1、Designation: D 4711 89 (Reapproved 2003)Standard Test Method forSulfonic and Sulfuric Acids in Alkylbenzene Sulfonic Acids1This standard is issued under the fixed designation D 4711; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method is applicable to the determination ofsulfonic and sulfuric acids in branched and linear
3、alkylbenzenesulfonic acids used as intermediates in synthetic detergents.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine
4、the applica-bility of regulatory limitations prior to use. Material SafetyData Sheets are available for reagents and materials. Reviewthem for hazards prior to usage.2. Referenced Documents2.1 ASTM Standards:D 459 Terminology Relating to Soaps and Other Deter-gents2E 180 Practice for Determining the
5、 Precision of ASTMMethods for Analysis and Testing of Industrial Chemicals33. Summary of Test Method3.1 A methanolic solution of the sample is titrated withcyclohexylamine in methanol to yield a potentiometric curve.(See Fig. 1.) The first inflection represents the neutralization ofstrong acids, suc
6、h as sulfonics and alkylsulfurics, and the firsthydrogen of sulfuric acid. The second inflection represents theneutralization of the second hydrogen of sulfuric acid. Theamount of sulfonic acid is calculated based on the titrantvolume of the first inflection minus that between the twoinflections. Th
7、e amount of sulfuric acid meanwhile is calcu-lated from the titrant volume between the two inflections,which is equivalent to the amount of base required forneutralization of the bisulfate anion.4. Significance and Use4.1 Alkylbenzene sulfonic acids are important intermediatesin the synthetic deterg
8、ent industry and are defined under “alkylbenzene sulfonate” in Terminology D 459. This test method issuitable for the rapid monitoring of the sulfonic and sulfuricacid levels, both of which have a vital bearing on final productperformance and appearance.5. Interferences5.1 Strong acids, like nitric
9、and hydrochloric, interfere, asdo weak acids, such as carboxylic acids. Small amounts ofwater originally present in the sample do not interfere in thedetermination. However, if as much as 5 % of water is presentin the total solution (solvent plus sample), the end pointbecomes less sharp.1This test m
10、ethod is under the jurisdiction of ASTM Committee D12 on Soapsand Other Detergents and is the direct responsibility of Subcommittee D12.12 onAnalysis of Soaps and Synthetic Detergents.Current edition approved May 26, 1989. Published July 1989. Originallypublished as D4711-87. Last previous edition D
11、4711-87.2Annual Book of ASTM Standards, Vol 15.04.3Annual Book of ASTM Standards, Vol 15.05.Solvent. Methanol A. Differentiating titration curveTitrant. 0.1 N Cyclohexylamine B. First derivative curve of the curve AFIG. 1 Titration of a detergent intermediate containing alkylsulfonic acid and sulfur
12、ic acids.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Potentiometric Titrator,4and combination calomel ref-erence electrode.6.2 Buret Assembly, having a 20 mL buret.46.3 Beaker, 180 mL tall form.6.4 Volumetric Flas
13、k, Class A, 500 mL.6.5 Magnetic Stirrer, and stirring bar.7. Reagents and Materials7.1 Methanol, anhydrous,7.2 Cyclohexylamine (0.10 N)Dissolve 10 g of reagentcyclohexylamine in 1000 mL of anhydrous methanol. Stan-dardize against sulfamic acid as described in Section 8.7.3 Sulfamic Acid, acidimetric
14、 standard.58. Standardization of 0.10 N Cyclohexylamine8.1 All standardizations should be run in triplicate. Thismeans separate weighings for solution preparations in 8.2.8.2 Using an analytical balance, accurately weigh 0.10 to0.12 g of sulfamic acid to the nearest 0.1 mg into a 180 mL tallform bea
15、ker. Dissolve in 100 mL of anhydrous methanol. Mixwell.8.3 Titrate with 0.10N cyclohexylamine using the combina-tion electrode on the automatic titrator until the completedevelopment of a single break. Record the mL at the inflectionpoint.8.4 Calculate the normality of the cyclohexylamine solutionas
16、 follows:Normality of Cyclohexylamine 5 G!1000!/M!97.09! (1)where:G = grams of sulfamic acid, andM = mL of cyclohexylamine to inflection point.9. Procedure9.1 Using an analytical balance, accurately weigh 1.2 to 1.5meq to the nearest 0.1 mg of sample directly into a 180 mL tallform beaker. Sample si
17、ze may be calculated from the follow-ing:Grams sample 5 1.35 meq/meq/g acidity expected (2)NOTE 1Most detergent range alkylbenzene sulfonic acids have a totalacidity of about 3.35 meq/g meaning that the sample weight should beabout 0.35 to 0.45 g. This yields a total titer of about 12 to 15 mL of 0.
18、10N cyclohexylamine and a difference of about 0.45 to 0.68 mL between thetwo breaks for a sample containing about 1.25 % sulfuric acid.9.2 Add a magnetic stirring bar, 100 mL of anhydrousmethanol, and stir with a magnetic stirrer until dissolved.9.3 Titrate potentiometrically on the automatic titrat
19、or usingthe combination electrode until a curve yielding two breaks isobtained. (See Fig. 1.)9.4 Record the volume of titrant to the first break as V1, andthat to the second break V2.10. Calculation10.1 Calculate the weight percent sulfuric acid (H2SO4) andweight percent sulfonic acid (RSO3H) as fol
20、lows:% H2SO45 V22 V1!N!98.08!100!/W!1000! (3)%RSO3H 5 2V12 V2!N!MW!100!/W!1000! (4)where:V1,V2= millilitres of titrant at the first and the second endpoints respectively.N = normality of titrant,W = sample weight, g, andMW = average equivalent weight of sulfonic acid.11. Precision and Bias6,711.1 Re
21、peatability (Single Analyst)The standard deviationof results (each the average of duplicates) obtained by the sameanalyst on different days, has been estimated to be 0.03 %absolute at 14 degrees of freedom. Two such averages shouldbe considered suspect (95 % confidence level) if they differ bymore t
22、han 0.08 % absolute.11.2 Reproducibility (Multilaboratory)The standard de-viation of results (each the average of duplicates) obtained byanalysts in different laboratories, has been estimated to be0.05 % absolute at 13 degrees of freedom. Two such averagesshould be considered suspect (95 % confidenc
23、e level) if theydiffer by more than 0.16 % absolute.11.3 Checking Limits for DuplicatesReport the activecontent of the sample to the nearest 0.01 %. Duplicate runs thatagree within 0.1 % are acceptable for averaging (95 % confi-dence level).SULFONIC ACID PERCENT11.4 Repeatability (Single Analyst)The
24、 standard deviationof results (each the average of duplicates) obtained by the sameanalyst on different days, has been estimated to be 0.16 %absolute at 14 degrees of freedom. Two such averages shouldbe considered suspect (95 % confidence level) if they differ bymore than 0.48 % absolute.11.5 Reprod
25、ucibility (Multilaboratory)The standard de-viation of results (each the average of duplicates) obtained byanalysts in different laboratories, has been estimated to be0.36 % absolute at 13 degrees of freedom. Two such averagesshould be considered suspect (95 % confidence level) if theydiffer by more
26、than 1.1 % absolute.11.6 Checking Limits for DuplicatesReport the activecontent of the sample to the nearest 0.01 %. Duplicate runs thatagree within 0.45 % are acceptable for averaging (95 % con-fidence level).11.7 BiasSince there is no accepted reference materialsuitable for determining the bias fo
27、r the procedure in this testmethod, no statement on bias is being made.4Metrohm A436, or its equivalent, has been found suitable for this purpose.Available from Brinkman Instruments.5J. T. Baker No. 4898, or its equivalent, has been found suitable for this purpose.Available from Sargent-Welch Scient
28、ific Co., 7300 Linder Ave., PO Box 1026,Skokie, IL 60077.6Supporting Data on file at ASTM Headquarters. Request RR:D12-1009.7Practice E 180 was used to determine precision and bias.D 4711 89 (2003)2NOTE 2The precision data were derived from results of cooperativetests by sixteen laboratories on a li
29、near alkylbenzene sulfonic acid havingan average equivalent weight of 318.12. Keywords12.1 alkylbenzene sulfonic acid; sulfonic acid; sulfuric acid;titrationASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standar
30、d. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed
31、 every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible t
32、echnical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 4711 89 (2003)3
