Crystal violet

Crystal violet is an example of a triphenylmethane dye. Its preparation in the laboratory may be illustrated by the condensation of 4 4 -tetramethyl-diaminobenzophenone (Michler s ketone) and dimethylaiiiliue in the presence of phosphorus oxychloride  

Michler s ketone is prepared industrially by the interaction of phosgene (COCl,) and dimethyl aniline. 

In a 1 htre round-bottomed flask, provided with an air condenser, place a mixture of 25 g. (26 ml.) of pure dimethylanihne, 10 g. of Michler s ketone (4 4 tetramethyldiaminobenzophenone) and 10 g. (6 ml.) of phosphorus oxychloride. Heat on a boding water bath for 5 hours. Add about 150 ml. of water and sufificient sodium hydroxide solution to render the solution alkaline. Calculate the quantity of sodium hydroxide required upon the basis of the hydrolysis product derived from the phosphorus oxychloride  

The pure pigment may be obtained by heating phthalonitrile (4 mols) and copper bronze (1 atom) at 200-220°  

Phthalonitrile may be prepared by the following series of reactions from phthalimide — 

+ SHjO — H3PO4 + 3HC1 Pass steam into the mixture (Fig. II, 40, 1) until no more drops of unattacked dimethylaniline pass over into the receiver. Allow to cool and filter the reddish precipitate of the colour base at the pump and wash it with water. Transfer the precipitate to a large beaker and boO it with a mixture of 5 ml. of concentrated hydrochloric acid and 1 litre of water. Filter the hot solution and set the filtrate aside for crystallisation to take place. Treat the residue with successive portions of fresh dilute hydrochloric acid until it has almost entirely dissolved. On cooling and standing, the crystal violet separates in green crystals filter these with suction. Treat the combined filtrates, whilst stirring, with finely-powdered sodium chloride until precipitation is complete and the liquid is just saturated collect the precipitate in a filter. The crystal violet may be recrystallised from a little water, and dried upon filter paper in the air. The yield is 12 g. 

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Single molecules also have promise as probes for local stmcture when doped into materials tliat are tliemselves nonfluorescent. Rlrodamine dyes in botli silicate and polymer tliin films exliibit a distribution of fluorescence maxima indicative of considerable heterogeneity in local environments, particularly for the silicate material [159]. A bimodal distribution of fluorescence intensities observed for single molecules of crystal violet in a PMMA film has been suggested to result from high and low viscosity local sites witliin tire polymer tliat give rise to slow and fast internal conversion, respectively [160]. 

The preparation of an ion-selective electrode for salicylate is described. The electrode incorporates an ion-pair of crystal violet and salicylate in a PVC matrix as the ion-selective membrane. Its use for the determination of acetylsalicylic acid in aspirin tablets is described. A similar experiment is described by Creager, S. E. Lawrence, K. D. Tibbets, C. R. in An Easily Constructed Salicylate-Ion-Selective Electrode for Use in the Instructional Laboratory, /. Chem. Educ. 1995, 72, 274-276. 

Acetyl chloride frequently contains 1—2% by weight of acetic acid or hydrochloric acid. Phosphoms or sulfur-containing acids may also be present in the commercial material. A simple test for purity involves addition of a few drops of Crystal Violet solution in CHCl. Pure acetyl chloride will retain the color for as long as 10 min, but hydrochloric, sulfuric, or acetic acid will cause the solution to become first green, then yellow (34). 

Carbonless Copy Paper. In carbonless copy paper, also referred to as pressure-sensitive record sheet, an acid-sensitive dye precursor, such as crystal violet lactone or /V-hen2oy11eucomethy1ene blue, is microencapsulated with a high boiling solvent or oil within a cross-linked gelatin (76,83,84) or in synthetic mononuclear microcapsules. Microcapsules that have a starch binder are coated onto the back of the top sheet. This is referred to as a coated-back (CB) sheet. The sheet intended to receive the image is treated on the front (coated-front (CF)) with an acid. When the top sheet is mechanically impacted, the dye capsules mpture and the dye solution is transferred to the receiving sheet where the acid developer activates the dye. 

Chemical reactions for the negative systems in CopiArt can be generalized by the reaction of the leuco form (9) of crystal violet [548-62-9] to produce the colored form (10). 

The first triaryknethane dyes were synthesized on a strictiy empirical basis in the late 1850s an example is fuchsine, which was prepared from the reaction of vinyl chloride with aniline. Thek stmctural relationship to triphenylmethane was estabHshed by Otto and Fmil Fischer (5) with the identification of pararosaniline [569-61-9] as 4,4, 4 -triaminotriphenyknethane and the stmctural elucidation of fuchsine. Several different stmctures have been assigned to the triaryknethane dyes (6—8), but none accounts precisely for the observed spectral characteristics. The triaryknethane dyes are therefore generally considered to be resonance hybrids. However, for convenience, usually only one hybrid is indicated, as shown for crystal violet [548-62-9] Cl Basic Violet 3 (1), for which = 589 nm. 

The manufacture of crystal violet (1), however, is a special case which does not involve the isolation of the intermediate Michler s ketone (Fig. 3). Thus, phosgene is treated with excess dimethyl aniline in the presence of zinc chloride. Under these conditions, the highly reactive intermediate "ketone dichloride" is formed in good yield this intermediate further condenses with another mole of dimethyl aniline to give the dye. 

V-methyl aniline formed in the initial step to give the leuco base of methyl violet. Treatment with aqueous acid produces the dye. Because Michler s hydrol may also react with dimethyl aniline instead of the /V-methyl aniline to give crystal violet, commercial-grade methyl violet is usually a mixture. A cobalt complex has converted 4,T-dimethylaminodipheny1methane and dimethyl aniline in the presence of atmospheric oxygen to crystal violet in one step (50). 

Procedure has been proposed for the P(V) and As(V) determination based on the selective extraction of ionic associate of Crystal Violet with reduced molybdophosphate with mixture of inert (toluene) and active (methyl isobutyl ketone) solvents. Extraction of reagent is negligible. After concentration determination lower than 10 mol/1 of P(V) and As(V) is possible. 

The extractive and photometric procedure of 2,4-D determination in aqueous solutions with crystal violet (CV) is developed. Determination method is based on interaction dye cation with formation of hydrophobic and ionic associate, which is extracted well by toluene. The colour intensity of toluene layer proportional to concentration of coloured cations and... 

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. 

Crystal Violet Chloride (Gentian vioiet, V-4[bis[4-(dimethyiaminophenyi)methyiene]-2,5-cyciohexadien-l-yiidene]-V-methyimethaninium chioride [548-62-9] M 408.0, pK 9.36. 

Gram positive Bacterial cells which retain the crystal violet stain during a staining procedure. Most strains of bacilli are gram positive. 

Gram negative Bacteria cells which lose the crystal violet during the decolorizing step and are then colored by the counterstain. Pseudomonas and Thiobacillus are examples of gram negative strains. 

The preparation of crystal violet from MichlePs compound and dimethylanihne in presence of POCI3 may be explained in a similar fashion,... 

Tlie constitution of the hydrochlmides of malachite gieen and crystal violet will appear as follows —... 

Vitreosil filtering, 103 see also Platinum apparatus Crushing and grinding 155 Crystal violet indicator, 308 Cupferron 170, 440, 471, 474 Cupron 442, 473 Current adsorption, 616 catalytic, 616 condenser, 595 diffusion, 592, 596 efficiency, 504 kinetic, 616... 

N -dimethylaniline into crystal violet (Ref 8), and thiourea into (H2NCS)2 (Ref 14). It is... 

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