Volatile Oils and Their Properties

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Questions and Answers

What is the primary purpose of enfleurage?

To separate terpenes from phenyl propanoids

To enhance the flavor of oils

To distill essential oils quickly

To extract volatile oils from plant materials (correct)

Which type of chemical structure primarily makes up many volatile oils?

Fatty acids

Simple sugars

Amino acids

Terpenes (correct)

How are isoprene units structured in terpenes?

As single units linked in random arrangements

In a head to tail fashion (correct)

In cyclic patterns only

As branched chains with no specific order

What is the molecular formula for monoterpenes?

C10H16 Signup and view all the answers

Which group of compounds do phenyl propanoids belong to?

Volatile oil constituents Signup and view all the answers

What two precursors arise from acetate via mevalonic acid in the biosynthesis of terpenes?

Isopentenyl pyrophosphate and dimethyl allyl pyrophosphate Signup and view all the answers

What is the role of geranyl pyrophosphate in terpene formation?

It serves as a direct precursor to monoterpenes Signup and view all the answers

Which statement about terpenes is incorrect?

Triterpenes have a molecular formula of C10H16. Signup and view all the answers

What prevents the darkening of volatile oils during storage?

Using tightly stoppered amber glass containers Signup and view all the answers

Where do volatile oils typically occur in the rose plant?

In the petals Signup and view all the answers

What is a primary benefit of using volatile oils as local irritants?

To relieve muscle pain Signup and view all the answers

Which of the following is NOT a characteristic of volatile oils?

They can be saponified with alkalis Signup and view all the answers

Which method is specifically used for extracting volatile oils from citrus fruits?

Cold expression Signup and view all the answers

What distinguishes volatile oils from fixed oils?

Volatile oils oxidize instead of becoming rancid Signup and view all the answers

What type of distillation is typically used when separating volatile oils based on their boiling points?

Zone distillation Signup and view all the answers

What is the biosynthetic origin of terpene derivatives found in volatile oils?

Acetate-mevalonic acid pathway Signup and view all the answers

Which of the following is NOT considered a use of volatile oils?

Antihistamine Signup and view all the answers

Which plant family includes glandular hairs as specialized secretory structures for volatile oils?

Labiatae Signup and view all the answers

How is the optical activity of volatile oils assessed?

Polarimeter Signup and view all the answers

What physical property is often a valuable diagnostic property of volatile oils?

Their specific rotation Signup and view all the answers

Which of the following volatile oils is used as a carminative?

Peppermint oil Signup and view all the answers

Which statement about the solubility of volatile oils is correct?

They are soluble in alcohol and ether Signup and view all the answers

Which compound is typically determined through the chemical evaluation of volatile oils?

Phenol Signup and view all the answers

What is the purpose of enzymatic hydrolysis in the context of volatile oils?

To distill glycosidic volatile oils Signup and view all the answers

Study Notes

Volatile Oils

Volatile oils are the fragrant compounds found in various plant parts.
They are also known as essential oils as they represent the odorous constituents of plants.
Volatile oils evaporate at room temperature and are typically colorless when fresh.
They are immiscible with water but soluble in alcohol, ether, and most organic solvents.

Physical Properties

Odor: Volatile oils possess characteristic odors.
Refractive Index: They have a high refractive index.
Optical Activity: Most volatile oils rotate the plane of polarized light, which is a valuable diagnostic property.

Chemical Properties

Volatile oils are classified into two broad classes based on their biosynthetic origin:
- Terpene derivatives: Formed via the acetate-mevalonic acid pathway.
- Aromatic compounds: Formed via the shikimic acid-phenyl propanoid route.

Uses of Volatile Oils

Flavoring agents: In food and beverages.
Local irritants: Examples include pinene and camphor.
Anesthetics: Clove oil containing eugenol has anesthetic properties.
Prophylactic against insects: Citronella oil is a common insect repellent.
Antibacterial and antiseptic: Examples include ginger, lemon, rosemary, and peppermint oils.
Expectorant: Used for asthma relief.
Carminatives: Peppermint oil aids in digestion.
Urinary antiseptic: Buchu leaves are used for urinary tract infections.
Anthelmintic: Ascaridol from chenopodium oil is used to treat parasitic worm infections.

Methods of Obtaining Volatile Oils

Distillation:
- Simple distillation: Used for separating volatile oils from plant material.
- Fractional distillation: Used to separate volatile oils with varying boiling points.
- Steam distillation: Commonly used method for extracting volatile oils.
- Vacuum distillation: Used to extract volatile oils at lower temperatures.
- Air-sensitive vacuum distillation: Used for sensitive volatile oils.
- Short path distillation: Suitable for extracting volatile oils with high boiling points.
- Zone distillation: Used to separate mixtures of volatile oils.
Expression Method: Used for extracting volatile oils from citrus fruits, like lemon and orange, to avoid decomposition.
Extraction: Method using organic solvents, but it can also extract unwanted substances.
Enzymatic Hydrolysis: Used for obtaining volatile oils from glycosides, like bitter almond and mustard oil.
Enfleurage: Used to extract volatile oils from flowers by absorbing them into a fatty base.

Chemistry of Volatile Oils

Volatile oils are typically mixtures of various compounds.
Terpenes: Major constituents of many volatile oils, formed by the joining of isoprene units.
- Monoterpenes: Consist of two isoprene units.
- Sesquiterpenes: Consist of three isoprene units.
- Diterpenes: Consist of four isoprene units.
- Triterpenes: Consist of six isoprene units.
Phenyl Propanoids: Contain a phenyl ring attached to a propane side chain.

Biosynthesis of Volatile Oil Constituents

Isoprene units, derived from acetate via mevalonic acid, are the building blocks for terpenes.
Geranyl pyrophosphate, a C-10 compound, is a key precursor to monoterpenes.
Geranyl pyrophosphate is believed to be the direct precursor to acyclic monoterpenes.

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Description

This quiz covers the essential concepts of volatile oils, including their physical and chemical properties. Learn about their classification, uses, and characteristics, such as odor and optical activity. Test your knowledge on how these fragrant compounds function in various applications.