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Home> Encyclopedia >   /  Heterocyclic compounds  /  Pharmaceutical Intermediates  /  Organic Intermediate  /  Dyestuff Intermediates  /  Agrochemical Intermediates
2-Naphthol structure
2-Naphthol structure


Iupac Name:naphthalen-2-ol
CAS No.:135-19-3
Molecular Weight:144.16992
Introduction: Has been used as antiseptic, anthelmintic and counter-irritant in alopecia. View more+
1. Names and Identifiers
1.1 Name
1.2 Synonyms

2-Hydroxynaphthalene 2-Naphthalenol 2-Napththol Betanaphthol B-HYDROXYNAPHTHALENE b-Naphthol b-Naphthyl alcohol c.i.37500 c.i.azoiccouplingcomponent1 c.i.developer5 Developer A Developer AMS Developer BN Developer NA developera developerams EINECS 205-182-7 Isonaphthol MFCD00004067 Microcidin naphthalen-2-ol Naphthol B Β-hydroxynaphthalene Β-Naphthol Β-Naphthyl alcohol

1.3 CAS No.
1.4 CID
1.6 Molecular Formula
C10H8O (isomer)
1.7 Inchi
1.8 InChkey
1.9 Canonical Smiles
1.10 Isomers Smiles
2. Properties
3.1 Density
3.1 Melting point
3.1 Boiling point
3.1 Refractive index
3.1 Flash Point
3.1 Vapour pressure
0.00162mmHg at 25°C
3.1 Precise Quality
3.1 PSA
3.1 logP
3.1 Solubility
methanol: soluble1g/10 mL, clear, colorless to light yellow
3.2 Λmax
226nm, 265nm, 275nm, 286nm, 320nm, 331nm
3.3 VaporDensity
4.97 (vs air)
3.4 Appearance
broken white shiny flakes or white powder
3.5 Atmospheric OH Rate Constant
1.70e-10 cm3/molecule*sec
3.6 Autoignition Temperature
550 °C
3.7 Chemical Properties
White lustrous leaflets or white powder. Insoluble in water, soluble in ethanol, ether, chloroform, glycerol, and alkaline solutions.
3.8 Color/Form
White, lustrious, bulky leaflets or white powder
3.9 HenrysLawConstant
2.74e-08 atm-m3/mole
3.10 Odor
Faint phenol-like odor
3.11 Odor Threshold
0.01 ppm - 11.4 ppm
3.12 pKa
9.51(at 25℃)
3.13 Water Solubility
1 g/L (20 oC)
3.14 Stability
Stable. Combustible. Dust may form explosive mixture with air. Incompatible with strong oxidizing agents, phenol.
3.15 StorageTemp
Store below +30°C.
3. Use and Manufacturing
4.1 Definition
ChEBI: A naphthol carrying a hydroxy group at position 2.
4.2 Fire Hazard
Noncombustible solid.
4.3 Potential Exposure
A potential danger to those involvedin rubber antioxidant production, synthesis of dyes; leatherprocessing; fungicides, pharmaceuticals, and perfumes.Used as an antioxidant for fats, oils; as an antiseptic; ininsecticides.
4.4 Purification Methods
Crystallise 2-naphthol from aqueous 25% EtOH (charcoal), H2O, *benzene, toluene or CCl4. Alternatively, extract it repeatedly with small amounts of EtOH, followed by dissolution in a minimum volume of EtOH and precipitation with distilled water, then drying over P2O5 under vacuum. It has also been dissolved in aqueous NaOH and precipitated by adding acid (repeat several times), then precipitated from *benzene by addition of heptane. Final purification can be by zone melting or sublimation in vacuo. The 4-nitrobenzoate has m 104o (from EtOH). [Bardez et al. J Phys Chem 89 5031 1985, Kikuchi et al. J Phys Chem 91 574 1987, Beilstein 6 IV 4253.]
4.5 Safety Profile
Poison by ingestion,inhalation, and subcutaneous routes.Mutation data reported. A skin and eyeirritant. Combustible when exposed to heator flame. To fight fire, use CO2, drychemical. Incompatible with antipyrine, camphor, phenol, ferric salts, menthol,potassium permanganate and otheroxidzing materials, urethane.
4.6 Shipping
UN2811 Toxic solids, organic, n.o.s., HazardClass: 6.1; Labels: 6.1-Poisonous materials, Technical NameRequired. UN3077 Environmentally hazardous substances,solid, n.o.s., Hazard Class: 9; Labels: 9-Miscellaneous hazardousmaterial, Technical Name Required.
4.7 Storage
Light Sensitive. Ambient temperatures.
4.8 Usage
Has been used as antiseptic, anthelmintic and counter-irritant in alopecia.
4.9 Waste Disposal
Mix with flammable solventand atomize into an incinerator. 2-Naphthol Preparation Products And Raw materials Raw materials
4. Safety and Handling
5.1 Symbol
GHS07, GHS09
5.1 Hazard Codes
5.1 Signal Word
5.1 Risk Statements
5.1 Safety Statements
5.1 Packing Group
5.1 Octanol/Water Partition Coefficient
Log Kow = 2.70
5.2 Hazard Class
5.2 Hazard Declaration
H302 + H332-H400
5.2 DisposalMethods
SRP: At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices.
UN 3077 9
5.3 FirePotential
Flammability potential is slight.
5.4 Caution Statement
5.4 Formulations/Preparations
Grade: Technical, sublimed, resublimed
5.5 Incompatibilities
Dust or powder may form explosivemixture with air. Incompatible with oxidizers (chlorates,nitrates, peroxides, permanganates, perchlorates, chlorine,bromine, fluorine, etc.); contact may cause fires or explosions.Keep away from alkaline materials, strong bases,strong acids, oxoacids, epoxides, iron salts; 2,3-dimethyl-1-phenyl-3-pyrazolin-5-one (antipyrine); camphor, phenol,menthol, urethane.
5.6 WGK Germany
5.6 Protective Equipment and Clothing
/2-Naphthol/ ... can produce ... eye irritation from a 1% solution.
5.7 Report

Reported in EPA TSCA Inventory. EPA Genetic Toxicology Program.

5.8 Skin, Eye, and Respiratory Irritations
/2-Naphthol/ ... can produce ... eye irritation from a 1% solution.
5.9 Safety

Hazard Codes:?HarmfulXn,?DangerousN
Risk Statements: 20/22-50?
R20/22:Harmful by inhalation and if swallowed.?
R50:Very toxic to aquatic organisms.
Safety Statements: 24/25-61?
S24/25:Avoid contact with skin and eyes.?
S61:Avoid release to the environment. Refer to special instructions / safety data sheets.
RIDADR: UN 3077 9/PG 3
WGK Germany: 2
RTECS: QL2975000
F: 8
HazardClass: 9
PackingGroup: III
HS Code: 29071590
Poison by ingestion, inhalation, and subcutaneous routes. Mutation data reported. A skin and eye irritant. Combustible when exposed to heat or flame. To fight fire, use CO2, dry chemical. Incompatible with antipyrine, camphor, phenol, ferric salts, menthol, potassium permanganate and other oxidizing materials, urethane.

5.10 Specification

?2-Naphthol?(CAS NO.135-19-3)?is also named as 2-Hydroxynaphthalene ; 2-Naftol ; 2-Naphthalenol ;?AI3-00081 ; Azogen developer A ; Betanaphthol ; C.I. 37500 ; C.I. Azoic Coupling Component 1 ; C.I. Developer 5 ; Caswell No. 590 ; Developer AMS ; Developer BN ; Developer sodium ; EINECS 205-182-7 ; EPA Pesticide Chemical Code 010301 ; HSDB 6812 ; Isonaphthol ; NAPHTHOL, BETA ; NSC 2044 ; Naphthol B ; UNII-P2Z71CIK5H ; beta-Hydroxynaphthalene ; beta-Monoxynaphthalene .?2-Naphthol (CAS NO.135-19-3) is broken white shiny flakes or white powder. It is?soluble in?ethanol, ether, chloroform, glycerol and alkaline solution, insolublr in water.

5.11 Toxicity
1. ???

skn-rbt 500?mg/24H MLD

??? BIOFX* ?? BIOFAX Industrial Bio-Test Laboratories, Inc., Data Sheets .(Northbrook, IL.:?)1973,26-4.
2. ???

eye-rbt 100?mg MOD

??? BIOFX* ?? BIOFAX Industrial Bio-Test Laboratories, Inc., Data Sheets .(Northbrook, IL.:?)1973,26-4.
3. ???

dnr-esc 2?mg/disc

??? MUREAV ?? Mutation Research. 97 (1982),1.
4. ???

dnr-bcs 5?g/L

??? MUREAV ?? Mutation Research. 42 (1977),19.
5. ???

orl-rat LD50:1960?mg/kg

??? GTPPAF ?? Gigiena Truda i Professionalnaya Patologiya v Estonskoi SSR. Labor Hygiene and Occupational Pathology in the Estonian SSR. 8 (1972),145.
6. ???

ihl-rat LC50:>20?mg/m3

??? GISAAA ?? Gigiena i Sanitariya 38 (10)(1973),15.
7. ???

scu-rat LDLo:2940?mg/kg

??? AEPPAE ?? Naunyn-Schmiedebergs Archiv fuer Experimentelle Pathologie und Pharmakologie. 186 (1937),195.
8. ???

orl-mus LDLo:100?mg/kg

??? HBAMAK ?? “Abdernaldens Handbuch der Biologischen Arbeitsmethoden.“ 4 (1935),1289.
9. ???

ipr-mus LD50:97,500?mg/kg

??? EJMCA5 ?? European Journal of Medicinal Chemistry. Chimie Therapeutique. 13 (1978),381.
10. ???

scu-mus LDLo:100?mg/kg


2.Hazard identification

2.1 Classification of the substance or mixture

Acute toxicity - Oral, Category 4

Acute toxicity - Inhalation, Category 4

Hazardous to the aquatic environment, short-term (Acute) - Category Acute 1

2.2 GHS label elements, including precautionary statements

Signal word


Hazard statement(s)

H302 Harmful if swallowed

H332 Harmful if inhaled

H400 Very toxic to aquatic life

Precautionary statement(s)

P264 Wash ... thoroughly after handling.

P270 Do not eat, drink or smoke when using this product.

P261 Avoid breathing dust/fume/gas/mist/vapours/spray.

P271 Use only outdoors or in a well-ventilated area.

P273 Avoid release to the environment.


P301+P312 IF SWALLOWED: Call a POISON CENTER/doctor/\u2026if you feel unwell.

P330 Rinse mouth.

P304+P340 IF INHALED: Remove person to fresh air and keep comfortable for breathing.

P312 Call a POISON CENTER/doctor/\u2026if you feel unwell.

P391 Collect spillage.




P501 Dispose of contents/container to ...

2.3 Other hazards which do not result in classification


9. Other Information
9.0 Merck
9.1 BRN
9.2 Chemical Properties
White lustrous leaflets or white powder. Insoluble in water, soluble in ethanol, ether, chloroform, glycerol, and alkaline solutions.
9.3 Application
  • It is used to produce Tobias acid, J acid, 2-hydroxy-3-naphthoic acid and azo dyes, and it is the raw material for rubber antioxidants, mineral dressing agents, fungicides, antiseptics, preservatives, etc.
  • As feed preservative. In China, it can be used for citrus preservation, the maximum dosage amount is 0.1 g/kg and the residue amount should be no more than 70 mg/kg.
  • 2-Naphthol, also called ?-naphthol, 2-naphthalenol, is the intermediate for plant growth regulator, 2-naphthoxyacetic acid.
  • As analytic agent, absorbent of ethylene and carbon monoxide, and fluorescence indicator.
  • Important organic raw material and dye intermediate, used to produce Tobias acid, butyric acid, β-hydroxynaphthoic acid and used to produce N-phenyl-2-naphthylamine, Diafen NN and other antioxidant, organic pigments, and fungicides.
  • For the detection of bromine, chlorine, chlorate, niobium, copper, nitrite, and potassium. Substrate for fluorometric assay of phenol sulfotransferase. Acid and alkali indicator, dyes, organic synthesis, qualitative determination of allyl alcohol, methanol, chloroform, etc. Absorbent of carbon monoxide, ethanol, and fluorescence indicator. Determination of carbon monoxide, copper, nitrite, and potassium. Ethylene absorbent.
9.4 Preparation
(1) Sulfonation alkali melting method
Obtained by sulfonation of naphthalene and alkali melting. Sulfonation alkali melting 2-naphthol synthesis process is widely used in both domestic and foreign production, but it is with serious corrosion, high cost, large amount of waste water and high biological oxygen consumption. American Cyanamid Company developed 2-isopropyl-naphthalene method with naphthalene and propylene as the raw materials, which produces 2-naphthol and with byproduct acetone. This method is similar to Cumene process to produce phenol. The consumed amount of raw materials: 1170 kg/t refined naphthalene, 1080 kg/t sulfuric acid, 700 kg/t sodium hydroxide (caustic soda).
Details: Refined naphthalene was put into the sulfonation kettle and heated up to 140°C (melting). Sulfuric acid (sulfuric acid/refined naphthalene (mol/mol=1.8) was added within 20 minutes. The temperature was raised up to 160-164°C and kept for 2.5 h. The reaction was terminated when the content of 2-naphthalenesulfonic acid is above 66% and the total acidity is 25%-27%. The sulfonates were hydrolyzed for 1 h at 140-150°C inside a hydrolysis kettle. Following neutralization at 80-90°C with sodium nitrite solution was performed until the Congo red test paper was no more blue. Steam and air were used to remove SO2 gas. When the temperature was cooled down to 30-40°C, vacuum filtration was applied. After washing with salt water (10%) and following vacuum filtration, 2-naphthalenesulfonic acid sodium salt was obtained.
Sodium hydroxide was put into an alkali melting kettle and heated to 290°C (melting). At about 3 hours 2-naphthalenesulfonic acid sodium salt was added until the freebase content was 5%-6%. Afterwards, the temperature was kept at 320-330°C for 1 hour. The alkali melt was diluted with water and SO2 gas was passed at 70-80°C until phenolphthalein did not show any color. Addition of water to boil and wash, sodium sulfite was removed, dehydration and then under reduced pressure to distill the final product. The total yield is 73%-74%.
(2) 2-isopropyl-naphthalene method.
With naphthalene and ethylene as the raw materials to produce 2-naphthaol with byproduct acetone.
Details: Sulfuric acid was added into the melted naphthalene at 140℃ and the sulfonation was carried out at 162-164°C. The sulfonates were hydrolyzed, the free naphthalene was blown away and sodium sulfite was added to react and generate 2-naphthalenesulfonic acid sodium salt. This salt together with sodium hydroxide were alkali melted at 285-320°C and kept at 320-330°C for 1 hour. After the dilution of this alkali melt, acidification with SO2 gas was performed to obtain crude products. Followed washing, dehydration and distillation were carried out to obtain the final products.
9.5 Chemical Properties
white or off-white powder with a slight
9.6 Chemical Properties
2-Naphthol is a white, crystalline solid. Slight phenolic odor. Darkens in air and on exposure to light.
9.7 Uses
Has been used as antiseptic, anthelmintic and counter-irritant in alopecia.
9.8 Uses
anthelmintic, antiseptic
9.9 Uses
2-Naphthol is used in the manufacture of dyes, perfumes, and medicinal organics, and in the production of antioxidants for synthetic rubber.
9.10 Preparation
products were made Naphthalen-2-ol, and sodium hydroxide melting, finally using hydrochloric acid or carbon dioxide exhalation.
9.11 Definition
ChEBI: A naphthol carrying a hydroxy group at position 2.
9.12 Synthesis Reference(s)
Journal of the American Chemical Society, 72, p. 4884, 1950 DOI: 10.1021/ja01167a009
Synthesis, p. 437, 1985 DOI: 10.1055/s-1985-31235
9.13 General Description
2-Naphthol (2OH) is a hydroxyarene molecule, which when electronically excited forms strong acid. Excited 2OH dissociates only in water. It has a slight phenolic odor. It is incompatible with strong oxidizing agents, strong bases, acid chlorides and acid anhydrides. It is one of the most commonly used fluorescence dye.
9.14 Usage
2-Naphthol can be used as a fluorescent indicator. It can be also used in the production of dyes and in organic synthesis.
10. Computational chemical data
  • Molecular Weight:144.16992g/mol
  • Molecular Formula:C10H8O
  • Compound Is Canonicalized:True
  • XLogP3-AA:
  • Exact Mass:144.057514874
  • Monoisotopic Mass:144.057514874
  • Complexity:133
  • Rotatable Bond Count:0
  • Hydrogen Bond Donor Count:1
  • Hydrogen Bond Acceptor Count:1
  • Topological Polar Surface Area:20.2
  • Heavy Atom Count:11
  • Defined Atom Stereocenter Count:0
  • Undefined Atom Stereocenter Count:0
  • Defined Bond Stereocenter Count:0
  • Undefined Bond Stereocenter Count:0
  • Isotope Atom Count:0
  • Covalently-Bonded Unit Count:1
11. Question & Answer
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