Aromatherapy Essential Oil Chemistry 3 — Questions and Answers
Question 1: The basic five-carbon building block from which all terpenes are constructed is called what?
- Isoprene (Correct answer)
- Glycerol
- Acetyl-CoA
- Phenylalanine
Correct answer: Isoprene
Terpenes are built from repeating isoprene (C5H8) units.
Question 2: Menthol, responsible for the cooling sensation of peppermint, is chemically classified as which of the following?
- Monoterpenol (alcohol) (Correct answer)
- Aldehyde
- Ketone
- Ester
Correct answer: Monoterpenol (alcohol)
Menthol is a monoterpene alcohol that triggers cold-sensing receptors in the skin.
Question 3: Citral, a key constituent of lemongrass, belongs to which reactive chemical family prone to skin sensitization?
- Aldehydes (Correct answer)
- Esters
- Oxides
- Sesquiterpenes
Correct answer: Aldehydes
Citral is an aldehyde that can cause skin sensitization and is often diluted for safety.
Question 4: Which chemical constituent found in bergamot oil is responsible for phototoxicity when applied before sun exposure?
- Bergapten (a furanocoumarin) (Correct answer)
- Limonene
- Geraniol
- Farnesol
Correct answer: Bergapten (a furanocoumarin)
Bergapten is a furanocoumarin that causes phototoxic reactions on UV-exposed skin.
Question 5: Alcohols such as geraniol and linalool are generally considered to have what safety profile?
- Gentle and well-tolerated (Correct answer)
- Highly neurotoxic
- Strongly phototoxic
- Corrosive to skin
Correct answer: Gentle and well-tolerated
Monoterpene alcohols are typically among the gentlest and safest aromatic constituents.
Question 6: The process by which monoterpene-rich oils degrade over time when exposed to air is called what?
- Oxidation (Correct answer)
- Esterification
- Polymerization
- Saponification
Correct answer: Oxidation
Oxidation degrades monoterpenes, increasing skin-sensitizing potential in aged oils.
Question 7: Coumarins, found in oils such as tonka and some citrus, are noted for which effect?
- Sedative and blood-thinning tendencies (Correct answer)
- Expectorant clearing
- Photosynthesis inhibition
- Rapid combustion
Correct answer: Sedative and blood-thinning tendencies
Coumarins can have sedative and anticoagulant tendencies, warranting caution.
Aromatherapy Essential Oil Chemistry 3
The basic five-carbon building block from which all terpenes are constructed is called what?