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2-Naphthol

2-Naphthol, also known as β-naphthol, is a polycyclic aromatic compound with the molecular formula C₁₀H₈O and a molecular weight of 144.17 g/mol. It consists of a naphthalene ring system substituted with a hydroxyl group at the 2-position, making it an isomer of 1-naphthol. This white to yellowish crystalline solid has a melting point of 121.6–123 °C and a boiling point of 285 °C, with limited solubility in water (approximately 755 mg/L at 25 °C) but good solubility in organic solvents such as alcohol, ether, and chloroform.^[1] As a versatile intermediate in organic synthesis, 2-naphthol is widely used in the production of dyes and pigments, particularly azo dyes for textiles and printing, due to its ability to couple with diazonium salts. It also serves as a precursor in pharmaceuticals, including the synthesis of drugs like tolnaftate (an antifungal), nafcillin (an antibiotic), and naproxen (an anti-inflammatory). Additional applications include antioxidants for polymers, antiseptics, fungicides, and insecticides. Industrially, it is produced via the caustic fusion of naphthalene-2-sulfonic acid with sodium hydroxide, a process that hydrolyzes the sulfonic acid group to yield the phenolic product.^[1] Despite its utility, 2-naphthol poses health and environmental risks; it is harmful if swallowed or inhaled, acts as a skin and eye irritant, and is highly toxic to aquatic life, necessitating careful handling and regulatory compliance in its use. It can cause allergic sensitization and is monitored as a biomarker of exposure in biological fluids like urine.^[1]

Properties

Physical properties

2-Naphthol is a colorless to pale yellow crystalline solid with a slight phenolic odor that darkens upon exposure to air or light.^[1] It has a molecular weight of 144.17 g/mol.^[1] The compound melts at 121–123 °C and boils at 285 °C under standard atmospheric pressure.^[1] Its density is 1.280 g/cm³ at 20 °C.^[1] The vapor pressure of 2-naphthol is approximately 0.015 mmHg (2 Pa) at 25 °C.^[1] In terms of solubility, it is sparingly soluble in water at 0.74 g/L (20 °C) but highly soluble in organic solvents, including up to 400 g/L in ethanol, as well as in diethyl ether, chloroform, and acetone.^[2]^[1]

Chemical properties

2-Naphthol exhibits moderate acidity, with a pKa value of 9.51 at 25 °C, rendering it a stronger acid than phenol, which has a pKa of 9.99.^[1] This increased acidity arises from the enhanced resonance stabilization of the conjugate base, the 2-naphtholate ion, where the negative charge is delocalized across the extended π-system of the naphthalene ring, providing additional resonance structures compared to the phenolate ion. The compound undergoes minimal keto-enol tautomerism, with the enol form (aromatic 2-naphthol) overwhelmingly predominant at greater than 99% in most conditions, while the keto form (2-tetralone) becomes detectable only in trace amounts in polar solvents due to solvent stabilization effects. 2-Naphthol also possesses notable fluorescent properties, emitting blue-violet light at approximately 354 nm when excited by UV light at 331 nm, a characteristic attributable to the conjugated naphthalene ring system that facilitates efficient π-π* transitions.^[3] In terms of stability, 2-naphthol is chemically stable under standard ambient conditions but can undergo slow oxidation in air, leading to discoloration, particularly in the presence of oxygen at neutral pH.^[4] Additionally, it is sensitive to light exposure, which can induce discoloration over time through photochemical degradation pathways.^[5] The electronic structure of 2-naphthol features a fully aromatic naphthalene core with the hydroxyl substituent at the 2-position, which increases electron density on the ring, rendering the hydroxyl group strongly activating and ortho/para-directing in electrophilic aromatic substitution reactions.

Occurrence and production

Natural occurrence

2-Naphthol occurs rarely in nature, primarily as a trace component in certain plant materials. It was isolated from the leaves of the tropical plant Actephila merrilliana (family Opiliaceae), marking its identification as a natural product in 2023. In this species, 2-naphthol exhibits nematicidal activity against the root-knot nematode Meloidogyne incognita, achieving 100% mortality at a concentration of 100 μg/mL with an EC₅₀ value of 38.00 μg/mL; it inhibits egg hatching and nematode penetration into tomato roots in both pot and field experiments.^[6] This compound is considered a potential secondary metabolite involved in plant defense mechanisms, particularly against soil-borne pathogens like nematodes, though its concentrations in plant tissues are typically low. Additionally, 2-naphthol has been detected in trace amounts in emissions from various tree species, including red oak (Quercus rubra), paper birch (Betula papyrifera), and white pine (Pinus strobus), suggesting a minor role in natural volatile organic compound profiles.^[1] While 2-naphthol is absent from common food sources, it is detectable as a urinary metabolite in humans resulting from exposure to naphthalene, a polycyclic aromatic hydrocarbon found in mothballs, cigarette smoke, and industrial emissions; it is often measured alongside 1-naphthol as a biomarker for such exposure.^[7]^[8]

Industrial production

The primary industrial production of 2-naphthol involves the sulfonation of naphthalene with fuming sulfuric acid at 160–180 °C to form 2-naphthalenesulfonic acid, followed by caustic fusion of its sodium salt with sodium hydroxide at approximately 300 °C to yield the sodium salt of 2-naphthol, and subsequent acidification with hydrochloric acid to isolate the product.^[1] The key caustic fusion step proceeds according to the equation:

\mathrm{C_{10}H_7SO_3Na + 2 NaOH \rightarrow C_{10}H_7ONa + Na_2SO_3 + H_2O}

followed by acidification:

\mathrm{C_{10}H_7ONa + HCl \rightarrow C_{10}H_7OH + NaCl}

This process achieves an overall yield of approximately 80%.^[1] The global market value for 2-naphthol was approximately $240 million as of 2024, with production concentrated primarily in China and India. China's annual production capacity exceeds 150,000 tons, though actual output is lower and constrained by market demand.^[9]^[10] The crude product is purified by recrystallization from water or distillation under reduced pressure to attain purity levels exceeding 98%.

Applications

Dyes and pigments

2-Naphthol serves as a key coupling component in the synthesis of azo dyes, where it reacts with diazonium salts derived from aromatic amines to form brightly colored azo compounds.^[11] This reaction is fundamental to producing insoluble azo dyes directly on fabric substrates, particularly in the Naphthol AS series, which includes derivatives such as 2-naphthol anilide.^[12] These dyes are valued for their application in textile coloration, yielding vibrant hues with enhanced substantivity to fibers like cotton. Specific examples of dyes produced using 2-naphthol include β-naphthol orange (also known as Acid Orange 7), formed by coupling diazotized sulfanilic acid with 2-naphthol, Ponceau 4R (Acid Red 18), which incorporates a sulfonated 2-naphthol structure for red shades, and various Hansa-type azo pigments where naphthol derivatives contribute to yellow tonalities.^[13]^[14] These applications account for a substantial portion of 2-naphthol consumption, estimated at around 70% in major azo dye formulations.^[15] In the dyeing process, 2-naphthol or its derivatives are applied to cotton fabrics as soluble naphtholates in alkaline baths, followed by treatment with diazonium salts to effect in situ coupling and form the insoluble dye on the fiber.^[16] This method produces bright reds and oranges with excellent light and wash fastness properties, making it suitable for durable textile colorations.^[17] Approximately 70% of industrial 2-naphthol is utilized in the dyes and pigments sector, with global production volumes approximately 40,000 metric tons per year as of 2025, supporting pigment applications for paints and inks via β-naphthol derivatives.^[15]^[9] Compared to aniline-based couplers, 2-naphthol enhances dye solubility in alkaline conditions and delivers superior color intensity and brilliance in the red-orange spectrum.^[18] The global market for 2-naphthol was valued at approximately US$240 million in 2025.^[9]

Pharmaceuticals and other uses

2-Naphthol serves as a key intermediate in the synthesis of various pharmaceuticals, including antioxidants that protect against oxidative stress and antiseptics for topical applications. It has been historically utilized as an antiseptic in the treatment of scabies, applied in forms such as ointments to combat mite infestations.^[1]^[19] Derivatives of 2-naphthol demonstrate potent anti-inflammatory activity by inhibiting 5-lipoxygenase, offering potential for localized skin treatments with minimal systemic absorption.^[20]^[21] Recent developments, including studies up to 2023, have identified 2-naphthol itself as exhibiting strong nematicidal activity against root-knot nematodes like Meloidogyne incognita, with 100% efficacy at 100 μg/mL and an EC₅₀ of 38 μg/mL, inspiring derivatives from natural plant analogs for agricultural and potential therapeutic uses.^[22] In agrochemicals, 2-naphthol functions as a precursor for the production of fungicides and insecticides, contributing to crop protection formulations.^[15] Its role in these sectors represents a notable portion of non-dye applications, supporting the development of active ingredients that enhance pest resistance in agriculture. Other uses of 2-naphthol extend to perfumes, where it acts as a fixative to stabilize fragrances, and to materials science as an antioxidant in rubber and polymers to prevent degradation from environmental exposure.^[1]^[23] It also finds trace application as a reagent in analytical chemistry for detection and quantification processes.^[24] Emerging applications in 2025 highlight 2-naphthol's versatility in advanced technologies, including its incorporation into sensors for heavy metal detection, such as azo dye derivatives based on 2-naphthol-aniline for selective Hg²⁺ recognition through fluorescence quenching mechanisms.^[25] Additionally, 2-naphthol is a foundational precursor for BINOL (1,1'-bi-2-naphthol) derivatives, widely adopted as chiral ligands in transition-metal-catalyzed asymmetric synthesis to produce enantiomerically pure compounds for pharmaceuticals and fine chemicals.^[26] Non-dye sectors, including pharmaceuticals and agrochemicals, represent a significant share of global 2-naphthol production, with pharmaceutical demand projected to rise at approximately 5% annually amid growing needs for specialized intermediates.^[27]

Chemical reactions

Electrophilic substitutions

2-Naphthol undergoes electrophilic aromatic substitution (EAS) reactions with high reactivity due to the activating hydroxyl group at position 2, which donates electrons to the naphthalene ring system. The preferred site of substitution is position 1 (the alpha position adjacent to the OH group), as it benefits from both the ortho-directing effect of the hydroxyl and the inherent higher reactivity of the alpha position in naphthalene. Position 3 (also ortho to OH) is less favored due to steric and electronic factors in the fused ring structure. Sulfonation of 2-naphthol typically occurs at position 1, yielding 1-sulfo-2-naphthol as the primary product under kinetic control.^[28] For example, reaction with 1 equivalent of SO₃ in acetonitrile at room temperature gives an 85:15 mixture favoring the 1-sulfonated isomer over the 8-sulfonated (peri) product.^[28] With excess SO₃, polysulfonation shifts selectivity toward other positions, such as 8.^[28] Halogenation proceeds selectively at position 1. Bromination using Br₂ in acetic acid affords 1-bromo-2-naphthol, as shown in the equation:

\mathrm{C_{10}H_7OH + Br_2 \rightarrow C_{10}H_6BrOH + HBr}

This reaction occurs under mild conditions (e.g., room temperature) and provides high yields of the monobrominated product when Br₂ is controlled. Excess bromine can lead to dibromination at positions 1 and 6.^[29] Nitration also targets position 1, producing 1-nitro-2-naphthol, but the free phenol often undergoes polysubstitution or oxidation due to its high reactivity. To achieve selectivity, the hydroxyl group is typically protected, such as by ethylation to form β-naphthyl ethyl ether, which is then nitrated with HNO₃/H₂SO₄ at 0–5°C, followed by deprotection via hydrolysis. Friedel-Crafts acylation occurs at position 1, for example, acetylation with acetyl chloride and AlCl₃ yields 1-acetyl-2-naphthol. However, this reaction is less common for unprotected 2-naphthol because the hydroxyl group coordinates strongly with the Lewis acid catalyst, deactivating the ring and complicating the process. Protection strategies, such as forming the acetate ester, are often employed to enable clean substitution.

Coupling and oxidation reactions

2-Naphthol acts as a nucleophile in azo coupling reactions with aryldiazonium salts under alkaline conditions, where electrophilic attack occurs preferentially at the 1-position due to enhanced electron density from the deprotonated hydroxyl group. The general reaction proceeds as follows:

\ce{ArN2+ + C10H7OH ->[alkaline] ArN=NC10H6OH + H+}

The resulting 1-arylazo-2-naphthols exhibit extended conjugation, making them essential precursors for azo dyes with vibrant colors and high stability.^[30] Oxidation of 2-naphthol transforms the phenolic moiety into a quinone, yielding 1,2-naphthoquinone through dehydrogenation. Traditional methods employ chromic acid oxidants, such as nicotinium dichromate in aqueous acetic acid, where the reaction follows first-order kinetics in both substrate and oxidant, proceeding via chromate ester formation and subsequent electron transfer. The simplified equation is:

\ce{C10H7OH + [O] -> C10H6O2 + H2O}

Yields typically exceed 80% under controlled conditions, with the product serving as an intermediate in organic synthesis. Catalytic aerobic oxidation using molecular oxygen and metal catalysts, such as vanadium or tungsten complexes, offers a greener alternative, though selectivity for the 1,2-isomer requires precise control to avoid over-oxidation to dicarboxylic acids.^[31] In the Mannich reaction, 2-naphthol condenses with formaldehyde and secondary amines to form 1-(aminomethyl)-2-naphthol derivatives, often termed β-(aminomethyl)-2-naphthols, via electrophilic attack at the 1-position activated by the ortho-hydroxy group. This multicomponent process generates aminomethylated products with high efficiency in acidic or neutral media, bypassing iminium ion isolation. These compounds exhibit pharmaceutical utility, including antibacterial activity against Gram-positive and Gram-negative strains, with minimum inhibitory concentrations as low as 12.5 μg/mL for select derivatives. The reaction's versatility extends to library synthesis for drug discovery, emphasizing its role in accessing bioactive scaffolds.^[32]^[33] Recent advancements include halogenative dearomatization of 2-naphthol using N-halosuccinimides (NXS, where X = Cl or Br) in water, enabling direct introduction of halogens at the 1-position without metal catalysts or organic solvents. This room-temperature process yields 1-halo-2-naphthols or related dearomatized intermediates in up to 95% yield, which can be further cyclized to spirocyclic compounds like spiroisoxazolidines via annulation with nitroolefins. The method's environmental benefits stem from water as the medium and succinimide byproduct recyclability, highlighting its potential for sustainable synthesis of complex spiro architectures used in medicinal chemistry. Enantioselective variants of these couplings employ BINAP-ligated transition metal catalysts, such as rhodium or palladium complexes, to access atropisomeric or chiral products with enantiomeric excesses exceeding 90%, particularly in oxidative cross-couplings leading to non-racemic binaphthol derivatives.^[34]^[35]

Safety and environmental impact

Health hazards

2-Naphthol is harmful if swallowed or inhaled, with an acute oral LD50 of 1320 mg/kg body weight in rats and an inhalation LC50 greater than 770 mg/m³ over 1 hour in rats, indicating moderate toxicity via these routes.^[15]^[1] Dermal absorption is possible but less toxic, with an LD50 exceeding 10,000 mg/kg in rats and rabbits.^[15] Acute exposure causes irritation to the skin, eyes, and respiratory tract, leading to symptoms such as redness, pain, blurred vision, cough, sore throat, nausea, vomiting, diarrhea, abdominal pain, and in severe cases, renal damage, syncope, convulsions, and hemolytic anemia.^[1] Chronic exposure to 2-naphthol can result in skin sensitization and allergic dermatitis, as demonstrated in guinea pig maximization tests and human patch tests showing positive reactions in sensitized individuals.^[15] Prolonged contact may also lead to kidney impairment and anemia, while ocular effects include lens opacities and potential vision impairment.^[1] High occupational exposures have been linked to oxidative stress, with urinary 2-naphthol levels serving as a biomarker; a 2018 study found associations between low-level urinary 2-naphthol and elevated oxidative stress markers in children, increasing risks for allergic disorders. Genotoxicity studies, including Ames tests and in vivo micronucleus assays, indicate that 2-naphthol is not mutagenic.^[15] Regarding carcinogenicity, the International Agency for Research on Cancer (IARC) has not classified 2-naphthol, placing it in Group 3 (not classifiable as to its carcinogenicity to humans) due to inadequate data.^[1] Occupational exposure limits for 2-naphthol are not specifically defined by OSHA, though related naphthol compounds are monitored under general dust limits; symptoms of overexposure include headache, cyanosis from hemolytic effects, and anemia. Historically, 2-naphthol was used as an antiseptic for scabies treatment, a counterirritant for alopecia, and an anthelmintic, but these applications are now avoided due to risks of systemic toxicity, including vomiting and death from extensive dermal use.^[1]

Environmental considerations

2-Naphthol exhibits moderate persistence in the environment, being readily biodegradable under aerobic conditions, with approximately 68% degradation observed after 14 days in standard tests.^[15] Although specific half-life data in soil are limited, its biodegradation profile suggests a degradation timeframe of several days to weeks under favorable aerobic conditions, similar to related aromatic compounds. The compound has an octanol-water partition coefficient (log Kow) of 2.01 to 2.84, indicating moderate hydrophobicity and limited potential for significant bioaccumulation in aquatic organisms, though uptake can occur in lipid-rich tissues.^[15] Ecotoxicity assessments reveal 2-naphthol as harmful to aquatic life, with acute toxicity values including a 96-hour LC50 of 3.46 mg/L for fathead minnows (Pimephales promelas), a 48-hour EC50 of 0.85 mg/L for the amphipod (Gammarus minus), and a 4-hour EC50 of 6.3 mg/L for the diatom (Nitzschia palea).^[15] These levels underscore its risk to fish, invertebrates, and algae, particularly in dye manufacturing effluents where it contributes to broader pollution from azo compounds and intermediates.^[36] The predicted no-effect concentration (PNEC) for aquatic ecosystems is 0.85 μg/L, reflecting the need for stringent controls to prevent ecosystem disruption.^[15] Regulatory frameworks address 2-naphthol's environmental risks due to its aquatic toxicity. In the European Union, it is registered under REACH (EC 205-125-9), with ongoing evaluation for releases into water, though not currently listed as a substance of very high concern (SVHC).^[37] In the United States, it is listed as an active chemical under the Toxic Substances Control Act (TSCA), subjecting it to reporting requirements for environmental exposure.^[1] Wastewater discharge limits for industrial effluents containing phenols like 2-naphthol are typically below 1 mg/L in many jurisdictions to safeguard aquatic systems, often enforced through permits under the Clean Water Act.^[38] Mitigation strategies for 2-naphthol in industrial effluents primarily involve adsorption using modified bentonites or activated carbons, achieving removal efficiencies up to 90% under optimized conditions, and advanced oxidation processes like electro-Fenton, which degrade it via hydroxyl radicals with near-complete mineralization.^[39]^[40] Recent studies highlight its adsorption onto microplastics, such as high-density polyethylene, facilitating long-range transport in oceanic environments and amplifying exposure risks through vector-mediated dispersal.^[41] The dye industry contributes substantially to 2-naphthol releases, with global dye production discharging hundreds of thousands of tons of colored effluents annually into waterways, including significant portions of aromatic intermediates like 2-naphthol from azo dye synthesis.^[42] This pollution prompts the adoption of green synthesis alternatives, such as bio-based or solvent-free methods, to minimize environmental releases and promote sustainable production.^[43]

History

Discovery and early synthesis

The discovery of 2-naphthol emerged in the mid-19th century as part of broader investigations into naphthalene derivatives, following the isolation of naphthalene itself in 1819 by Scottish chemist Alexander Garden from coal tar distillates.^[44] French chemist Auguste Laurent conducted extensive work on naphthalene and aromatic compounds during the 1840s and early 1850s, contributing to foundational principles of organic structural theory.^[45] 2-Naphthol was first isolated in the mid-19th century through the fusion of 2-naphthalenesulfonic acid with potassium hydroxide, a method that replaced the sulfonic acid group with a hydroxyl group under high-temperature conditions. The exact attribution for this initial isolation is not widely documented, reflecting the collaborative nature of early coal tar chemistry. The early synthesis began with the sulfonation of naphthalene using concentrated sulfuric acid, which produced a mixture of 1- and 2-naphthalenesulfonic acid isomers depending on reaction temperature.^[46] The 2-isomer was selectively converted to 2-naphthol by alkali fusion at 280–320 °C, with the resulting naphtholate salt then acidified.^[47] This process can be summarized by the equation:

\ce{C10H7SO3H + 2 KOH ->[fusion, 280-320°C] C10H7OK + K2SO3 + H2O}

Acidification of the potassium 2-naphtholate (C₁₀H₇OK) with sulfuric acid then yielded the free 2-naphthol (C₁₀H₇OH). 2-Naphthol was distinguished from its positional isomer, 1-naphthol, primarily through differences in melting points—122 °C for 2-naphthol versus 95 °C for 1-naphthol—as well as variations in solubility, with 2-naphthol exhibiting lower water solubility but higher solubility in alkaline solutions.^[1] Initial characterization relied on these physical properties alongside diagnostic color reactions, such as the formation of deep blue or green complexes with ferric chloride or other reagents, confirming its phenolic nature and structural identity.^[1]

Industrial and commercial development

The commercialization of 2-naphthol began in the late 19th century, driven by its role as a key intermediate in the synthesis of azo dyes, which were rapidly expanding following the discovery of diazotization processes in the 1860s. By the 1880s, German chemical firms had scaled up production of naphthalene-based dyes to meet the growing demand for synthetic colorants in the textile industry, with 2-naphthol coupling with diazonium salts to produce vibrant red and orange hues like para red.^[48] This period marked the shift from natural to synthetic colorants, establishing 2-naphthol as an essential component for industrial-scale dyeing.^[49] In the early 20th century, innovations like the naphthol AS series—substituted derivatives of 2-naphthol designed for improved fastness—further propelled its commercial adoption, with initial patents for such azo pigments filed around 1911, later refined by firms like IG Farben.^[50] By the 1910s, 2-naphthol-based pigments, such as Naphthol Green B (a lake of Acid Green 1), were introduced for non-textile applications, including artists' paints and inks, expanding its market beyond dyes.^[51] The interwar and postwar eras saw peak usage in textiles during the 1920s to 1950s, as azo dyes became predominant in dyestuff production, with 2-naphthol enabling fast, brilliant colors on cotton and wool fabrics amid booming apparel manufacturing.^[52] Post-1950s, stringent environmental regulations in Europe and North America, including controls on wastewater from dye production, prompted a shift in manufacturing to Asia starting in the 1980s, where lower costs and less stringent oversight facilitated growth. By the 1970s, recognition of 2-naphthol's toxicity and persistence in effluents—linked to its role in azo dye degradation products—drove the adoption of cleaner processes, such as improved sulfonation controls and recycling of alkaline wastes to minimize pollution.^[36] China emerged as a major producer, with a capacity of approximately 40,000 tons per year as of 2002, representing about 40% of the global total of around 100,000 tons.^[15]^[53] In the modern era as of 2025, the global 2-naphthol market is valued at around $263 million, with a projected compound annual growth rate (CAGR) of 3.3% through 2031, increasingly driven by pharmaceutical applications such as intermediates for analgesics and antiseptics rather than traditional dyes.^[54] Since the early 2000s, developments in greener synthesis methods have emphasized sustainability by reducing energy use and hazardous byproducts. Economically, bulk prices fluctuate between $10 and $15 per kg, influenced by raw naphthalene costs and demand from emerging markets in Asia.^[55]

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formation of 1,2 Naphthoquinone as shown. The above mechanism leads to the following rate law. = K2 [ 2.Naphthol] [NDC]. The proposed mechanism and the ...
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Antibacterial Activity of Mannich Bases Derived From 2-naphthols ...
May 15, 2016 · A small library of 1-aminoalkyl 2-naphthols has been synthesized through the direct Mannich reaction of 2-naphthols with (hetero)aromatic ...Missing: formaldehyde β aminomethyl
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Antibacterial activity of Mannich bases derived from 2-naphthols ...
2-Naphthol 1 was amino alkylated in the Mannich reaction using 2-carboxaldehyde thiophene as the aldehyde reagent and 1H-benzotriazole as the amine reagent ( ...
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Direct halogenative dearomatization of 2-naphthols by NXS (X = Cl ...
A direct halogenative dearomatization of substituted 2-naphthols was achieved by NXS (X = Cl, Br) in environmentally friendly water at room temperature.Missing: spiro | Show results with:spiro
[37]
Rapid Assembly of Spiroisoxazolidines by [4 + 1] Dearomative ...
A direct halogenative dearomatization of substituted 2-naphthols was achieved by NXS (X = Cl, Br) in environmentally friendly water at room temperature. ... spiro ...
[38]
Wastes From Manufacture of Azo Dyes and Pigments (Excluding ...
The azoic coupling components are principally beta-naphthol ... For example, bifunctional azo dyes with salicylic acid as the coupling component have two ...
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2-naphthol - Registration Dossier - ECHA
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration and C&L Inventory data. There are more details on the ...Missing: 2025 | Show results with:2025
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[PDF] Ambient Water Quality Criteria for Naphthalene
The LCSOand ECSOvalues for one freshwater invertebrate and two fish species are within the range of 2,300 to 8,900 lJg/l. The LCSOfor the mosquitofish is ...
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A novel approach for removing 2-naphthol from wastewater using ...
Methods commonly used in 2-naphthol removal include photocatalysis [13] and chemical oxidation [14], advanced oxidation procedures (AOPs) [15] and ...Missing: effluents | Show results with:effluents
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Degradation of 2-Naphthol in Aqueous Solution by Electro-Fenton ...
As one of the AOPs, the electro-Fenton (EF) method can generate H2O2 at the cathode (Equation (1)), thereby generating hydroxyl radicals (•OH) under the ...Missing: chromic | Show results with:chromic
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Adsorption of naphthalene and its derivatives onto high-density ...
Adsorption of naphthalene and its derivatives onto high-density polyethylene microplastic: Computational, isotherm, thermodynamic, and kinetic study. December ...<|separator|>
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A review of bioremediation of textile dye containing wastewater
Currently, over 100,000 commercial dyes are used globally, and it is estimated that approximately 280,000 tons of dyes are discharged into wastewater annually ...Missing: waterways per
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Environment-friendly green chemistry approaches for an efficient ...
In conclusion, we have found tannic acid as the green, economical and easily available catalyst for the efficient synthesis of 1-amidoalkyl-2-naphthols which ...
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Naphthalene — production and uses - SpringerLink
History of Chemistry · Industrial Chemistry ... Keywords. Phthalic Anhydride · Crystallization Point · Alkali Fusion · Naphthalene Fraction · Naphthalenesulfonic ...
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Auguste Laurent. Radical and radicals - ScienceDirect.com
Afterwards, Laurent examined the action of chlorine on naphthalene itself and found two products that he believed were chlorides of naphthalene, one a white ...Missing: naphthol | Show results with:naphthol
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2-Naphthalenesulfonic acid | C10H8O3S | CID 8420 - PubChem - NIH
Naphthalene-2-sulfonic acid is a naphthalenesulfonic acid in which the sulfo group is linked to position 2 of the naphthalene ring.Missing: first isolation 1855 fusion
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The synthesis of 1 and 2-naphthols from Napththalene
Jan 4, 2009 · The synthesis involves sulfonation of naphthalene, isolation of the sulfonic acid, fusion with potassium hydroxide, and acidification. 1- and 2 ...
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[PDF] BASF History We create chemistry
In 1880, BASF starts work on the synthesis of the popular blue dye based on the procedure developed by Adolf von Baeyer (1835 – 1917). But the industrial.
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Azo dyes and pigments - CAMEO
May 30, 2025 · Within the year, Peter Greiss prepared Bismarck brown, the first azo dye. By the 1880s numerous other azo dyes, such as para red and primuline ...
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(PDF) A History of the International Dyestuff Industry ... - ResearchGate
Mar 11, 2016 · This article surveys the prehistory of modem dyes, the rise of the synthetic dyestuffs industry during the nineteenth century.
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Search specific patents by importing a CSV or list of patent publication or application numbers. ... US688646A 1901-12-10 Black sulfur dye and process of ...
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Naphthol Green – a forgotten artists' pigment of the early 20th ...
The late 19th and early 20th century was a period of tremendous and highly dynamic developments in the so-called coal-tar industry leading to the ...Missing: beta- | Show results with:beta-
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The History and Manufacture of Lithol Red, a Pigment Used by Mark ...
In the 1950s the only lithol reds that were surface treated were those intended for the textile printing industry, where it was essential that the pigment wet ...Missing: peak | Show results with:peak
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[PDF] Health Effects Support Document for Naphthalene, February 2003.
salicylate by aerobic microorganisms (ATSDR, 1995). Therefore, soil aerobic conditions strongly influence the half-life of the chemical. In addition, soil ...
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Beta Naphthol Exports from China - Volza.com
Rating 4.7 (1,434) China leads the world in Beta Naphthol exports with 2,200 shipments, followed by India with 296 shipments , and South Korea taking the third spot with 39 ...Missing: percentage | Show results with:percentage
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Global ?-naphthol Market Growth 2025-2031
Rating 4.5 (10) The global ?-naphthol market size is predicted to grow from US$ 263 million in 2025 to US$ 320 million in 2031; it is expected to grow at a CAGR of 3.3% from ...
[59]
Novel process for efficiently and continuously synthesizing 2-naphthol
The main method of industrial comparatively sophisticated synthetic naphthols has sulfonated alkali fusion method and the different third naphthalene method.In ...
[60]
Hydroxylation of naphthalene by aromatic peroxygenase ... - PubMed
Agrocybe aegerita peroxidase/peroxygenase (AaP) is an extracellular fungal biocatalyst that selectively hydroxylates the aromatic ring of naphthalene.
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2- Naphthol Price - Made-in-China.com
4.1 267 · Free delivery2-Naphthol Beta Naphthol Alpha Naphthol Intermediate with Fast Delivery. US$ 1700-3700 / kg. 50 kg (MOQ). Chengdu ...Missing: per | Show results with:per