chemistry

Retene

Retene 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 Retene rather than just read about it. In short: Retene, methyl isopropyl phenanthrene or 1-methyl-7-isopropyl phenanthrene, C18H18, is a polycyclic aromatic hydrocarbon present in the coal tar fraction, boiling above 360 °C. It occurs naturally in the tars obtained by the distillation of resinous woods.

Key takeaways

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

Reference excerpt

Retene, methyl isopropyl phenanthrene or 1-methyl-7-isopropyl phenanthrene, C18H18, is a polycyclic aromatic hydrocarbon present in the coal tar fraction, boiling above 360 °C. It occurs naturally in the tars obtained by the distillation of resinous woods. It crystallizes in large plates, which melt at 98.5 °C and boil at 390 °C. It is readily soluble in warm ether and in hot glacial acetic acid. Sodium and boiling amyl alcohol reduce it to a tetrahydroretene, but if it heated with phosphorus and hydriodic acid to 260 °C, a dodecahydride is formed. Chromic acid oxidizes it to retene quinone, phthalic acid and acetic acid. It forms a picrate that melts at 123-124 °C. Retene is derived by degradation of specific diterpenoids biologically produced by conifer trees. The presence of traces of retene in the air is an indicator of forest fires; it is a major product of pyrolysis of conifer trees. It is also present in effluents from wood pulp and paper mills. Retene, together with cadalene, simonellite and ip-iHMN, is a biomarker of vascular plants, which makes it useful for paleobotanic analysis of rock sediments. The ratio of retene/cadalene in sediments can reveal the ratio of the genus Pinaceae in the biosphere.

Health effects A recent study has shown retene, which is a component of the Amazonian organic PM10, is cytotoxic to human lung cells.

References

This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Retene". Encyclopædia Britannica. Vol. 23 (11th ed.). Cambridge University Press. p. 202.

Illustrations

Worked examples

Example 1 — a first encounter with Retene

Start with the simplest possible case. Write down what Retene 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 Retene 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 Retene 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 Retene

In research: Retene 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 Retene 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: Retene is common in secondary-school and first-year university syllabi. It links to neighbouring topics Biomarkers, Isopropyl compounds, Petroleum products, so understanding it makes those chapters shorter.
In everyday life: Look for Retene 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.

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How to study Retene in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Retene 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 Retene out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Retene in simple terms?

Why does Retene 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 Retene?

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 Retene.