1-Naphthol, or α-naphthol, is a

fluorescent Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, ...

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

with the formula . It is a white solid. It is an isomer of 2-naphthol differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are naphthalene homologues of

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...

, with the hydroxyl group being more reactive than in the phenols. Both isomers are soluble in simple alcohols,

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...

s, and chloroform. They are precursors to a variety of useful compounds. Naphthols (both 1 and 2 isomers) are used as biomarkers for livestock and humans exposed to

polycyclic aromatic hydrocarbon A polycyclic aromatic hydrocarbon (PAH) is a class of organic compounds that is composed of multiple aromatic rings. The simplest representative is naphthalene, having two aromatic rings and the three-ring compounds anthracene and phenanthrene. ...

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 Tetralin (1,2,3,4-tetrahydronaphthalene) is a hydrocarbon having the chemical formula C10H12. It is a partially hydrogenated derivative of naphthalene. It is a colorless liquid that is used as a hydrogen-donor solvent. Production Tetralin is pro ...

, which is oxidized to

1-tetralone 1-Tetralone is a bicyclic aromatic hydrocarbon and a ketone. In terms of its structure, it can also be regarded as benzo-fused cyclohexanone. It is a colorless oil with a faint odor. It is used as starting material for agricultural and pharmace ...

, which undergoes

dehydrogenation In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...

Occurrence and degradation

1-Naphthol is a metabolite of the insecticide

carbaryl Carbaryl (1-naphthyl methylcarbamate) is a chemical in the carbamate family used chiefly as an insecticide. It is a white crystalline solid previously sold under the brand name Sevin, which was a trademark of the Bayer Company. The Sevin trademark ...

and naphthalene. Along with

TCPy TCPy or 3,5,6-trichloro-2-pyridinol is a cyclic hydrocarbon, specifically a chlorinated version of 2-pyridone. Pesticides can be a precursor to TCPy. TCPy is a metabolite of the herbicide triclopyr, and of the insecticides chlorpyrifos and chlorp ...

, it has been shown to decrease testosterone levels in adult men. It biodegrades via formation of 1-naphthol-3,4-oxide, which converts to 1,4-naphthoquinone.

Applications

1-Naphthol is a precursor to a variety of insecticides including

and pharmaceuticals including

nadolol Nadolol, sold under the brand name Corgard among others, is a medication used to treat high blood pressure, heart pain, atrial fibrillation, and some inherited arrhythmic syndromes. It has also been used to prevent migraine headaches and compl ...

as well as for the antidepressant

sertraline Sertraline, sold under the brand name Zoloft among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. The efficacy of sertraline for depression is similar to that of other antidepressants, and the differ ...

and the anti-protozoan therapeutic atovaquone. It undergoes

azo coupling In organic chemistry, an azo coupling is an organic reaction between a diazonium compound () and another aromatic compound that produces an azo compound (). In this electrophilic aromatic substitution reaction, the aryldiazonium cation is the ...

to give various azo dyes, but these are generally less useful than those derived from 2-naphthol.
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Other uses

1-Naphthol is used in each of the following chemical tests: *

Molisch's test Molisch's test is a sensitive chemical test, named after Austrian botanist Hans Molisch, for the presence of carbohydrates, based on the dehydration of the carbohydrate by sulfuric acid or hydrochloric acid to produce an aldehyde, which condenses ...

gives a red- or purple-colored compound to indicate the presence of

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...

. *

rapid furfural test The rapid furfural test is a chemical test used to distinguish between glucose and fructose. The rapid furfural test is similar to Molisch's test but uses concentrated hydrochloric acid instead of concentrated sulfuric acid and the solution is bo ...

turns purple quickly (<30s) if fructose is present, distinguishing it from glucose. * Sakaguchi test turns red to indicate the presence of arginine in proteins. *

Voges–Proskauer test Voges–Proskauer or VP is a test used to detect acetoin in a bacterial broth culture. The test is performed by adding alpha-naphthol and potassium hydroxide to the Voges-Proskauer broth, which is a glucose-phosphate broth that has been inoculat ...

changes color from yellow to red to indicate that

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

is being broken down into acetoin which is used by bacteria for external energy storage.

References

External links

NIST Chemistry WebBook 1-Naphthalenol
{{DEFAULTSORT:Naphthol, 1- 1-Naphthyl compounds