Reference number
ISO 4327:1979
ISO 4327:1979
© ISO 2024
International Standard
ISO 4327:1979
Non-ionic surface active agents — Polyalkoxylated derivatives — Determination of hydroxyl value — Phthalic anhydride method
Edition 1
1979-12
1979-12
ISO 4327:1979
10201
Published
(Edition 1, 1979)
This publication was last reviewed and confirmed in 2024.
Therefore this version remains current.
Abstract
The hydroxyl groups are esterified by phthalic anhydride in pyridine solution. The excess of phthalic anhydride is hydrolyzed with water containing in the sodium hydroxide solution used for the neutralization. The acidity which appears during the esterification and of the phthalic acid formed during the hydrolysis is neutralized by sodium hydroxide solution in the presence of phenolphthalein as indicator. The hydroxyl value is calculated from the difference between the volumes of sodium hydroxide solution used for the titration of the blank and of the test solution.