is also oxidized to its radical cation by the same reagent (k = 2.5 x 107 M 1s 1). Since then it has been... 

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