chemistry

Radialene

Radialene 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 Radialene rather than just read about it. In short: [n]Radialenes are alicyclic organic compounds containing n cross-conjugated exocyclic double bonds. The double bonds are commonly alkene groups but those with a carbonyl (C=O) group are also called radialenes.

Key takeaways

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

Reference excerpt

[n]Radialenes are alicyclic organic compounds containing n cross-conjugated exocyclic double bonds. The double bonds are commonly alkene groups but those with a carbonyl (C=O) group are also called radialenes. For some members the unsubstituted parent radialenes are elusive but many substituted derivatives are known. Radialenes are related to open-chain dendralenes and also to compounds like butadiene and benzene which also consist of a ring of sp2 hybridized carbon atoms. Radialenes are investigated in organic chemistry for their unusual properties and reactivity but have not ventured outside the laboratory. Reported uses are as experimental building blocks for novel organic conductors and ferromagnets. The first radialene called hexaethylidencyclohexane was synthesised in 1961.

Conformation [3] and [4]radialenes are expected to have a planar molecular geometry with all carbon atoms in the same plane. This is verified experimentally in hexamethyl[3]radialene and cyclobutanetetraonetetrakis(hydrazone). Decamethyl[5]radialene has a twist envelope geometry with C2 symmetry while a chair conformation is calculated for [6]radialene and found experimentally for hexa-(ethylidene)cyclohexane Due to their specific pi-electron distributions, hydrocarbons such as perylene and triphenylene are not considered radialenes. One study describes a [6]radialene composed of thiophene units:

This compound is reported as planar with D3h symmetry (X-ray diffraction) but not aromatic: the carbon-carbon bond lengths are unusually long (145 pm vs. 140 pm for benzene) and the calculated NICS value is close to zero. An analogous [8]radialene which adopts a saddle conformation with D2d symmetry is an intermediate in the synthesis of sulflower (C8S8):

Synthesis and properties The parent [3], [4], [5] and [6]radialenes polymerize when in contact with oxygen.

[3]Radialenes [3]Radialene or trimethylenecyclopropane was synthesised in 1965. Reported derivatives are triquinocyclopropanes, salts of trimethylenecyclopropane dianions, tris(thioxanthen-9-ylidene)cyclopropane, tris(fluoren-9-ylidene)cyclopropane and hexakis(trimethylsilylethynyl)[3]radialene. Phosphorus derivatives (based on 4,5,6-triphospha[3]radialene) have also been reported. Phospharadialenes have been investigated as quantum efficiency improvers in solar cells Hexakis[4-(diarylamino)phenyl][3]radialene derivatives have been investigated for their low oxidation potentials.

[4]Radialenes The unsubstituted [4]radialene has been prepared in an elimination reaction of cis,trans,cis-tetra(bromomethyl)cyclobutane with sodium methoxide in ethanol.

Hydrogenation with platinum on carbon gives cis,cis,cis-tetramethylcyclobutane in accordance with the proposed structure.

[5]Radialenes Successful low-temperature synthesis of the parent compound [5]radialene was reported in 2015.

[6]Radialenes The parent [6]radialene is unstable and polymerises immediately on formation. It has been synthesised from 1,5,9-cyclododecatriyne, 1,3,6-tri(chloromethyl)mesitylene and tricyclobutabenzene. Only substituted [6]radialenes exist as stable compounds. Stable derivatives are the hexamethyl substituted, dodecamethyl substituted and hexabromo substituted radialene. A trisalkoxy-substituted radialene has also been reported, the central ring adopting a non-planar twist-boat conformation:

Uses Radialenes have been researched as a potential way to access complex synthetic molecules and in polymer synthesis.

References

Illustrations

Worked examples

Example 1 — a first encounter with Radialene

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

In research: Radialene 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 Radialene 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: Radialene is common in secondary-school and first-year university syllabi. It links to neighbouring topics Cyclic compounds, Hydrocarbons, Oligomers, so understanding it makes those chapters shorter.
In everyday life: Look for Radialene 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 Radialene in 20 minutes

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

Frequently asked questions

What is Radialene in simple terms?

Why does Radialene 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 Radialene?

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 Radialene.