Значење и употреба

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

Корак 1: Обим

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 и 1600 hydroxyl number ranges), while test method B is less accurate at higher hydroxyl content levels than at lower hydroxyl content levels. Ниво. 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. Међутим, 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

Белешка 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. Никакве друге мерне јединице нису укључене у овај стандард.

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

1.5 Овај стандард није намењен да реши све безбедносне проблеме (ако их има) повезана са његовом употребом. Одговорност корисника овог стандарда је да успоставе одговарајуће безбедносне и здравствене праксе и да утврде применљивост регулаторних ограничења пре употребе. See section 7 for a description of specific hazards.

1.6 Овај међународни стандард је заснован на међународно признатим принципима стандардизације утврђеним у “Одлука о принципима за развој међународних стандарда, Смернице и препоруке” issued by the WTO Committee on Technical Barriers to Trade (ТБТ).