ASTM D4936-2005 Standard Test Method for Mercaptobenzothiazole Sulfenamide Assay by Reduction Titration《用还原 滴定法对硫基苯并噻唑亚磺酰胺鉴定的标准试验方法》.pdf
《ASTM D4936-2005 Standard Test Method for Mercaptobenzothiazole Sulfenamide Assay by Reduction Titration《用还原 滴定法对硫基苯并噻唑亚磺酰胺鉴定的标准试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM D4936-2005 Standard Test Method for Mercaptobenzothiazole Sulfenamide Assay by Reduction Titration《用还原 滴定法对硫基苯并噻唑亚磺酰胺鉴定的标准试验方法》.pdf(8页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: D 4936 05Standard Test Method forMercaptobenzothiazole Sulfenamide Assay by Reduction/Titration1This standard is issued under the fixed designation D 4936; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st 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 covers the determination of assay onmercaptobenzothiazole (MBT) sulfenamides. It is based on atitratio
3、n of the basic amines liberated upon reduction of thesulfenamides with hydrogen sulfide gas (H2S)2,3or2-mercaptobenzothiazole.1.2 Any free amine (HNR2) or weak acid salts of thecorresponding amine (HXHNR2) are titrated prior to reduc-tion. This titer is used to calculate percent basic impurity (asfr
4、ee amine) in the sample.1.3 With the indicated modifications, this test method isapplicable to all MBT sulfenamides, that is, N-cyclohexyl-2-benzothiazolesulfenamide (CBS), N,N-diisopropyl-2-benzothiazyl sulfenamide (DIBS), 2 (morpholinothio) ben-zothiazole (MBS), N,N-dicylohexyl-2-benzothiazylsulfe
5、namide (DCBS), N-tert-butyl-benzothiazole-sulfenamide(TBBS), and 4-morpholinyl-2-benzothiazyl disulfide (MBSS).1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety c
6、oncerns, 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. For specific hazardstatements, see Section 9.2. Referenced Documents2.1 ASTM S
7、tandards:4D 4483 Practice for Determining Precision for Test MethodStandards in the Rubber and Carbon Black Industries3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 IpOH/Tol solvent, ntitration solvent containing fivevolumes isopropanol and three volumes toluene.3.1.2 “lot” s
8、ample, na production sample representativeof a standard production unit.3.1.3 potassium hydrogen phthalate acidimetric standard,nFisher P-243.53.1.4 primary titrant, n0.25 to 0.30 N aqueous hydrochlo-ric acid (HCl).3.1.5 reducing solution, nIpOH/Tol solvent saturated withhydrogen sulfide gas (H2S) a
9、t 25C (about 1.1 g H2S/100 mLsolvent).3.1.6 test unit, nthe actual material used in the analysis. Itmust be representative of the “lot” sample.3.2 Abbreviations:3.2.1 THAMtris (hydroxymethyl) aminomethane alkali-metric standard (Fisher T-395).34. Summary of Test Method4.1 Procedure AFor CBS, TBBS, M
10、BSS, MBS-90, andMBS, a weighed specimen is dissolved in the appropriatesolvent, the “free amine” blank is titrated with standard acid,and the sulfenamide is reduced with H2S. That is,BtSNR21 H2SBtSH 1 HNR21 S (1)where:Bt = the 2-benzothiazole radical.BtSH = 2-mercaptobenzothiazole.HNR2= free amine.T
11、he liberated amine is then titrated with standard acid to anindicator end point.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.11 on Chemical Analysis.Current edition approved Oct. 1, 2005. Published November 2005. Orig
12、inallyapproved in 1989. Last previous edition approved in 2001 as D 493696(2001).2Goodyear Paper, Industrial and Engineering Chemistry Production Researchand Development, Vol 2, 1963, p. 16.3Elastomerics, August 1981, pp. 3444.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orc
13、ontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.5The sole source of supply of the apparatus known to the committee at this timeis Fisher Scientific Co., 711 Forbes Ave., Pittsburgh,
14、PA 15219. If you are aware ofalternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee,1which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Bo
15、x C700, West Conshohocken, PA 19428-2959, United States.4.2 Procedure BFor sulfenamides of hindered amines(DIBS and DCBS), it is necessary to measure the liberatedamine by back titration at 40 to 45C. Excess hydrochloric acid(HCl) is added, then back titrated with standard sodiumhydroxide (NaOH).4.3
16、 Procedure CThis alternative is appropriate for allsulfenamides. A weighed specimen is dissolved in ethanol, the“free amine” blank is titrated with standard acid, and thesulfenamide reduced with MBT. That is,BtSNR21 BtSHBtSSBt 1 HNR2(2)where:BtSSBt = benzothiazole disulfide.The liberated amine is ca
17、ptured in a known amount ofstandard acid and the excess acid back titrated with standardsodium hydroxide.5. Significance and Use5.1 This test method is designed to assess the purity of2-mercaptobenzothiazole sulfenamide accelerators. Theseproducts are used in combination with sulfur for the vulcani-
18、zation of rubber.5.2 The test method is suitable for assessing product speci-fications in that the property it measures is related to productperformance. Since it is the primary property for comparison ofproduct quality at different production facilities, good inter-laboratory accuracy and precision
19、 is required.5.3 Based on past experience, two significant sources oferror in this test method are: (1) incomplete reduction and (2)titration end point assessment. Problems in these areas can beavoided by closely following the procedure.6. Interferences6.1 Theoretically, any material that is reduced
20、 to an acidtitratable entity will be measured by this test method. Extensivehigh-pressure liquid chromatograph (HPLC) analysis of sulfe-namides indicates that the most significant interfering impurityis the corresponding sulfinamide, BtSONR2.6.2 The corresponding sulfonamide, BtSO2NR2, is presentin
21、some samples, but it does not reduce under the analyticalconditions.7. Apparatus7.1 Standard Laboratory Glassware and Equipment.7.2 Buret, 10-cm3, Class A, graduated in 0.05-cm3incre-ments.7.3 Buret,25cm3, Class A, graduated in 0.05 cm3incre-ments.7.4 Buret, 50-cm3, Class A, graduated in 0.10-cm3inc
22、re-ments.7.5 Pipet,2cm3, Class A, graduated in 0.1 cm3increments.7.6 Pipet,25cm3, Class A.7.7 Hydrogen Sulfide Lecture Sphere (99.5 % purity),5ispreferred for convenience, ease, and correctness of saturatedsolution preparation. Lecture bottles or larger H2S containersare acceptable, but means should
23、 be developed to establishamount used in preparing a saturated solution.7.8 H2S Trap Train,1dm3NaOH (12 %) followed by 1 dm3NaOH (25 %) followed bya1dm3water trap (see Fig. 1).7.9 Platform Balance, 8000 g, for weighing the H2S cylin-der to the nearest 1 g.7.10 Magnetic Stirrer.7.11 Gas Dispersion Tu
24、be,123 250 mm stem, 40-60 mpore size; 12C.7.12 Gas Valve, for H2S cylinder, stainless steel, GCA 110inlet (fits lecture sphere on lecture bottles).7.13 pH Meter with a sensitivity of 0.1 pH unit with a glassmeasuring electrode and a calomel reference electrode.7.14 Bath, thermostatically controlled.
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