chemistry

Lindlar catalyst

Lindlar catalyst 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 Lindlar catalyst rather than just read about it. In short: A Lindlar catalyst is a heterogeneous catalyst consisting of palladium deposited on calcium carbonate (CaCO3) or barium carbonate (BaCO3) then poisoned with various forms of lead or sulfur. It is used for the hydrogenation of alkynes to alkenes (i.e. without further reduction into alkanes), specifically the syn product.

Key takeaways

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

Reference excerpt

A Lindlar catalyst is a heterogeneous catalyst consisting of palladium deposited on calcium carbonate (CaCO3) or barium carbonate (BaCO3) then poisoned with various forms of lead or sulfur. It is used for the hydrogenation of alkynes to alkenes (i.e. without further reduction into alkanes), specifically the syn product. It is named after its inventor Herbert Lindlar, who discovered it in 1952.

Synthesis Lindlar catalyst can be created by reducing palladium chloride in a slurry of calcium carbonate (CaCO3) or barium carbonate (BaCO3) and adding lead acetate. A variety of other "catalyst poisons" have been used, including lead oxide and quinoline. The palladium content of the supported catalyst is usually 5% by weight.

Catalytic properties The catalyst is used for the hydrogenation of alkynes to alkenes (i.e. without further reduction into alkanes). The lead serves to deactivate the palladium sites, and further deactivation of the catalyst with quinoline or 3,6-dithia-1,8-octanediol enhances its selectivity, preventing formation of alkanes. Thus if a compound contains a double bond as well as a triple bond, only the triple bond is reduced. An example being the reduction of phenylacetylene to styrene.

Alkyne hydrogenation is stereospecific, occurring via syn addition to give the cis-alkene. For example the hydrogenation of acetylenedicarboxylic acid using Lindlar catalyst gives maleic acid rather than fumaric acid.

An example of commercial use is the organic synthesis of vitamin A which involves an alkyne reduction with the Lindlar catalyst. These catalysts are also used in the synthesis of dihydrovitamin K1.

See also Rosenmund reduction, a reduction using palladium on barium sulfate, poisoned with sulfur compounds. Urushibara Nickel, a nickel based catalyst used to hydrogenate alkynes to alkenes.

References

Illustrations

Worked examples

Example 1 — a first encounter with Lindlar catalyst

Start with the simplest possible case. Write down what Lindlar catalyst 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 Lindlar catalyst 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 Lindlar catalyst 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 Lindlar catalyst

In research: Lindlar catalyst 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 Lindlar catalyst 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: Lindlar catalyst is common in secondary-school and first-year university syllabi. It links to neighbouring topics Catalysts, Hydrogenation catalysts, Palladium compounds, so understanding it makes those chapters shorter.
In everyday life: Look for Lindlar catalyst 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 Lindlar catalyst in 20 minutes

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

Frequently asked questions

What is Lindlar catalyst in simple terms?

Why does Lindlar catalyst 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 Lindlar catalyst?

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 Lindlar catalyst.