Page 96 - Phytochemistry 2 (06-PG 605)

Reserpine
Properties

Reserpine occurs as fine, white or pale buff or slightly yellow
colored crystals or crystalline powder, m.p.270 ˚C, with
decomposition. It is laevorotatory. It is insoluble in water, slightly
soluble in benzene and ethanol, soluble in chloroform and freely
soluble in acetic acid. Its solution acquires a yellow colour and a
pronounced fluorescence especially after the addition of acids or
upon exposure to light.

Reserpine and related alkaloids are weakly basic ester,
tertiary alkaloids and possess a carboxylic ring "E".

Hydrolysis
On hydrolysis: reserpine yields reserpic acid,

trimethoxybenzoic acid and methanol while recinnamine gives
reserpic acid, trimethoxycinnamic acid and methanol.

Deserpedine is the demethoxylated derivative of reserpine. It
lacks the methoxyl group on ring "A". On hydrolysis it yields
deserpic acid, trimethoxybenzoic and methanol.

Tests for identification
 Vanillin /HCl reagent (1%): gives a violet colour with reserpine.
 p-Dimethylaminobenzaldehyde reagent (PADB): gives with

reserpine in presence of glacial acetic acid and H2SO4 a green
colour that turns red in excess of acids.
 Froehd’s reagent gives a yellow colour that turns to blue.
 Marqui’s reagent gives a grayish green colour that turns to
brown.

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