Vinyl acetate

Key takeaways

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

Reference excerpt

Vinyl acetate is an organic compound with the formula CH3CO2CH=CH2. This colorless liquid is the precursor to polyvinyl acetate, ethylene-vinyl acetate, polyvinyl alcohol, and other important industrial polymers.

Production The worldwide production capacity of vinyl acetate was estimated at 6,969,000 tonnes/year in 2007, with most capacity concentrated in the United States (1,585,000 all in Texas), China (1,261,000), Japan (725,000) and Taiwan (650,000). The average list price for 2008 was US$1600/tonne. Celanese is the largest producer (ca 25% of the worldwide capacity), while other significant producers include China Petrochemical Corporation (7%), Chang Chun Group (6%), and LyondellBasell (5%). Vinyl acetate is mainly (80%) polymerized, and the resulting polymer is hydrolyzed to give polyvinyl alcohol.

Preparation Vinyl acetate is the acetate ester of vinyl alcohol. Since vinyl alcohol is highly unstable (with respect to acetaldehyde), the preparation of vinyl acetate is more complex than the synthesis of other acetate esters. The major industrial route involves the reaction of ethylene and acetic acid with oxygen in the presence of a palladium catalyst.

2 C2H4 + 2 CH3CO2H + O2 → 2 CH3CO2CHCH2 + 2 H2O This method has replaced the addition of acetic acid to acetylene. The main side reaction is the combustion of organic precursors.

Mechanism Isotope labeling and kinetics experiments suggest that the mechanism involves PdCH2CH2OAc-containing intermediates. Beta-hydride elimination would generate vinyl acetate and a palladium hydride, which would be oxidized to give hydroxide.

Alternative routes Vinyl acetate was once mainly prepared by hydroesterification, i.e., the addition of acetic acid to acetylene in the presence of metal catalysts. Using mercury(II) catalysts, vinyl acetate was first prepared by Fritz Klatte in 1912. Presently, zinc acetate is used as the catalyst:

CH3CO2H + C2H2 → CH3CO2CHCH2. Approximately 1/3 of the world's production relies on this route, which, because it is environmentally messy, is mainly practiced in countries with relaxed environmental regulations, such as China. Another route to vinyl acetate involves thermal decomposition of ethylidene diacetate:

(CH3CO2)2CHCH3 → CH3CO2CHCH2 + CH3CO2H.

Polymerization It can be polymerized to give polyvinyl acetate (PVAc). With other monomers it can be used to prepare various copolymers such as ethylene-vinyl acetate (EVA), vinyl acetate-acrylic acid (VA/AA), polyvinyl chloride acetate (PVCA), and polyvinylpyrrolidone (Vp/Va copolymer, used in hair gels). Due to the instability of the radical, attempts to control the polymerization by most "living/controlled" radical processes have proved problematic. However, RAFT (or more specifically, MADIX) polymerization offers a convenient method of controlling the synthesis of PVA by the addition of a xanthate or a dithiocarbamate chain transfer agent.

Other reactions Vinyl acetate is useful in organic synthesis. Vinyl acetate undergoes many of the reactions anticipated for an alkene and an ester. The most important ester reaction is transesterification with a variety of carboxylic acids. Transacetylation is used to obtain enantioenriched alcohols and esters. Iridium-catalyzed transacetylation have also been demonstrated:

ROH + CH2=CHOAc → ROCH=CH2 + HOAc. As an electron-rich alkene, vinyl acetate undergoes a variety of additions. Diels-Alder reactions occur with dienes, and 2+2 photocycloadditions occur with monoalkenes. Bromine adds to give the dibromide. Hydrogen halides add to give 1-haloethyl acetates, which cannot be generated by other methods because of the non-availability of the corresponding halo-alcohols. Acetic acid adds in the presence of palladium catalysts to give ethylidene diacetate, CH3CH(OAc)2.

Toxicity evaluation Vinyl acetate has low toxicity. Oral LD50 for rats is 2920 mg/kg. On January 31, 2009, the Government of Canada's final assessment concluded that exposure to vinyl acetate is not harmful to human health. This decision under the Canadian Environmental Protection Act (CEPA) was based on new information received during the public comment period, as well as more recent information from the risk assessment conducted by the European Union. In the context of large-scale release into the environment, it is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), under which it "does not meet toxicity criteria[,] but because of its acute lethality, high production volume [or] known risk is considered a chemical of concern". By this law, it is subject to strict reporting requirements by facilities that produce, store, or use it in quantities greater than 1,000 pounds (450 kilograms).

See also Polyvinyl alcohol Vinyl propionate

References

External links EPA health assessment information on vinyl acetate CDC - NIOSH Pocket Guide to Chemical Hazards Summary of risk assessment by the Government of Canada

Illustrations

Worked examples

Example 1 — a first encounter with Vinyl acetate

Start with the simplest possible case. Write down what Vinyl acetate 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 Vinyl acetate 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 Vinyl acetate 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 Vinyl acetate

In research: Vinyl acetate 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 Vinyl acetate 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: Vinyl acetate is common in secondary-school and first-year university syllabi. It links to neighbouring topics Acetate esters, Commodity chemicals, IARC Group 2B carcinogens, so understanding it makes those chapters shorter.
In everyday life: Look for Vinyl acetate 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 Vinyl acetate in 20 minutes

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

Frequently asked questions

What is Vinyl acetate in simple terms?

Vinyl acetate is an organic compound with the formula CH3CO2CH=CH2. This colorless liquid is the precursor to polyvinyl acetate, ethylene-vinyl acetate, polyvinyl alcohol, and other important industrial polymers.

Why does Vinyl acetate 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 Vinyl acetate?

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 Vinyl acetate.