chemistry

Trichloroacetic acid

Trichloroacetic 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 Trichloroacetic acid rather than just read about it. In short: Trichloroacetic acid (TCA; TCAA; also known as trichloroethanoic acid) is an organochlorine compound with the formula CCl3CO2H. It is analogue of acetic acid in which the three hydrogen atoms of the methyl group have all been replaced by chlorine atoms.

Key takeaways

Trichloroacetic 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 Trichloroacetic acid to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Trichloroacetic acid from memory before moving on to harder problems.

Reference excerpt

Trichloroacetic acid (TCA; TCAA; also known as trichloroethanoic acid) is an organochlorine compound with the formula CCl3CO2H. It is analogue of acetic acid in which the three hydrogen atoms of the methyl group have all been replaced by chlorine atoms. It is a colorless solid that dissolves in water. Salts and esters of trichloroacetic acid are called trichloroacetates.

Synthesis and reactivity It is prepared by the reaction of chlorine with acetic acid in the presence of a suitable catalyst such as red phosphorus.

CH3CO2H + 3 Cl2 → CCl3CO2H + 3 HCl Another route to trichloroacetic acid is the oxidation of trichloroacetaldehyde. In water, trichloroacetic acid converts to trichloroacetate as indicated by its low pKa. Thus trichloroacetic acid does not exist in aqueous solution, on the conjugate base. It can be converted to trichloroacetyl chloride using thionyl chloride.

Use It is a precursor to various herbicides. Sodium trichloroacetate was marketed as such in the 1950s but has since been highly regulated.

Niche Trichloroacetic acid is widely used in biochemistry for the precipitation of macromolecules, such as proteins, DNA, and RNA. TCA is used during oligonucleotide synthesis during the "deblocking" step to remove the dimethoxytrityl protecting group from the growing DNA/RNA strand for the next nucleotide incorporation. TCA and DCA are both used in cosmetic treatments (such as chemical peels and tattoo removal) and as topical medication for chemoablation of warts, including genital warts. It can kill normal cells as well. It is considered safe for use for this purpose during pregnancy.

Toxicity According to the European Chemicals Agency, "This substance causes severe skin burns and eye damage, is very toxic to aquatic life and has long lasting toxic effects."

History The discovery of trichloroacetic acid by Jean-Baptiste Dumas in 1839 delivered a striking example to the slowly evolving theory of organic radicals and valences. The theory was contrary to the beliefs of Jöns Jakob Berzelius, starting a long dispute between Dumas and Berzelius.

Popular culture In the 1958 film The Blob, a bottle of trichloroacetic acid is tossed at the Blob in a futile attempt to fend it off.

Illustrations

Worked examples

Example 1 — a first encounter with Trichloroacetic acid

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

In research: Trichloroacetic 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 Trichloroacetic 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: Trichloroacetic acid is common in secondary-school and first-year university syllabi. It links to neighbouring topics Haloacetic acids, IARC Group 2B carcinogens, Recreational drug metabolites, so understanding it makes those chapters shorter.
In everyday life: Look for Trichloroacetic 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 Trichloroacetic acid in 20 minutes

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

Frequently asked questions

What is Trichloroacetic acid in simple terms?

Why does Trichloroacetic 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 Trichloroacetic 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 Trichloroacetic acid.