PRODUCTS

1,4-DIHYDROXYBENZENE

CAS Number: 123-31-9
EC Number: 204-617-8
Chemical formula: C6H6O2
IUPAC name: Benzene-1,4-dio

1,4-Dihydroxybenzene, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2.
1,4-Dihydroxybenzene has two hydroxyl groups bonded to a benzene ring in a para position.
1,4-Dihydroxybenzene is a white granular solid.

Production:
1,4-Dihydroxybenzene is produced industrially in two main ways.

The most widely used route is similar to the cumene process in reaction mechanism and involves the dialkylation of benzene with propene to give 1,4-diisopropylbenzene.
This compound reacts with air to afford the bis(hydroperoxide), which is structurally similar to cumene hydroperoxide and rearranges in acid to give acetone and 1,4-Dihydroxybenzene.
A second route involves hydroxylation of phenol over a catalyst.
The conversion uses hydrogen peroxide and affords a mixture of 1,4-Dihydroxybenzene and its ortho isomer catechol (benzene-1,2-diol).

Other, less common methods include:
A potentially significant synthesis of 1,4-Dihydroxybenzene from acetylene and iron pentacarbonyl has been proposed Iron pentacarbonyl serves as a catalyst, rather than as a reagent, in the presence of free carbon monoxide gas.
Rhodium or ruthenium can substitute for iron as the catalyst with favorable chemical yields but are not typically used due to their cost of recovery from the reaction mixture.

1,4-Dihydroxybenzene and its derivatives can also be prepared by oxidation of various phenols.
Examples include Elbs persulfate oxidation and Dakin oxidation.
1,4-Dihydroxybenzene was first obtained in 1820 by the French chemists Pelletier and Caventou via the dry distillation of quinic acid.

Reactions:
The reactivity of 1,4-Dihydroxybenzene's hydroxyl groups resembles that of other phenols, being weakly acidic.
The resulting conjugate base undergoes easy O-alkylation to give mono- and diethers.
Similarly, 1,4-Dihydroxybenzene is highly susceptible to ring substitution by Friedel–Crafts reactions such as alkylation.
This reaction is exploited en route to popular antioxidants such as 2-tert-butyl-4-methoxyphenol (BHA).
The useful dye quinizarin is produced by diacylation of 1,4-Dihydroxybenzene with phthalic anhydride.

Redox:
1,4-Dihydroxybenzene undergoes oxidation under mild conditions to give benzoquinone.
This process can be reversed.
Some naturally occurring 1,4-Dihydroxybenzene derivatives exhibit this sort of reactivity, one example being coenzyme Q.
Industrially this reaction is exploited both with 1,4-Dihydroxybenzene itself but more often with its derivatives where one OH has been replaced by an amine.

When colorless 1,4-Dihydroxybenzene and benzoquinone, a bright yellow solid, are cocrystallized in a 1:1 ratio, a dark-green crystalline charge-transfer complex (melting point 171 °C) called quinhydrone (C6H6O2·C6H4O2) is formed.
This complex dissolves in hot water, where the two molecules dissociate in solution.

Uses
1,4-Dihydroxybenzene has a variety of uses principally associated with its action as a reducing agent that is soluble in water.
1,4-Dihydroxybenzene is a major component in most black and white photographic developers for film and paper where, with the compound metol, it reduces silver halides to elemental silver.

There are various other uses associated with its reducing power.
As a polymerisation inhibitor, exploiting its antioxidant properties, 1,4-Dihydroxybenzene prevents polymerization of acrylic acid, methyl methacrylate, cyanoacrylate, and other monomers that are susceptible to radical-initiated polymerization.
By acting as a free radical scavenger, 1,4-Dihydroxybenzene serves to prolong the shelflife of light-sensitive resins such as preceramic polymers.

1,4-Dihydroxybenzene can lose a hydrogen cation from both hydroxyl groups to form a diphenolate ion. The disodium diphenolate salt of 1,4-Dihydroxybenzene is used as an alternating comonomer unit in the production of the polymer PEEK.

Skin depigmentation
1,4-Dihydroxybenzene is used as a topical application in skin whitening to reduce the color of skin.
1,4-Dihydroxybenzene does not have the same predisposition to cause dermatitis as metol does.
This is a prescription-only ingredient in some countries, including the member states of the European Union under Directives 76/768/EEC:1976.

In 2006, the United States Food and Drug Administration revoked its previous approval of 1,4-Dihydroxybenzene and proposed a ban on all over-the-counter preparations.
The FDA officially banned 1,4-Dihydroxybenzene in 2020 as part of a larger reform of the over-the-counter drug review process.
The FDA stated that 1,4-Dihydroxybenzene cannot be ruled out as a potential carcinogen.

This conclusion was reached based on the extent of absorption in humans and the incidence of neoplasms in rats in several studies where adult rats were found to have increased rates of tumours, including thyroid follicular cell hyperplasias, anisokaryosis (variation in nuclei sizes), mononuclear cell leukemia, hepatocellular adenomas and renal tubule cell adenomas.
The Campaign for Safe Cosmetics has also highlighted concerns.

The FDA had classified 1,4-Dihydroxybenzene in 1982 as a safe product generally recognized as safe and effective (GRASE), however additional studies under the National Toxicology Program (NTP) were suggested in order to determine whether there is a risk to humans from the use of 1,4-Dihydroxybenzene.
NTP evaluation showed some evidence of long-term carcinogenic and genotoxic effects.

Several such agents are already available or under research, including azelaic acid, kojic acid, retinoids, cysteamine, topical steroids, glycolic acid, and other substances.
One of these, 4-butylresorcinol, has been proven to be more effective at treating melanin-related skin disorders by a wide margin, as well as safe enough to be made available over the counter.

Natural occurrences:
1,4-Dihydroxybenzenes are one of the two primary reagents in the defensive glands of bombardier beetles, along with hydrogen peroxide (and perhaps other compounds, depending on the species), which collect in a reservoir.
The reservoir opens through a muscle-controlled valve onto a thick-walled reaction chamber.

This chamber is lined with cells that secrete catalases and peroxidases.
When the contents of the reservoir are forced into the reaction chamber, the catalases and peroxidases rapidly break down the hydrogen peroxide and catalyze the oxidation of the 1,4-Dihydroxybenzenes into p-quinones.
These reactions release free oxygen and generate enough heat to bring the mixture to the boiling point and vaporize about a fifth of it, producing a hot spray from the beetle's abdomen.

1,4-Dihydroxybenzene is thought to be the active toxin in Agaricus hondensis mushrooms.

1,4-Dihydroxybenzene has been shown to be one of the chemical constituents of the natural product propolis.

1,4-Dihydroxybenzene is also one of the chemical compounds found in castoreum.
1,4-Dihydroxybenzene is gathered from the beaver's castor sacs.

Consumer Uses of 1,4-Dihydroxybenzene:
1,4-Dihydroxybenzene is used in the following products: photo-chemicals.
Other release to the environment of 1,4-Dihydroxybenzene is likely to occur from: indoor use as reactive substance.

Widespread uses by professional workers:
1,4-Dihydroxybenzene is used in the following products: photo-chemicals, coating products, inks and toners and polymers.
1,4-Dihydroxybenzene is used in the following areas: printing and recorded media reproduction, health services and scientific research and development.
Other release to the environment of 1,4-Dihydroxybenzene is likely to occur from: indoor use (e.g. machine wash liquids/detergents, automotive care products, paints and coating or adhesives, fragrances and air fresheners).

Formulation or re-packing of 1,4-Dihydroxybenzene:
1,4-Dihydroxybenzene is used in the following products: photo-chemicals, water treatment chemicals and fuels.
Release to the environment of 1,4-Dihydroxybenzene can occur from industrial use: formulation of mixtures and formulation in materials.

Uses at industrial sites of 1,4-Dihydroxybenzene:
1,4-Dihydroxybenzene is used in the following products: photo-chemicals, polymers, coating products, inks and toners and water treatment chemicals.
1,4-Dihydroxybenzene has an industrial use resulting in manufacture of another substance (use of intermediates).
1,4-Dihydroxybenzene is used in the following areas: printing and recorded media reproduction and formulation of mixtures and/or re-packaging.

1,4-Dihydroxybenzene is used for the manufacture of: chemicals and plastic products.
Release to the environment of 1,4-Dihydroxybenzene can occur from industrial use: as processing aid, as an intermediate step in further manufacturing of another substance (use of intermediates) and for thermoplastic manufacture.

Molar mass: 110.112 g·mol−1
Appearance: White solid
Density: 1.3 g cm−3, solid
Melting point: 172 °C

Boiling point: 287 °C
Solubility in water: 5.9 g/100 mL (15 °C)
Vapor pressure 10−5 mmHg (20 °C)
Acidity (pKa): 9.9

Magnetic susceptibility (χ): −64.63×10−6 cm3/mol
XLogP3: 0.6
Hydrogen Bond Donor Count: 2
Hydrogen Bond Acceptor Count: 2

Rotatable Bond Count: 0
Exact Mass: 110.036779430
Monoisotopic Mass: 110.036779430
Topological Polar Surface Area 40.5 Å²

Heavy Atom Count: 8
Complexity: 54.9
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0

Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes

1,4-Dihydroxybenzene is produced as an inhibitor, an antioxidant, and an intermediate in the synthesis of dyes, motor fuels, and oils; in photographic processing; and naturally in certain plant species, 1,4-Dihydroxybenzene is a phenol derivative with antioxidant properties that can cause toxicity in several organs, notably the kidney.
Used as a topical treatment for skin hyperpigmentation and in various cosmetic products, it is metabolized mainly to glutathione conjugates and forms mutagenic DNA adducts in in-vitro systems.

1,4-Dihydroxybenzene is a benzenediol comprising benzene core carrying two hydroxy substituents para to each other.
1,4-Dihydroxybenzene has a role as a cofactor, a carcinogenic agent, an Escherichia coli metabolite, a human xenobiotic metabolite, a skin lightening agent, an antioxidant and a mouse metabolite.
1,4-Dihydroxybenzene is a benzenediol and a member of 1,4-Dihydroxybenzenes.

1,4-Dihydroxybenzene is added to a number of industrial monomers to inhibit polymerization during shipping, storage, and processing.
1,4-Dihydroxybenzene is a light-tan, light-gray, or colorless crystal.

Exposure to 1,4-Dihydroxybenzene may cause irritation to the eyes and central nervous system.
Workers may be harmed from exposure to 1,4-Dihydroxybenzene.

The level of exposure depends upon the dose, duration, and work being done.
1,4-Dihydroxybenzene is a Skin-lightening agent.

1,4-Dihydroxybenzene bleaches the skin which is helpful in treating a different form of hyperpigmentation.
1,4-Dihydroxybenzene bleaches the skin and decreases the number of melanocytes present.

Melanocytes make melanin that produces the skin tone.
1,4-Dihydroxybenzene is available in the form of cream, gel, lotion and emulsion.

1,4-Dihydroxybenzene Premium is a polymerisation inhibitor used in process, transport and storage.
1,4-Dihydroxybenzene is designed for various applications such as: synthesis intermediate for rubber, dyes and for Agrochemicals and Pharmaceuticals industries.

1,4-Dihydroxybenzene is a topical lightening product found in OTC products, and is used to correct skin discoloration associated with disorders of hyperpigmentation including melasma, post-inflammatory hyperpigmention, sunspots, and freckles.
1,4-Dihydroxybenzene can be used alone, but is more frequently found in combination with other agents such as alpha-hydroxy acids, corticosteroids, retinoids, or sunscreen.

1,4-Dihydroxybenzene is a depigmenting agent used to treat dyschromia, a condition of skin discoloration or patches of uneven skin color.
1,4-Dihydroxybenzene is an organic compound naturally found in many plants including coffee.

1,4-Dihydroxybenzene is a skin-lightening agent.
1,4-Dihydroxybenzene bleaches the skin, which can be helpful when treating different forms of hyperpigmentation.

Historically, there’s been some back-and-forth on the safety of 1,4-Dihydroxybenzene.
1,4-Dihydroxybenzene bleaches your skin by decreasing the number of melanocytes present.

In cases of hyperpigmentation, more melanin is present due to an increase in melanocyte production.
By controlling these melanocytes, your skin will become more evenly toned over time.

1,4-Dihydroxybenzene takes about four weeks on average for the ingredient to take effect.
1,4-Dihydroxybenzene may take several months of consistent use before you see full results.

1,4-Dihydroxybenzene is used to treat skin conditions related to hyperpigmentation.
Although 1,4-Dihydroxybenzene can help fade red or brown spots that have lingered, 1,4-Dihydroxybenzene won’t help with active inflammation.

For example, the ingredient can help minimize acne scarring, but it won’t have an effect on redness from active breakouts.
1,4-Dihydroxybenzene is used to lighten the dark patches of skin (also called hyperpigmentation, melasma, "liver spots," "age spots," freckles) caused by pregnancy, birth control pills, hormone medicine, or injury to the skin.

This medicine works by blocking the process in the skin that leads to discoloration.
Follow all directions on the product package, or use as directed by your doctor.

Before using, apply a small amount of this medicine to an area of unbroken skin, and check the area within 24 hours for any serious side effects.
If the test area is itching, red, puffy, or blistering, do not use this product and contact your doctor.

If there is just mild redness, then treatment with this product may begin.
Apply this medication to the affected areas of skin, usually twice daily or as directed by your doctor.

This medication is for use on the skin only.
If 1,4-Dihydroxybenzene is used incorrectly, unwanted skin lightening may occur.

Avoid getting this product in your eyes or on the inside of your nose or mouth.
If you do get this medication in those areas, flush with plenty of water.

This medication may make the treated areas of skin more sensitive to the sun.
Avoid prolonged sun exposure, tanning booths, and sunlamps. Use a sunscreen and wear protective clothing on the treated areas of skin when outdoors.

Use this medication regularly to get the most benefit from it.
To help you remember, use 1,4-Dihydroxybenzene at the same times each day.

1,4-Dihydroxybenzene, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2.
1,4-Dihydroxybenzene has two hydroxyl groups bonded to a benzene ring in a para position.

1,4-Dihydroxybenzene is a white granular solid.
Substituted derivatives of 1,4-Dihydroxybenzene are also referred to as 1,4-Dihydroxybenzenes.

The name "1,4-Dihydroxybenzene" was coined by Friedrich Wöhler in 1843.
1,4-Dihydroxybenzene is produced industrially by two main routes.

The most widely used route is similar to the cumene process in reaction mechanism and involves the dialkylation of benzene with propene to give 1,4-diisopropylbenzene.
1,4-Dihydroxybenzene reacts with air to afford the bis(hydroperoxide), which is structurally similar to cumene hydroperoxide and rearranges in acid to give acetone and 1,4-Dihydroxybenzene.

A second route involves hydroxylation of phenol over a catalyst.
A potentially significant synthesis of 1,4-Dihydroxybenzene from acetylene and iron pentacarbonyl has been proposed.

1,4-Dihydroxybenzene serves as a catalyst, rather than as a reagent, in the presence of free carbon monoxide gas.
Rhodium or ruthenium can substitute for iron as the catalyst with favorable chemical yields but are not typically used due to their cost of recovery from the reaction mixture.

1,4-Dihydroxybenzene and its derivatives can also be prepared by oxidation of various phenols.
Examples include Elbs persulfate oxidation and Dakin oxidation.

1,4-Dihydroxybenzene was first obtained in 1820 by the French chemists Pelletier and Caventou via the dry distillation of quinic acid.
The reactivity of 1,4-Dihydroxybenzene's hydroxyl groups resembles that of other phenols, being weakly acidic.

The resulting conjugate base undergoes easy O-alkylation to give mono- and diethers.
Similarly, 1,4-Dihydroxybenzene is highly susceptible to ring substitution by Friedel–Crafts reactions such as alkylation.

This reaction is exploited en route to popular antioxidants such as 2-tert-butyl-4-methoxyphenol (BHA).
The useful dye quinizarin is produced by diacylation of 1,4-Dihydroxybenzene with phthalic anhydride.

1,4-Dihydroxybenzene undergoes oxidation under mild conditions to give benzoquinone.
1,4-Dihydroxybenzene can be reversed.

Some naturally occurring 1,4-Dihydroxybenzene derivatives exhibit this sort of reactivity, one example being coenzyme Q.
Industrially this reaction is exploited both with 1,4-Dihydroxybenzene itself but more often with its derivatives where one OH has been replaced by an amine.

When colorless 1,4-Dihydroxybenzene and benzoquinone, a bright yellow solid, are cocrystallized in a 1:1 ratio, a dark-green crystalline charge-transfer complex (melting point 171 °C) called quinhydrone (C6H6O2·C6H4O2) is formed.
1,4-Dihydroxybenzene dissolves in hot water, where the two molecules dissociate in solution.

1,4-Dihydroxybenzenes are one of the two primary reagents in the defensive glands of bombardier beetles, along with hydrogen peroxide (and perhaps other compounds, depending on the species), which collect in a reservoir.
The reservoir opens through a muscle-controlled valve onto a thick-walled reaction chamber.

These reactions release free oxygen and generate enough heat to bring the mixture to the boiling point and vaporize about a fifth of it, producing a hot spray from the beetle's abdomen.
1,4-Dihydroxybenzene derivatives are the principal irritants exuded by the poodle-dog bush, which can cause severe contact dermatitis in humans.

1,4-Dihydroxybenzene is thought to be the active toxin in Agaricus hondensis mushrooms.
1,4-Dihydroxybenzene has been shown to be one of the chemical constituents of the natural product propolis.

1,4-Dihydroxybenzene is also one of the chemical compounds found in castoreum.
1,4-Dihydroxybenzene is gathered from the beaver's castor sacs.

1,4-Dihydroxybenzene cream is the standard depigmentation or skin lightening agent.
1,4-Dihydroxybenzene is used to treat areas of dyschromia, such as in melasma, chloasma, solar lentigines, freckles, and post-inflammatory hyperpigmentation.

This activity outlines the indications, mechanism of action, methods of administration, important adverse effects, contraindications, and monitoring of 1,4-Dihydroxybenzene, so providers can direct patient therapy to optimal outcomes in conditions where it is indicated.
1,4-Dihydroxybenzene acts as a skin depigmentation agent by inhibiting melanin synthesis.

1,4-Dihydroxybenzene inhibits the conversion of L-3,4- dihydroxyphenylalanine (L-DOPA) to melanin by inhibiting tyrosinase due to its structural similarity to an analog of melanin precursors
1,4-Dihydroxybenzene is only used topically as a depigmentation agent.

A thin layer is applied with fingertips and rubbed into the face (or other affected areas) 1 to 2 times a day for 3 to 6 months.
If there are no results after 2 to 3 months, 1,4-Dihydroxybenzene should be discontinued.

1,4-Dihydroxybenzene is essential to evenly apply 1,4-Dihydroxybenzene over the entire face to prevent uneven pigmentation and use concurrently with sunscreen to protect from damaging UV light, which increases pigmentation.
Physicians recommended stopping treatment after this time for a few months before restarting to decrease the risk of side effects.

1,4-Dihydroxybenzene can also be applied during weekends only or three times a week for more extended maintenance therapy with minimal complications.
1,4-Dihydroxybenzene is available in 2% over the counter or as 4% prescribed.

1,4-Dihydroxybenzene comes in the following dose forms: cream, emulsion, gel, or solution.
1,4-Dihydroxybenzene is used in a cream or lotion formulation in a concentration of 1-5%.

1,4-Dihydroxybenzene is often found in a combination formulation with other skin lightening agents such as topical retinoids (to increase efficiency) and low potency topical steroids (to reduce irritancy).
1,4-Dihydroxybenzene is applied topically just to the hyperpigmented skin only, twice daily for 3 months, after which time many patients maintain their improvement by using it twice each week.

If there has been no benefit after 3 months of treatment, then the 1,4-Dihydroxybenzene should be stopped.
Management of the underlying cause of the hyperpigmentation is also recommended.

1,4-Dihydroxybenzene is particularly effective for the treatment of postinflammatory hyperpigmentation which is unlikely to recur provided the underlying inflammatory dermatosis is also controlled.
1,4-Dihydroxybenzene is a chemical that a person can use to lighten their skin tone.

1,4-Dihydroxybenzene is available as a cream, gel, lotion, or emulsion.
1,4-Dihydroxybenzene is generally safe to use, but some people may experience side effects, such as dry skin.

1,4-Dihydroxybenzene is a chemical that bleaches the skin.
1,4-Dihydroxybenzene can come as a cream, emulsion, gel, or lotion.

A person can apply 1,4-Dihydroxybenzenes directly to the skin.
Creams that contain 1,4-Dihydroxybenzene are available with a prescription from a doctor.

People may use 1,4-Dihydroxybenzene as a form of treatment for hyperpigmentation skin conditions, wherein some areas of skin grow darker than surrounding areas.
1,4-Dihydroxybenzene is a depigmenting agent used to lighten areas of darkened skin such as freckles, age spots, chloasma, and melisma caused by pregnancy, birth control pills, hormone medicine, or injury to the skin. 1,4-Dihydroxybenzene decreases the formation of melanin in the skin.

Melanin is the pigment in skin that gives it a brown color.
1,4-Dihydroxybenzene is the most commonly used tyrosinase inhibitor and is often the primary treatment option for postinflammatory hyperpigmentation and melasma.

The use of HQ results in the reversible inhibition of cellular metabolism by affecting both DNA and RNA production and reduces tyrosinase activity by 90%.
Although effective alone, HQ is often combined with other agents such as tretinoin, glycolic acid, kojic acid, and azelaic acid

1,4-Dihydroxybenzene is a white, odorless, crystalline solid with an extremely low vapor pressure.
1,4-Dihydroxybenzene is moderately soluble in water and highly soluble in alcohol.

1,4-Dihydroxybenzene occurs in the environment as a result of anthropogenic processes, as well as in natural products from plants and animals.
In the soil, 1,4-Dihydroxybenzene is expected to biodegrade under aerobic conditions.

1,4-Dihydroxybenzene may be removed from the soil by oxidation processes or by direct photolysis on the surface.
1,4-Dihydroxybenzene is a topical skin-bleaching agent used in the cosmetic treatment of hyperpigmented skin conditions.

The effect of skin lightening caused by 1,4-Dihydroxybenzene is reversible when exposed to sunlight and therefore requires regular use until desired results are achieved.
Various preparations are available including creams, emulsions, gels, lotions and solutions.

1,4-Dihydroxybenzene is available over the counter in a 2% cream and can be prescribed by your dermatologist in higher concentrations.
1,4-Dihydroxybenzene produces reversible lightening of the skin by interfering with melanin production by the melanocytes.

Specifically, inhibition of the enzymatic conversion of tyrosine to DOPA (dihydroxyphenylalanine) results in the desired chemical reduction of pigment.
1,4-Dihydroxybenzene causes a decrease in the number of melanocytes and decreased transfer of melanin leading to lighter skin.

1,4-Dihydroxybenzene is frequently found in skin-lightening products like bleaching creams.
1,4-Dihydroxybenzene works by limiting your production of melanin, the hormone that darkens your skin.

While some people use 1,4-Dihydroxybenzene to lighten their darker skin, 1,4-Dihydroxybenzene creams are most commonly used to lighten small, dark patches like sunspots or hyperpigmentation.
1,4-Dihydroxybenzene belongs to a combination of 'skin cosmetics' primarily used for brighter, more radiant skin complexation.

1,4-Dihydroxybenzene is also used to clears the complexion and acne scars, hyperpigmentation, melasma, and photoaging (premature ageing of the skin caused by repeated exposure to UV radiation).
Hyperpigmentation is a skin condition in which patches of skin become darker in colour than the normal surrounding skin.

Melasma is a common skin problem that causes dark, discoloured patches on your skin.
Dark spots occur when some skin areas start producing more melanin (a natural pigment that gives colour to eyes, hair and skin), ranging from light to dark brown.

1,4-Dihydroxybenzene contains 1,4-Dihydroxybenzene (skin lightening or bleaching agent) which works by decreasing the amount of melanin (a skin pigment) that is responsible for the darkening of the skin.
1,4-Dihydroxybenzene is primarily used to treat melasma (dark brown patch on skin), hyperpigmentation.

1,4-Dihydroxybenzene is available in topical (for skin use) gel, cream, and emulsion forms.
1,4-Dihydroxybenzene is for external use only.

Avoid contact with eyes, eyelids, lips, mouth, and nose.
If the medicine comes in contact with any of these areas, rinse with water immediately.

Do not use 1,4-Dihydroxybenzene on sunburned, windburned, dry, or irritated skin.
Common side effects of 1,4-Dihydroxybenzene include dry skin, erythema (skin redness), burning sensation, mild itching, skin irritation.

Most of these side effects of 1,4-Dihydroxybenzene do not require medical attention and gradually resolve over time.
1,4-Dihydroxybenzene is used as a developing agent in black-and-white photography, lithography, and x-ray films.
1,4-Dihydroxybenzene is also used as an intermediate to produce antioxidants for rubber and food.

1,4-Dihydroxybenzene (HQ) is produced by the oxidation of aniline or phenol, by the reduction of quinone, or from a reaction of acetylene and carbon monoxide.
1,4-Dihydroxybenzene occurs naturally as a glucose ether, also known as arbutin, in the leaves of many plants and in fruits, as well as one of the agents used in the defense mechanism of the bombardier beetle, family Carabidae.

1,4-Dihydroxybenzene, a colorless, hexagonal prism, has been reported to be a good antimitotic and tumor-inhibiting agent.
1,4-Dihydroxybenzene is a reducing agent used in a photographic developer, which polymerizes in the presence of oxidizing agents.

In the manufacturing industry it may occur include bacteriostatic agent, drug, fur processing, motor fuel, paint, organic chemicals, plastics, stone coating, and styrene monomers.
1,4-Dihydroxybenzene interferes with the production of the pigment melanin by epidermal melanocytes through at least two mechanisms: it competitively inhibits tyrosinase, one of the principal enzymes responsible for converting tyrosine to melanin, and it selectively damages melanocytes and melanosomes.

1,4-Dihydroxybenzene was introduced in 1965 as a topical depigmenting agent for hyperpigmentation.
At high concentrations 1,4-Dihydroxybenzene is corrosive and in most countries has been restricted to the level of approximately 2% and limited to the period of less than 2 months.

1,4-Dihydroxybenzene is a slight explosion hazard when exposed to heat. Incompatible with strong oxidizing agents.
1,4-Dihydroxybenzene reacts with oxygen and sodium hydroxide.

1,4-Dihydroxybenzene is used in photography developers (black and white, X-ray, and microfilms), in plastics, in hair dyes as an antioxidant and hair colorant.
1,4-Dihydroxybenzene is found in many skin bleaching creams.

USES:
1,4-Dihydroxybenzene has a variety of uses principally associated with its action as a reducing agent that is soluble in water.
1,4-Dihydroxybenzene is added to a number of industrial monomers to inhibit polymerization during shipping, storage, and processing.

1,4-Dihydroxybenzene is a major component in most black and white photographic developers for film and paper where, with the compound metol, it reduces silver halides to elemental silver.
There are various other uses associated with its reducing power.

As a polymerisation inhibitor, exploiting its antioxidant properties, 1,4-Dihydroxybenzene prevents polymerization of acrylic acid, methyl methacrylate, cyanoacrylate, and other monomers that are susceptible to radical-initiated polymerization.
By acting as a free radical scavenger, 1,4-Dihydroxybenzene serves to prolong the shelflife of light-sensitive resins such as preceramic polymers.

1,4-Dihydroxybenzene can lose a hydrogen cation from both hydroxyl groups to form a diphenolate ion.
The disodium diphenolate salt of 1,4-Dihydroxybenzene is used as an alternating comonomer unit in the production of the polymer PEEK.

1,4-Dihydroxybenzene is used as a topical application in skin whitening to reduce the color of skin.
1,4-Dihydroxybenzene does not have the same predisposition to cause dermatitis as metol does.

The FDA stated that 1,4-Dihydroxybenzene cannot be ruled out as a potential carcinogen.
This conclusion was reached based on the extent of absorption in humans and the incidence of neoplasms in rats in several studies where adult rats were found to have increased rates of tumours, including thyroid follicular cell hyperplasias, anisokaryosis (variation in nuclei sizes), mononuclear cell leukemia, hepatocellular adenomas and renal tubule cell adenomas.

Numerous studies have revealed that 1,4-Dihydroxybenzene, if taken orally, can cause exogenous ochronosis, a disfiguring disease in which blue-black pigments are deposited onto the skin; however, skin preparations containing the ingredient are administered topically.
The FDA had classified 1,4-Dihydroxybenzene in 1982 as a safe product - generally recognized as safe and effective (GRASE), however additional studies under the National Toxicology Program (NTP) were suggested in order to determine whether there is a risk to humans from the use of 1,4-Dihydroxybenzene.

NTP evaluation showed some evidence of long-term carcinogenic and genotoxic effects.
While using 1,4-Dihydroxybenzene as a lightening agent can be effective with proper use, it can also cause skin sensitivity.

Using a daily sunscreen with a high PPD (persistent pigment darkening) rating reduces the risk of further damage.
1,4-Dihydroxybenzene is sometimes combined with alpha-hydroxy acids that exfoliate the skin to quicken the lightening process.

In the United States, topical treatments usually contain up to 2% in 1,4-Dihydroxybenzene.
Otherwise, higher concentrations (up to 4%) should be prescribed and used with caution.

While 1,4-Dihydroxybenzene remains widely prescribed for treatment of hyperpigmentation, questions raised about its safety profile by regulatory agencies in the EU, Japan, and USA encourage the search for other agents with comparable efficacy.
Several such agents are already available or under research, including azelaic acid, kojic acid, retinoids, cysteamine, topical steroids, glycolic acid, and other substances.
One of these, 4-butylresorcinol, has been proven to be more effective at treating melanin-related skin disorders by a wide margin, as well as safe enough to be made available over the counter.

Other names:
hydroquinone
Benzene-1,4-diol
1,4-benzenediol
123-31-9
Quinol
1,4-Dihydroxybenzene
p-Benzenediol
p-Hydroquinone
p-Hydroxyphenol
4-Hydroxyphenol
p-Dihydroxybenzene
Benzoquinol
Eldoquin
hydroquinol
Eldopaque
Phiaquin
p-Dioxybenzene
Solaquin forte
Dihydroquinone
Hydroquinole
Idrochinone
Tecquinol
Benzohydroquinone
Arctuvin
Hidroquinone
Tequinol
Dihydroxybenzene
Eldopaque Forte
Eldoquin Forte
Derma-Blanch
Tenox HQ
Hydrochinon
Hydrochinone
Artra
Diak 5
Benzene, p-dihydroxy-
1,4-Dihydroxy-benzol
Usaf ek-356
1,4-Diidrobenzene
NCI-C55834
p-Dioxobenzene
1,4-Dihydroxybenzen
para-Dioxybenzene
para-Hydroquinone
Pyrogentistic acid
1,4-Dihydroxy-benzeen
HE 5
para-Dihydroxybenzene
Melanex
CHEBI:17594
NSC 9247
UN2662
AI3-00072
NSC-9247
MFCD00002339
HQ
CHEMBL537
XV74C1N1AE
1,4-Benzenediol, homopolymer
DTXSID7020716
NCGC00015523-02
beta-quinol
DSSTox_CID_716
para-Hydroxyphenol
DSSTox_RID_75754
DSSTox_GSID_20716
Eldopacque
Hydroquinone (Benzene-1,4-diol)
Epiquin
Sunvanish
p Benzendiol
p-Dihydroquinone
alpha-hydroquinone
26982-52-5
CAS-123-31-9
SMR000059154
CCRIS 714
1,4-Hydroxybenzene
HSDB 577
SR-01000075920
4-DIHYDROXYBENZENE
EINECS 204-617-8
UNII-XV74C1N1AEhydroquinon
Hydroquinoue
hydroq uinone
hydroquinone gr
a-Hydroquinone
Black & White Bleaching Cream
p-Hydroxybenzene
b-Quinol
4-Benzenediol
Hydroquinone, HQ
.beta.-Quinol
1,4 benzenediol
Hydroquinone,(S)
p-dihydroxy benzene
HQE
Hydroquinone polymer
PLQ
Artra (Salt/Mix)1, 4-Benzenediol
HYDROP
.alpha.-Hydroquinone
phenol derivative, 4
4-hydroxyphenyl alcohol
Spectrum_001757
4e3h
SpecPlus_000769
1,4-Dihydrobenzoquinone
Spectrum2_001672
Spectrum3_000656
Spectrum4_000633
Spectrum5_001430
Lopac-H-9003
WLN: QR DQ
bmse000293
Epitope ID:116206
EC 204-617-8
1,4-Dihydroxybenzene Quinol
Lopac0_000577
SCHEMBL15516
BSPBio_002291
HYDROQUINONE [MART.]
KBioGR_001246
KBioSS_002237
1,4-Dihydroxybenzene, XIII
MLS000069815
MLS001074911
BIDD:ER0340
DivK1c_006865
SPECTRUM1504237
SPBio_001883
BDBM26190
KBio1_001809
KBio2_002237
KBio2_004805
KBio2_007373
KBio3_001511
NSC9247
HMS1922H15
HMS2093E08
HMS3261D16
Pharmakon1600-01504237
HY-B0951
ZINC5133378
Tox21_110169
Tox21_202345
Tox21_300015
Tox21_500577
CCG-39082
NSC758707
s4580
STK397446
AKOS000119003
Tox21_110169_1
TRI-LUMA COMPONENT HYDROQUINONE
AM10548
DB09526
LP00577
NSC-758707
SDCCGSBI-0050559.P003
UN 2662
BP-21160
DA-33570
EU-0100577
FT-0606877
H0186
C00530
D00073
H 9003
AB00053361_08
J-004910
J-521469
SR-01000075920-1
SR-01000075920-4
Q27102742
Z57127551
094CADDB-59BF-4EDF-B278-59791B203EA2
F1908-0167