What is Benzoyl Peroxide Definition Formula Preparation and Uses
What is Benzoyl Peroxide?
Benzoyl Peroxide is an organic compound with structural formula C₅H₅−C(=O)O−)₂, abbreviated as BzO₂. It is a peroxide with a keratolytic, comedolytic, antibacterial, irritant, and anti-inflammatory action. It decomposes to release oxygen which is lethal to the bacteria Propionibacterium acnes. Benzoyl Peroxide appears as odourless white granules or powder. It is sparingly soluble in water. It enhances the turnover rate of epithelial cells, through peeling the skin. The Benzoyl Peroxide is an oxidizer, which is generally utilised in the generation of polymers.
Structure of Benzoyl Peroxide
The chemical structure of a molecule in the Benzoyl Peroxide involves the arrangement of the atoms and the chemical bonds that holds all the atoms collectively. The Benzoyl Peroxide molecule comprises 29 bonds. There are 14 multiple bonds, 5 rotatable bonds, 19 non-H bonds, 2 double bonds, 12 aromatic bonds, and 2 six-membered rings. In the structure of Benzoyl Peroxide, the carbon atoms are intended to be placed at the edges, and the hydrogen atoms attached to carbon atoms are not indicated. Each carbon atom is estimated to be associated with sufficient hydrogen atoms to render the carbon atom with 4 bonds.
Properties of Benzoyl Peroxide
The Physical and Chemical Data of Benzoyl Peroxide are given below.
Chemical Properties of Benzoyl Peroxide
Benzoyl Peroxide is an explosive and hazardous chemical compound.
It causes swelling of the skin.
Benzoyl Peroxide is prepared by the treatment of Benzoyl Chloride with Barium Peroxide.
This compound readily supports homolytic fission to yield free radical products that are incredibly reactive.
As it contacts human skin, it breaks down to produce oxygen and benzoic acid.
Physical Properties of Benzoyl Peroxide
Benzoyl peroxide has a colourless crystalline structure.
It has a faint odour with a smell of benzaldehyde.
It is insoluble in water and slightly soluble in alcohols.
It is considerably soluble in chloroform and ethers.
The dry form of Benzoyl Peroxide is highly reactive and can explode.
Benzoyl Peroxide melts within 103 °C and 106 °C with dissolution.
1 g Benzoyl Peroxide fluxes in 40 ml of Carbon Disulfide.
Uses of Benzoyl Peroxide
Benzoyl Peroxide was first prepared by Liebig in 1858. Treatment with Benzoyl Peroxide was introduced for wounds by Peck and Chagrin in 1934, and for acne varioliformis and sycosis Vulgaris by Reynolds and Lyon in 1929.
Benzoyl Peroxide is an effective organic peroxide because of its wide variety of uses. It is also manufactured on a large scale industrially. Some of the uses of this organic compound are listed below.
This organic compound can be applied to human skin to treat acne if the concentrations are between 2.5% to 10%.
Benzoyl Peroxide is used to extract ink and dye stains from many gadgets such as vinyl dolls.
Benzoyl Peroxide is used as a bleaching agent in bread and cheese.
It is used in cosmetic hair colouring and tooth whitening processes.
It is also a very useful oxidant.
With the help of the Benzoyl Peroxide, the polymerization process of resins can be started.
In the synthesis of thermosetting polyester resins, it can also be used as a catalyst.
Benzoyl Peroxide Side Effects
Some of the side effects of benzoyl peroxide are given below.
Dry skin
Skin Irritation
Red skin or flaying skin
Skin Blisters
Swollen skin, tongue, face, or throat
Severe Dizziness
Breathing Problems
FAQs on Benzoyl Peroxide Structure Properties and Applications
1. What is benzoyl peroxide in chemistry?
Benzoyl peroxide is an organic peroxide with the molecular formula C14H10O4 that contains a peroxide (–O–O–) linkage between two benzoyl groups. It is derived from benzoic acid and consists of two C6H5CO– units connected by an –O–O– bond. Because the O–O bond is relatively weak, benzoyl peroxide readily decomposes to form free radicals, making it important in polymer chemistry and medicinal applications.
2. What is the structural formula of benzoyl peroxide?
The structural formula of benzoyl peroxide is C6H5–CO–O–O–CO–C6H5, showing two benzoyl groups linked by a peroxide bond. Key structural features include:
- A central –O–O– (peroxide) linkage.
- Two carbonyl (C=O) groups.
- Two phenyl (C6H5–) rings.
The weak O–O bond is responsible for its high reactivity and ability to generate radicals.
3. Why is benzoyl peroxide considered a peroxide?
Benzoyl peroxide is considered a peroxide because it contains an oxygen–oxygen single bond (–O–O–), which defines the peroxide functional group. Peroxides are characterized by:
- The presence of an O–O bond.
- Relatively low bond dissociation energy.
- Ability to form free radicals upon homolytic cleavage.
In benzoyl peroxide, breaking the O–O bond forms benzoyloxy radicals, which initiate chemical reactions such as polymerization.
4. How does benzoyl peroxide decompose chemically?
Benzoyl peroxide decomposes by homolytic cleavage of its O–O bond to form free radicals. The primary step is:
(C6H5CO–O–O–COC6H5)(s) → 2 C6H5COO·
- The product is a benzoyloxy radical.
- These radicals may further decompose to form CO2 and phenyl radicals.
- The process is accelerated by heat, light, or shock.
This radical formation explains its use as a polymerization initiator and its reactive nature.
5. What is the molar mass of benzoyl peroxide?
The molar mass of benzoyl peroxide (C14H10O4) is approximately 242.23 g·mol−1. It is calculated as:
- Carbon: 14 × 12.01 = 168.14 g·mol−1
- Hydrogen: 10 × 1.008 = 10.08 g·mol−1
- Oxygen: 4 × 16.00 = 64.00 g·mol−1
Total = 168.14 + 10.08 + 64.00 = 242.22–242.23 g·mol−1 (depending on rounding).
6. How is benzoyl peroxide used as a polymerization initiator?
Benzoyl peroxide acts as a free radical initiator in addition polymerization by generating radicals that start chain reactions. The process involves:
- Initiation: Thermal decomposition forms benzoyloxy radicals.
- Propagation: Radicals add to a monomer such as ethene (CH2=CH2).
- Termination: Two radical chains combine.
For example, in polymerization of ethene:
n CH2=CH2 → (–CH2–CH2–)n
The initiator provides the first radical that begins the chain reaction.
7. What is the difference between benzoyl peroxide and hydrogen peroxide?
The main difference is that benzoyl peroxide is an organic peroxide (C14H10O4) containing benzoyl groups, while hydrogen peroxide is an inorganic peroxide (H2O2) composed only of hydrogen and oxygen. Key differences include:
- Structure: Benzoyl peroxide has aromatic rings; hydrogen peroxide does not.
- Uses: Benzoyl peroxide is used in polymerization and acne treatment; hydrogen peroxide is used as a disinfectant and bleaching agent.
- Stability: Both contain O–O bonds, but benzoyl peroxide is more shock-sensitive in solid form.
8. Why is benzoyl peroxide effective in acne treatment?
Benzoyl peroxide is effective against acne because it decomposes to release reactive oxygen species that kill bacteria and reduce inflammation. Chemically:
- It breaks down to form radicals and oxygen.
- The released oxygen creates an environment unfavorable for Cutibacterium acnes.
- It also has mild keratolytic (skin-peeling) action.
Its oxidizing and antibacterial properties make it widely used in dermatology.
9. Is benzoyl peroxide an oxidizing agent?
Yes, benzoyl peroxide is a strong oxidizing agent because it readily forms reactive radicals and can transfer oxygen. As an oxidizer:
- It can initiate oxidation reactions in organic compounds.
- It may react vigorously with reducing agents.
- It must be stored away from heat and combustible materials.
Its oxidizing nature is directly related to the weak peroxide bond.
10. What safety precautions should be taken when handling benzoyl peroxide?
Benzoyl peroxide should be handled carefully because it is an organic peroxide that can decompose explosively under certain conditions. Important precautions include:
- Store in a cool, dry place away from heat and light.
- Avoid friction, shock, and contamination with reducing agents.
- Wear gloves and eye protection in laboratory settings.
- Keep away from flammable materials.
Proper storage and handling reduce the risk of rapid decomposition and fire hazards.
