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Schenck ene reaction

Schenck ene reaction 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 Schenck ene reaction rather than just read about it. In short: The Schenck ene reaction or the Schenk reaction is the reaction of singlet oxygen with alkenes to yield hydroperoxides. The hydroperoxides can be reduced to allylic alcohols or eliminate to form unsaturated carbonyl compounds.

Schenck ene reaction — main illustration
Schenck ene reaction — illustration

Key takeaways

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

Reference excerpt

The Schenck ene reaction or the Schenk reaction is the reaction of singlet oxygen with alkenes to yield hydroperoxides. The hydroperoxides can be reduced to allylic alcohols or eliminate to form unsaturated carbonyl compounds. It is a type II photooxygenation reaction, and is discovered in 1944 by Günther Otto Schenck. Its results are similar to ene reactions, hence its name.

Reaction conditions The singlet oxygen reagent can be produced via photochemical activation of triplet oxygen (regular oxygen) in the presence of photosensitizers like rose bengal. Chemical processes like the reaction between hydrogen peroxide and sodium hypochlorite are also viable.

Mechanism and selectivity Historically, four mechanisms have been proposed:

Experimental and computational studies show that the reaction actually proceeds via a two step no intermediate process. One can loosely interpret it as a mix of the perepoxide mechanism and the concerted mechanism. There is no perepoxide intermediate as in the classical sense of reaction intermediates, for there exists no energy barrier between it and the hydroperoxide product. Such a mechanism can account for the selectivity of the Schenck ene reaction. The singlet oxygen is more likely to abstract hydrogen from the side with more C-H bonds due to favorable interactions in the transition state:

Very bulky groups, like the tertiary butyl group, will hinder hydrogen abstraction on that side.

Applications The Schenck ene reaction is utilized in the biological and biomimetic synthesis of rhodonoids, yield

Many hydroperoxides derived from fatty acids, steroids, and terpenes are also formed via the Schenck ene reaction. For instance, the generation of cis-3-hexenal from linolenic acid: This enzyme catalyzed path follows a different mechanism from the usual Schenck ene reaction. Radicals are involved, and triplet oxygen is used instead of singlet oxygen.

See also Ene reaction Photooxygenation Singlet oxygen Hydroperoxide

References

Illustrations

Schenck ene reaction: Four proposed intermediates of the Schenck ene reaction
Four proposed intermediates of the Schenck ene reaction
Schenck ene reaction illustration
Schenck ene reaction: Biological synthesis of rhodonoid A
Biological synthesis of rhodonoid A
Schenck ene reaction: Organic synthesis of rhodonoid E and F
Organic synthesis of rhodonoid E and F
Schenck ene reaction: Cis-3-hexenal is generated by conversion of linolenic acid to the hydroperoxide by the action of a lipoxygenase followed by the lyase-induced formation of the hemiacetal.[5]
Cis-3-hexenal is generated by conversion of linolenic acid to the hydroperoxide by the action of a lipoxygenase followed by the lyase-induced formation of the hemiacetal.[5]

Worked examples

Example 1 — a first encounter with Schenck ene reaction

Start with the simplest possible case. Write down what Schenck ene reaction 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 Schenck ene reaction 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 Schenck ene reaction 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 Schenck ene reaction

In research
Schenck ene reaction 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 Schenck ene reaction 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
Schenck ene reaction is common in secondary-school and first-year university syllabi. It links to neighbouring topics Organic reactions, Reaction mechanisms, so understanding it makes those chapters shorter.
In everyday life
Look for Schenck ene reaction 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 Schenck ene reaction in 20 minutes

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

Frequently asked questions

What is Schenck ene reaction in simple terms?

The Schenck ene reaction or the Schenk reaction is the reaction of singlet oxygen with alkenes to yield hydroperoxides. The hydroperoxides can be reduced to allylic alcohols or eliminate to form unsaturated carbonyl compounds.

Why does Schenck ene reaction 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 Schenck ene reaction?

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 Schenck ene reaction.

Tags

  • Organic reactions
  • Reaction mechanisms

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