1、Designation:D116684(Reapproved 2013)Standard Test Method forMethoxyl Groups in Wood and Related Materials1This standard is issued under the fixed designation D1166;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revi
2、sion.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 covers the determination of methoxylgroups in wood and related materials(1-7).2The test method isapplicable to wood
3、 sawdust and,by suitable adjustment in sizeof the test specimen,to fractions isolated from wood andlignin.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 h
4、ealth practices and determine the applica-bility of regulatory limitations prior to use.Specific precau-tionary statements are given in Section 6.2.Principle of Method2.1 The principle of the test method is the same as that in theoriginal method of Zeisel(1),except that the methyl iodide iscollected
5、 in an acetic acid solution of potassium acetatecontaining bromine.The following reactions then occur:CH3I1Br2CH3Br1IBr(1)IBr12Br213H2OHIO315HBrThe iodic acid is determined by titration of iodine liberatedby the reaction:HIO315HI3I213H2O(2)From the above equations,it follows that one methoxylgroup(C
6、H3O)liberates six atoms of iodine.3.Significance and Use3.1 Most of the methoxyl in wood is attributable to thelignin.This test method is used extensively in the study oflignin.4.Apparatus4.1 The apparatus shall be similar to that illustrated in Fig.1 and shall consist of the following:4.1.1 Reactio
7、n Flask,4.1.2 Heat SourceA microburner,provided with a cylin-drical shield to eliminate the effect of air drafts,4.1.3 Vertical Air-Cooled Condenser,4.1.4 Scrubber,and4.1.5 Two Absorption Vessels.5.Purity of Reagents and Water5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Un
8、less otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently
9、high purity to permit its use without lessening theaccuracy of the determination.5.2 WaterUnless otherwise indicated,references to watershall be understood to mean distilled water.6.Reagents6.1 Hydriodic Acid(sp gr 1.70)The best reagent grade HI,if stored in the absence of light and at a low tempera
10、ture,maybe used without redistillation.If purification is necessary,theHI may be redistilled.If purification is necessary,the HI maybe redistilled after addition of a few grams of red phosphorus,taking care not to overheat the sides of the flask above theliquid level,and collecting the distillate wh
11、ich comes overbetween 124 and 130C.A slow stream of CO2should bemaintained through the receiver during the distillation.(WarningDuring the distillation,the poisonous gasphosphine,PH3,may be formed under certain conditions,andthis may unite with molecular iodine to form the explosive PI3,similar in p
12、roperties to NI3.The PI3may explode on contactwith air.It is therefore advisable to keep the current of CO2going after the distillation has been finished,until the apparatushas cooled;this prevents air from being sucked into theapparatus.As a safety precaution,the distillation should be1This test me
13、thod is under the jurisdiction of ASTM Committee D07 on Woodand is the direct responsibility of Subcommittee D07.01 on Fundamental TestMethods and Properties.Current edition approved Aug.1,2013.Published August 2013.Originallyapproved in 1956.Last previous edition approved in 2007 as D1166 84(2007).
14、DOI:10.1520/D1166-84R13.2The boldface numbers in parentheses refer to the references listed at the end ofthis test method.3Reagent Chemicals,American Chemical Society Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical S
15、ociety,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaand National Formulary,U.S.Pharmaceutical Convention,Inc.(USPC),Rockville,MD.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1
16、conducted in a hood or behind a wire-glass shield.)A perma-nently colorless solution of hydriodic acid may be obtained ifthe liquid,heated to approximately 100C,is treated withslightly more than the quantity of H3PO2(50%)necessary toeffect complete de-colorization.6.2 Phenol.6.3 Cadmium Sulfate Solution(50 g CdSO4/L)Dissolve67.2 g of CdSO44H2O in water and dilute to 1 L.NOTE1A water suspension of red phosphorus is equally satisfactoryin the scrubber.6.4 Sodium Thiosulfate Solution(50 g Na2S2O3/L