mathematics

Phosphite ester

Phosphite ester is a mathematics 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 Phosphite ester rather than just read about it. In short: In organic chemistry, a phosphite ester or organophosphite usually refers to an organophosphorous compound with the formula P(OR)3. They can be considered as esters of an unobserved tautomer phosphorous acid, H3PO3, with the simplest example being trimethylphosphite, P(OCH3)3.

Key takeaways

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

Reference excerpt

In organic chemistry, a phosphite ester or organophosphite usually refers to an organophosphorous compound with the formula P(OR)3. They can be considered as esters of an unobserved tautomer phosphorous acid, H3PO3, with the simplest example being trimethylphosphite, P(OCH3)3. Some phosphites can be considered esters of the dominant tautomer of phosphorous acid (HP(O)(OH)2). The simplest representative is dimethylphosphite with the formula HP(O)(OCH3)2. Both classes of phosphites are usually colorless liquids.

Synthesis From PCl3 Phosphite esters are typically prepared by treating phosphorus trichloride with an alcohol. For alkyl alcohols the displaced chloride ion can attack the phosphite, causing dealkylation to give a dialkylphosphite and an organochlorine compound. The overall reaction is as follows:

PCl3 + 3 C2H5OH → (C2H5O)2P(O)H + 2 HCl + C2H5Cl Alternatively, when the alcoholysis is conducted in the presence of proton acceptors (typically an amine base), one obtains the C3-symmetric trialkyl derivatives:

PCl3 + 3 C2H5OH + 3 R3N → (C2H5O)3P + 3 R3NHCl A base is not essential when using aromatic alcohols such as phenols, as they are not susceptible to attack by chloride, however it does catalyse the esterification reaction and is therefore often included.

By transesterification Phosphite esters can also be prepared by transesterification, as they undergo alcohol exchange upon heating with other alcohols. This process is reversible and can be used to produce mixed alkyl phosphites. Alternatively, if the phosphite of a volatile alcohol is used, such as trimethyl phosphite, then the by product (methanol) can be removed by distillation, allowing the reaction to be driven to completion.

Reactions and applications of tris(organo)phosphites

Reactions

Phosphites are oxidized to phosphate esters:

P(OR)3 + [O] → OP(OR)3 This reaction underpins the commercial use of some phosphite esters as stabilizers in polymers. Alkyl phosphite esters are used in the Perkow reaction for the formation of vinyl phosphonates, and in the Michaelis–Arbuzov reaction to form phosphonates. Aryl phosphite esters may not undergo these reactions and hence are commonly used as stabilizers in halogen-bearing polymers such as PVC. Phosphite esters may be used as reducing agents in more specialised cases. For example, triethylphosphite is known to reduce certain hydroperoxides to alcohols formed by autoxidation:

In this process the phosphite is converted to a phosphate ester. This reaction type is also utilized in the Wender Taxol total synthesis. As strong nucleophiles, phosphite esters add to aldehydes in the Abramov reaction.

Homogeneous catalysis

Phosphite esters are Lewis bases and hence can form coordination complexes with various metal ions. Representative phosphite ligands include trimethylphosphite ((MeO)3P), triethylphosphite ((EtO)3P), trimethylolpropane phosphite, and triphenylphosphite ((PhO)3P). Phosphites exhibit a smaller ligand cone angles than the structurally related phosphine ligand family. Phosphite ligands are components of industrial catalysts for hydroformylation and hydrocyanation.

Chemistry of HP(O)(OR)2

Diorganophosphites are derivatives of phosphorus(V) and can be viewed as the di-esters of phosphorous acid ((HO)2P(O)H). They exhibit tautomerism, however, the equilibrium overwhelmingly favours the right-hand (phosphonate-like) form:

(RO)2POH ⇌ (RO)2P(O)H The P-H bond is the site of high reactivity in these compounds (for example in the Atherton–Todd reaction and Hirao coupling), whereas in tri-organophosphites the lone pair on phosphorus is the site of high reactivity. Diorganophosphites do however undergo transesterification.

See also Phosphinite P(OR)R2 Phosphonite P(OR)2R Ortho ester CH(OR)3 Borate ester B(OR)3

References

Illustrations

Worked examples

Example 1 — a first encounter with Phosphite ester

Start with the simplest possible case. Write down what Phosphite ester 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 Phosphite ester 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 Phosphite ester 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 Phosphite ester

In research: Phosphite ester 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 Phosphite ester 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: Phosphite ester is common in secondary-school and first-year university syllabi. It links to neighbouring topics Esters, Functional groups, Organophosphites, so understanding it makes those chapters shorter.
In everyday life: Look for Phosphite ester 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 Phosphite ester in 20 minutes

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

Frequently asked questions

What is Phosphite ester in simple terms?

Why does Phosphite ester 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 Phosphite ester?

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 Phosphite ester.