Sulfonyl halide

Key takeaways

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

Reference excerpt

In chemistry, a sulfonyl halide consists of a sulfonyl (>S(=O)2) group singly bonded to a halogen atom. They have the general formula RSO2X, where X is a halogen. The stability of sulfonyl halides decreases in the order fluorides > chlorides > bromides > iodides, all four types being well known. The sulfonyl chlorides and fluorides are of dominant importance in this series. Sulfonyl halides have tetrahedral sulfur centres attached to two oxygen atoms, an organic radical, and a halide. In a representative example, methanesulfonyl chloride, the S=O, S−C, and S−Cl bond distances are respectively 142.4, 176.3, and 204.6 pm.

Sulfonyl chlorides

Sulfonic acid chlorides, or sulfonyl chlorides, are a sulfonyl halide with the general formula RSO2Cl.

Production Arylsulfonyl chlorides are made industrially in a two-step, one-pot reaction from an arene (in this case, benzene) and chlorosulfuric acid:

C6H6 + HOSO2Cl → C6H5SO3H + HCl C6H5SO3H + HOSO2Cl → C6H5SO2Cl + H2SO4 The intermediate benzenesulfonic acid can be chlorinated with thionyl chloride as well. Benzenesulfonyl chloride, the most important sulfonyl halide, can also be produced by treating sodium benzenesulfonate with phosphorus pentachlorides. Benzenediazonium chloride reacts with sulfur dioxide and copper(I) chloride to give the sulfonyl chloride:

[C6H5N2]Cl + SO2 → C6H5SO2Cl + N2 For alkylsulfonyl chlorides, one synthetic procedure is the Reed reaction:

RH + SO2 + Cl2 → RSO2Cl + HCl

Reactions Sulfonyl chlorides react with water to give the corresponding sulfonic acid:

RSO2Cl + H2O → RSO3H + HCl These compounds react readily with many other nucleophiles as well, most notably alcohols and amines (see Hinsberg reaction). If the nucleophile is an alcohol, the product is a sulfonate ester; if it is an amine, the product is a sulfonamide:

RSO2Cl + R'2NH → RSO2NR'2 + HCl However, sulfonyl chlorides also react frequently as a source of RSO−2 and Cl+. For example benzenesulfonyl chloride chlorinates ketene acetals and mesyl chloride chlorinates para-xylene under Friedel-Crafts conditions. Using sodium sulfite as the nucleophilic reagent, p-toluenesulfonyl chloride is converted to its sulfinate salt, CH3C6H4SO2Na. Chlorosulfonated alkanes are susceptible to crosslinking via reactions with various nucleophiles. Sulfonyl chlorides readily undergo Friedel–Crafts reactions with arenes giving sulfones, for example:

RSO2Cl + C6H6 → RSO2C6H5 + HCl A readily available arylsulfonyl chloride source is tosyl chloride. The desulfonation of arylsulfonyl chlorides provides a route to aryl chlorides:

ArSO2Cl → ArCl + SO2 1,2,4-Trichlorobenzene is made industrially in this way. Treatment of alkanesulfonyl chlorides having α-hydrogens with amine bases can give sulfenes, highly unstable species that can be trapped:

RCH2SO2Cl → RCH=SO2 + HCl Reduction with tetrathiotungstate ions (WS2−4) induces dimerization to the disulfide.

Common sulfonyl chlorides Chlorosulfonated polyethylene (CSPE) is produced industrially by chlorosulfonation of polyethylene. CSPE is noted for its toughness, hence its use for roofing shingles. An industrially important derivative is benzenesulfonyl chloride. In the laboratory, useful reagents include tosyl chloride, brosyl chloride, nosyl chloride and mesyl chloride.

Sulfonyl fluorides Sulfonyl fluorides have the general formula RSO2F. They can be produced by treating sulfonic acids with sulfur tetrafluoride:

SF4 + RSO3H → SOF2 + RSO2F + HF Perfluorooctanesulfonyl derivatives, such as PFOS, are produced from their sulfonyl fluoride, which are produced by electrofluorination In the molecular biology, sulfonyl fluorides are used to label proteins. They specifically react with serine, threonine, tyrosine, lysine, cysteine, and histidine residues. The fluorides are more resistant than the corresponding chlorides and are therefore better suited to this task. Some sulfonyl fluorides can also be used as deoxyfluorinating reagents, such as 2-pyridinesulfonyl fluoride (PyFluor) and N-tosyl-4-chlorobenzenesulfonimidoyl fluoride (SulfoxFluor).

Sulfonyl bromides Sulfonyl bromides have the general formula RSO2Br. In contrast to sulfonyl chlorides, sulfonyl bromides readily undergo light-induced homolysis affording sulfonyl radicals, which can add to alkenes, as illustrated by the use of bromomethanesulfonyl bromide, BrCH2SO2Br in Ramberg–Bäcklund reaction syntheses.

Sulfonyl iodides Sulfonyl iodides, having the general formula RSO2I, are quite light-sensitive. Methanesulfonyl iodide evolves iodine in vacuum and branched-alkyl sulfonyl iodides are worse. Perfluoroalkanesulfonyl iodides, prepared by reaction between silver perfluoroalkanesulfinates and iodine in dichloromethane at −30 °C, react with alkenes to form the normal adducts, RFSO2CH2CHIR and the adducts resulting from loss of SO2, RFCH2CHIR. Arenesulfonyl iodides, prepared from reaction of arenesulfinates or arenehydrazides with iodine, are much more stable and can initiate the synthesis of poly(methyl methacrylate) containing C–I, C–Br and C–Cl chain ends. Their reduction with silver gives the disulfone:

2 ArSO2I + 2Ag → (ArSO2)2 + 2 AgI

In popular culture In the episode "Encyclopedia Galactica" of his TV series Cosmos: A Personal Voyage, Carl Sagan speculates that some intelligent extraterrestrial beings might have a genetic code based on polyaromatic sulfonyl halides instead of DNA.

References

Worked examples

Example 1 — a first encounter with Sulfonyl halide

Start with the simplest possible case. Write down what Sulfonyl halide claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, 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 Sulfonyl halide 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 Sulfonyl halide 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 Sulfonyl halide

In research: Sulfonyl halide appears in mathematics 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 Sulfonyl halide 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: Sulfonyl halide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Functional groups, Sulfonyl halides, Sulfuryl compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Sulfonyl halide 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.

How to study Sulfonyl halide in 20 minutes

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

Frequently asked questions

What is Sulfonyl halide in simple terms?

In chemistry, a sulfonyl halide consists of a sulfonyl (>S(=O)2) group singly bonded to a halogen atom. They have the general formula RSO2X, where X is a halogen.

Why does Sulfonyl halide matter?

Because it connects several mathematics 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 Sulfonyl halide?

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 Sulfonyl halide.