Naphthalenesulfonic acids, hydrolysis

By the alkaline hydrolysis of the sultone formed on boiling an aqueous solution of the diazonium salt of S-amino-l-naphthalenesulfonic acid or its appropriate derivatives. 

By alkali fusion or alkaline hydrolysis under pressure of appropriate naphthalenedisulfonic or naphthalenetrisulfonic acid or hydroxynaphthalenedisulfonic acid f By alkaline hydrolysis of sulfone formed on boiling aqueous solution of diazonjum salt of S-arnino-l-naphthalenesulfonic acid or appropriate derivatives. 

The action of steam on a-naphthalenesulfonic acid similarly yields naphthalene. Practically all aromatic sulfonic acids may be hydrolyzed with mineral acids to the parent hydrocarbons, but each sulfonic acid requires a specific minimiim temperature. a-Naphthalenesulfonic acid hydrolyzes at a much lower temperature than the beta compound. However, the beta compound with fused caustic acts quite like the corresponding benzenesulfonic acid to give /3-naphthol, sodium sulfite, and water. Under certain conditions, steam may replace the more expensive fused caustic alkalies in the hydrolysis of aromatic sulfonates that are volatile with steam ... 

Acid-cataly2ed hydroxylation of naphthalene with 90% hydrogen peroxide gives either 1-naphthol or 2-naphthiol at a 98% yield, depending on the acidity of the system and the solvent used. In anhydrous hydrogen fluoride or 70% HF—30% pyridine solution at — 10 to + 20°C, 1-naphthol is the product formed in > 98% selectivity. In contrast, 2-naphthol is obtained in hydroxylation in super acid (HF—BF, HF—SbF, HF—TaF, FSO H—SbF ) solution at — 60 to — 78°C in > 98% selectivity (57). Of the three commercial methods of manufacture, the pressure hydrolysis of 1-naphthaleneamine with aqueous sulfuric acid at 180°C has been abandoned, at least in the United States. The caustic fusion of sodium 1-naphthalenesulfonate with 50 wt % aqueous sodium hydroxide at ca 290°C followed by the neutralization gives 1-naphthalenol in a ca 90% yield. 

Of-Naphthoic acid has been prepared by the hydrolysis of a-naphthyl cyanide and (in poor yield) by the fusion of sodium a-naphthalenesulfonate and sodium formate. It has also been prepared by passing carbamyl chloride into naphthalene and aluminum chloride and hydrolyzing the a-napthamide thus formed.3... 

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