Diphenylmethane-4-sulfonic acid

Hydrobenzyl alcohol groups as well as sulfonic acid groups on the carbon a to the aromatic rings of some of the phenylpropane units of the random polymer react in the presence of strong mineral acids with the aromatic nuclei of other phenylpropane units. This reaction, leading to diphenylmethanes, is of the same type as the formation of phenolic resins from phenol and formaldehyde. Lignin also reacts with formaldehyde and can be cross-linked by it in the same manner as that of synthetic polyphenohc resins. 

Arylalkanes and Arylalkenes (Table VIII, p. 181). Diphenylmethane is sulfonated exclusively in the para position rather than in the more hindered ortho position. The 4-sulfonic acid is prepared by treating diphenylmethane with chlorosulfonic acid in chloroform solution at 0 the 4,4 -disulfonic acid, by the action of oleum at 100 . 1,2-Diphenyl-ethane (bibenzyl) when heated with sulfuric acid " jdelds a mixture of a disulfonic acid (probably 4,4 ) and a tetrasulfonic acid. Oleum reacts with stilbene without affecting the olefinic linkage to 3deld a disulfonic acid of unknown structure. Triphenylmethane, sj/m-tetraphenyl-ethane, and tetraphenylethylene yield sulfonic acids containing one sulfo group for each benzene ring, probably in the para position. 

Diphenylmethane Base Method. In this method, the central carbon atom is derived from formaldehyde, which condenses with two moles of an arylamine to give a substituted diphenylmethane derivative. The methane base is oxidized with lead dioxide or manganese dioxide to the benzhydrol derivative. The reactive hydrols condense fairly easily with arylamines, sulfonated arylamines, and sulfonated naphthalenes. The resulting leuco base is oxidized in the presence of acid (Fig. 4). 

Kennedy and Stock reported the first use of Oxone for many common oxidation reactions such as formation of benzoic acid from toluene and of benzaldehyde, of ben-zophenone from diphenylmethane, of fratw-cyclohexanediol from cyclohexene, of acetone from 2-propanol, of hydroquinone from phenol, of s-caprolactone from cyclohexanone, of pyrocatechol from salicylaldehyde, of p-dinitrosobenzene from p-phenylenediamine, of phenylacetic acid from 2-phenethylamine, of dodecylsulfonic acid from dodecyl mercaptan, of diphenyl sulfone from diphenyl sulfide, of triphenylphosphine oxide from triphenylphosphine, of iodoxy benzene from iodobenzene, of benzyl chloride from toluene using NaCl and Oxone and bromination of 2-octene using KBr and Oxone126. Thus, they... 

Before coupling, excess nitrous acid must be destroyed. Nitrite can react with coupling components to form nitroso compounds causing deliterious effects on the final dyestuff. The presence of nitrite can be detected by 4,4,-diamino-diphenylmethane-2,2,-sulfone [10215-25-5] (Green reagent) or starch—iodide. Removal of nitrite is achieved by addition of sulfamic acid or urea [57-13-6], however, sulfamic acid [5329-14-6] has been more effective in kinetic studies of nine nitrous acid scavangers (18). 

Diphenylethane 22 is more reactive towards chlorosulfonic acid than diphenyl-methane 18, probably as a result of increased hyperconjugative electron release from the ethylene bridge bond. When diphenylethane 22 was heated with a large excess of chlorosulfonic acid (20 equivalents) at 100 °C (4 hours), the cyclized product 24 was isolated in excellent (90%) yield (Equation 8). The cyclization to the seven-membered ring sulfone 24 was more easily achieved than the analogous conversion of diphenylmethane 18 to the six-membered ring sulfone 21... 

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