Dimethyl-p-phenylenediamine

AMNES - AMINES,AROMATIC - PHENYLENEDIAMINES] (Vol 2) N,N-Dimethyl-p-phenylenediamine [99-98-9]... 

Dimethylphenol, 57 Dimethyl-p-phenylenediamine, 57 Dimethyl phosphorochloridothioate, 57 Dimethyl phthalate, 57... 

N,N-Dimethyl-p-phenylenediamine Radical Cation (DMPD ) DMPD Assay... 

Another assay that is very similar to the ABTS assay is the AGV-dimethyl-p-phenylenediamine (DMPD assay). In the presence of a suitable oxidant solution at an acidic pH, DMPD is converted to a stable and colored DMPD radical cation (DMPD +). Antioxidants capable of transferring a hydrogen atom to the radical cause the decol-orization of the solution, which is spectrophotometrically measured at 505 nm. The reaction is stable, and the endpoint is taken to be the measure of antioxidant efficiency. Antioxidant ability is expressed as Trolox equivalents using a calibration curve plotted with different amounts of Trolox (Fogliano and others 1999). This method is used to measure hydrophilic compounds. The presence of organic acids, especially citric acid, in some extracts may interfere with the DMPD assay, and so this assay should be used with caution in those extracts rich in organic acids (Gil and others 2000). 

Synthesis of diazonium salts. The details of the synthesis of 4-N, N-dimethylaminobenzenediazonium trifluoromethanesulfonate (Dl) are described below. N, N-Dimethyl-p-phenylenediamine... 

Diethyl pdimethylaminophenylphosphoramidate was readily obtained as a colourless crystalline solid by the action of NiV -dimethyl-p-phenylenediamine on diethyl phosphoro-chloridate.2... 

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... 

Dimethyl-p-phenylenediamine (7-6 g.) is dissolved in 70 c.c. of iV-hydrochloric acid, and 35 g. of zinc chloride in 50 c.c. of water are added. With good stirring 12 g. of aluminium sulphate in 20 c.c. of water and then 15 g. of sodium thiosulphate in 20 c.c. of water are poured in. To the solution thus obtained one-third of a solution of 16 g. of sodium dichromate in 30 c.c. of water is at once added and the temperature of the solution is raised as rapidly as possible to 40°. The addition of 6 g. of dimethylaniline dissolved in 8 c.c. of concentrated hydrochloric acid follows, and finally the remainder of the oxidising agent is poured in. Of course, all these solutions are prepared before the experiment is begun. 

Elemental composition Na 58.93%, S 41.07%. An aqueous solution is analyzed to determine sodium content. Also, an aqueous solution may be analyzed for sulfide by methylene blue colorimetric test or by iodometric titration (APHA, AWWA, and WEF. 1999. Standard methods for the Examination of Water and Wastewater, 20 ed. Washington, DC American Pubhc Health Association). The methylene blue test is based on reacting sulfide, ferric chloride and dimethyl-p-phenylenediamine to produce methylene blue. Also, sulfide can be measured by using a sdver-sdver sulfide electrode. Quahtatively, sulfide may be identified from the hberation of H2S on treatment with acid. The H2S turns the color of paper soaked with lead acetate black (See Hydrogen Sulfide). 

N, A, -Dimethyl-p-phenylenediamine dihydrochloride, hydroperoxide determination, 678 Dimethylphenylsilyl hydrotrioxide... 

To 0.5 mL of sample solution in 0.01 N methanolic perchloric acid, 1 mL of 0.1% methanolic dimethyl-p-phenylenediamine oxalate is added. The resulting solution is left to stand for 30 minutes in the dark, 2.5 mL of... 

DMPD (N,N-dimethyl-p-phenylenediamine) radical cation decolorization assay... 

A method of analysing antioxidant activity with respect to the DMPD" cation-radical (N,N-dimethyl-p-phenylenediamine cation radical) has been proposed by Fogliano and co-workers [31]. The determination principle involves colorimetric observation of the disappearance of the cation-radical colour at the absorbed light wavelength of 505 nm after a reaction time of 10 min. Coloured cation-radical DMPD" in the assay is obtained by reaction of DMPD with iron chloride in an acetate buffer at pH 5.25. The decrease in absorbance of the reaction mixture caused by antioxidants is compared to the calibration curve, prepared with a series of dilutions of Trolox [32]. 

Khs prepd by Hofmann et al (Ref 3) on treating N,N-dimethyl-p-phenylenediamine hydrochloride with Na nitrite and perchloric acid of 20% strength... 

The oxidation of dopamine by ceruloplasmin yielded a free radical with a very short lifetime, characterized by an EPR signal at g = 2.006 Dimethyl-p-phenylenediamine was oxidized faster by the enzyme to the free radical Wurster s red, which was further oxidized by the enzyme in another one-electron step. The free radical seemed, moreover, to be stabilized by ceruloplasmin... 

Aminosulfuric acid 27 g A/A -dimethyl-p-phenylenediamine oxalate in 100 mL 1 1 H2S04 solution in a volumetric flask. Store in dark. 25 mL of this solution is diluted to 1 L with 1 1 H2S04. The reagent should be stored in a dark bottle. 

VIS (methylene Reaction of sulfide, ferric chloride, blue method) and dimethyl-p-phenylenediamine to produce methylene blue, which has X at 660 nm. 

Dimethyl-p-phenylenediamine Sodium thiosulfate Zinc chloride... 

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