What is Benzene Hexachloride Definition Preparation Properties and Uses
Benzene hexachloride (BHC) is an organochlorine chemical compound which is an isomer of gammexane with the formula C6H6C16. As it is produced by the chlorination of benzene that’s why it is commonly known as benzene hexachloride. Although it is also known as Lindane or gamma – hexachlorocyclohexane (𝛾 - HCH). It has various other names as well such as gammaxene or Gammallin etc. Its IUPAC name is 1,2,3,4,5,6 – hexachlorocyclohexane. Its production and agricultural use are banned in almost 182 countries. Although its pharmaceutical use is allowed in almost all the countries.
Preparation of Benzene Hexachloride
English scientist Michael Faraday synthesized benzene hexachloride for the first time in 1825. Although it was 1st isolated in 1912 by Dutch Chemist Teunis van der Linden. That’s why the compound is named after him.
It is prepared by light induced chlorination of benzene. In presence of UV light and heat, benzene undergoes an additional reaction with chlorine molecules and gives lindane or benzene hexachloride. Reaction is given below –
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In this reaction benzene loses its aromaticity and changes into an alkane. Thus, in the reaction delocalization of pi – bonds in the benzene ring is removed by addition of chlorine atoms to each carbon atom of the benzene ring.
Benzene Hexachloride Structure – C6H6C16
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Benzene Hexachloride Structural Formula
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Lindane consists of six atoms of carbon, hydrogen, and chlorine. C6H6C16is the chemical formula of lindane. Chlorine and hydrogen atoms of lindane can stick above and below the ring randomly. Due to this it has a number of geometric isomers. Although it is not an aromatic compound and doesn't have a delocalized pi-electron system in the ring. Its isomers such as gamma – hexachlorocyclohexane (𝛾 - HCH), Gammexane etc. are used as insecticides.
Properties of Benzene Hexachloride
Properties of benzene hexachloride are as follows –
Its molecular formula is C6H6C16.
Its molecular weight is 291g/mol
Its density is 1.89 at 66℉.
Its boiling point is 323℃.
Its melting point is 113℃.
Uses of Benzene Hexachloride
Benzene hexachloride and isomers are used in various fields. Some of its uses are listed below –
It is used for pharmaceutical treatment of lice and scabies (or seven – year itch).
It is also used as an agricultural insecticide. Although presently its agricultural use is regulated or banned in many countries. During 1950-2000, 600000 tons of BHC was produced globally for agricultural use.
It is used in medicinal shampoo or lotions.
It is used for second line treatments of various diseases.
It is used for seed treatment.
Benzene Hexachloride Health Risks
According to the World Health Organization, BHC or lindane is moderately acutely toxic. This is the reason its usage in agriculture has been regulated or banned. Its higher amount can affect the nervous system and its production process is harmful for the environment.
Large amounts of lindane can cause headache, dizziness, convulsions or even death in rare cases. It can affect the brain development of the child and can alter the thyroid hormone levels. At the level of 50 mg/m3 and above, lindane may cause immediate death or can be very dangerous for life and health.
It is listed as one of the extremely hazardous substances in the list of extremely hazardous substances in the US. ‘International Agency for Research on Cancer’ declared lindane a human carcinogen. Although WHO declared lindane as non – carcinogenic to humans, India’s BIS considered BHC a ‘confirmed carcinogen’.
It causes some adverse reactions which may cause seizures, skin irritation, itching, rash, burning sensation. These reactions of lindane make the skin very sensitive. It cannot be used for premature babies as it may cause severe neurotoxicity.
Lindane pollutes the environment. It is termed as a persistent organic pollutant or forever chemical. As it is a long lasting chemical in the environment. Its agricultural use is the primary reason for its presence in the environment. Through agriculture, it enters the food chains as well. The production process of lindane gives a large amount of toxic waste. According to studies, every ton of BHC production gives ten tons of toxic waste. BHC in soil can leach to groundwater and can reach to the atmosphere by volatilization and therefore can be deposited by rainfall.
Due to its agricultural applications a large quantity of lindane has been reported in the human body which is very dangerous for human health.
Thus, lindane or BHC should be used vigilantly. All guidelines of the environmental protection agency and world health organization regarding lindane must be followed during its production and usage for a healthy environment and ecosystem.
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Chemical Properties of Benzene Hexachloride
Benzene hexachloride is one of the important topics in school chemistry and students must thoroughly know about its chemical properties as it holds high chances of appearing in the exams and has high weightage too which could make it easier for students to score high in their exams. Now let’s understand what are the chemical properties of benzene hexachloride. C6H6C16 is the molecular formula for benzene hexachloride, and it’s molecular weight is 290.8, whereas its parent compound is CID 241 (Benzene) and component compounds as CID 313 (Hydrochloric acid) CID 241 (Benzene)Potential
Exposure of Benzene Hexachloride
BHC's main commercial application is for its insecticidal capabilities. Agricultural chemicals, pesticides, pharmaceuticals, and veterinary drugs all include -BCC. Although the 7-isomer has the maximum acute toxicity, the other isomers have some action as well. Purifying the 7-isomer from the less active isomers is often favorable. The -isomer affects the neurological system of insects, mostly at the nerve ganglia level. As a result, lindane has been used to combat insects in a variety of settings, including the treatment of animals, buildings, humans for ectoparasites, clothing; water for mosquitoes; living plants; seeds, and soils.
Some applications, such as storing food, have been abandoned due to high residues. On September 1, 1976, the primary domestic producer of technical grade BHC requested revocation of its BHC registrations through voluntary action. All of the pesticide products containing the registrants of BHC voluntarily terminated their registrations or switched their previous BHC products to lindane formulations as of July 21, 1978.
Incompatibilities of Benzene Hexachloride
Contact with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, and others) can result in fires or explosions. Alkaline materials, strong bases, strong acids, oxoacids, and epoxides should be avoided. When it comes into contact with powdered iron, aluminum, zinc, or strong bases, it decomposes into trichlorobenzene.
Waste Disposal
The destructive pyrolysis of benzene hexachloride at temperatures of 400 to 500°C has been developed using a catalyst mixture containing 5 to 10% zinc chloride, cupric chloride, or aluminum chloride on activated carbon and ferric chloride.
FAQs on Benzene Hexachloride Structure Properties and Applications
1. What is Benzene Hexachloride?
Benzene Hexachloride (BHC) is an organochlorine compound with the molecular formula C6H6Cl6, formed by the addition of chlorine to benzene. It is also known as hexachlorocyclohexane (HCH) because its structure is a saturated cyclohexane ring with six chlorine atoms attached. BHC is mainly used as an insecticide, and its most active isomer is gamma-hexachlorocyclohexane (lindane). It is different from hexachlorobenzene because BHC is not aromatic.
2. What is the chemical formula of Benzene Hexachloride?
The chemical formula of Benzene Hexachloride is C6H6Cl6. It is produced when one molecule of benzene reacts with three molecules of chlorine under ultraviolet light. The balanced reaction is:
C6H6(l) + 3Cl2(g) → C6H6Cl6(s)
This reaction is an example of an addition reaction rather than substitution.
3. How is Benzene Hexachloride prepared?
Benzene Hexachloride is prepared by the photochemical addition of chlorine to benzene in the presence of sunlight or ultraviolet light. The preparation involves:
- Passing Cl2 gas through liquid benzene
- Exposing the mixture to UV light
- Formation of solid C6H6Cl6
4. Why is Benzene Hexachloride called an addition product of benzene?
Benzene Hexachloride is called an addition product because chlorine adds across the double bonds of benzene without replacing hydrogen atoms. In this reaction:
- The aromatic ring of benzene loses its aromatic character
- Three molecules of Cl2 add to the ring
- No hydrogen atoms are substituted
5. What are the isomers of Benzene Hexachloride?
Benzene Hexachloride has several stereoisomers, mainly alpha (α), beta (β), gamma (γ), delta (δ), and epsilon (ε) forms. These isomers differ in the spatial arrangement of chlorine atoms on the cyclohexane ring. Among them:
- Gamma-HCH (lindane) is the most insecticidally active
- Alpha and beta isomers are less active
- The difference arises due to different axial and equatorial positions of chlorine atoms
6. What is the difference between Benzene Hexachloride and Hexachlorobenzene?
The main difference is that Benzene Hexachloride (C6H6Cl6) is an addition product, while Hexachlorobenzene (C6Cl6) is a substitution product of benzene. Key differences include:
- BHC: Formed by addition of 3Cl2, non-aromatic, contains hydrogen
- Hexachlorobenzene: Formed by complete substitution of all hydrogens, aromatic, no hydrogen atoms
- BHC has several stereoisomers; hexachlorobenzene does not
7. What are the uses of Benzene Hexachloride?
Benzene Hexachloride is mainly used as an insecticide and pesticide, especially in its gamma isomer form (lindane). Its uses include:
- Control of agricultural pests in crops
- Treatment of lice and scabies (lindane lotion)
- Protection of stored grains
8. Is Benzene Hexachloride harmful to the environment?
Yes, Benzene Hexachloride is environmentally harmful because it is a persistent organic pollutant (POP). It:
- Accumulates in soil and water
- Undergoes bioaccumulation in food chains
- Can cause toxic effects in humans and wildlife
9. What type of reaction forms Benzene Hexachloride from benzene?
Benzene Hexachloride is formed by a free radical addition reaction under UV light. In this process:
- Chlorine molecules undergo homolytic cleavage: Cl2 → 2Cl·
- Chlorine radicals add to the benzene ring
- The aromatic system is converted into a saturated cyclohexane structure
10. Why does benzene usually undergo substitution but forms Benzene Hexachloride by addition?
Benzene usually undergoes electrophilic substitution to preserve aromaticity, but under UV light and excess chlorine, it forms Benzene Hexachloride by addition. This happens because:
- UV light promotes a free radical mechanism
- The reaction conditions override the stability of the aromatic ring
- Three Cl2 molecules add across the ring
