L-amino-2-naphthol hydrochloride

In the first experiment of this chapter the dye Orange II is reduced in aqueous solution with sodium hydrosulfite to water-soluble sodium sulfa-nilate and l-amino-2-naphthol (2), which precipitates. This intermediate is purified as the hydrochloride and oxidized to 1,2-naphthoquinone (3). 

Antioxidant. In the conversion of l-amino-2-naphthol or 4-amino-1-naphthol to the hydrochloride, or on recrystallization of such an air-sensitive hydrochloride, addition of a small amount of stannous chloride (2 g. per 0.5 mole) serves as an efficient antioxidant. ... 

Routes to benzoxadiazoles are based on approaches to the tautomeric 6-diazo-2,4-cyclo-hexadienones (Scheme 11) <9UST(247)135>. The appropriate 2-aminophenol hydrochloride is diazo-tized using either sodium nitrite or isoamyl nitrite and the diazonium chloride is then carefully neutralized with sodium carbonate or potassium carbonate. An alternative approach is from the monotosylhydrazone of the appropriate o-benzoquinone. Naphthoxadiazole (6) was prepared, in a manner analogous to the first route of Scheme 11, from 3-amino-2-naphthol <91AG(E)1476>. A slightly modified preparation is described in a later paper the method was applied to the synthesis of [9a- C]naphth[2,3-( ]-l,2,3-oxadiazole from 3-amino-[2- C]-2-naphthol <92Mi 403-03>. 

Amino-2-methyl-l-naphthol hydrochloride [130-24-5] M 209.6, m 283°(dec). Crystd from dilute HC1. 

Vitamin K5 (4-Amino-2-methyl-l-naphthol hydrochloride) [130-24-5] M 209.6, m 283"(dec), pKEst(i) 5.6 (NH2), pKj.jj(2) 10.4 (OH). Crystallise it from dilute HCl. [Sah Reel Trav Chim Pays-Bas 59 458 1941, Sah Reel Trav Chim Pays-Bas 60 373 1940, Veldstra Wiardi Reel Trav Chim Pays-Bas 61 547 1942, Veldstra Wiardi Reel Trav Chim Pays-Bas 62 75 1943, Beilstein 13 III 1921.]... 

Methyl-4-amino-l-naphthol hydrochloride (vitamin Ks), antibiotic properties of, VI, 36... 

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