ASTM D1166-21

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D1166 − 84 (Reapproved 2013) D1166 − 21
Standard Test Method for
Methoxyl Groups in Wood and Related Materials
This standard is issued under the fixed designation D1166; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of methoxyl groups in wood and related materials (1-7). The test method is
applicable to wood sawdust and, milled wood or sawdust, or by suitable adjustment in size of the test specimen, to fractions
isolated from wood and lignin.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 6.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Principle of Method
2.1 The principle of the test method is the same as that in the original method of Zeisel (1), except that the methyl iodide is
collected in an acetic acid solution of potassium acetate containing bromine. The following reactions then occur:
CH I1Br →CH Br1IBr (1)
3 2 3
IBr12Br 13H O→HIO 15HBr
2 2 3
The iodic acid is determined by titration of iodine liberated by the reaction:
HIO 15HI→3I 13H O (2)
3 2 2
From the above equations, it follows that one methoxyl group (CH O) liberates six atoms of iodine.
3. Significance and Use
3.1 Most of the methoxyl in wood is attributable to the lignin. This test method is used extensively in the study of lignin.
4. Apparatus
4.1 The apparatus shall be similar to that illustrated in Fig. 1 and shall consist of the following:
4.1.1 Reaction Flask,
This test method is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.01 on Fundamental Test Methods
and Properties.
Current edition approved Aug. 1, 2013April 1, 2021. Published August 2013April 2021. Originally approved in 1956. Last previous edition approved in 20072013 as
D1166 – 84 (2007).(2013). DOI: 10.1520/D1166-84R13.10.1520/D1166-21.
The boldface numbers in parentheses refer to the references listed at the end of this test method.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1166 − 21
FIG. 1 Apparatus for Methoxyl Determination
4.1.2 Heat Source—A microburner, provided with a cylindrical shield to eliminate the effect of air drafts,temperature controlled
heating mantle,
4.1.3 Vertical Air-Cooled Condenser,
4.1.4 Scrubber, and
4.1.5 Two Absorption Vessels.
5. Purity of Reagents and Water
5.1 Purity of Reagents—Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the determination.
5.2 Water—Unless otherwise indicated, references to water shall be understood to mean distilled water.
Reagent Chemicals, American Chemical Society Specifications , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville, MD.
D1166 − 21
6. Reagents
6.1 Hydriodic Acid (sp Hydroiodic Acid (HI) (57 % in water sp gr 1.70)—TheThis best reagent grade HI, if should be stored in
the absence of light and at a low temperature, may be used without redistillation. If purification is necessary, the HI may be
redistilled. If purification is necessary, the HI may be redistilled after addition of a few grams of red phosphorus, taking care not
to overheat the sides of the flask above the liquid level, and collecting the distillate which comes over between 124 and 130°C.
A slow stream of COtemperature to keep its purity. should be maintained through the receiver during the distillation.
(Warning—During the distillation, the poisonous gas phosphine, PH , may be formed under certain conditions, and this may unite
with molecular iodine to form the explosive PI , similar in properties to NI . The PI may explode on contact with air. It is therefore
3 3 3
advisable to keep the current of CO going after the distillation has been finished, until the apparatus has cooled; this prevents air
from being sucked into the apparatus. As a safety precaution, the distillation should be conducted in a hood or behind a wire-glass
shield.) A permanently colorless solution of hydriodic acid may be obtained if the liquid, heated to approximately 100°C, is treated
with slightly more than the quantity of H PO (50 %) necessary to effect complete de-colorization.
3 2
6.2 Phenol.
6.3 Cadmium Sulfate Solution (50 g CdSO /L)—Dissolve 67.2 g of CdSO ·4H O in water and dilute to 1 L.
4 4 2
NOTE 1—A water suspension of red phosphorus is equally satisfactory in the scrubber.
6.4 Sodium Thiosulfate Solution (50 g Na S O /L)—Dissolve 78.5 g of Na S O ·5H O in water and dilute to 1 L (Note 1).
2 2 3 2 2 3 2
6.5 Carbon Dioxide Gas—The CO may be drawn from a cylinder of the compressed gas. It may be obtained also by the use of
a Kipp generator and washed, before introduction into the apparatus, through two wash bottles, the first containing saturated
NaHCO solution and the second containing H SO (sp gr 1.84). Solid CO , or “dry ice,” is a convenient source (5) and the gas
2 4 2
requires no purification.
6.6 Potassium Acetate Solution in Acetic Acid—Dissolve 100 g of anhydrous potassium acetate in 1 L of glacial acetic acid. Traces
of moisture are not significant.
6.7 Liquid Bromine.
6.8 Sodium Acetate Solution (250 g/L)—Dissolve 415 g of sodium acetate trihydrate in water and dilute to 1 L.
6.9 Formic Acid (90 %).
6.10 Potassium Iodide Solution (100 g KI/L)—Dissolve 100 g of KI in water and dilute to 1 L.
NOTE 2—The KI solution, on standing, develops a yellow color due to free iodine. If a blank titration on the solution consumes Na S O , a fresh solution
2 2 3
should be prepared.
6.11 Sulfuric Acid (1 + 9) —Mix one volume of H SO (sp gr 1.84) with nine volumes of water.
2 4
6.12 Standard Sodium Thiosulfate Solution (0.1 N)—Dissolve 25 g of Na S O ·5H O in 200 mL of water and dilute to 1 L. Use
2 2 3 2
freshly boiled and cooled water. It is preferable to allow the solution to stand for a few days before standardization. Standardize
the solution against an approximately 0.1 N solution of KMnO that has been standardized against sodium oxalate oxidimetric
standard furnished by the National Bureau of Standards (standard sample No. 40). In each of two glass-stoppered Erlenmeyer
flasks put 2 g of KI and 100 mL of freshly boiled and cooled water. Shake to dissolve the KI and add 2 mL of HCl (sp gr 1.18).
To one flask add slowly from a buret either 20.0 mL of 0.1 N KMnO or 10.0 mL of 0.18 N KMnO , while swirling the flask gently.
4 4
To the other flask add an equal volume of water. Stopper the flasks and let them stand in the dark for 10 min. Titrate the iodine
that has been set free with the Na S O until the solution is of a faint straw color. Add 2 m
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