Rosaniline

SchifT s reagent A solution of rosaniline in water decolorized with sulphurous acid. Aliphatic aldehydes and aldose sugars give a magenta colour with this reagent with aromatic aldehydes and aliphatic ketones the colour develops more slowly aromatic ketones do not react. 

Schiff s Reagent. Dissolve 1 g. of rosaniline in 50 ml. of water with gentle warming. Cool, saturate with SO, add about i g. of animal charcoal, shake and filter make up to i litre with water. If the pink colour reappears on standing, add a few drops of SOj-water carefully with stirring until the colour Just disappears. 

Schiff s reagent is a dilute solution of fuchsin hydrochloride (p-rosaniline) that has been decolourised by sulphur dioxide. This decolourisation is the result of a... 

Preparation of SchlfT s reagent. Method 1. Dissolve 0- 2 g. of pure p.rosaniline hydrochloride in 20 ml. of a cold, freshly-prepared, saturated aqueous solution of sulphur dioxide allow the solution to stand for a few hours until it becomes colourless or pale yellow. Dilute the solution to 200 ml. and keep it in a tightly, stoppered bottle. If the bottle is not adequately stoppered, the reagent will gradually lose sulphur dioxide and the colour wUl return. The solution keeps well if not unnecessarily exposed to light and air. 

After adding p-rosaniline and formaldehyde, the colored solution was diluted to 25 ml in a volumetric flask. The absorbance was measured at 569 nm in a 1-cm cell, yielding a value of 0.485. A standard sample was prepared by substituting a 1.00-mL sample of a standard solution containing the equivalent of 15.00 ppm SO2 for the air sample. The absorbance of the standard was found to be 0.181. Report the concentration of SO2 in the air in parts per million. The density of air maybe taken as 1.18 g/L. 

Picric acid-rosaniline Picrocarmine Picrochromite Picrotin [21416-53-5]... 

A method suitable for analysis of sulfur dioxide in ambient air and sensitive to 0.003—5 ppm involves aspirating a measured air sample through a solution of potassium or sodium tetrachloromercurate, with the resultant formation of a dichlorosulfitomercurate. Ethylenediaminetetraacetic acid (EDTA) disodium salt is added to this solution to complex heavy metals which can interfere by oxidation of the sulfur dioxide. The sample is also treated with 0.6 wt % sulfamic acid to destroy any nitrite anions. Then the sample is treated with formaldehyde and specially purified acid-bleached rosaniline containing phosphoric acid to control pH. This reacts with the dichlorosulfitomercurate to form an intensely colored rosaniline—methanesulfonic acid. The pH of the solution is adjusted to 1.6 0.1 with phosphoric acid, and the absorbance is read spectrophotometricaHy at 548 nm (273). 

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. 

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

Note The color of the zones persists for a long period, but changes to blue-violet [1]. Rosaniline [1, 2] can be employed instead of fuchsin. With sugar alcohols lead(IV) acetate alone yields white zones on a brown background (detection limit 1 — 2 pg per chromatogram zone) [3]. 

Rosaniline or magenta was originally obtained by oxidising with arsenic acid a mixture of aniline with 0- and />-toluidine. The product was then lixiviated and treated with common salt, which converted the ai senate into the hydrochloride of rosaniline. Pararosaniline was prepared in a similar way fiom a niixtuie of aniline and /-toluidine. The series... 

Several examples of typical triarylmethane dyes have already been mentioned, in particular, pararosaniline (6.161), malachite green (6.162) its o-chloro derivative (6.169), crystal violet (6.164), rosaniline (6.165) and diphenylamine blue (6.173). Cl Basic Green 1 (6.168 R = C2H5), the ethyl analogue of malachite green, is prepared by the aldehyde route and is isolated as the sulphate. The ethyl analogue of crystal violet is Cl Basic Violet 4 (6.167 R = C2H5) and is obtained by the ketone route. 

The principle of forming the important inner salts of sulfonated triphenylmethane derivatives had thus been discovered. All of the commercially important products within this group are derived from phenylated rosaniline corresponding to the structure 121. 

Manipulation of the number of phenyl groups R1 to R3 on the rosaniline nucleus and their substitution pattern has proven a useful tool in producing a variety of commercially important derivatives. Currently, compounds with two (R1, R2 = C6H4CH3/C6H5 R3 = H) and especially three phenyl and/or toluene moieties (R1, R2, R3 = QH5/QH4CH3) are technically important. The CH3 groups are primarily located in m-position relative to the secondary amino group. 

The list of significant Alkali Blue type triarylcarbonium pigments includes compounds which are derived from diarylated and triarylated rosanilines. Table 33 shows triarylcarbonium pigments which are listed in the Colour Index. 

Schiff s reagent analy chem An aqueous solution of rosaniline and sulfurous add used in the Schiff test. shifs re,a-(3nt ... 

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