chemistry

Phenylsulfinic acid

Phenylsulfinic acid 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 Phenylsulfinic acid rather than just read about it. In short: Phenylsulfinic acid is an organosulfur compound with the formula C6H5SO2H. It is a colorless or white crystalline solid that is usually stored in the form of its sodium salt.

Key takeaways

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

Reference excerpt

Phenylsulfinic acid is an organosulfur compound with the formula C6H5SO2H. It is a colorless or white crystalline solid that is usually stored in the form of its sodium salt. In aqueous solution it is strongly acidic and is easily oxidized in air. Phenylsulfinic acid and its esters are chiral.

Acidity There is a large range of pKa values in the literature, with most authors giving a value of around 1.30. This inconsistency can be explained by differences in ionic strength between quoted values. By measuring the pKa at various ionic strengths and extrapolating to zero ionic strength, the pKa of phenylsulfinic acid was determined to be 2.76. This makes phenylsulfinic acid a stronger acid than its corresponding carboxylic acid, benzoic acid (pKa = 4.2), but weaker than its corresponding sulfonic acid, benzenesulfonic acid (pKa = −6.5).

Preparation Phenylsulfinic acid can be prepared in several ways, most easily through reduction of sulfonyl chlorides with zinc dust or iron. However other starting materials can be used. Due to the air sensitivity of this compound it is often formed as a salt.

2 C6H5SO2Cl + 2 Zn → (C6H5SO2)2Zn + ZnCl2 (C6H5SO2)2Zn + Na2CO3 → 2 C6H5SO2Na + ZnCO3 A convenient method is the reduction of the sulfonyl chloride or sulfonyl fluoride with sodium sulfite, producing the acid instead of a salt:

C6H5SO2Cl + Na2SO3 + H2O → C6H5SO2H + NaCl + NaHSO4 Many other methods have been reported for production of sulfinic acids such as the use tin(II) chloride, or the Grignard reagent with sulfur dioxide. The preparation of sulfinic acids by the oxidation of thiols is difficult due to overoxidation.

Properties In sulfinic acids, sulfur has the +4 oxidation state. They are prone to oxidation to sulphonic acids as well as reduction via sulphenic acids (+2) to thiols. Sulphinic acid derivatives disproportionate in the presence of acid:

2 PhSO2H → PhSO2SOPh + H2O PhSO2SOPh → PhSO2• + PhSO → PhSO3SPh PhSO3SPh + PhSO2H → PhSO3H + PhSO2SPh When phenylsulfinic acid reacts with sulfur to give thiosulfinates and thiosulfinic acids.

Use The main use of phenylsulfinic acid is for the asymmetric synthesis of carbon-carbon bonds due to its ability to stabilize negative charges on an adjacent carbon atom. Phenylsulfinic acid has been a component for electroplating of palladium alloys.

References

Illustrations

Worked examples

Example 1 — a first encounter with Phenylsulfinic acid

Start with the simplest possible case. Write down what Phenylsulfinic acid 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 Phenylsulfinic acid 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 Phenylsulfinic acid 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 Phenylsulfinic acid

In research: Phenylsulfinic acid 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 Phenylsulfinic acid 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: Phenylsulfinic acid is common in secondary-school and first-year university syllabi. It links to neighbouring topics Phenyl compounds, Sulfinic acids, so understanding it makes those chapters shorter.
In everyday life: Look for Phenylsulfinic acid 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 Phenylsulfinic acid in 20 minutes

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

Frequently asked questions

What is Phenylsulfinic acid in simple terms?

Phenylsulfinic acid is an organosulfur compound with the formula C6H5SO2H. It is a colorless or white crystalline solid that is usually stored in the form of its sodium salt.

Why does Phenylsulfinic acid 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 Phenylsulfinic acid?

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 Phenylsulfinic acid.