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1、BRITISH STANDARD BS 6829-4.6: 1988 ISO 4326:1980 Analysis of surface active agents (raw materials) Part 4: Ethylene oxide adducts Section 4.6 Method for determination of hydroxyl value ISO title: Non-ionic surface active agents Polyethoxylated derivatives Determination of hydroxyl value Acetic anhyd
2、ride method UDC 661.185.1:543.2 112 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:27:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6829-4.6:1988 This British Standard, having been prepared under the direction of the Chemicals Standards Committee, was published under the authority of t
3、he Board of BSI and comes into effect on 31 August 1988 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference CIC/34 Draft for comment 87/53365 DC ISBN 0 580 16690 2 Committees responsible for this British Standard The preparation of this British Standard
4、was entrusted by the Chemicals Standards Committee (CIC/-) to Technical Committee CIC/34, upon which the following bodies were represented: Chemical Industries Association Consumer Policy Committee of BSI Department of the Environment Department of Trade and Industry (Laboratory of the Government Ch
5、emist) London Regional Transport Ministry of Defence Royal Society of Chemistry Soap and Detergent Industry Association Society of Dyers and Colourists Society of Occupational Medicine Textile Institute Textile Research Council Amendments issued since publication Amd. No.Date of issueComments Licens
6、ed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:27:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6829-4.6:1988 BSI 12-1999i Contents Page Committees responsibleInside front cover National forewordii 0Introduction1 1Scope1 2Field of application1 3References1 4Definition1 5Principle2 6Reactions
7、2 7Reagents2 8Apparatus2 9Sampling2 10Procedure2 11Expression of results3 12Test report4 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:27:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6829-4.6:1988 ii BSI 12-1999 National foreword This Section
8、 of BS 6829 has been prepared under the direction of the Chemicals Standards Committee. It is identical with ISO 4326:1980 “Non-ionic surface active agents Polyethoxylated derivatives Determination of hydroxyl value Acetic anhydride method”, published by the International Organization for Standardiz
9、ation (ISO). Terminology and conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to th
10、e following. The comma has been used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. The symbol “l” has been used to denote litre (and in its submultiples). In British Standards it is current practice to use the symbol “L”.
11、Wherever the words “International Standard” appear, referring to this standard, they should be read as “Section of BS 6829”. There are no British Standards corresponding to ISO 4317:1977 and ISO 4327:1979. The Technical Committee has reviewed the provisions of these standards, and of ISO 648, and ha
12、s decided that they are acceptable for use in conjunction with this standard. With reference to 8.1, ISO/R 385 has been revised as ISO 385-1:1984, ISO 385-2:1984 and ISO 385-3:1984, the relevant requirements of which are technically equivalent to those in BS 846:1985 “Specification for burettes”. Wi
13、th reference to 8.4, a related British Standard to ISO 648:1977 is BS 1583:1986 “Specification for one-mark pipettes”. Additional information. With reference to clause 5, water complying with grade 3 of BS 3978 “Specification for water for laboratory use” is suitable. With reference to 7.3, the conc
14、entration of the sodium hydroxide standard volumetric solution, expressed as an amount-of-substance concentration, is c (NaOH) = 5 mol/L. In the definition of T in 11.1, “normality” should be read as “amount-of-substance concentration (mol/L)”. Cross-references International StandardCorresponding Br
15、itish Standard ISO 607:1980BS 3762 Analysis of formulated detergents Part 1:1983 Methods of sample division (Identical) ISO 2211:1973BS 5339:1976 Method of measurement of colour in Hazen units (platinum-cobalt scale) of liquid chemical products (Identical) ISO 4314:1977BS 6829 Analysis of surface ac
16、tive agents (raw materials) Section 1.2:1988 Method for determination of free alkalinity or free acidity (Identical) Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:27:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6829-4.6:1988 BSI 12-1999iii This Section describes a method of test only
17、 and should not be used or quoted as a specification defining limits of purity. Reference to this Section should indicate that the method of test used is in accordance with BS 6829-4.6. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standa
18、rds are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 4, an inside back cover and a back cover. This sta
19、ndard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:27:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI iv blank Licensed Copy: sheffieldu
20、n sheffieldun, na, Wed Dec 06 14:27:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6829-4.6:1988 BSI 12-19991 0 Introduction The classical method for the determination of the hydroxyl value described in this International Standard requires, because of the toxic effects of pyridine and acetic anhyd
21、ride, that all handling and the titration be conducted under a well ventilated fume hood. However, for information, it is pointed out that Annex C of ISO 4327 provides a procedure using a special apparatus which reduces the danger due to pyridine and acetic anhydride. 1 Scope This International Stan
22、dard specifies a method for the determination of the hydroxyl value of polyethoxylated condensates by esterification of the hydroxyl groups with acetic anhydride. 2 Field of application This method is applicable to the determination of the hydroxyl groups of polyethoxylated condensates of aliphatic
23、and alicyclic compounds (in particular, of ethylene oxide adducts of primary fatty alcohols, of alkylphenols and of fatty acids) and can be used for the determination of hydroxyl values from 10 to 1 000. However, certain substances present in these materials may react with the acetic anhydride or wi
24、th the standard volumetric sodium hydroxide solution used and consequently falsify the results. The possible interferences are detailed below: Primary and secondary amines, amides, tertiary alcohols, thiols and epoxides undergo side reactions which affect the accuracy of the method. Long-chain fatty
25、 acids and esters may interfere by forming anhydrides which are more stable than acetic anhydride and are not completely decomposed at the end of the method. Other free acids interfere by reacting with the standard volumetric sodium hydroxide solution; bases, including some tertiary amines, interfer
26、e by reacting with the acetic acid produced. In these cases a correction may be made for the acidity or alkalinity (see ISO 4314). Epoxides are known to interfere, but the method can still be used if it is possible to eliminate them, by cold vacuum distillation, without affecting the hydroxyl value.
27、 By this means, free ethylene oxide, which interferes at levels above 0,5 % (m/m), can be eliminated. The presence of water in the sample is revealed by reaction with the acetic anhydride, but the method may nevertheless be used without risk if the precautions described in the procedure are followed
28、. This method is not applicable to propoxylated products. 3 References ISO 607, Surface active agents and detergents Methods of sample division. ISO 2211, Liquid chemical products Measurement of colour in Hazen units (platinum-cobalt scale). ISO 4314, Surface active agents Determination of free alka
29、linity or free acidity Titrimetric method. ISO 4317, Surface active agents Determination of water content Karl Fischer method. ISO 4327, Non-ionic surface active agents Polyalkoxylated derivatives Determination of hydroxyl value Phthalic anhydride method. 4 Definition hydroxyl value I(OH) the number
30、 of milligrams of potassium hydroxide needed to neutralize the acetic acid required to acetylate the hydroxyl groups in 1 g of the material, or the number of milligrams of potassium hydroxide corresponding to the hydroxyl groups in 1 g of the material NOTEThe number of moles of potassium hydroxide c
31、orresponding to the hydroxyl value is equal to the number of hydroxyl groups present in 1 kg of the material. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:27:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6829-4.6:1988 2 BSI 12-1999 5 Principle Esterification of the hydroxyl group by
32、acetic anhydride in pyridine solution. Hydrolysis of the excess of acetic anhydride with water. Neutralization of the acidity which appears during the esterification, and of the acetic acid formed during the hydrolysis, by sodium hydroxide solution in the presence of phenolphthalein as indicator. Ca
33、lculation of the hydroxyl value from the difference between the volumes of sodium hydroxide solution used for the titration of the blank and of the test solution. 6 Reactions The reactions occurring are as follows: a) Esterification b) Hydrolysis of the excess acetic anhydride c) Neutralization of t
34、he acetic acid formed CH3 COOH + NaOH F CH3 COONa + H2O 7 Reagents During the analysis, use only reagents of recognized analytical grade, and only distilled water or water of equivalent purity. 7.1 Pyridine, boiling temperature between 114,5 and 115,5 C. 7.2 Acetic anhydride solution in pyridine (ac
35、etylation reagent). Mix carefully 1 volume of acetic anhydride, of minimum purity 97 %, and 10 volumes of the pyridine (7.1), avoiding overheating. Store in a dark glass bottle fitted with a ground glass stopper. Do not use this solution if its colour exceeds 200 Hazen units on the platinum-cobalt s
36、cale (determined by ISO 2211). 7.3 Sodium hydroxide, 0,5 N standard volumetric solution. 7.4 Phenolphthalein, 10 g/l solution in pyridine. Dissolve 1 g of phenolphthalein 3,3-bis(4-hydroxyphenyl) phthalide in 100 ml of the pyridine (7.1). 8 Apparatus Ordinary laboratory apparatus and: 8.1 Burette, c
37、apacity 50 ml, complying with the requirements of class A of ISO/R 385. 8.2 Flat-bottomed flasks, capacity 250 ml, with conical ground glass sockets. 8.3 Air condensers, of effective length 800 mm, with conical ground glass joints. 8.4 One-mark pipettes, capacities 15 and 25 ml, complying with the r
38、equirements of ISO 648. 9 Sampling Laboratory samples of polyethoxylated surface active agents shall be prepared and stored according to the instructions given in ISO 607. 10 Procedure All the necessary apparatus shall be absolutely clean and dry. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec
39、06 14:27:19 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6829-4.6:1988 BSI 12-19993 10.1 Test portion It is essential that the approximate water content of the test portion be known; if necessary, determine the water content of the sample by the method specified in ISO 4317. Weigh, to the nearest 0
40、,001 g, into a dry and previously tared flask (8.2), a mass of the laboratory sample as specified in the table below: NOTEFor water contents between 0,25 and 1 % (m/m), the mass (m0), in grams, of the test portion shall not exceed: where V0is the volume, in millilitres, of the standard volumetric so
41、dium hydroxide solution (7.3) used for the blank test (see clause 11); I(OH)is the estimated hydroxyl value, in milligrams of potassium hydroxide per gram; H2Ois the percentage, by mass, of water in the test sample. WARNING All the operations specified below shall be conducted under a well ventilate
42、d fume hood. 10.2 Determination 10.2.1 Acetylation Using a pipette, add, as carefully as possible, exactly 15 ml of the acetylation reagent (7.2) to the flask. Moisten the condenser joint with the pyridine (7.1) and attach the condenser (8.3) to the flask. Swirl to mix the contents. Heat the flask f
43、or 1 h in a boiling water bath, the contents of the flask being below the level of the water. Swirl to mix after about 10 min in the bath. 10.2.2 Hydrolysis and titration of excess reagent Add 2 ml of water, through the condenser, to the flask and swirl. Heat the flask in the boiling water bath for
44、5 min. Cool the flask and contents to below 30 C. Add 70 ml of water through the condenser. Remove the condenser and rinse the ground glass joint with water. Using a pipette (8.4), add 25 ml of the standard volumetric sodium hydroxide solution (7.3). Add 0,2 ml of the phenolphthalein indicator solut
45、ion (7.4) and titrate with the standard volumetric sodium hydroxide solution (7.3) with vigorous stirring, until the solution remains pink for 15 s. 10.3 Blank test Carry out a blank test at the same time as the determination, using the same reagents, but replacing the test portion with 2 or 3 drops
46、 of water. 11 Expression of results 11.1 Method of calculation The hydroxyl value, I(OH), corresponding to the test portion, is given by the formula where V0is the volume, in millilitres, of the standard volumetric sodium hydroxide solution (7.3) used for the blank test; V1is the volume, in millilit
47、res, of the standard volumetric sodium hydroxide solution (7.3) used for the determination; Hydroxyl value I(OH) Mass of test portion, m0 g Lower than 408 to 10 40 to 200 Over 200 380 I OH() - - 0,5 380 100 I OH() - Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:27:19 GMT+00:00 2006, Unco
48、ntrolled Copy, (c) BSI BS 6829-4.6:1988 4 BSI 12-1999 Tis the exact normality of the standard volumetric sodium hydroxide solution (7.3); m0is the mass, in grams, of the test portion; Cis the positive acid value, or the negative alkali value, of the material (see ISO 4314); this value shall be ignor
49、ed if it is 0,3 or less. 11.2 Precision For compounds having hydroxyl values of 40 or more, comparative analyses have given the following statistical results: 11.2.1 Repeatability The difference found between the results of two determinations carried out on the same sample simultaneously or in rapid succession by the same analyst using the same apparatus should not exceed 1,1 % of the mean value. 11.2.2 Reproducibility The difference between the results obtained on the same samp