chemistry

Hexachlorocyclohexane

Hexachlorocyclohexane is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hexachlorocyclohexane rather than just read about it. In short: Hexachlorocyclohexane (HCH), C6H6Cl6, is any of several polyhalogenated organic compounds consisting of a six-carbon ring with one chlorine and one hydrogen attached to each carbon. This structure has nine stereoisomers (eight diastereomers - one which has two enantiomers, and seven which are meso compounds), which differ by the stereochemistry of the individual chlorine substituents on the cyclohexane.

Key takeaways

Hexachlorocyclohexane belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Hexachlorocyclohexane to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Hexachlorocyclohexane from memory before moving on to harder problems.

Reference excerpt

Hexachlorocyclohexane (HCH), C6H6Cl6, is any of several polyhalogenated organic compounds consisting of a six-carbon ring with one chlorine and one hydrogen attached to each carbon. This structure has nine stereoisomers (eight diastereomers - one which has two enantiomers, and seven which are meso compounds), which differ by the stereochemistry of the individual chlorine substituents on the cyclohexane. It is sometimes erroneously called "benzene hexachloride" (BHC). They have been used as models for analyzing the effects of different geometric positions of the large atoms with dipolar bonds on the stability of the cyclohexane conformation. The isomers are poisonous, pesticidal, and persistent organic pollutants, to varying degrees. Hexachlorocyclohexane was dimerized to produce mirex, a banned pesticide. Common forms are:

alpha-hexachlorocyclohexane, α-HCH, or α-BHC (CAS RN: 319-84-6 ), the optically active isomer beta-hexachlorocyclohexane, β-HCH, or β-BHC (CAS RN: 319-85-7 ) gamma-hexachlorocyclohexane, γ-HCH, γ-BHC, or lindane (CAS RN: 58-89-9 ), the most insecticidal isomer delta-hexachlorocyclohexane, δ-HCH, or δ-BHC (CAS RN: 319-86-8 ) technical hexachlorocyclohexane, t-HCH, or t-BHC (CAS RN: 608-73-1 ), a mixture of isomers

Chlorination of benzene under electrophilic aromatic substitution conditions (Cl2/FeCl3 or Cl2/AlCl3) produces chlorobenzene. Since mono chloro-de-hydrogenation deactivates the molecule against further electrophilic reactions, the reaction can be halted at one chlorine atom substitution.

Electrophilic chlorination: C6H6 + Cl2 → C6H5Cl + HCl In contrast, chlorination of benzene under radical addition conditions (Cl2, hν (photochlorination) or Cl2, Δ, high P) yields hexachlorocyclohexane isomers after three successive radical dichlorination steps. Addition rather than substitution takes place, due to the very high C–H bond dissociation energy (112 kcal/mol) that disfavors abstraction of a hydrogen atom. Addition of Cl2 destroys the aromaticity of the benzene ring, and the addition of two more Cl2 molecules is rapid compared to the first. Hence, only thrice-dichlorinated product can be isolated from this reaction.

Radical addition: C6H6 + 3Cl2 → C6H6Cl6 Hexachlorocyclohexane isomers with more than one chlorine atom per carbon are:

1,1,2,3,4,5-hexachlorocyclohexane 1,1,2,3,4,6-hexachlorocyclohexane 1,1,2,3,5,6-hexachlorocyclohexane 1,1,2,2,3,4-hexachlorocyclohexane 1,1,2,2,3,5-hexachlorocyclohexane 1,1,2,2,3,6-hexachlorocyclohexane 1,1,2,2,4,5-hexachlorocyclohexane 1,1,2,3,3,4-hexachlorocyclohexane 1,1,2,3,3,5-hexachlorocyclohexane 1,1,2,3,4,4-hexachlorocyclohexane 1,1,2,4,4,5-hexachlorocyclohexane 1,1,2,4,4,6-hexachlorocyclohexane 1,1,2,4,5,5-hexachlorocyclohexane 1,1,2,5,6,6-hexachlorocyclohexane 1,1,2,2,3,3-hexachlorocyclohexane 1,1,2,2,4,4-hexachlorocyclohexane 1,1,3,3,5,5-hexachlorocyclohexane

See also Hexachlorobenzene - benzene derivative with one chlorine and no hydrogens bound to each carbon atom Inositol / Cyclohexane-1,2,3,4,5,6-hexol - cyclohexane derivatives with one hydroxyl bound to each carbon atom

References

External links Hexachlorocyclohexane (HCH), CDC

Illustrations

Worked examples

Example 1 — a first encounter with Hexachlorocyclohexane

Start with the simplest possible case. Write down what Hexachlorocyclohexane claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hexachlorocyclohexane before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hexachlorocyclohexane ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hexachlorocyclohexane

In research: Hexachlorocyclohexane appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Hexachlorocyclohexane in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Hexachlorocyclohexane is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cyclohexanes, Meso compounds, Organochlorides, so understanding it makes those chapters shorter.
In everyday life: Look for Hexachlorocyclohexane outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Hexachlorocyclohexane” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Hexachlorocyclohexane in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Hexachlorocyclohexane means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Hexachlorocyclohexane out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hexachlorocyclohexane in simple terms?

Why does Hexachlorocyclohexane matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hexachlorocyclohexane?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hexachlorocyclohexane.