1-Naphthol

Production

1-Naphthol is prepared by two main routes. In one method, naphthalene is nitrated to give 1-nitronaphthalene, which is hydrogenated to the amine followed by hydrolysis: : : :

Alternatively, naphthalene is hydrogenated to tetralin, which is oxidized to 1-tetralone, which undergoes dehydrogenation.

Reactions

Some reactions of 1-naphthol are explicable with reference to its tautomerism, which produces a small amount of the keto tautomer. :[[File:Alpha-naphthol tautomerism.svg|frameless|left|384px]] One consequence of this tautomerism is the Bucherer reaction: the ammonolysis of 1-naphthol to give 1-aminonaphthalene. Low temperature sulfonation of 1-naphthol gives 1-hydroxynaphthalene-2-sulfonic acid.

1-Naphthol biodegrades via formation of 1-naphthol-3,4-oxide, which converts to 1,4-naphthoquinone.

The 4-position of 1-naphthol is susceptible to electrophilic attack. This regioselective reaction is exploited in the preparation of diazo dyes, which are form using diazonium salts. Reduction of the diazo derivatives gives 4-amino-1-naphthol.

Partial reduction of 1-naphthol gives the tetrahydro derivative, leaving intact the phenol ring. Full hydrogenation is catalyzed by rhodium.

Applications and occurrence

1-Naphthol is a precursor to a variety of insecticides including carbaryl and pharmaceuticals including nadolol{{cite journal|surname1=M.E. Condon|display-authors=et al|journal=Journal of Medicinal Chemistry|title=Nondepressant β-adrenergic blocking agents. 1. Substituted 3-amino-1-(5,6,7,8-tetrahydro-1-naphthoxy)-2-propanols|volume=21|issue=9|pages=913–922|date=1978|language=German|doi=10.1021/jm00207a014

1-Naphthol is a metabolite of the insecticide carbaryl and naphthalene. Along with TCPy, it has been shown to decrease testosterone levels in adult men.

Other uses

1-Naphthol is used in each of the following chemical tests, which predate the use of spectroscopic and chromatographic methods:

• Molisch's test gives a red- or purple-colored compound to indicate the presence of carbohydrate.
• rapid furfural test turns purple quickly (
• Sakaguchi test turns red to indicate the presence of arginine in proteins.
• Voges–Proskauer test changes color from yellow to red to indicate that glucose is being broken down into acetoin which is used by bacteria for external energy storage.

Safety

1-Naphthol has been described as "moderately toxic".

References

References

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3. (2011). "The Chemical Biology of Naphthoquinones and Its Environmental Implications". [[Annual Review of Pharmacology and Toxicology]].
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5. Louis F. Fieser. (1937). "1,2-Aminonaphthol Hydrochloride". Organic Syntheses.
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7. (1971). "Hydrogenation of Aromatic Nuclei: 1-Decalol". Organic Syntheses.
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11. (1977). "Adrenergic agents. 4. Substituted phenoxypropanolamine derivatives as potential β-adrenergic agonists".
12. (January 2006). "Exposure to Nonpersistent Insecticides and Male Reproductive Hormones". [[Epidemiology (journal).