Page 224 - PG 504-theoretical notes-phyto-1-2024-2025..

Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

Avoid alkali hydroxides in decomposition (to prevent resinification)

OH
CHO NaHSO 3 HC

SO Na
3

Citronellal Crystalline bisulfite derivative

Decomposition

(dil) acid or Na CO 3
2

Uses:

• In perfumes, soaps,…to impart lemon-like odour
• in preparation of citronellol (rose-like odour)
• Insect repellent.

2- Citral

• Occurrence: in lemongrass oil (Cymbopogon citratus), several citrus species

• Isolation: by preparing sod. bisulfite crystalline product
CHO H
(citral a only form crystalline product while citral b form soluble product)
H CHO

Properties:
Citral a Citral b
• lemon-like odour (Geranial) (Neral)
Trans Cis
• Easily oxidized on exposure to air

• With dehydrating agents like dil H2SO4 gives p-cymene
• Uses: in industry, perfuming, flavoring (7up) and insect repellant.

• Citral form a condensation product with compounds containing reactive methylene
groups e.g. acetone, it form pseudo-ionone and it can be cyclized in acid medium to
ionone. (What is the importance of ionones???)

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