chemistry

Hofmann–Martius rearrangement

Hofmann–Martius rearrangement 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 Hofmann–Martius rearrangement rather than just read about it. In short: The Hofmann–Martius rearrangement in organic chemistry is a rearrangement reaction converting an N-alkylated aniline to the corresponding ortho and / or para aryl-alkylated aniline. The reaction requires heat, and the catalyst is an acid like hydrochloric acid.

Key takeaways

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

Reference excerpt

The Hofmann–Martius rearrangement in organic chemistry is a rearrangement reaction converting an N-alkylated aniline to the corresponding ortho and / or para aryl-alkylated aniline. The reaction requires heat, and the catalyst is an acid like hydrochloric acid.

When the catalyst is a metal halide the reaction is also called the Reilly–Hickinbottom rearrangement (named after Wilfred Hickinbottom and Joseph Reilly). The reaction is also known to work for aryl ethers and two conceptually related reactions are the Fries rearrangement and the Fischer–Hepp rearrangement. Its reaction mechanism centers around dissociation of the reactant with the positively charged organic residue R attacking the aniline ring in a Friedel–Crafts alkylation. In one study this rearrangement was applied to a 3-N(CH3)(C6H5)-2-oxindole:

The reaction is named after German chemists August Wilhelm von Hofmann and Carl Alexander von Martius.

See also Friedel–Crafts alkylation-like reactions: Fries rearrangement Fischer–Hepp rearrangement

References

Illustrations

Worked examples

Example 1 — a first encounter with Hofmann–Martius rearrangement

Start with the simplest possible case. Write down what Hofmann–Martius rearrangement 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 Hofmann–Martius rearrangement 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 Hofmann–Martius rearrangement 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 Hofmann–Martius rearrangement

In research: Hofmann–Martius rearrangement 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 Hofmann–Martius rearrangement 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: Hofmann–Martius rearrangement is common in secondary-school and first-year university syllabi. It links to neighbouring topics Rearrangement reactions, so understanding it makes those chapters shorter.
In everyday life: Look for Hofmann–Martius rearrangement 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 Hofmann–Martius rearrangement in 20 minutes

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

Frequently asked questions

What is Hofmann–Martius rearrangement in simple terms?

Why does Hofmann–Martius rearrangement 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 Hofmann–Martius rearrangement?

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 Hofmann–Martius rearrangement.