naphtholn.
/ˈnafθɒl/, /ˈnapθɒl/, U.S. /ˈnæpˌθɔl/, /ˈnæpˌθɑl/, /ˈnæfˌθɔl/, /ˈnæfˌθɑl/ Chemistry.
Either of two isomeric crystalline phenols, C10H7OH, which are derivatives of naphthalene and are used in the manufacture of antiseptics and certain dyes.The two isomers are respectively naphthalen-1-ol ( α-naphthol or 1-naphthol) and naphthalen-2-ol ( β-naphthol or 2-naphthol).
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1842 T. Graham Elements Chem. iii. iii. 847 Naphtol, C24H22; like naphtene, greatly resembles naphtha in its chemical properties.
1849 J. Craig New Universal Dict. at Naphtha Native naphtha is composed of three liquids, namely—naphtha.., naphthene.., and napthole.
1869 H. E. Roscoe Lessons Elem. Chem. (new ed.) xxxix. 393 On heating the aqueous solution of this body, a substance called naphthol, C10H8O, analogous to phenol, is formed.
1898 Amer. Naturalist 32 354 Such a substance is indicated in the normal root-tip by such changes as these:..strong violet reaction..in sections subjected to an aqueous solution of α-napthol.
1927 C. E. Mullin Acetate Silk (1928) xxx. 375 In applying the developed colors on cotton, the fiber is usually first padded in the naphthol bath and then the color developed in a second bath.
1960 F. G. Mann & B. C. Saunders Pract. Org. Chem. (ed. 4) ii. 218 Dissolve 10 g. of pure 2-naphthol in 30 ml. of 10% sodium hydroxide solution.
1963 A. J. Hall Student's Handbk. Textile Sci. iv. 181 A deep bright red shade developed in the fabric as the result of formation within the fibres of an insoluble pigment by coupling of the beta-naphthol with the diazotised para~nitraniline.
1981 P. Sykes Guidebk. to Mechanism in Org. Chem. (ed. 5) vi. 172 The formation of the Diels–Alder..adduct.., which undergoes ready acid-catalysed ring fission to yield the more familiar 1-naphthol.
1999 New Scientist 19 June 7/1 The alpha-naphthyl phosphate reacts with the enzyme acid phosphatase in the semen to produce alpha-naphthol.
Compounds
attributive. In the names of synthetic dyes derived from naphthols, as naphthol blue-black, naphthol green, naphthol yellow, etc.
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1889 Science 8 Nov. 309/1 Among these injurious substances are included..coloring-matters containing nitrous vapors, as naphthol yellow, victoria yellow.
1900 Kynoch Jrnl. 2 36/2 The use of picric acid as a dye has been superseded by the use of alizarine and naphtol yellows.
1922 J. J. Sudborough Bernthsen's Text-bk. Org. Chem. (new ed.) lv. 824 Other examples are:—Resorcin Brown = m-Xylidine → resorcinol ← sulphanilic acid. Naphthol Blue-black = p-Nitraniline → aminonaphtholdisulphonic acid H ← aniline.
1952 A. M. Smith Manures & Fertilisers vii. 174 To reduce the reflection of light and increase the heat absorbed and the rate of evaporation, a dyestuff (naphthol green is satisfactory) is added to the surface brine.
1991 Artist Nov. 16/1 Napthol red. Also called permanent red. Semi-transparent substitute for cadmiums/vermilion... Used mainly in oil, acrylic and alkyd paints.
1998 Internat. Jrnl. Plant Sci. 159 755 Controls for protein..were prepared..and then stained in mercuric bromophenol blue or in naphthol blue black.
This entry has been updated (OED Third Edition, June 2003; most recently modified version published online March 2022).
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