science

Myrcene

Myrcene is a science 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 Myrcene rather than just read about it. In short: Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils.

Key takeaways

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

Reference excerpt

Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils. It is produced mainly semi-synthetically from Myrcia, from which it gets its name. It is an intermediate in the production of several fragrances. A less-common isomeric form, having one of the three alkene units in a different position, is α-myrcene.

Production

Myrcene is often produced commercially by the pyrolysis (400 °C) of β-pinene, which is obtained from turpentine. It is rarely obtained directly from plants. Plants biosynthesize myrcene via geranyl pyrophosphate (GPP), which isomerizes into linalyl pyrophosphate. An elimination reaction, releasing the pyrophosphate (OPP) and a proton, completes the conversion.

Occurrence It could in principle be extracted from any number of plants, such as verbena or wild thyme, the leaves of which contain up to 40% by weight of myrcene. Many other plants contain myrcene, sometimes in substantial amounts. Some of these include cannabis, hops, Houttuynia, lemon grass, mango, Myrcia, West Indian bay tree, and cardamom. Of the several terpenes extracted from Humulus lupulus (hops), the largest monoterpenes fraction is β-myrcene. One study of the chemical composition of the fragrance of Cannabis sativa found β-myrcene to compose between 29.4% and 65.8% of the steam-distilled essential oil for the set of fiber and drug strains tested. Additionally, myrcene is thought to be the predominant terpene found in modern cannabis cultivars within North America. Interestingly, photo-oxidation of myrcene has been shown to rearrange the molecule into a novel terpene known as "hashishene" which is named for its abundance in hashish. It is found in the South African Adenandra villosa (50%) and Brazilian Schinus molle (40%). Myrcene is also found in Myrcia cuprea petitgrain (up to 48%), bay leaf, juniper berry, cannabis, and hops.

Use in fragrance and flavor industries

Myrcene is an intermediate used in the perfumery industry. It has a pleasant odor but is rarely used directly. It is also unstable in air, tending to polymerize. Samples are stabilized by the addition of alkylphenols or tocopherol. It is thus more highly valued as an intermediate for the preparation of flavor and fragrance chemicals, such as menthol, citral, citronellol, citronellal, geraniol, nerol, and linalool. Both myrcene and myrcenol undergo Diels–Alder reactions with several dienophiles, such as acrolein, to give cyclohexene derivatives that are also useful fragrances, for instance Lyral. Myrcene also contributes a peppery and balsam aroma in beer. As of October 2018, the U.S. FDA withdrew authorization for the use of myrcene as a synthetic flavoring substance for use in food, without regard to its continuing stance that this substance does not pose a risk to public health under the conditions of its intended use.

Basic organic reactions Like other dienes, including other terpenes myrcene is prone to polymerization. Similarly, it participates in Diels-Alder reactions.

Health and safety In 2015, β-myrcene was added to California's Prop 65 list of chemicals known to the state of California to cause cancer or reproductive harm. The International Agency for Research on Cancer (IARC) determined that β-myrcene is "possibly carcinogenic to humans" (Group 2B) in 2019.

Illustrations

Worked examples

Example 1 — a first encounter with Myrcene

Start with the simplest possible case. Write down what Myrcene claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Myrcene 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 Myrcene 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 Myrcene

In research: Myrcene appears in science 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 Myrcene 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: Myrcene is common in secondary-school and first-year university syllabi. It links to neighbouring topics Flavors, Monoterpenes, Perfume ingredients, so understanding it makes those chapters shorter.
In everyday life: Look for Myrcene 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Myrcene in 20 minutes

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

Frequently asked questions

What is Myrcene in simple terms?

Myrcene, or β-myrcene, is a monoterpene. A colorless oil, it occurs widely in essential oils.

Why does Myrcene matter?

Because it connects several science 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 Myrcene?

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 Myrcene.