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Group transfer reaction

Group transfer 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 Group transfer reaction rather than just read about it. In short: In organic chemistry, a group transfer reaction is a class of the pericyclic reaction where one or more groups of atoms is transferred from one molecule to another. Group transfer reactions can sometimes be difficult to identify when separate reactant molecules combine into a single product molecule (like in the ene reaction).

Group transfer reaction — main illustration
Group transfer reaction — illustration

Key takeaways

  • Group transfer 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 Group transfer reaction to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Group transfer reaction from memory before moving on to harder problems.

Reference excerpt

In organic chemistry, a group transfer reaction is a class of the pericyclic reaction where one or more groups of atoms is transferred from one molecule to another. Group transfer reactions can sometimes be difficult to identify when separate reactant molecules combine into a single product molecule (like in the ene reaction). Unlike other pericyclic reaction classes, group transfer reactions do not have a specific conversion of pi bonds into sigma bonds or vice versa, and tend to be less frequently encountered. Like all pericyclic reactions, group transfer reactions must obey the Woodward–Hoffmann rules. Group transfer reactions can be divided into two distinct subcategories: the ene reaction and the diimide reduction. Group transfer reactions have diverse applications in various fields, including protein adenylation, biocatalytic and chemoenzymatic approaches for chemical synthesis, and strengthening skim natural rubber latex.

Mechanism A defining feature of the group transfer reaction is that it is a concerted reaction, in which a bond is broken and formed in one step. The concerted reaction occurs due to the orbital overlap between the alkene and the allylic enophile. The electrons in the highest occupied molecular orbital (HOMO) of the ene are transferred to the lowest occupied molecular orbital (LUMO) of the enophile.

Sub-categories of Group Transfer Reactions

Ene Reaction The ene reaction is one of the most common forms of group transfer reactions, where an allylic hydrogen is transferred to an alkene in a cyclic concerted mechanism. The ene reaction is further divided into subgroups including intramolecular ene, metallo-ene, and carbonyl ene reactions. The reverse reaction, commonly called the retro-ene reaction, can occur under high temperatures.

Reductions with Diimide Reductions with diimide is another class of group transfer reactions, in which alkenes and alkynes are reduced concertedly with diimide as the reducing agent. In the generic mechanism of a reduction with diimide (Figure 3), nitrogen gas is lost as a result. The diimide reduction displays a higher selectivity for the symmetrical homonuclear C=C double bond compared to the heteronuclear C=O double bond. Along with a preference for reducing the least conjugated double bond, showcasing the precision of reductions with diimides in targeted organic synthesis.

Applications of Group Transfer Reactions

Protein Adenylylation Group transfer reactions are prevalent in many biological mechanisms. One example is protein adenylylation, where adenosine triphosphate (ATP) transfers an adenosine monophosphate group to another protein at threonine or tyrosine residues. Adenylylation protein modification adds a negative charge to the protein and thus changes its protein function. Protein adenylylation is especially documented in bacterial modification of GTPases, since this modification of GTPases via adenylylation prevents the host cell's ability to prevent infection.

Biocatalytic and Chemoenzymatic Approaches for Chemical Synthesis The application of the ene reduction can be observed in both biocatalytic and chemoenzymatic approaches for chemical synthesis. The capacity of ene reduction to catalyze diverse reactions with high selectivity renders it a valuable tool in the synthesis of complex and stereospecific compounds. Ene reduction plays a role in the production of fine chemicals, pharmaceutical compounds, agrochemicals, and biofuels. Highlighting the functionality of ene reductases emphasizes their crucial role in catalyzing a variety of reactions. One example is the ene-reductase Old-Yellow-Enzyme (OYE) which can reduce a carbon-carbon double bond (C=C) with a catalytic amount of NADH.

References

Illustrations

Group transfer reaction: Figure 2. Generic ene reaction.
Figure 2. Generic ene reaction.
Group transfer reaction: Figure 3. Generic mechanism of a reduction with diimide adapted from Mandal.[9]
Figure 3. Generic mechanism of a reduction with diimide adapted from Mandal.[9]
Group transfer reaction: Figure 4. Scheme of protein adenylylation of threonine and tyrosine side chains, a biological application of group transfer reactions. This figure is adapted from Hedberg and Itzen.[4]
Figure 4. Scheme of protein adenylylation of threonine and tyrosine side chains, a biological application of group transfer reactions. This figure is adapted from Hedberg and Itzen.[4]
Group transfer reaction: Figure 5. The ene reduction of an alkene using OYE2 ene reductase. This figure is adapted from an article on the Discovery, Characterization, Engineering, and Applications of Ene-Reductases for Industrial Biocatalysis.[5]
Figure 5. The ene reduction of an alkene using OYE2 ene reductase. This figure is adapted from an article on the Discovery, Characterization, Engineering, and Applications of Ene-Reductases for Industrial Biocatalysis.[5]

Worked examples

Example 1 — a first encounter with Group transfer reaction

Start with the simplest possible case. Write down what Group transfer 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 Group transfer 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 Group transfer 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 Group transfer reaction

In research
Group transfer 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 Group transfer 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
Group transfer reaction is common in secondary-school and first-year university syllabi. It links to neighbouring topics Pericyclic reactions, Rearrangement reactions, so understanding it makes those chapters shorter.
In everyday life
Look for Group transfer 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 Group transfer reaction in 20 minutes

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

Frequently asked questions

What is Group transfer reaction in simple terms?

In organic chemistry, a group transfer reaction is a class of the pericyclic reaction where one or more groups of atoms is transferred from one molecule to another. Group transfer reactions can sometimes be difficult to identify when separate reactant molecules combine into a single product molecul…

Why does Group transfer 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 Group transfer 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 Group transfer reaction.

Tags

  • Pericyclic reactions
  • Rearrangement reactions

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