Nitronaphthalene Sulphonic

Nitration [63], unlike sulphonation, is not reversible and results very largely in a substitution, yielding 1-nitronaphthalene (4.27). 

Nitration of naphthalene-1-sulphonic acid produces two isomeric nitronaphthalenes that have very similar solubilities. It is convenient to reduce the mixture without separation, giving a mixture of l-naphthylamine-8-sulphonic acid (4-44 Peri acid) and 1-naphthylamine-5-sulphonic acid (4.45 Laurent s acid), as in Scheme 4-29. These two... 

On nitration of a-naphthalene-snlphonic acid, or on sulphonation of a-nitronaphthalene, a mixture of two acids is formed. These are separated by taking advantage of the different solubilities of their sodium salts in water. 

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