Malachite, green

Lian T, Locke B, Kholodenko Y and Hochstrasser R M 1994 Energy flow from solute to solvent probed by femtosecond IR spectroscopy malachite green and heme protein solutions J. Rhys. 

Von Baeyer (Nobel Prize, 1905) should be credited for having recognized in 1902 the saltlike character of the compounds formed. He then suggested a correlation between the appearance of color and salt formation—the so-called halochromy. Gomberg (who had just shortly before discovered the related stable triphenylmethyl radical), as well as Walden, contributed to the evolving understanding of the structure of related cationic dyes such as malachite green. 

Detecting the presence of small, even invisible, amounts of blood is routine. Physical characteristics of dried stains give minimal information, however, as dried blood can take on many hues. Many of the chemical tests for the presence of blood rely on the catalytic peroxidase activity of heme (56,57). Minute quantities of blood catalyze oxidation reactions between colorless materials, eg, phenolphthalein, luco malachite green, luminol, etc, to colored or luminescent ones. The oxidant is typically hydrogen peroxide or sodium perborate (see Automated instrumentation,hematology). 

Titrations with dibutylamine [111-92-2] can also be used to determine the NCO content of isocyanates and prepolymers. Generally, an excess of amine in a suitable solvent such as chlorobenzene [108-90-7] is added to the sample. The resulting solution is allowed to react and the unreacted amine is back- titrated with dilute hydrochloric acid. For low NCO content levels, a colorimetric method is often used. The isocyanate-containing species is titrated with amine and the unreacted amine is deterrnined using malachite green [569-64-2]. 

Pigment Green 4 [61725-50-6] 42000 2 triarylcarbonium chloride (Malachite Green) condensation of ben2aldehyde with /V,/V-dimethy1ani1ine, followed by oxidation and salt formation... 

The triaryknethane dyes are broadly classified into the triphenyknethanes (Cl 42000—43875), diphenylnaphthyknethanes (Cl 44000—44100), and miscellaneous triphenylmethane derivatives (Cl 44500—44535). The triphenyknethanes are classified further on the basis of substitution in the aromatic nuclei, as follows (/) diamino derivatives of triphenylmethane, ie, dyes of the malachite green series (Cl 42000—42175) (2) triamino derivatives of triphenylmethane, ie, dyes of the fuchsine, rosaniline, or magenta series (Cl 42500—42800) (J) aminohydroxy derivatives of triphenylmethane (Cl 43500—43570) and (4) hydroxy derivatives of triphenylmethane, ie, dyes of the rosoHc acid series (Cl 43800—43875). Monoaminotriphenyknethanes are known but they are not included in the classification because they have Httie value as dyes. 

A further strong bathochromic shift is observed as the basicity of the primary amines is increased by A/-alkylation, eg, malachite green [569-64-2] Cl Basic Green 4, =621 nm (5). 

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]. 

Statistics for the production of basic dyes include those products hsted as cationic dyes, eg, cyanines, for dyeing polyacrylonitrile fibers and the classical triaryhnethane dyes, eg, malachite green, for coloring paper and other office apphcations (2,53). Moreover, statistics for triaryhnethane dyes are also hidden in the production figures for acid, solvent, mordant, and food dyes, and also organic pigments. Between 1975 and 1984, the aimual production of basic dyes in the United States varied from 5000—7700 t. However, from 1985—1990, aimual production of basic dyes varied from 5000—5700 t, and the annual sales value increased from 56 to 73 million per year. 

A kinetic method for the determination of 2,4-dinitrophenol is proposed. The method is based on the inhibiting effect of 2,4-dinib ophenol on the Mn(II) catalysis of the oxidation of malachite green with potassium periodate. The reaction was followed spectrophotometrically at 615 nm. The optimal experimental conditions for the determination of 2,4-dinitrophenol were established under the optimal reaction conditions ... 

In this work hybrid method is suggested to determine anionic surfactants in waters. It is based on preconcentration of anionic surfactants as their ion associates with cationic dyes on the membrane filter and measurement of colour intensity by solid-phase spectrophotometry method. Effect of different basic dyes, nature and hydrophobicity of anionic surfactants, size of membrane filter pores, filtration rate on sensitivity of their determination was studied. Various cationic dyes, such as Methylene Blue, Crystal Violet, Malachite Green, Rhodamine 6G, Safranin T, Acridine Yellow were used as counter ions. The difference in reflection between the blank and the sample was significant when Crystal Violet or Rhodamine 6G or Acridine Yellow were used. 

Adsorption of lA of POMs with CV and Malachite Green (MG) on the polyurethane foams (PF) and some other adsorbents is investigated. While lA is fully adsorbed on the PF in wide pH range (0,4 M H SO - pH 4) extent of dye adsoi ption does not exceed 0,4%. lA are adsorbed faster then POMs. Extent of sorption of lA is 60-70% at 5 minutes and is complete after 15 minutes. lA can be eluted from PF most effectively by methylbutylketone, acetone or alcohols can be used too. 

The presence of a COOH functionality on a polystyrene resin can be detected using a 0.25% solution of malachite green-oxalate in ethanol in the presence of a drop of triethylamine. Beads with COOH functionalities are coloured dark green or appear as clear gel beads [Attardi, Porcu and Taddei Tetrahedron Lett 41 7391 2000]. 

Malachite green Metanil yellow Nigrosine Orange Y Paramido phenol Paraphenylendiamine Pyrogene violet brown Rosaniline Safranine... 

Malachite green (0.0...2.0) uracil derivatives, triazine herbicides [163] polar lipids [246, 247] phospholipids [248, 249] fatty acids, fatty aldehydes, phospholipids and glycolipids [250] microbiocidal isothiazolones [251]... 

The replacement of a benzene nucleus by a thiophene nucleus in compounds containing other chromophores causes more or less pronounced bathochromic shifts. These effects have been noticed in the thiophene analogs of malachite green (23), in cumulenes such as... 

MAlAchit-grUn, n. malachite green, -griinnahr-boden, m. malachite green nutrient medium, -kiesel, m. ehrysoeolla. 

The ionic associates of malachite green cation with dodecyl sulfate anion has been suggested for monitoring nonionic surfactant levels in industrial wastewaters by spectrophotometric determination at 650 nm [196]. 

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