chemistry

Methanesulfonic anhydride

Methanesulfonic anhydride 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 Methanesulfonic anhydride rather than just read about it. In short: Methanesulfonic anhydride (Ms2O) is the organosulfur compound with the formula (CH3SO2)2O. It is the acid anhydride of methanesulfonic acid.

Key takeaways

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

Reference excerpt

Methanesulfonic anhydride (Ms2O) is the organosulfur compound with the formula (CH3SO2)2O. It is the acid anhydride of methanesulfonic acid. Like methanesulfonyl chloride (MsCl), it may be used to generate mesylates (methanesulfonyl esters).

Preparation Ms2O may be prepared by the dehydration of methanesulfonic acid with phosphorus pentoxide as described by this idealized equation:

P2O5 + 6 CH3SO3H → 3 (CH3SO2)2O + 2 H3PO4 Ms2O can be purified by vacuum distillation or by recrystallization from methyl tert-butyl ether/toluene.

Reactions Passage of hydrogen chloride through molten Ms2O yields MsCl. Similar to MsCl, Ms2O can perform mesylation of alcohols to form sulfonate esters:

(CH3SO2)2O + ROH → CH3SO3R + CH3SO3H Use of Ms2O avoids the alkyl chloride, which can appear as a side-product when MsCl is used. Unlike MsCl, Ms2O may not be suitable for mesylation of the unsaturated alcohols. Examples of mesylation of alcohols with Ms2O:

Octadecyl methanesulfonate was prepared from octadecanol in pyridine. Secondary alcohol at the anomeric carbon of 2,3,4,5-O-Benzyl-protected glucose reacted to form a glycosyl mesylate, which was found to be more stable than its triflate counterpart, in 2,4,6-collidine. Ms2O also converts amines to sulfonamides.

Aromatic sulfonation Assisted by Lewis acid catalyst, Friedel-Crafts methylsulfonation of aryl ring can be achieved by Ms2O. In contrast to MsCl, either activated or deactivated benzene derivatives can form the corresponding sulfonates in satisfactory yields with Ms2O. Examples of aromatic sulfonation with Ms2O:

Sulfonation of chlorobenzene resulted in addition of methylsulfonyl group at para and ortho positions (with respect to chloride), with a ratio of 2 to 1, respectively; while reaction with Meta-dichlorobenzene gave monosulfonylated product at C4 position. With sulfuric acid, di-aryl sulfones were synthesized.

Esterification Ms2O catalyzes the esterification of alcohols by carboxylic acids. 2-Naphthyl acetate was prepared from 2-naphthol and glacial (anhydrous) acetic acid in the presence of Ms2O. Ethylene glycol undergoes double benzoylation by benzoic acid in the presence of Ms2O. Monosaccharides do not, however, undergo full acetylation using Ms2O.

Oxidation of alcohols Like Pfitzner–Moffatt oxidation and Swern oxidation, with DMSO, Ms2O can oxidize primary and secondary alcohols to aldehydes and ketones, respectively, in HMPA. This method applies to benzylic alcohol. HMPA may be substituted by dichloromethane but may result in more side-products.

See also Methanesulfonyl chloride Disulfuric acid Sodium pyrosulfate Acetic anhydride Trifluoromethanesulfonic anhydride

References

Illustrations

Worked examples

Example 1 — a first encounter with Methanesulfonic anhydride

Start with the simplest possible case. Write down what Methanesulfonic anhydride 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 Methanesulfonic anhydride 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 Methanesulfonic anhydride 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 Methanesulfonic anhydride

In research: Methanesulfonic anhydride 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 Methanesulfonic anhydride 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: Methanesulfonic anhydride is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acid anhydrides, Mesyl compounds, Organic compounds with 2 carbon atoms, so understanding it makes those chapters shorter.
In everyday life: Look for Methanesulfonic anhydride 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 Methanesulfonic anhydride in 20 minutes

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

Frequently asked questions

What is Methanesulfonic anhydride in simple terms?

Methanesulfonic anhydride (Ms2O) is the organosulfur compound with the formula (CH3SO2)2O. It is the acid anhydride of methanesulfonic acid.

Why does Methanesulfonic anhydride 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 Methanesulfonic anhydride?

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 Methanesulfonic anhydride.