This method is applicable to the determination of the hydroxyl functions of polyethoxylated condensates of aliphatic and alicyclic compounds (in particular, ethoxylated derivatives of primary fatty alcohols, alkylphenols and fatty acids), and allows the determination of hydroxyl numbers having values ranging from 10 to 1000. However, certain substances present in these compounds can react with acetic anhydride or with the standard solution of sodium hydroxide used, and, consequently, dis ort the results. Possible interferences are detailed below:
——Primary and secondary amines, amides, tertiary alcohols, thiols and epoxides undergo secondary reactions, which affect the precis on of the method. - Long-chain fatty acids and esters can interfere by forming anhydrides which are more stable than acetic anhydride, and they are not completely broken down at the end of the method.
NBN T 63-142-1980 history
1980NBN T 63-142-1980 Non-ionic surface active agents - Polyethoxylat?d derivatives -Determination of hydroxyl value - Acetic anhydride method