Page 95 - phytochemistry I - PharmD Clinical

3. The hydroxylamine hydrochloride method:

This method based on reaction of the aldehydes and ketones with
hydroxylamine HCl giving the oxime with liberation of HCI equivalent to
the aldehyde or ketone content. The liberated HCl could be titrated
against alkali.

2.5. Phenols:

General methods of isolation:
Phenols are sufficiently acidic form water soluble salts (water soluble
phenolates) with dilute fixed aIkali solution.
This property is used for separation of phenolic from non-phenolic
constituents. Thus the oil is shaken with aqueous fixed alkali, the aqueous
layer containing the phenolic contents is separated from the oil.

General characters of phenols:
1- Phenols react with bromine (substitution reaction) evolving HBr. The
resulting crystalline bromide is useful for identification.
2- Phenols react with ferric chloride giving a highly colored iron
compounds.
3- The phenolic group undergoes many reaction similar to those the

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