Page 13 - Phytochemistry -1 (PG404) / Clinical Pharmacy 2nd level students ( 2019 )

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

. I Test s for pentoses and methyl pentoses

1. Bial's test .

Bial's reagent: Freshly prepared Orcinol in Conc. HCl + traces of FeCl₃

Xylose: blue color (typical test: positive) Rhamnose: green color

2. Aniline acetate paper test (Furfural test) .

Mechanism:

Action of acids: The sugar molecule is very stable towards dilute acids,

but with concentrated acids it is distorted, Conc. HCl reacts with aldoses
giving different products:-

i) With pentoses and methyl pentoses, it yields furfural and methyl

furfurals, which are steam volatile, therefore can be used for the estimation
of pentoses.

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