1,4-DIHYDROXYANTHRAQUINONE

1,4-Dihydroxyanthraquinone is a hydroxy-substituted anthraquinone compound widely known as Quinizarin and used principally as an intermediate for anthraquinone dyes and specialty colorants.
The molecule contains hydroxyl groups at the 1- and 4-positions of the anthraquinone framework, creating a strongly conjugated hydroxyquinone structure with characteristic orange-red coloration and useful substitution chemistry.
1,4-Dihydroxyanthraquinone is particularly important as a precursor for aminoanthraquinone dyes, disperse dyes, solvent dyes, acid and reactive dye intermediates, vat-related colorants, polymer-soluble colorants, and other functional anthraquinone derivatives.

CHEMICAL IDENTITY AND COMMON NAMES

1,4-Dihydroxyanthraquinone is the 1,4-dihydroxy derivative of anthraquinone and is traditionally known as Quinizarin.
The systematic structure can be described as 1,4-dihydroxyanthracene-9,10-dione.

The two hydroxyl groups occupy positions adjacent to the quinone carbonyl system and strongly influence the electronic distribution and visible absorption of the molecule.
This substitution pattern distinguishes 1,4-Dihydroxyanthraquinone from other dihydroxyanthraquinone isomers such as alizarin, anthrarufin, anthraflavic acid, and danthron.

The positional isomers have the same molecular formula but differ in hydroxyl-group location, colour characteristics, metal-complexing behaviour, reactivity, and downstream synthetic applications.
Accurate identification of the 1,4-isomer is therefore important when the material is selected for anthraquinone colorant manufacture.

Quinizarin and Quinizarine are long-established common names for 1,4-Dihydroxyanthraquinone.
The Colour Index designation C.I. 58050 is also associated with this chemical identity.

Synonyms and Common Names: Quinizarin, Quinizarine, Chinizarin, 1,4-Dihydroxyanthraquinone, 1,4-Dihydroxy-9,10-anthraquinone, 1,4-Dihydroxy-9,10-anthracenedione, 1,4-Dihydroxyanthracene-9,10-dione, 9,10-Anthracenedione, 1,4-dihydroxy-, Anthraquinone, 1,4-dihydroxy-, 1,4-Dioxyanthraquinone, 1,4-Dioxy-9,10-anthraquinone, Anthracene-9,10-dione-1,4-diol, 1,4-Anthracenediol-9,10-dione, 1,4-Anthraquinonediol, para-Dihydroxyanthraquinone, p-Dihydroxyanthraquinone, C.I. 58050, Solvent Orange 86, C.I. Solvent Orange 86, Smoke Orange R, 1,4-DHAQ, NSC 15367, NSC 646569

TECHNICAL IDENTIFICATION

CAS Number: 81-64-1
EC / EINECS Number: 201-368-7
Molecular Formula: C14H8O4
Molar Mass: 240.21 g/mol
IUPAC Name: 1,4-Dihydroxyanthracene-9,10-dione
Chemical Class: Hydroxyanthraquinone
Functional Groups: Phenolic hydroxyl groups, conjugated quinone carbonyl groups
Colour Index Number: C.I. 58050
Common Industrial Name: Quinizarin
InChIKey: GUEIZVNYDFNHJU-UHFFFAOYSA-N

PHYSICAL AND CHEMICAL PROPERTIES

Appearance: Orange, orange-red, red-brown, or reddish crystalline powder
Physical State: Solid
Molecular Formula: C14H8O4
Molar Mass: 240.21 g/mol
Melting Point: Approximately 195–196 °C
Water Solubility: Very low
Volatility: Very low under normal ambient conditions
Chemical Class: Dihydroxyanthraquinone
Hydroxyl Functionality: Two phenolic hydroxyl groups
Carbonyl Functionality: Two conjugated quinone carbonyl groups
Chromophoric System: Extended anthraquinone π-conjugated structure
Vapour Pressure: Extremely low at ambient temperature
Acid-Base Behaviour: Phenolic hydroxyl groups undergo deprotonation in sufficiently alkaline media
Organic Solvent Behaviour: Solubility increases in suitable organic solvents compared with water
Thermal Behaviour: High-melting aromatic solid
Light Absorption: Strong absorption in the visible and ultraviolet regions
Redox Behaviour: Characteristic quinone-hydroquinone-type anthraquinone chemistry
Incompatibilities: Strong oxidizing agents

The rigid anthraquinone framework gives 1,4-Dihydroxyanthraquinone a high melting point and low volatility.
These properties make the material suitable for solid-state handling and high-temperature organic synthesis while limiting direct vapour generation under normal storage conditions.

The hydroxyl groups are positioned so that intramolecular and intermolecular hydrogen bonding can occur with the anthraquinone carbonyl system.
These interactions contribute to the compound's crystal structure, colour, solubility, and spectroscopic behaviour.

The two phenolic hydroxyl groups can be deprotonated under sufficiently alkaline conditions.
Formation of phenolate species changes electron distribution across the conjugated structure and produces distinct changes in visible absorption and colour.

The anthraquinone carbonyl groups retain reversible reduction and oxidation behaviour.
Reduced forms can participate in synthetic pathways and processing strategies used in anthraquinone colorant chemistry.

FUNCTIONAL CHARACTERISTICS

1,4-Dihydroxyanthraquinone functions primarily as a chromophoric chemical intermediate.
Its commercial value comes from the combination of an already developed anthraquinone colour system and two hydroxyl groups that can be replaced, derivatized, or used to influence subsequent substitution reactions.

Reaction with suitable amines can replace one or both hydroxyl groups and produce aminohydroxyanthraquinones or diaminoanthraquinone derivatives.
These transformations form the basis of important blue, violet, red, and related anthraquinone colorants.

The 1,4-substitution arrangement is especially useful because functional groups at these positions interact strongly with the anthraquinone carbonyl system.
Amino substitution can shift absorption substantially and produce intense blue or violet coloration.

1,4-Dihydroxyanthraquinone can also participate in halogenation, sulfonation, reduction, condensation, and other aromatic transformations.
These reactions allow solubility, polarity, fibre affinity, polymer compatibility, thermal behaviour, and shade to be modified according to the intended downstream colorant.

The extended π-conjugated anthraquinone system is responsible for strong visible absorption.
Modification of electron-donating or electron-withdrawing substituents around this structure allows the absorption maximum and colour tone of derivatives to be systematically adjusted.

PRODUCTION AND COMMERCIAL FORM

An established industrial synthesis of 1,4-Dihydroxyanthraquinone uses phthalic anhydride and p-chlorophenol as starting materials.
The aromatic components undergo condensation and ring-forming reactions in strongly acidic media in the presence of boric acid or boron-containing reaction auxiliaries.

The process builds the complete anthraquinone skeleton while establishing the required 1,4-hydroxyl substitution pattern.
Hydrolysis and subsequent isolation steps provide 1,4-Dihydroxyanthraquinone from the reaction mixture.

Hydroquinone-derived routes have also been used to construct the quinizarin framework through condensation with phthalic anhydride.
Process selection depends on feedstock availability, yield, impurity formation, reaction conditions, wastewater load, and required final purity.

Industrial reaction mixtures require purification to remove residual starting materials, positional by-products, sulfuric-acid-derived residues, inorganic materials, and coloured organic impurities.
Filtration, washing, crystallization, and controlled drying may be combined according to the manufacturing process.

Commercial 1,4-Dihydroxyanthraquinone is generally supplied as a crystalline powder or solid.
Purity, colour, moisture, melting behaviour, ash, insoluble material, and related anthraquinone compounds can be important commercial specification parameters.

Some downstream aminoanthraquinone manufacturing processes use 1,4-Dihydroxyanthraquinone together with its partially reduced leuco form.
The ratio between oxidized and reduced forms can influence amination rate, conversion, impurity formation, and subsequent colour quality.

APPLICATIONS AND INDUSTRIES

ANTHRAQUINONE DYE INTERMEDIATE

The most important industrial function of 1,4-Dihydroxyanthraquinone is as an intermediate for anthraquinone colorants.
The parent molecule supplies the central chromophoric skeleton from which more highly substituted dyes can be produced.

The hydroxyl groups provide chemically useful positions for replacement by amino and substituted amino groups.
Such modifications substantially alter electron distribution and permit blue, violet, red, orange, and related shades to be developed.

Anthraquinone colorants derived from 1,4-Dihydroxyanthraquinone are used in textile, polymer, solvent, coating, ink, and specialty coloration applications.
The final product class depends on the substituents introduced after the quinizarin stage.

AMINOANTHRAQUINONE PRODUCTION

1,4-Dihydroxyanthraquinone is an important precursor for aminoanthraquinones.
Reaction with ammonia or primary and secondary amines allows hydroxy groups to be replaced by amino functionality.

Partial substitution can produce 1-amino-4-hydroxyanthraquinone structures.
Further substitution produces 1,4-diaminoanthraquinones and N-substituted diaminoanthraquinone derivatives.

These products are important intermediates and colorants in their own right.
The nature of the amino substituent strongly affects shade, solubility, affinity for fibres or polymers, thermal stability, and migration behaviour.

1,4-DIAMINOANTHRAQUINONE DERIVATIVES

1,4-Dihydroxyanthraquinone is a principal starting material for the preparation of 1,4-diaminoanthraquinone derivatives.
Replacement of both hydroxyl groups with suitable amines generates strongly coloured compounds in which amino groups interact directly with the anthraquinone chromophore.

Aliphatic, hydroxyalkyl, alkoxyalkyl, aromatic, and other substituted amines can be used according to the targeted colorant.
Changing these substituents modifies polarity, solubility, compatibility, colour strength, and application performance.

Dialkylamino and related derivatives are particularly important in solvent-soluble and polymer-compatible anthraquinone colorants.
Hydroxyalkyl and polyether-containing groups can provide different solubility or formulation characteristics.

DISPERSE DYES

1,4-Dihydroxyanthraquinone is an established intermediate for disperse anthraquinone dyes.
These dyes are designed to possess limited water solubility while maintaining affinity for hydrophobic synthetic fibres.

Amination and further substitution of the quinizarin framework produce derivatives with intense blue, violet, red, and related colours.
Fine dispersion of the resulting dye allows application from aqueous dye baths even though the molecular dye itself has limited water solubility.

Polyester is a major substrate for anthraquinone disperse dyes.
Acetate and other hydrophobic fibres may also be coloured with appropriately designed derivatives.

The final dye structure determines sublimation resistance, diffusion behaviour, shade, build-up, fastness, and thermal-transfer characteristics.
1,4-Dihydroxyanthraquinone provides the upstream anthraquinone skeleton from which these properties are developed.

TRANSFER-PRINTING DYES

Derivatives manufactured from 1,4-Dihydroxyanthraquinone can be used as disperse dyes for heat-transfer printing.
This technology relies on controlled sublimation or thermal migration of dye from a printed transfer medium into a synthetic fibre substrate.

Anthraquinone structures can provide bright shades and useful thermal stability when molecular design is matched to transfer temperature.
Substituent selection determines volatility, polyester affinity, colour strength, and resistance to unwanted migration.

The parent 1,4-Dihydroxyanthraquinone is not itself the universal transfer dye.
Its importance lies in providing the chemical framework from which suitable sublimable derivatives are synthesized.

SOLVENT DYES

1,4-Dihydroxyanthraquinone is associated with solvent-dye chemistry both as a colour-bearing compound and as an intermediate for more strongly oil- and solvent-soluble derivatives.
The Colour Index designation Solvent Orange 86 is associated with the quinizarin structure.

Hydrophobic amino substitution can further improve compatibility with non-aqueous media.
The resulting anthraquinone dyes can dissolve molecularly in selected organic solvents, oils, resins, waxes, and polymer systems.

Molecular dissolution provides transparent colour because no large insoluble pigment particles are required.
This characteristic is useful in applications where clarity and colour intensity are both important.

PLASTICS COLORANTS

1,4-Dihydroxyanthraquinone is a precursor for anthraquinone colorants used in thermoplastic and thermosetting polymer systems.
Appropriate substitution can produce dyes with the solubility and thermal stability required for incorporation into polymer melts or resin matrices.

Polystyrene, acrylic materials, styrenic polymers, and other compatible plastics can be coloured with selected anthraquinone derivatives.
The exact polymer determines the required dye polarity, melt stability, migration resistance, and colour strength.

Transparent plastics particularly benefit from molecularly soluble dyes.
A well-designed anthraquinone derivative can produce intense colour while preserving optical transparency that would be reduced by highly scattering pigment particles.

POLYSTYRENE COLORANTS

Aminoanthraquinone derivatives prepared from 1,4-Dihydroxyanthraquinone are suitable for coloration of polystyrene and related styrenic materials when their molecular structure provides appropriate resin solubility.
Blue and violet anthraquinone dyes are particularly significant in this field.

The colorant must tolerate polymer-processing temperatures without excessive decomposition or shade change.
Migration and bleeding behaviour are also important because the dye remains molecularly dispersed within the polymer.

High-purity starting 1,4-Dihydroxyanthraquinone helps reduce formation of unwanted colour bodies that could modify the final transparent shade.

ACRYLIC POLYMER COLORANTS

1,4-Dihydroxyanthraquinone derivatives can be designed for compatibility with acrylic polymers such as polymethyl methacrylate.
These materials are widely used in transparent sheet, molded articles, optical components, displays, and decorative products.

Anthraquinone-derived solvent dyes provide strong colour at relatively low concentrations.
The final derivative can be selected for clarity, heat stability, light resistance, and limited migration within the acrylic matrix.

Colour-sensitive polymer applications place particular emphasis on colorant purity.
Minor anthraquinone impurities can produce visible secondary shades in highly transparent materials.

POLYURETHANE COLORANTS

Functional anthraquinone derivatives prepared from 1,4-Dihydroxyanthraquinone can be incorporated into polyurethane colorant systems.
Suitable substituents can improve compatibility with polyols, polyurethane precursors, and completed polymer networks.

Reactive or strongly compatible colorant structures can reduce migration compared with simple low-molecular-weight dyes.
These characteristics are useful in foams, elastomers, coatings, and specialty polyurethane products.

The molecular design of the derivative is more important than the parent quinizarin alone.
1,4-Dihydroxyanthraquinone serves as the chromophoric starting platform.

ACID DYE INTERMEDIATES

1,4-Dihydroxyanthraquinone is used as an upstream intermediate for acid anthraquinone dyes.
Amination creates strongly coloured aminoanthraquinones, while sulfonation or introduction of sulfonated substituents provides the water solubility required for acid-dye applications.

Appropriately designed acid anthraquinone dyes are used on wool, silk, polyamide fibres, and selected proteinaceous substrates.
The sulfonic acid functionality provides ionic character while the anthraquinone nucleus supplies the chromophore.

Blue and violet shades are especially important within anthraquinone acid-dye chemistry.
Substitution pattern determines shade, leveling characteristics, solubility, fibre affinity, and fastness.

REACTIVE DYE INTERMEDIATES

1,4-Dihydroxyanthraquinone provides a starting structure for selected reactive anthraquinone dyes.
The chromophore is first converted into suitably substituted aminoanthraquinone intermediates and then linked with reactive groups capable of covalent attachment to compatible fibres.

Sulfonic acid groups are generally introduced to provide the aqueous solubility required for textile application.
Reactive groups are selected according to fibre type, fixation chemistry, processing temperature, and desired application method.

Anthraquinone reactive dyes are especially important for bright blue, turquoise-blue, violet, and related colours.
The electronic effect of amino substituents derived from the quinizarin structure is central to these shades.

VAT AND VAT-RELATED COLORANT CHEMISTRY

1,4-Dihydroxyanthraquinone is used as an intermediate in anthraquinone chemistry leading to vat and vat-related dyes.
Condensation, substitution, and ring-building reactions can generate larger fused aromatic structures with strong colour and low water solubility.

Vat dyes are applied through reduction to a soluble leuco form followed by oxidation on the fibre.
The quinone functionality characteristic of anthraquinone systems provides the redox chemistry required for this application principle.

The final vat colorant usually contains a substantially more complex structure than 1,4-Dihydroxyanthraquinone.
Quinizarin serves as one of the useful building blocks from which these structures can be developed.

WOOL DYE INTERMEDIATES

Amino- and sulfonated anthraquinone derivatives prepared from 1,4-Dihydroxyanthraquinone have established relevance to wool dye chemistry.
The anthraquinone chromophore can provide bright shades while sulfonic acid groups provide water compatibility and affinity under acid-dyeing conditions.

1-amino-4-hydroxyanthraquinone derivatives produced from the quinizarin framework are particularly useful intermediates.
Additional aromatic or aliphatic substitution can then adjust colour and application properties.

SOLVENT-SOLUBLE BLUE AND VIOLET COLORANTS

Amination of 1,4-Dihydroxyanthraquinone produces a family of strongly coloured solvent-compatible anthraquinones.
Depending on the amino substituents, these compounds commonly develop blue or violet absorption profiles.

Oil-, wax-, resin-, and solvent-compatible substituents can be incorporated to improve solubility in hydrophobic media.
This chemistry is useful when transparent coloration is required without introducing particulate pigment.

PRINTING INKS

1,4-Dihydroxyanthraquinone is a precursor for anthraquinone dyes used in selected printing-ink systems.
Substituted derivatives can be designed for compatibility with organic solvents, resin binders, and specialty ink vehicles.

Strong colour strength allows relatively low colorant levels.
The molecular structure can also be adjusted for transparency, heat stability, light resistance, and solvent compatibility.

Ink applications require the final derivative to match the resin system and printing process.
Viscosity, drying behaviour, substrate adhesion, rub resistance, and migration are controlled by the complete formulation rather than by 1,4-Dihydroxyanthraquinone alone.

SPECIALTY INKJET COLORANTS

Anthraquinone derivatives originating from 1,4-Dihydroxyanthraquinone can be functionalized for use in specialty liquid ink systems.
Solubilizing substituents can provide compatibility with aqueous or organic formulations, while polymer-compatible groups can support non-aqueous inks.

The anthraquinone chromophore offers strong visible absorption and can provide blue, violet, red, or related shades.
The final dye requires control of solubility, filtration behaviour, nozzle compatibility, light resistance, and interaction with the receiving substrate.

THERMAL-TRANSFER COLORANTS

Quinizarin-derived anthraquinone dyes can be designed for thermal-transfer recording and dye-sublimation systems.
These applications require controlled thermal mobility from a donor material into a receiving polymer layer.

Molecular weight, substituent structure, intermolecular forces, and compatibility with the receiving layer influence transfer behaviour.
The anthraquinone skeleton provides useful colour strength and thermal performance when appropriately substituted.

COATING COLORANTS

1,4-Dihydroxyanthraquinone is a precursor for solvent-soluble and resin-compatible colorants used in selected coating systems.
Molecularly dissolved dyes can provide transparent coloration in clear coatings where opacity from pigment particles is undesirable.

The final derivative must be compatible with the coating resin and solvent package.
Light stability, heat resistance, migration, chemical resistance, and transparency are important selection parameters.

SPECIALTY PIGMENT CHEMISTRY

1,4-Dihydroxyanthraquinone can serve as a precursor for more complex anthraquinone compounds used as organic pigments or pigment intermediates.
Condensation, substitution, and metal-complexing chemistry can produce less soluble and more structurally elaborate colorants.

Pigment applications require controlled crystal form, particle size, surface properties, and dispersion in addition to molecular colour.
These performance characteristics arise in downstream processing rather than from the parent intermediate alone.

COLOURED-SMOKE APPLICATIONS

1,4-Dihydroxyanthraquinone has historical recognition under names including Smoke Orange R.
Its intense coloration and thermal behaviour have led to specialised use or investigation in coloured-smoke compositions.

This application is distinct from conventional textile or polymer dyeing.
Thermal response, sublimation behaviour, purity, particle characteristics, and compatibility with the complete composition are important where such specialised systems are formulated.

CHEMICAL SYNTHESIS

1,4-Dihydroxyanthraquinone is a useful synthetic building block for preparing functionalized anthraquinones.
Its two hydroxyl groups and conjugated carbonyl system provide several pathways for substitution and derivatization.

Amination, alkylation, acylation, halogenation, sulfonation, reduction, oxidation, and condensation can all be used to modify the molecule under appropriate conditions.
These transformations provide access to molecules with different colour, solubility, redox behaviour, and material compatibility.

The compound is especially useful where a target structure requires functional groups positioned at the 1- and 4-sites of the anthraquinone nucleus.
Starting from the correct isomer avoids complex positional control later in synthesis.

ANALYTICAL REFERENCE MATERIAL

High-purity 1,4-Dihydroxyanthraquinone is used as an analytical reference material in chromatography, spectroscopy, reaction monitoring, and anthraquinone research.
Its defined chromophore produces characteristic ultraviolet-visible absorption that supports identity confirmation.

High-performance liquid chromatography is useful for determining purity and separating 1,4-Dihydroxyanthraquinone from other hydroxyanthraquinones and process-related impurities.
Chromatographic control is especially valuable when the material is used for synthesis of colour-sensitive derivatives.

Mass spectrometry, infrared spectroscopy, and ultraviolet-visible spectroscopy provide complementary structural information.
The hydroxyl and carbonyl groups produce characteristic spectroscopic features.

UV-VISIBLE SPECTROSCOPY

1,4-Dihydroxyanthraquinone is particularly useful in spectroscopic research because its visible absorption responds strongly to solvent environment and ionization of the phenolic groups.
Changes in hydrogen bonding and polarity can alter absorption position and intensity.

Alkaline deprotonation produces strongly modified electronic structures.
This behaviour makes the molecule useful for investigating relationships between protonation state, conjugation, and colour in hydroxyanthraquinones.

Comparison with alizarin and other dihydroxyanthraquinone isomers demonstrates how hydroxyl-group position affects intramolecular hydrogen bonding and electronic transitions.

ACID-BASE AND INDICATOR RESEARCH

The phenolic groups of 1,4-Dihydroxyanthraquinone undergo deprotonation under alkaline conditions.
The resulting colour changes have made quinizarin useful in analytical and physical-chemistry studies involving acid-base equilibria.

Solvent composition, ionic strength, temperature, concentration, and interacting species can influence the observed transition.
These characteristics make 1,4-Dihydroxyanthraquinone useful as a research probe for non-aqueous and mixed-solvent acid-base behaviour.

METAL-COMPLEXATION RESEARCH

1,4-Dihydroxyanthraquinone can coordinate selected metal ions through its oxygen-containing functional groups.
The hydroxyquinone structure allows interaction involving phenoxide and carbonyl donor sites under appropriate conditions.

Complex formation produces changes in visible absorption and can also affect fluorescence.
These responses have made quinizarin useful in analytical research involving spectrophotometric and fluorescence-based metal-ion determination.

Metal binding depends strongly on pH, solvent, competing ligands, ion concentration, and substitution state.
The compound is therefore principally useful as a defined analytical reagent or research ligand rather than as a universal metal-sequestering additive.

COLORIMETRIC AND SENSING RESEARCH

The strong optical response of 1,4-Dihydroxyanthraquinone to ionization and coordination makes it useful in chemical sensing research.
Changes in absorbance or fluorescence can indicate interaction with selected cations or changes in chemical environment.

The chromophore can also be incorporated into modified molecules or material systems designed for more selective sensing.
Such applications exploit the established optical behaviour of the parent quinizarin nucleus.

PROCESS CONTROL IN COLORANT MANUFACTURE

1,4-Dihydroxyanthraquinone can be measured during amination and other derivative-manufacturing processes to determine conversion of the starting material.
Residual quinizarin is an important process-control parameter when complete substitution is required.

Chromatographic analysis can distinguish 1,4-Dihydroxyanthraquinone from monoamino, diamino, reduced, and other anthraquinone reaction products.
This information helps optimize reaction time, reagent charge, purification, and final colorant quality.

Residual starting material can influence shade, strength, solubility, and impurity profile of a finished dye.
Accurate monitoring therefore supports reproducible manufacturing.

GRADE SELECTION AND PRODUCT SUITABILITY

Assay is a principal purchasing parameter for 1,4-Dihydroxyanthraquinone intended for dye synthesis.
Higher active content improves control of amination stoichiometry, conversion, isolation yield, and final colorant composition.

Positional-isomer control can be important because other hydroxyanthraquinones do not react identically to the 1,4-isomer.
Isomeric impurities may produce colorants with different absorption characteristics and can therefore alter shade.

Residual starting materials from synthesis can also be significant.
p-Chlorophenol, phthalic-acid-derived compounds, hydroquinone-related material, and other organic residues may require control according to the production route.

Related anthraquinone compounds are particularly important in high-purity colorant manufacture.
Even strongly coloured impurities present at relatively low concentration can influence final dye shade.

Leucoquinizarin content can be relevant in material intended specifically for aminoanthraquinone synthesis.
Certain amination technologies intentionally employ a controlled mixture of 1,4-Dihydroxyanthraquinone and its reduced leuco form.

Colour and appearance provide useful practical quality indicators.
Commercial material is expected to show a characteristic orange to reddish-brown coloration, while unusual shade changes can indicate variation in impurity composition or oxidation state.

Melting behaviour provides useful supplementary identity and purity information.
A melting point around 195–196 °C is characteristic of 1,4-Dihydroxyanthraquinone.

Moisture should be controlled because it affects assay calculation, powder handling, packaging stability, and reagent charging.
Dry-basis and as-is assay values should therefore be interpreted consistently during purchasing and production.

Ash or inorganic residue can be relevant when the manufacturing process employs sulfuric acid, boric acid, neutralizing agents, or inorganic filtration aids.
Excess inorganic material reduces active organic content and can affect downstream reaction media.

Particle size influences charging, dust generation, dispersion, dissolution rate, reaction contact, and filtration.
A consistent powder form supports reproducible industrial processing.

FORMULATION AND PROCESS CONSIDERATIONS

1,4-Dihydroxyanthraquinone has very limited water solubility, so simple aqueous dissolution is unsuitable for many manufacturing operations.
Organic solvents, high-temperature reaction media, acid or alkaline systems, and heterogeneous processing are commonly more appropriate.

Amination frequently requires elevated temperature because substitution of the hydroxy groups is not necessarily rapid under mild conditions.
Suitable reaction media and controlled use of reduced quinizarin can improve conversion in selected processes.

The reduced leuco form can increase reactivity toward primary amines.
Processes may therefore establish an intentional quinizarin-to-leucoquinizarin ratio before or during amination.

Efficient mixing is important when the starting material remains partly suspended.
Poor contact between solid 1,4-Dihydroxyanthraquinone and the reactive liquid phase can produce incomplete conversion and variable impurity profiles.

Heat transfer should be considered carefully because high-temperature aromatic substitution can be sensitive to localized overheating.
Uniform reactor temperature supports consistent colour chemistry and reduces formation of undesirable degradation products.

Solvent selection affects solubility of both starting material and colorant product.
An effective process medium can improve reaction rate while also simplifying subsequent crystallization or precipitation.

Filtration and washing are important after many anthraquinone reactions.
Colour bodies can adsorb strongly onto solids, so washing conditions should remove soluble impurities without creating excessive product loss.

Strong light should be controlled when prolonged exposure could influence colour or photochemical behaviour.
Dark or light-protective storage is particularly useful for high-purity analytical material.

QUALITY, SPECIFICATIONS AND DOCUMENTATION

Relevant quality parameters for 1,4-Dihydroxyanthraquinone include assay, chromatographic purity, appearance, colour, melting range, moisture, ash, insoluble matter, related anthraquinones, and selected process-related organic impurities.
The appropriate specification depends on the downstream colorant and reaction route.

High-performance liquid chromatography is particularly useful for determining assay and related-substance profile.
HPLC can distinguish structurally similar hydroxyanthraquinones and identify residual starting material during downstream amination.

Melting-point analysis provides a useful supporting identity and purity test.
A narrow range near the characteristic melting point indicates consistent crystalline material.

UV-visible spectroscopy provides a rapid means of examining the chromophore.
Absorption characteristics can be useful for identity confirmation, process monitoring, and investigation of coloured impurities.

Infrared spectroscopy supports identification of phenolic hydroxyl and quinone carbonyl functionality.
The combined spectral pattern is characteristic of the hydroxyanthraquinone framework.

Water or loss-on-drying measurements allow assay to be interpreted on a consistent material basis.
This becomes important when comparing materials from different drying processes.

Ash testing can provide useful information regarding residual inorganic material.
Low and controlled ash is particularly relevant for high-purity synthesis and analytical applications.

A Certificate of Analysis provides batch-specific analytical results for the selected release parameters.
A Technical Data Sheet provides relevant product and processing characteristics, while the Safety Data Sheet provides information for hazard communication, handling, exposure control, storage, and emergency procedures.

SAFETY AND REGULATORY CONSIDERATIONS

1,4-Dihydroxyanthraquinone should be handled using normal industrial controls for coloured aromatic powders.
Dust generation should be minimized during weighing, charging, sampling, milling, transfer, and repackaging.

Direct contact with skin and eyes should be avoided.
Current hazard information commonly identifies 1,4-Dihydroxyanthraquinone as capable of causing skin and eye irritation.

Protective gloves, safety eyewear, appropriate protective clothing, and effective workplace ventilation are suitable routine controls.
Local exhaust ventilation is particularly useful where dry powder is handled frequently or on an industrial scale.

The intense colour of 1,4-Dihydroxyanthraquinone can cause visible contamination of surfaces, clothing, and equipment even at relatively low material quantities.
Good housekeeping and closed handling improve both occupational hygiene and cross-contamination control.

Combustion or severe thermal decomposition can generate carbon monoxide, carbon dioxide, and irritating organic decomposition products.
Fire response should use protective equipment appropriate for combustion of aromatic organic solids.

Environmental release should be minimized.
Process wastewater from dye-intermediate manufacture can contain intensely coloured anthraquinones and related aromatic compounds that require appropriate industrial treatment.

FIRST AID

Inhalation: Move the exposed person to fresh air and keep at rest.
Obtain medical attention if coughing, respiratory irritation, breathing discomfort, or other persistent symptoms occur.

Skin Contact: Remove contaminated clothing and wash affected skin thoroughly with soap and plenty of water.
Obtain medical attention if redness, irritation, or persistent discomfort develops.

Eye Contact: Rinse cautiously with plenty of clean water for several minutes while holding the eyelids open.
Remove contact lenses when easy to do, continue rinsing, and obtain medical attention if irritation persists.

Ingestion: Rinse the mouth thoroughly with water.
Obtain medical advice following significant ingestion or if symptoms develop.

Note to Physicians: Treatment should be based on the route and degree of exposure and the observed clinical condition.

HANDLING AND STORAGE

Handling: Avoid generating 1,4-Dihydroxyanthraquinone dust and prevent unnecessary skin and eye contact.
Use controlled charging, sampling, transfer, and cleaning procedures.

Ventilation: Provide effective general ventilation and local exhaust ventilation where weighing, charging, milling, sampling, or transfer can generate airborne powder.

Storage: Store 1,4-Dihydroxyanthraquinone in tightly closed containers in a cool, dry, well-ventilated location.
Protect the product from moisture, contamination, excessive heat, and prolonged intense light.

Incompatibilities: Keep separated from strong oxidizing agents and other highly reactive substances capable of attacking phenolic or quinone structures.

Packaging: Use clean, dry, chemically compatible packaging that protects the product from contamination, moisture uptake, physical loss, and uncontrolled dust release.

PACKAGING AND PROCUREMENT CONSIDERATIONS

1,4-Dihydroxyanthraquinone is primarily purchased according to the requirements of the downstream dye, colorant, synthesis, or analytical process.
No single specification is equally important for every application.

CAS Number 81-64-1 and EC Number 201-368-7 should be stated clearly in purchasing documentation.
The positional identity is especially important because other dihydroxyanthraquinone isomers have different chemical and coloristic behaviour.

Dye manufacturers should place particular emphasis on assay, chromatographic purity, related anthraquinones, colour, and moisture.
These parameters influence reaction stoichiometry, conversion, shade, purification load, and final dye strength.

Manufacturers of aminoanthraquinone colorants can additionally consider leucoquinizarin content or the suitability of the material for controlled reduction before amination.
The preferred oxidized-to-reduced ratio depends on the downstream synthesis.

Solvent-dye and plastics-colorant producers benefit from tight control of impurities that generate secondary shades.
Transparent polymer coloration is particularly sensitive because even small quantities of another coloured anthraquinone can alter final hue.

Analytical and research grades require greater emphasis on chromatographic characterization and identity.
High-purity material is appropriate for spectroscopy, chromatography, reaction-mechanism studies, and preparation of reference solutions.

Particle size should be matched with processing requirements.
Fine powder provides rapid surface contact during heterogeneous reactions but requires more effective dust containment, while coarser crystalline material can provide easier solids handling.

Moisture-resistant inner liners help maintain consistent material condition during storage.
Packaging should also protect the strongly coloured product from cross-contamination with other chemical intermediates.

Procurement specifications can include assay, HPLC purity, appearance, colour, melting range, moisture, ash, related anthraquinones, physical form, particle characteristics, packaging, and required analytical documentation.
Selecting parameters according to the intended anthraquinone derivative provides more practical control than applying unnecessary generic specifications.

Ataman Kimya can support enquiries for 1,4-Dihydroxyanthraquinone concerning purity, grade selection, related-substance requirements, dye and colorant applications, aminoanthraquinone manufacture, technical specifications, analytical documentation, packaging, and supply requirements.
For product and procurement information, contact Ataman Kimya at +90 216 577 10 10 or [info@atamankimya.com](mailto:info@atamankimya.com).