Aniline, 2,3,4,5-Tetramethyl

Rearangement of furoxans leads to the formation of new heterocyclic systems derivatives of triazoles, diazoles, isoxazoles, and pyrimidinones. For example, on the basis of the experimental results using labeled compound 52-15N , the formation of 8-phenyltheophylline 53, the 1,3-dimethylalloxazines (54 n = 0, 1), and l,3,7,9-tetramethyl-l//,9//-pyrimido[5,4-g]-pteridine-2,4,6,8-tetraone 55 in the thermal reaction of the iV-oxide 52 with benzylamine, aniline, or piperidine and the generation of NO or NO-related species in the reaction with iV-acetylcysteamine were reasonably explained by... 

A substantial divergence from the behaviour described up to now occurs with the 2,6-(V,(V-tetramethyl anilines (Table 7). The effect of the para substituent is no longer systematic, and no good correlation with substituent electronic properties is displayed. Evidently, the extent of nitrogen lone-pair delocalization in these compounds reflects a balance between electronic demand for, and steric inhibition of, delocalization that varies with the individual compounds. Nitrogen chemical shifts are a sensitive probe for these effects. 

One-electron oxidation of aniline derivatives gives a radical-cation in which the unpaired electron is distributed over both the nitrogen atom and the aromatic system. The further reactions of these intermediates more resemble those of aromatic compounds than of aliphatic amines. Some of the radical-cations are very stable in solution Wurster s blue, prepared by oxidation of tetramethyl-1,4-pheny ene-diamine [152], and Wurster s red from N,N-dimethyI-l,4-phenylenediamine [153] have been known since 1879. They were recognised as radical-cations by Mi-chaelis [154]. 

Crystal violet (20) can be produced directly from formaldehyde and dimethyl-aniline. The methane base (18), WAfW,W-tetramethyl-4,4 -mcthylcncdianilinc, is formed initially. This is then oxidized to Michler s hydrol (12), which condenses with another molecule of dimethylaniline to give leuco crystal violet (19). The latter is converted to the dye in a second oxidation step. Pararosaniline, methyl violet, and Victoria blue can also be obtained by this reaction sequence. 

Early evidence that the open-chain formula is, in itself, inadequate to explain the behavior of the glycosylamines emerged from the methylation experiments of Irvine and his coworkers." iV-Phenyl-D-glucosylamine was methylated to afford a crystalline tetramethyl ether which was hydrolyzed by acid to 2,3,4,6-tetra-O-methyl-D-glucose. Condensation of the latter compound with aniline afforded the original ether, which consequently must be 2,3,4,6-tetra-O-methyl-iV-phenyl-D-glucosylamine. 

N, JV-Dimethyl-2-nitro-p -toluidine N, JV-Dimethyl-2-nitro-p -anisidine A,jV-E>iethyl-3-nitroaniline A -Dimethyl-d-nitrosoaniline A -Dimethyl-d-nitroaniline A,A-I)iethyl-4-nitroaniline N, A-Diethyl-3-methyl-4-nitro aniline N,N, 3,5-Tetramethyl-4-nitroaniline 4-N,N -Dimethylaminobenzophenone Ethyl 4-Ar,iV-dimethylaminobenzoate 4-(Ar,Ar-Dimethylamino)-/S-nitrostyrene 4-(jV,jV-Dimethylamino)benzaldehyde... 

A similar mechanism could also be proposed for the 9-methylcarbazole-sensitized C—O bond cleavage of the picolinium esters (142-144) (Scheme 21)251. The formation of Af-methyl-4-picolyl radical 145 is verified by the observation of IV-methylpicolinium ion (146) in the presence of 1,4-cyclohexadiene, a good H-atom donor. Other anilines such ALALW. /V -tetramethyl benzidine and triphenylamine are also efficient sensitizers in this reaction. 

A similar tetramethyl derivative was obtained as adduct by electrolysis of 2,4-dibromo-2,4-dimethylpentan-3-one (18) in methanol in the presence of aniline. The formation of adduct 20 might be explained by addition of methanol to the electrosynthesized tetramethylcyclo-propylideneamine 19. 

Tetramethyl pyridazine-3,4,5,6-tetracarboxylate, but not 3,6-dichloropyridazine or dimethyl phthalazine-l, 4-dicarboxylate, takes part in a Diels-Alder reaction with indole under very concentrated conditions (Scheme 31). The adduct produced after elimination of nitrogen aromatizes by ring opening and the resultant aniline attacks the adjacent ester group to give the phenanthridone... 

The nanosecond pulse radiolysis technique has been described (8, 14). Carbon tetrachloride was purified as follows Matheson Research grade CC14 was dried over anhydrous potassium carbonate for several days, and subsequently distilled, discarding initial and final fractions. However, untreated research grade CCLj gave identical results to that treated as above. Zone refined naphthalene, anthracene, biphenyl, and N,N,N, N -tetramethyl-paraphenylenediamine (TMPD) were used pyrene, 1 2 benzanthracene were recrystallized from absolute alcohol, and aniline was purified as described in an earlier paper (6). Normal hexane, cyclohexane, 3-methylpentane, benzene, and toluene were Matheson research grade methanol and ethyl alcohol were analytical grade. 

However, Boozer and Hammond [7] have obtained additional support for the postulated chain termination via reaction (9) as opposed to reaction (5) on the basis of isotopic labelling experiments and from the inhibiting effect of amines not possessing a labile N—H function in their structure [8]. The use of deuterium-labelled methyl aniline and diphenyl-amine as inhibitors in the oxidation of tetralin and cumene did not show the isotope effect which would be expected if reaction (5) was important. Similarly, both AT-dimethylaniline and AT,AP-tetramethyl-p-phenylene-diamine have measurable inhibitory activity despite the fact that neither has a labile hydrogen [8]. However, it has been argued [12] that neither a kinetic isotope effect nor a labile hydrogen is necessary if inhibition results from an electron transfer reaction of the type... 

Beaumont and Davis examined the u.v. spectra of mixtures of CgFg with a variety of electron donors for evidence of charge-transfer absoiption bands. No bands were observed for mixtures containing 7c-donors but moderately strong n-donors such as AWAr W -tetramethyl-p-phenylenediamine and several substituted anilines were found to exhibit quite intense u.v. absorption when mixed... 

An environmentally benign synthesis of 4-aminodiphenylamine was developed by Monsanto. In this process, nitrobenzene and aniline are heated in presence of tetramethyl ammonium hydroxide to give condensation products as tetramethyl ammonium salts, which on catalytic hydrogenation give 4-aminodiphenylamine while regenerating tetramethyl ammonium hydroxide (Scheme 12). 

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