P-Amino dimethylaniline

A wet sample (0.01 - 0.1 g) is added to the digestion flask and 4 ml of mixed reagent are added. The gas flow is started and the sample is refluxed for an hour. Potassium sulfate is used for a standard. The hydrogen sulfide produced is estimated by the p-amino dimethylaniline-ferric ammonium sulfate spectrophotometric method [76] utilising the 670 nm absorption maximum. Reagent blanks are run. Reagent blanks are low (< 0.03 xM s). 

As peroxy compounds differ from one another in solubility, it is obvious that several solvent systems are necessary for their separation. The following solvent systems have been found suitable (49—51) dimethylformamide/ /hexane to benzene ethylene glycol/hexane formamide/hexane -butanol-ethanol-water (45 5 50) or (10 10 1). For detection, sensitive down to 1 pg, the following sprays have been recommended (a) 0.1% p-amino-dimethylaniline hydrochloride and (b) a mixture of 3 ml of glacial acetic acid, 2 ml of a saturated potassium iodide solution, and 5 ml of starch solution. For the chromatography of organic peroxides on thin layers see (52, 53). 

It is interesting to note that azo compounds may be conveniently reduced either by a solution of tin(n) chloride in hydrochloric acid or by sodium di-thionite. Thus l-phenylazo-2-naphthol yields both aniline and l-amino-2-naphthol, and methyl orange gives p-amino-Af,Af-dimethylaniline and sulphanilic acid. 

Amino-dimethylaniline hydrochloride (1 %). Dissolve 1 g p-amino-NN-dimethylaniline dihydrochloride, H2N. C6H4. N(CH3)2.2HC1, in 100 ml water. 

Problem 23.22 Show how p-amino-N,N-dimethylaniline can be madftnia n azo compound. 

Although sulfonation resembles nitration and halogenation in many respects, there are certain important differences. The two most noticeable of these differences are the reversibility of sulfonation processes and the striking sensitivity of orientation to changes in the reaction temperature. Amino derivatives offer a further complication in that considerable amounts of ortho and para derivatives are often obtained. Thus at low temperatures, aniline gives a mixture of 0, m, and p-amino-benzenesulfonic acid,48 whereas dimethylaniline gives an almost equal... 

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],... 

Unmetallised disazo dyes of the type A—>M—>E in Winther symbols (section 4.7) dominate this sector. The A component is usually a disulphonated aniline or naphthylamine. Orthanilic acid or p-xylidine (2,5-dimethylaniline) for yellow browns, or a variety of monosulphonated 1-naphthylamines for redder browns, are selected as the M and E components. The terminal amino group provides the site for attachment of the reactive... 

Fig. 3.61. HPLC-UV chromatogram at 230 nm for the analysis of the aromatic amines listed. (1) 1,4-Diaminobenzene (2) 2-chloro-l,4-diaminobenzene (3) 2,4-diaminotoluene (4) benzidine (5) 4,4 -oxidianiline (6) aniline and 4-nitroaniline (7) o-toluidine (8) 4,4 -methylenedianiline (9) 3,3 -dimethoxibenzidine (10) 3,3 -dimethylbenzidine (11) 4-chloroaniline and 2-amino-4-nitrotoluene (12) 4,4 -thiodianiline (13) p-cresidine (14) 2,4-dimethylaniline (15) 2-naphty-lamine (16) 4-chloro-o-toluidine (17) 4,4 -methylene-di-o-toluidine (18) 2,4,5-trimethylaniline (19) 4-aminobiphenyl (20) 3,3 -dichlorobenzidine (21) 4,4 -methylenbis (2-chloroaniline) and (22) o-aminoazotoluene. Reprinted with permission from M. C. Garrigos et al. [130].

The last compound 4 4 -tetramethyl-di-amino-benzophenone is also known as Michler s ketone, and is an important intermediate in the preparation of dyestuffs of the fuchsine series, e.g., crystal violet. For the preparation of this ketone by treatment of dimethylaniline with carbon dioxide in presence of aluminium chloride, see E.P., 353464. 

If either the o- or -position is occupied, only one isomer is obtained transformation to the mefo-position does not occur. This is a standard method of preparation of acyl-amino-ketones, or by a further hydrolysis of amino-ketones. The tendency, illustrated in this reaction, of groups to wander from the amino group to the nucleus, is also shown in previous reactions and in the preparation of aminoazobenzene from diazoamino-benzene (Preparation 456), of sulphanilic acid from aniline sulphate (Preparation 292), of o- and p-chloroacetanilides from acetochloranilide (Preparation 328), of o- and p-toluidine from methylaniline hydrochloride, and of 1 2 4-aminodimethylbenzene (2 4-xylidine) from dimethylaniline hydrochloride. 

The nitration of aniline in the presence of a large amount of strong sulfuric acid results wholly in the formation of m-nitro-aniline, but the similar nitration of dimethylaniline gives principally a mixture of the ortho- and para-derivatives. Mono-methylaniline stands between aniline and dimethylaniline in respect to the orienting effect of its amino group it yields a considerable amount of the m-nitro- compound—and dimethylaniline is preferred for the preparation of tetryl. Commercial dimethylaniline contains a certain amount of monomethylaniline, from which it is extremely difficult to free it, and this in the manufacture of tetryl is converted in part into 2,3,4,6-tetranitro-phenylmethylnitramine, or m-nitrotetryl, pale yellow, almost white, crystals from benzene, m.p. 146-147.087... 

Attack other than on the amino group apparently does represent a competitive reaction course when the substituents on the aromatic ring are less electronegative than the nitro group. This is demonstrated by the strong coloration and tar formation observed when N,IV-dimethyl-aniline and p-chloro-N,A7-dimethylaniline are ozonized and by the fact that more ozone is consumed by these compounds than can be accounted for by side chain oxidation (Table III, Experiments 1 and 2). 

SYNS 1-AMINO-2.4-DIMETHYLBENZENE 4-AJMINO-l,3-DIMETHYLBENZENE 4-AMINO-3-METHYLTOLUENE 4-AMINO-l,3-XYLENE 2,4-DIMETHYLANILINE 2,4-DIMETHYLBENZENAMINE 2,4-DIMETHYLPHEiNYLAMINE 2-METHYL-p-TOLUIDINE 4-METHYL-o-TOLUIDINE 2,4-XYLIDENE (MAK) m-XYLIDINE m-4-XYLIDINE... 

The rate of initial electron transfer from A,7V-dimethylaniline to [Fe(phen)3] + is diffusion-limited. This is followed by the rate-determining proton transfer from the radical cation to pyridine to give the deprotonated a-amino radical which is rapidly oxidized by a second equivalent of [Fe(phen)3] + to yield the product iminium ion. Kinetic isotope effects [kii/kjf) for the proton transfer were determined from the J3/tfo ratios of the products derived from p-substituted A-methyl-A-trideuteromethylanilines. The k /kx) value first increases and then decreases with increasing pAa of p-substituted A,A-dimethylaniline. Such a bell-shaped isotope effect profile is typical of proton-transfer reactions [82, 85]. The maximum kn/fco value is determined as 8.8 which is much larger than the corresponding value for the demethylation of the same substrate by cytochrome P-450 (2.6) [79]. 

The presence of an amino group on an aromatic ring often results in oxidation of the ring to a quinone. The classical and industrial method is the treatment of anilines with potassium dichromate and sulfuric acid. Thus, aniline at room temperature is converted into p-benzoquinone in 86% yield [647], and 2,5-dimethylaniline at 80 °C gives a 55% yield of p-xyloquinone [648. A specific reagent for such oxidations is the Fremy salt, potassium nitrosodisulfonate (equation 528) [490. The oxidation of the amino group takes place even if it is acylated (equation 529) [1190. ... 

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