Pararosaniline base

Triaminotriphenylcarbinol. Tris p-aminophenyl) methanol. Pararosaniline base. C.I. 42500. C.I. Basic red 9. Magenta 0. Basic parafuchsin [25620-78-4]... 

Pararosaniline base, see T-00383 Pararosaniline embonate, in T-00383 Pararosaniline pamoate, in T-00383 Pardisol, in E-00050... 

These compounds are triphenylmethane pigments. Strictly speaking, they should be referred to as triaminophenylmethane derivatives. The parent structure is known as reddish violet parafuchsin (118) or its anhydro base pararosaniline (119). The parent compound may bear between one and three methyl substituents (fuchsin, new fuchsin). 

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. 

The earliest detectors of S02 in the atmosphere were automated calorimetric wet chemical devices. The reference technique for determining the SOz content of atmospheric air is based on the absorption of S02 from an air sample by a solution of sodium tetrachloromercurate, which, upon the addition of formaldehyde and a pararosaniline dye, forms a strong purple dye complex. Several manufacturers have automated this procedure. Properly maintained, these units provide an excellent record of S02 concentration in the air, because they operate on the basis of a chemical reaction that is specific for S02. 

Palmitic acid, 354 Paramagnetism. 17 Pararosaniline, 428 Pauli exclusion principle, 14 Peak areas in nmr, 241 Peak base in nmr, 248 Peak-splitting in nmr. 242 ... 

In the preparation of commercial fuchsine aniline is heated with a mixture of ortho and para toluidine. p-Toluidine is oxidized to the aminoaldehyde which condenses with one molecule of both aniline and o-toluidine to form homorosaniline hydrochloride- At the same time there is also formed pararosaniline hydrochloride owing to the reaction of two molecules of aniline with the aldehyde. The differences in the structure of leuco base, color base, and dye are shown by comparison of their respective formulas (1), (2), and (3). 

The synthesis of pararosaniline (from paranitrobenzaldehyde, c.) [14, 15, 17, 18] has until now not been carried out on a large scale, but it may be expected that in course of time the technical diflSculties which stand in the way of these processes will be overcome. Recently pararosaniline has been manufactured by a synthetic process based on the following lines. Anhydroform-iildehydeaniline, obtained by action of formaldehyde on aniline, is heated with aniline and aniline hydrochloride, whereby diamido-(liphenylmethane is formed. This latter compound, on heating with aniline, aniline hydrochloride, and an oxidising agent yields pararosaniline. 

An automated and microprocessor-controlled flow injection analysis system was developed for formaldehyde emission measurements. This system was based on the modified pararosaniline method and a sampling rate of about 40 samples/hour was obtained. 

The need for an automated and reliable system for formaldehyde determination is now clearly recognized. In response to this need, an automated and microprocessor-controlled flow injection analysis (FIA) system was developed in our laboratory. This system is based on the use of the modified pararosaniline colorimetric method (j6). The simplicity, versatility, good precision, high sampling rate, complete automation and relatively low cost of the system make it attractive for the analysis of large numbers of formaldehyde samples. In this chapter, sufficient background in the principle of FIA will be presented to allow the readers to evaluate the technique and its potential application to the routine analysis of formaldehyde will be explored. 

Procedure Formaldehyde sample from the sampler was injected into the carrier stream where it was mixed with pararosaniline and then sulfite to form an alkylsulfonic acid chromophore which can be monitored spectrophotometrically at 570 nm For calibration, standard formaldehydes were sequentially introduced after a stable baseline was obtained At least five consecutively reproducible peaks were recorded for each concentration After each study or each day of operation, the FIA system was cleaned to remove any pararosaniline film, alkylsulfonic acid colored product, or particulate matters This reduced the scattered light in the absorption cell and the staining of the tubing walls. The clean-up procedure was initiated by running distilled deionized water through the system for five minutes followed by another five minutes washing with 0 1 N nitric acid and then flushing the unit for 30 minutes with deionized water The chromotropic acid method was used for comparative studies, and the analytical procedure for the chromotropic acid method was based on the procedure recommended by the American Public Health Association (12) ... 

The CEA 555 continuous monitor(17) is used for real-time monitoring of chamber and actual field survey formaldehyde determinations. The monitor is a useful instrument in field surveys because it is one method that provides real time formaldehyde measurements which is useful in tracing and iden tifying usually high formaldehyde sources. The monitor s analytical method is based on the modified Schiff procedure developed by Lyles, Dowling and Blanchard (18). Formaldehyde is absorbed in a sodium tetrachloromercurate solution that contains a fixed quantity of sodium sulfite. Acid bleached pararosaniline is added, and the intensity of the resultant dye is measured at 500 nm. Both formaldehyde in air and liquid standards can be analyzed. 

A purple dye is formed from formaldehyde and pararosaniline in the presence of sodium sulfite (see Eq. 1). Miksch et al. (1981) postulated the formation of a colorless Schiff base from acidified pararosaniline and formaldehyde in the first step. Under acidic conditions this intermediate reacts with SO2 to form the chromophore. The strong absorbance at 570 nm is used for colorimetric detection. Other aldehydes such as acetaldehyde, acrolein and propanal interfere, but at pH < 1.0 the reaction is specific for formaldehyde. In the presence of atmospheric SOj a toxic Hg(II)-reagent is necessary for the elimination of sulfite formed fi-om SO2. Although the sensitivity of the modified pararosaniline method is limited and it is susceptible to interference, is has been one of the most widely used techniques for the determination of formaldehyde (VDI3484, Part 1 Roffael, 1993). 

The rosanilins are powerful triacid bases, are colorless, but combine with acids to form brilliantly colored salts. Fuchsine is industrially obtained from anilin oil, which contains both anilin and toluidin, neither of which in the pure state will produce a red color. The process consists essentially in heating the-oU with a mixture of nitro-benzene, hydrochloric acid and iron filings. The product is a mixture of the chlorids of rosanilin and pararosanilin, is in hard, green crystals, soluble in water and alcohol, to which it communicates a brilliant red color. 

It is believed that hydrochloric acid adds to one amino group, and that the elimination of water then takes place in such a way that a quinoid ring is formed. A change in the reverse direction occurs when an alkali is added to a salt of pararosaniline the salt is decomposed and the free base is formed. 

The triphenylmethane dyes are salts formed by the action of acids on certain derivatives of triphenylcarbinol. For this reason these derivatives are called color-bases, although they are, themselves, colorless. By reduction the color-bases are converted into the so-called leuco-bases which are formed as the result of the replacement of the hydroxyl group of the car-bionl by hydrogen. The leuco-bases may be oxidized to the color-bases. In the case of pararosaniline the bases have the following formulas —... 

Pararosaniline can be converted into triphenylmethane the color-base is reduced by zinc and hydrochloric acid to the leuco-base, triaimno-triphenylmethane, which in turn is con-... 

Rosaniline is the color-base of magenta. The hydrochloride of the base is generally called magenta or fuchsine, although the acetate is also used under these names. Rosaniline is manufactured by ojddizing a mixture of aniline, o-toluidine, and p-toluidine, with arsenic acid, mercuric nitrate, or nitrobenzene. The reaction is analogous to that which takes place in the preparation of pararosaniline, of which rosaniline is a methyl derivative with the structure indicated by the following formula —... 

Calcozine Magenta N Fuchsine DR 001 Fuchsine SP Fuchsine SPC Orient Para Magenta Base Parafuchsin Parafuchsine Pararosaniline Pararosaniline chloride Pararosaniline hydrochloride / -Fuchsin / -Fuchsine p-Rosaniline hydrochloride... 

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