Meaning and use

4.1 Hydroxyl is an important functional group whose content needs to be understood in many intermediate and end-use applications. The test methods described herein are used for the determination of primary and secondary hydroxyl groups and can be used for the determination of compounds containing them.

ASTM E222-2017 Standard Test Method for Hydroxyl Groups Acetylated with Acetic anhydride

Step 1: Scope

1.1 These test methods include the determination of hydroxyl groups associated with primary and secondary carbon atoms in aliphatic and alicyclic compounds and phenols.

1.2 Three test methods are as follows:

1.2.1 Test Method A is recommended for general use. Includes test method B to give a standard procedure for widely used methods. Test method C is recommended when results are required in the shortest time or when ambient temperature is required.

1.2.2 The results obtained using test methods A and B are basically the same, but the results obtained using test method C will be higher than those obtained using the other two methods (relatively up to about 4%).

1.2.3 Each test method includes an accuracy description. The accuracy of test methods A and C is consistent across a wide range of hydroxyl content (tested between 250 and 1600 hydroxyl number ranges), while test method B is less accurate at higher hydroxyl content levels than at lower hydroxyl content levels. Level. Typically, test method A is about twice as accurate as test method C. Test method B has roughly the same accuracy as test method C at lower hydroxyl content levels, but has poor accuracy at higher hydroxyl content levels.

1.2.4 The interference of the three methods is basically the same. Some compounds can be analyzed using test methods A or B, but test method C is not used because of the interference reaction of the strong acid catalyst with the compound being analyzed or the acetate products formed in the determination. However, because of their increased reactivity, test method C is suitable for the determination of certain compounds, particularly steric secondary alcohols, which react too slowly or not at all in test methods A and B.

ASTM E222-2017 Standard Test Method for Hydroxyl Groups Acetylated with Acetic anhydride

Note 1: Other methods for the determination of hydroxyl are given in methods D1957, D2195, E326, E335 and E567.

1.3 Values expressed in SI units shall be regarded as standard values. No other units of measurement are included in this standard.

1.4 Review the currently applicable Safety Data Sheet (SDS) for details on toxicity, first aid procedures and safety precautions.

1.5 This standard is not intended to address all safety concerns (if any) associated with its use. It is the responsibility of users of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory restrictions prior to use. See section 7 for a description of specific hazards.

1.6 This international standard is based on internationally recognized standardization principles established in the “Decision on Principles for the Development of International Standards, Guidelines and Recommendations” issued by the WTO Committee on Technical Barriers to Trade (TBT).