1、Designation: E222 10E222 17Standard Test Methods forHydroxyl Groups Using Acetic Anhydride Acetylation1This standard is issued under the fixed designation E222; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the determination of hydroxyl groups attached to primary and secondary carbon atoms in aliphaticand al
3、icyclic compounds and phenols.1.2 Three test methods are given as follows:SectionsTest Method A (Pressure Bottle Method) 8 14Test Method B (Reflux Method) 15 21Test Method B (Reflux Method) 16 22Test Method C (Perchloric Acid Catalyzed Method) 22 28Test Method C (Perchloric Acid Catalyzed Method) 24
4、 301.2.1 Test Method A is recommended for general use. Test Method B is included to give a standard procedure for the methodthat has been used widely. Test Method C is recommended when the results are required in a minimum period of time or whereambient temperature for the reaction is desired.1.2.2
5、The results obtained using Test Methods A and B will be essentially the same, but the results obtained using Test MethodC will be higher (up to approximately 4 % relative) than those obtained using the other two methods.1.2.3 Statements on precision are included with each test method. The precision
6、of Test Methods A and C is consistent over awide range of hydroxyl content (tested over hydroxyl number range of 250 to 1600), whereas Test Method B is less precise at thehigher hydroxyl content level than it is at the lower hydroxyl content level. In general, Test Method A is approximately two-fold
7、as precise as Test Method C. Test Method B has approximately the same precision as Test Method C at the lower hydroxyl contentlevel but poorer precision at the higher hydroxyl content level.1.2.4 The interferences are essentially the same for the three methods. Some compounds can be analyzed using T
8、est MethodsAor B but not using Test Method C because of interfering reactions of the strong acid catalyst with the compound being analyzedor the acetate product formed in the determination. However, because of its increased reactivity, Test Method C is applicable fordetermination of some compounds,
9、particularly sterically hindered secondary alcohols, which react too slowly or not at all in TestMethods A and B.NOTE 1Other methods for determination of hydroxyl groups are given in Test Methods D1957, D2195, E326, E335, and E567.1.3 The values stated in SI units are to be regarded as standard. No
10、other units of measurement are included in this standard.1.4 Review the current appropriate Material Safety Data Sheets (MSDS)(SDS) for detailed information concerning toxicity, firstaid procedures, and safety precautions.1.5 This standard does not purport to address all of the safety concerns, if a
11、ny, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific hazards statements are given in Section 77NOTE 1Other methods for determination of hy
12、droxyl groups are given in Test Methods D1957, D2195, E326, E335, and E567.1.6 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Rec
13、ommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.1 These test methods are under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons Aromatic, Industrial, Specialty and Related Chemicals and are thedirect responsibility of Subcommittee D16.15
14、on Industrial and Specialty General Standards.Current edition approved March 1, 2010June 1, 2017. Published April 2010July 2017. Originally approved in 1963. Last previous edition approved in 20052010 asE222 00 (2005)E222 10.1. DOI: 10.1520/E0222-10.10.1520/E0222-17.This document is not an ASTM stan
15、dard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all case
16、s only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States12. Referenced Do
17、cuments2.1 ASTM Standards:2D1193 Specification for Reagent WaterD1957 Test Method for Hydroxyl Value of Fatty Oils and Acids (Withdrawn 2007)3D2195 Test Methods for Pentaerythritol (Withdrawn 2011)3D6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related
18、 MaterialsE180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals(Withdrawn 2009)3E200 Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical AnalysisE203 Test Method for Water Using Vol
19、umetric Karl Fischer TitrationE326 Test Method for Hydroxyl Groups by Phthalic Anhydride Esterification (Withdrawn 2001)3E335 Test Method for Hydroxyl Groups by Pyromellitic Dianhydride Esterification (Withdrawn 2002)3E567 Test Method for Tertiary Hydroxyl Groups with Hydrogen Bromide (Withdrawn 199
20、6)33. Terminology3.1 Definitions:3.1.1 hydroxyl numberthe milligrams of potassium hydroxide equivalent to the hydroxyl content of 1 g of material. In the caseof a pure compound, the hydroxyl number is inversely proportional to the hydroxyl equivalent weight:equivalent weight g/equivalent!5 56100hydr
21、oxyl number (1)4. Significance and Use4.1 Hydroxyl is an important functional group, and knowledge of its content is required in many intermediate and end useapplications. The test methods described herein are for the determination of primary and secondary hydroxyl groups and can beused for the assa
22、y of compounds containing them.5. Interferences5.1 Unless stated otherwise, the following interferences apply to all three test methods:5.1.1 Pentavalent nitrogen compounds, amides, some ethers, and some carbonyl compounds may interfere with the accuracy ofthe test method.5.1.2 Tertiary alcohols, cy
23、anohydrins, some hydroxylated fatty acids, certain substituted phenols, and some polyhydroxylcompounds will react in a nonstoichiometric manner.5.1.3 Primary and secondary amines and mercaptans usually will react quantitatively along with the hydroxyl group.5.1.4 Excessive amounts of water in the sa
24、mple will interfere by consuming the reagent. Provisions are made to accommodatea small amount of water by adjustment of the sample size used for the analysis.5.1.5 Free acids interfere by consuming the standard alkali solution, and strong bases interfere by consuming an equivalentamount of acetic a
25、cid; provisions for determining and applying corrections for these interferences are included in the test methods.Some of the higher fatty acids may be converted to anhydrides, releasing water which will consume acetylation reagent.5.1.6 In Test Method C, epoxy, poly(oxyethylene), poly(oxypropylene)
26、, and furan rings interfere. Enols, imides, hydrazides, andsome oximes will react in a nonstoichiometric manner.5.1.7 Phenol (in contrast to other phenolics) gives low results with Test Methods A and B.5.1.8 With Test Methods A and B, epoxy compounds will give erroneously high results.NOTE 2In a stu
27、dy performed by the American Oil ChemistsSociety, satisfactory results were obtained with epoxidized soybean oil, epoxidized talloil, and epoxidized castor oil when the acetylation was carried out at room temperature for 24 h.5.1.9 Presence of an olefinic or acetylenic unsaturation in the hydroxyl-c
28、ontaining compound should have no effect on thehydroxyl content result obtained with Test Methods A and B, but may give a positive interference with Test Method C.5.1.10 Test Methods A and B as written (using a visual indicator) may not be applicable to samples containing heat-sensitiveimpurities, l
29、eading to high color in the reacted solution.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that allreagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society,
30、where2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard
31、is referenced on www.astm.org.E222 172such specifications are available.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently highpurity to permit its use without lessening the accuracy of the determination.6.2 Unless otherwise indicated, references to wate
32、r shall be understood to mean Type II or Type III reagent water conformingto Specification D1193.7. Hazards7.1 Acetic anhydride, pyridine, and 1,2-dichloroethane are eye, skin, and respiratory irritants. Avoid bodily contact with thesereagents and use only in a well-ventilated area.7.2 Perchloric ac
33、id is commonly available in 60 to 72 % concentrations. These solutions may form explosive mixtures withcertain organic materials. Dehydrating agents may cause the formation of the anhydrous acid which is unstable at ambienttemperature and explodes on contact with most organic materials. The acid is
34、an acute irritant to the eyes, skin, and mucousmembranes. Avoid bodily contact. Wash all spills with copious amounts of water.TEST METHOD A(Pressure Bottle Method)8. Summary of Test Method8.1 The sample is acetylated with a solution of acetic anhydride in pyridine in a pressure bottle at 98C. The ex
35、cess reagent ishydrolyzed with water, and the acetic acid is titrated with standard sodium hydroxide solution. The hydroxyl content is calculatedfrom the difference in titration of the blank and sample solutions.9. Apparatus9.1 Bag, heavy fabric, with draw string, to hold bottle (9.2). As an alterna
36、tive a stainless steel mesh jacket fitted to cover thebottle may be used.9.2 Bottle, pressure, heat-resistant, approximately 350 mL.9.3 Buret, 100-mL total capacity, range of graduated portion 50 mL, 0.1-mL graduations, preferably equipped with PTFEstopcock (see Note 6).9.4 Steam Bath, 98 6 2C, cont
37、aining enough water to cover the liquid in the sample bottles. It is critical that the water levelbe as prescribed and that the temperature be within the prescribed range and uniform throughout the bath.10. Reagents10.1 Acetic Anhydride. (Caution: see 7.1.)10.2 Acetylation ReagentMix 127 mL of aceti
38、c anhydride with 1000 mL of pyridine (10.5). The reagent shall be preparedfresh daily and kept in a dark bottle. It should not be used if darker than a pale yellow color.10.3 Hydrochloric Acid, Standard Solution (0.5 meq/mL)Prepare and standardize in accordance with the appropriate sectionsof Practi
39、ce E200. Determine and record the temperature at which the standardization was performed. The concentration of thesolution shall be corrected to the temperature at which the determination is performed as described in 10.6Note 8. The factor forthe thermal expansion of this solution is 0.00014. This s
40、olution is required only if a correction is to be applied for the presenceof strong base in the sample being analyzed.10.4 The factor for the thermal expansion of this solution is 0.00014. This solution is required only if a correction is to beapplied for the presence of strong base in the sample be
41、ing analyzed.10.5 Phenolphthalein Indicator SolutionDissolve 1 g of phenolphthalein in 100 mL of pyridine.10.6 Pyridine, containing 0.30 to 0.45 % water. Determine the water content of the pyridine using Test Method E203, and addthe required amount of water. The volume of water to add per litre of p
42、yridine may be calculated as follows:Water to add,mL54.029A (2)where:A = percent water in pyridine.10.7 Sodium Hydroxide, Standard Solution (0.5 meq/mL) (Caution: See 7.1)Prepare and standardize in accordance with theappropriate sections of Practice E200. Determine and record the temperature at whic
43、h the standardization was performed. The4 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dor
44、set, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.E222 173factor for thermal expansion of this solution is 0.00014. For calculation of the hydroxyl content, the normality of the solution shallbe corrected to the temperature
45、 at which the determination is performed by the following:Nt25Nt11t12t2!F! (3)where:Nt1 = meq/mL when standardized,Nt2 = meq/mL during analysis of samples,t1 = temperature of solution (C) during standardization,t2 = temperature of solution (C) during analysis of samples, andF = factor to correct for
46、 thermal expansion of the solution (see each solution for appropriate factor).11. Procedure11.1 To each of a sufficient number of pressure bottles to make all blank and sample determinations in duplicate, pipet 20.0 mLof the acetylation reagent. A uniform drainage time must be used for all aliquots.
47、11.2 Reserve two of the bottles for the blank determination. Into the other bottles introduce an appropriate weight of sample(Note 3, Note 4, and Note 7).NOTE 3The sample size is based on a maximum of 9.8 meq of hydroxyl being present. Determine the sample weight using one of the followingequations:
48、Sample weight,g556130.98!/approximate hydroxyl number (4)Sample weight,g50.00983MW/n (5)where:MW = molecular weight of the hydroxyl-containing compound, andn = number of hydroxyl groups present in the molecule.Since the calculated sample weight will be near the maximum permitted by the test method,
49、adhere closely to the indicated weight. The sample shouldnot exceed 10 g.NOTE 4If the sample contains an appreciable amount of water, the sample weight must be adjusted to accommodate this interference. In this case,determine the sample weight using one of the following equations:Sample weight,g5 0.170130.980.0094R10.01S 3n 317.01!/MW# (6)Sample weight,g5 550approximate hydroxyl number131.23R! (7)where:R = water in the sample, %,S = purity of the sample, %,MW = molecular weight of the hydroxyl-containing compound, andn = number of hydroxyl gro
