Benzoyl peroxide

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Benzoyl peroxide
IUPAC name	Dibenzoyldioxidane
Molecular formula	(C6H5CO)2O2 or C14H10O4
Molar mass	242.23 g/mol
CAS number	[94-36-0]
Density	1.334 g/cm3
Solubility	Poor
Melting point	103–5 °C decomp.
SMILES	c1ccccc1C(=O)OOC(=O)c2ccccc2
Hazards
EU classification	Explosive (E) Irritant (Xi)
EU Index	617-008-00-0
NFPA 704	4 1 4 OX
R-phrases	R2, R36, R43
S-phrases	S2, S3/7, S14, S36/37/39
Autoignition temperature	80°C
RTECS number	DM8575000
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Benzoyl peroxide (IPA [ˈbɛnzəʊɪl pəˈrɒksaɪd]) is a chemical in the organic peroxide family. It consists of two benzoyl groups (benzaldehyde with the H of CHO removed) joined by a peroxide group.

Trademarks for benzoyl peroxide include OXY, NeoBenz Micro, Basiron, Brevoxyl, Stioxyl, and Panoxyl.

Contents 1 Precautions 2 Uses 3 Safety 4 Double Displacement 5 Decomposition 6 References 7 External links

[edit] Precautions

Benzoyl peroxide, like most peroxides, is a powerful bleaching agent. Contact with fabric (including clothing and bed linens) or hair can cause permanent color dampening almost immediately. At high concentrations, benzoyl peroxide is highly flammable and explosive and should be handled with care. In the United States, the typical concentration for benzoyl peroxide is 2.5% to 10% for both prescription and over the counter use.

[edit] Uses

Benzoyl peroxide is effective in the treatment of most forms of acne. It is typically placed over the affected areas in gel or cream form, in concentrations of 2.5% increasing through the usually effective 5% to up to 10%. Research suggests that 5 and 10% concentrations are not significantly more effective than 2.5% and 2.5% is usually better tolerated.^[1][2] It commonly causes initial dryness and sometimes irritation, although skin tolerance usually occurs after a week or so. A small percentage of people are much more sensitive to it and liable to suffer burning, itching, peeling and possibly swelling^[3]. It is sensible to apply the lowest concentration and build up as appropriate. Once tolerance is achieved, increasing the quantity or concentration a second time and gaining tolerance at a higher level usually gives better subsequent acne clearance. Benzoyl peroxide works as a peeling agent, increasing skin turnover and clearing pores, thus reducing the bacterial count there as well as directly as an antibacterial.

Other common uses for benzoyl peroxide include dyeing hair, and as an active ingredient in teeth whitening systems. It is also used in the preparation of flour, and can be used as an initiator and catalyst for polyester thermoset resins (as an alternative to the much more hazardous methyl ethyl ketone peroxide).

[edit] Safety

Benzoyl peroxide breaks down in contact with skin, producing benzoic acid and oxygen, neither of which are significantly toxic.^[4]

When applied to skin benzoyl peroxide has been shown to induce cancer, but only when used at 100% concentrations; it has not been shown to do this at the far lower concentrations used for treating acne, and at lower concentrations benzoyl peroxide has been found not to be mutagenic or carcinogenic.^{[citation needed]}

Benzoyl peroxide removes the top layer of skin, which also decreases the sun protective effect (roughly SPF 3). This can cause sunburn and premature aging if sun protection is not worn. If sun protection is used, benzoyl peroxide has a similar effects to glycolic acid peels which are so-called anti-aging treatments.

[edit] Double Displacement

Mixing sodium peroxide with benzoyl chloride gives benzoyl peroxide and sodium chloride.

[edit] Decomposition

The half-life of benzoyl peroxide is one hour at 92°C. At 131°C, the half-life is one minute. ^[5]

[edit] References

1. ^ Mills, OH Jr; Kligman AM, Pochi P, Comite H (1986). "Comparing 2.5%, 5%, and 10% benzoyl peroxide on inflammatory acne vulgaris.". International Journal of Dermatology 25 (10): 664–667. PMID 2948929. 
2. ^ Yong, CC (1979). "Benzoyl peroxide gel therapy in acne in Singapore.". International Journal of Dermatology 18 (6): 485–488. PMID 158569. 
3. ^ Typical product information leaflets and monographs
4. ^ "Benzoyl Peroxide" section 3.1.1
5. ^ Hui Li (1998). "Synthesis, Characterization and Properties of Vinyl Ester Matrix Resins" (PDF). Retrieved on 2007-02-17.

[edit] External links

• International Chemical Safety Card 0225
• NIOSH Pocket Guide to Chemical Hazards 0052
• Institut national de recherche et de sécurité (1999). "Peroxyde de dibenzoyle." Fiche toxicologique n° 33. Paris:INRS. (PDF file, in French)

• IARC Monograph "Benzoyl peroxide."
• MedLine Drug Information: Benzoyl Peroxide
• Benzoyl Peroxide
• Links to external chemical sources

v • d • e Acne-treating agents (D10)
Topical agents	Azelaic acid, Benzoyl peroxide, Glycolic acid, Light therapy, Salicylic acid, Tea tree oil
Antibiotics	Clindamycin, Co-trimoxazole, Erythromycin, Sulfacetamide, Teicoplanin, Tetracyclines, Trimethoprim, Vancomycin
Hormonal	Antiandrogens, Contraceptives
Retinoids	Adapalene, Isotretinoin, Tazarotene, Tretinoin