chemistry

Tributylphosphine

Tributylphosphine 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 Tributylphosphine rather than just read about it. In short: Tributylphosphine is the organophosphorus compound with the chemical formula P(CH2CH2CH2CH3)3, often abbreviated as PBu3. It is a tertiary phosphine.

Key takeaways

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

Reference excerpt

Tributylphosphine is the organophosphorus compound with the chemical formula P(CH2CH2CH2CH3)3, often abbreviated as PBu3. It is a tertiary phosphine. It is an oily liquid at room temperature, with a nauseating odor. It reacts slowly with atmospheric oxygen, and rapidly with other oxidizing agents, to give tributylphosphine oxide. It is usually handled using air-free techniques.

Preparation Tributylphosphine is prepared industrially by the hydrophosphination of phosphine with 1-butene: the addition proceeds by a free radical mechanism, and so the Markovnikov rule is not followed.

PH3 + 3 CH2=CHCH2CH3 → P(CH2CH2CH2CH3)3 Tributylphosphine can be prepared in the laboratory by reaction of the appropriate Grignard reagent with phosphorus trichloride although, as it is commercially available at reasonable prices, it is rare to have to perform the small-scale preparation.

3 CH3CH2CH2CH2MgCl + PCl3 → P(CH2CH2CH2CH3)3 + 3 MgCl2

Reactions Tributylphosphine reacts with oxygen to give the corresponding phosphine oxide (here tributylphosphine oxide):

2 P(CH2CH2CH2CH3)3 + O2 → 2 O=P(CH2CH2CH2CH3)3 Because this reaction is so fast, the compound is usually handled under an inert atmosphere. The phosphine is also easily alkylated. For example, benzyl chloride gives a phosphonium salt (here tributyl(phenylmethyl)phosphonium chloride):

P(CH2CH2CH2CH3)3 + PhCH2Cl → [PhCH2P(CH2CH2CH2CH3)3]+Cl− Tributylphosphine is a common ligand for the preparation of complexes of transition metals in low oxidation states. It is cheaper and less air-sensitive than trimethylphosphine and other trialkylphosphines. Although its complexes are generally highly soluble, they are often more difficult to crystallize compared to complexes of more rigid phosphines. Furthermore, the 1H NMR properties are less easily interpreted and can mask signals for other ligands. Compared to other tertiary phosphines, it is compact (cone angle: 136°) and basic (χ-parameter: 5.25 cm−1)

Use Tributylphosphine finds some industrial use as a catalyst modifier in the cobalt-catalyzed hydroformylation of alkenes, where it greatly increases the ratio of straight-chain aldehydes to branched-chain aldehydes in the product mixture. However, tricyclohexylphosphine is even more effective for this purpose (although more expensive) and, in any case, rhodium catalysts are usually preferred to cobalt catalysts for the hydroformylation of alkenes. It is the precursor to the pesticide (2,4-dichlorobenzyl)tributylphosphonium chloride ("Phosfleur"). Although tributylphosphine is generally regarded as toxic, its biological effects can be manipulated by drug delivery strategies. For example, a photoactivatable version of tributylphosphine has been used to induce disulfide bond cleavage and reductive stress in living cells.

Odor The main laboratory inconvenience of tributylphosphine is its unpleasant smell.

Hazards Tributylphosphine is moderately toxic, with an LD50 of 750 mg/kg (oral, rats).

References

External links NMR data for tributylphosphine Material Safety Data Sheet Use of tributyl phosphine for the reduction of disulfide bonds in proteins

Illustrations

Worked examples

Example 1 — a first encounter with Tributylphosphine

Start with the simplest possible case. Write down what Tributylphosphine 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 Tributylphosphine 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 Tributylphosphine 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 Tributylphosphine

In research: Tributylphosphine 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 Tributylphosphine 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: Tributylphosphine is common in secondary-school and first-year university syllabi. It links to neighbouring topics Butyl compounds, Organophosphorus compounds, Tertiary phosphines, so understanding it makes those chapters shorter.
In everyday life: Look for Tributylphosphine 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 Tributylphosphine in 20 minutes

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

Frequently asked questions

What is Tributylphosphine in simple terms?

Tributylphosphine is the organophosphorus compound with the chemical formula P(CH2CH2CH2CH3)3, often abbreviated as PBu3. It is a tertiary phosphine.

Why does Tributylphosphine 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 Tributylphosphine?

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 Tributylphosphine.