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Benzoyl peroxide

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Benzoyl peroxide
Skeletal formula
Ball-and-stick model
Names
IUPAC name
dibenzoyl peroxide
Other names
benzoyl peroxide
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.002.116 Edit this at Wikidata
KEGG
RTECS number
  • DM8575000
UNII
  • InChI=1S/C14H10O4/c15-13(11-7-3-1-4-8-11)17-18-14(16)12-9-5-2-6-10-12/h1-10H checkY
    Key: OMPJBNCRMGITSC-UHFFFAOYSA-N checkY
  • InChI=1/C14H10O4/c15-13(11-7-3-1-4-8-11)17-18-14(16)12-9-5-2-6-10-12/h1-10H
    Key: OMPJBNCRMGITSC-UHFFFAOYAV
  • c1ccc(cc1)C(=O)OOC(=O)c2ccccc2
Properties
C14H10O4
Molar mass 242.230 g·mol−1
Appearance colourless solid
Density 1.334 g/cm3
Melting point 103–105 °C decomp.
poor
Pharmacology
License data
topical
Legal status
Hazards
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
3
1
3
OX
Supplementary data page
Benzoyl peroxide (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)
Tube of Basiron, a water-based 5% benzoyl peroxide preparation for the treatment of acne.

Benzoyl peroxide /ˈbɛnzɔɪl pəˈrɒksaɪd/ is an organic compound in the peroxide family. It consists of two benzoyl groups bridged by a peroxide link. Its structural formula is [C6H5C(O)]2O2. It is one of the most important organic peroxides in terms of applications and the scale of its production. Benzoyl peroxide is used as an acne treatment, for improving flour, for bleaching hair and teeth, for polymerising polyester and many other uses.

Benzoyl peroxide is included in the World Health Organization (WHO) Model Lists of essential medicines, which is a list of minimum medical needs for a basic health care system.

Synthesis, structure and physical properties

Benzoyl peroxide was the first organic peroxide prepared by intentional synthesis. It was prepared by treating benzoyl chloride with barium peroxide,[1] a reaction that probably follows this equation:

2 C6H5C(O)Cl + BaO2 → [C6H5C(O)]2O2 + BaCl2

Benzoyl peroxide is usually prepared by treating hydrogen peroxide with benzoyl chloride.

The oxygen-oxygen bond in peroxides is weak. Thus benzoyl peroxide readily undergoes homolysis (symmetrical fission), forming free radicals:

[C6H5C(O)]2O2 → 2 C6H5CO2•

The symbol • indicates that the products are radicals; i.e., they contain at least one unpaired electron. Such species are highly reactive. The homolysis is usually induced by heating. The half-life of benzoyl peroxide is one hour at 92 °C. At 131 °C, the half-life is one minute.[2]

Benzoyl peroxide breaks down in contact with skin, producing benzoic acid and oxygen, neither of which is significantly toxic.[3] It is important to note that the safety of the decomposition products does not mean that the substance itself is safe, as it is benzoyl peroxide's action as an oxidizing agent that is of importance. Hydrogen peroxide can be corrosive due to its oxidizing properties, but decomposes to form water and oxygen. Sodium hypochlorite (commonly known as "bleach") also shares these properties, but disproportionates to form harmless products such as sodium chloride.[citation needed]

Uses

Most benzoyl peroxide is used as a radical initiator to induce polymerizations.[4] Other major applications include its antiseptic and bleaching properties.

Acne treatment

Benzoyl peroxide works as a peeling agent. It increases skin turnover, clearing pores and reducing the bacterial count (specifically P. acnes) as well as acting directly as an antimicrobial.[5] It may be combined with salicylic acid, sulfur, erythromycin or clindamycin (antibiotics), and adapalene (a synthetic retinoid). Two common combination drugs include benzoyl peroxide/clindamycin and adapalene/benzoyl peroxide, a unique formulation considering most retinoids are deactivated by peroxides.

Benzoyl peroxide for acne treatment is typically applied to the affected areas in gel or cream form, in concentrations of 2.5% increasing through 5%, and up to 10%. Research suggests that 5% and 10% concentrations are slightly more effective than 2.5%, while 2.5% is usually better tolerated than the 10% concentration, though the majority of major studies comparing it to other treatments use the higher concentrations.[6][7]

Benzoyl peroxide commonly causes initial dryness and sometimes irritation, although the skin develops tolerance 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.[citation needed] It is sensible to apply the lowest concentration and build up as appropriate. Once tolerance is achieved, increasing the quantity or concentration and gaining tolerance at a higher level may give better subsequent acne clearance.[citation needed]

Other uses

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).[citation needed]

In the U.S., the typical concentration for benzoyl peroxide is 2.5% to 10% for both prescription and over-the-counter drug preparations that are used in treatment for acne. Higher concentrations are used for hair bleach and teeth whitening. Benzoyl peroxide, like most peroxides, is a powerful bleaching agent. Contact with fabrics or hair can cause permanent color dampening almost immediately. Even secondary contact can cause bleaching; for example, contact with a towel that has been used to wash off benzoyl peroxide-containing hygiene products.[8] In the paint industry, benzoyl peroxide is used as a hardener in order to start the polymerization process in resins. For instance, PMMA resins can be polymerized with benzoyl peroxide.[9]

Adverse effects

In a 1977 study using a human maximization test, 76% of subjects acquired a contact sensitization to benzoyl peroxide. Formulations of 5% and 10% were used.[10]

  • Skin irritation due to benzoyl peroxide
    Skin irritation due to benzoyl peroxide
  • A bleached fabric stain caused by contact with benzoyl peroxide.
    A bleached fabric stain caused by contact with benzoyl peroxide.

Safety

Concentrated benzoyl peroxide is potentially explosive,[11] and can cause fires without external ignition. The hazard is acute for the pure material, and for this reason, the compound is generally used as a solution or a paste. For example, cosmetics contain only a few percent of benzoyl peroxide and pose no explosion risk.

Studies have highlighted the carcinogenic potential of benzoyl peroxide. A 1981 study from the journal Science concluded that "caution should be recommended in the use of this and other free radical-generating compounds".[12]

References

  1. ^ Brodie, B. C. (1858), "Ueber die Bildung der Hyperoxyde organischer Säureradicale", Justus Liebigs Ann. Chem., 108: 79–83, doi:10.1002/jlac.18581080117
  2. ^ Li, Hui, III (1998), Synthesis, Characterization and Properties of Vinyl Ester Matrix Resins (PDF), Ph.D. Dissertation, University of Vermont, vol. Chapter 2{{citation}}: CS1 maint: multiple names: authors list (link)
  3. ^ Benzoyl peroxide (PDF), SIDS Initial Assessment Report, Geneva: United Nations Environment Programme, April 2004
  4. ^ Klenk, Herbert; Götz, Peter H.; Siegmeier, Rainer; Mayr, Wilfried. "Peroxy Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_199. ISBN 978-3527306732.
  5. ^ "Treating Acne Vulgaris: Systemic, Local and Combination Therapy: Benzoyl Peroxide". Medscape.com. 2010-08-17. Retrieved 2012-09-08.
  6. ^ Mills, O. H., Jr.; Kligman, A. M.; Pochi, P.; Comite, H. (1986), "Comparing 2.5%, 5%, and 10% benzoyl peroxide on inflammatory acne vulgaris", Int. J. Dermatol., 25 (10): 664–67, doi:10.1111/j.1365-4362.1986.tb04534.x, PMID 2948929{{citation}}: CS1 maint: multiple names: authors list (link)
  7. ^ Yong, C. C. (1979), "Benzoyl peroxide gel therapy in acne in Singapore", Int. J. Dermatol., 18 (6): 485–88, doi:10.1111/j.1365-4362.1979.tb01955.x, PMID 158569
  8. ^ Bojar, RA; Cunliffe, William; Holland, KT (1995), "The short-term treatment of acne vulgaris with benzoyl peroxide: effects on the surface and follicular cutaneous microflora.", Br J Dermatol, 132: 204–8, PMID 7888356
  9. ^ http://www.degaroute.com/sites/dc/Downloadcenter/Evonik/Product/DEGAROUTE/en/Degaroute%20Brosch%C3%BCre.pdf
  10. ^ Leyden, James J.; Kligman, Albert M. (1977), "Contact sensitization to benzoyl peroxide", Contact Dermatitis, 3 (5): 273–75, doi:10.1111/j.1600-0536.1977.tb03674.x
  11. ^ Cartwright, Hugh (17 March 2005). "Chemical Safety Data: Benzoyl peroxide". Oxford University. Retrieved 13 August 2011.
  12. ^ USA (2012-05-24). "Skin tumor-promoting activity of benzoyl peroxide, a... [Science. 1981] - PubMed - NCBI". Ncbi.nlm.nih.gov. Retrieved 2012-09-08.
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