Nitrotoluene sulfonic acid

Self-condensation products of 4-nitrotoluene-2-sulfonic acid or its derivative 4,4 -dinitto-2,2 -stilbenedisulfonic acid or 4,4 -dinitto-2,2 -dibenzyldisulfonic acid [728-42-7] and products of their treatment with teduciag or oxidizing agents. An example is Direct Yellow 11 (Cl... 

Condensation dyes from 4-nitrotoluene-2-sulfonic acid are the most important of the stilbene dyes. Direct YeUow 11 (Cl 40000), discovered in 1883 and commonly known as Sun YeUow [1325-37-7] is widely used in the paper industry (2,4). 

This controUed synthesis gives a purer product than alkaline condensation of 4-nitrotoluene-2-sulfonic acid alone and is the reason for its brightness (4). 

Solutions of 4-nitrotoluene in 93% sulfuric acid decompose very violently if heated to 160°C. This happened on plant-scale when automatic temperature control failed [1], but the temperature was erroneously abstracted as 135°C [2], The explosion temperature of 160°C for the mixture (presumably containing a high proportion of 4-nitrotoluene-2-sulfonic acid) is 22°C lower than that observed for onset of decomposition when 4-nitrotoluene and 93% sulfuric acid are heated at a rate of 100°C/h [3], Mixtures of 4-nitrotoluene with 98% acid or 20% oleum begin to decompose at 180 and 190°C, respectively [3,4], Thereafter, decomposition accelerates (190-224° in 14 min, 224-270 in 1.5 min) until eruption occurs with evolution of much gas [4],... 

Stilbene dyes contain the stilbene structural moiety (C6H5C=CC6H5) but are synthesized from 4- nitrotoluene-2-sulfonic acid. Direct yellow stilbene dyes for dyeing paper are probably the most commercially important. 

Walther obtained the first direct dyes by self-condensation of 4-nitrotoluene-2-sulfonic acid. So-called Sun Yellow is a mixture of different components, depending on the concentration of sodium hydroxide, the temperature, and the duration of the reaction. Oxidation of the intermediate dye and subsequent reduction with iron and hydrochloric acid gives 4,4 diaminostilbene-2,2 -disulfonic acid, which is used for fluorescent whitening agents and azo dyes. The shades are mostly yellow to red. The structure of Direct Yellow 11, 40000 [65150-80-3] (13 is one of the main components) probably contains a mixture of stilbene, azo, and/or azoxy groups. 

The starting compound for all triazinylaminostilbenes is 4,4 -dinitrostilbene-2,2 -disulfonic acid [128-42-7], which is obtained by oxidizing 4-nitrotoluene-2-sulfonic acid with aqueous sodium hypochlorite in the presence of sodium hydroxide or, more recently, by atmospheric oxidation in an aqueous ammoniacal medium [39], The Bechamps reduction using iron filings etched with hydrochloric acid yields 4,4 -diaminostilbene-2,2 -disulfonic acid [81-11-8] (DAS). 

Condensation ofNitro Compounds. The stflbene dyes derived from condensation of 4-nitrotoluene-2-sulfonic acid [121-03-9] (para acid) in aqueous caustic solution either alone or with aryl amines, are mixtures of dyes containing azo and azoxy groups with indefinite structures. The primary products are 4,4,-dinitro-2>2,-stilbenedisulfonic acid [128 42-7] and 4,4,dinitrodibenzyl-2>2,-disulfonic acid [6404-60-0] which condense further to form the dye. The properties of the stilbene dyes vary with the amounts and concentrations of the reactants and with the time and temperature of heating. The hue... 

Condensation products of 4-nitrotoluene-2-sulfonic acid or its derivatives together with phenols, naphthols, or aminophenols. An example here is Direct Yellow 19 (Cl 40030) (3) ... 

Nitrotoluene is used mainly in the manufacture of pure 2,4-toluene diisocyanate. The second most important product is 4-nitrotoluene-2-sulfonic acid, obtained by sulfonation, which is converted into 4,4 -dinitrostilbene-2,2 -disulfonic acid (DNSDSA) by oxidation with sodium hypochlorite. The reduction of DNSDSA yields the corresponding amino-compound (DASDSA), which is used in the manufacture of optical brighteners and dyes. 

In addition, 4-nitrotoluene-2-sulfonic acid is used as a raw material in the production of dyes. 

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