ASTM_D_4711_-_89_2009.pdf

Designation:D471189(Reapproved 2009)Standard Test Method forSulfonic and Sulfuric Acids in Alkylbenzene Sulfonic Acids1This standard is issued under the fixed designation D4711;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()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 alkylbenzenesulfonic acids used as intermediates in synthetic detergents.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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 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:2D459 Terminology Relating to Soaps and Other DetergentsE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)33.Summary of Test Method3.1 A methanolic solution of the sample is titrated withcyclohexylamine in methanol to yield a potentiometric curve.(See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,such 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.The 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 detergent industry and are defined under“alkylbenzene sulfonate”in Terminology D459.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 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.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 Flask,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 standard.51This test method is under the jurisdiction of ASTM Committee D12 on Soapsand Other Detergents and is the direct responsibility of Subcommittee D12.12 onAnalysis and Specifications of Soaps,Synthetics,Detergents and their Components.Current edition approved Oct.1,2009.Published March 2010.Originallyapproved in 1987.Last previous edition approved in 2003 as D4711-89(2003).DOI:10.1520/D4711-89R09.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.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 Scientific Co.,7300 Linder Ave.,PO Box 1026,Skokie,IL 60077.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.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 beaker.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 follows:Normality of Cyclohexylamine5G!1000!/