ASTM D5776-21

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: D5776 − 14a D5776 − 21
Standard Test Method for
Bromine Index of Aromatic Hydrocarbons by Electrometric
Titration
This standard is issued under the fixed designation D5776; 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 determines the amount of bromine-reactive material in aromatic hydrocarbons and is thus a measure of trace
amounts of unsaturates in these materials. It is applicable to materials having bromine indexes below 35. Materials with a higher
bromine index can be analyzed by this method; however, the precision section does not apply.
1.2 This test method is applicable to aromatic hydrocarbons containing no more than trace amounts of olefins and that are
substantially free from material lighter than isobutane and have a distillation end point under 288°C.materials having bromine
indexes below 35. Materials with a higher bromine index can be analyzed by this method; however, the precision section does not
apply.
1.2.1 This test method is applicable to aromatic hydrocarbons containing no more than trace amounts of olefins and that are
substantially free from material lighter than isobutane and have a distillation end point under 288 °C.
1.3 In determining the conformance of the test results using this method to applicable specifications, results shall be rounded off
in accordance with the rounding-off method of Practice E29.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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. For a specific hazard statement see Section 8.
1.6 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. Referenced Documents
2.1 ASTM Standards:
D1159 Test Method for Bromine Numbers of Petroleum Distillates and Commercial Aliphatic Olefins by Electrometric Titration
D1193 Specification for Reagent Water
D3437 Practice for Sampling and Handling Liquid Cyclic Products
This test method is under the jurisdiction of ASTM Committee D16 on Aromatic Hydrocarbons Aromatic, Industrial, Specialty and Related Chemicals and is the direct
responsibility of Subcommittee D16.04 on Instrumental Analysis.
Current edition approved July 1, 2014Nov. 1, 2021. Published August 2014November 2021. Originally approved in 1995. Last previous edition approved in 2014 as
D5776 – 14.D5776 – 14a. DOI: 10.1520/D5776-14A.10.1520/D5776-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5776 − 21
D6809 Guide for Quality Control and Quality Assurance Procedures for Aromatic Hydrocarbons and Related Materials
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
2.2 Other Document:
OSHA Regulations, 29 CFR paragraphs 1910.1000 and 1910.1200
3. Terminology
3.1 Definitions:
3.1.1 bromine index, n—the number of milligrams of bromine consumed by 100 g of sample under given conditions.
4. Summary of Test Method
4.1 The specimen dissolved in a specified solvent is titrated with standard bromide-bromate solution. The end point is indicated
by a fixed end-point electrometric titration apparatus, when the presence of free bromine causes a sudden change in the polarization
voltage of the system.
5. Significance and Use
5.1 This test method is suitable for setting specification,specifications, for use as an internal quality control tool, and for use in
development or research work on industrial aromatic hydrocarbons and related material. This test method gives a broad indication
of olefinic content. It does not differentiate between the types of aliphatic unsaturation.
6. Apparatus
6.1 Fixed End Point Electrometric Titration Apparatus—Any fixed end-point apparatus may be used incorporating a high
resistance polarizing current supply capable of maintaining approximately 1 to 50 μA 50 μA across two platinum plate electrodes
or a combination platinum electrode and with a sensitivity such that a voltage change of approximately 500 mV 500 mV at these
electrodes is sufficient to indicate the end point (see Note 1).
NOTE 1—The reagents and techniques may be checked by determining the bromine index of a 100 mg/kg cyclohexene in heptane. This is expected to
give a bromine index of 18 to 20 mg/100 g sample. Refer to Test Method D1159 for a list of expected bromine indexes of various compounds.
6.2 Titration Vessel—A tall form glass beaker of approximately 250-mL250 mL capacity or a water jacketed titration vessel of
approximately 250-mL250 mL capacity connected to a refrigerated circulating water bath controlling the temperature at 0 to
5°C.5 °C. A pair of platinum electrodes spaced not more than 5 mm apart, shall be mounted to extend well below the liquid level.
Stirring shall be by a mechanical or electromagnetic stirrer and shall be rapid but not so vigorous as to draw air bubbles down to
the electrodes.
6.3 Iodine Number Flasks, glass-stoppered, 500-mL capacity.
7. Reagents and Materials
7.1 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 American Chemical Society where such specifications are available. Other
grades may be used, providing it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening
the accuracy of the determination.
7.2 Purity of Water—Unless otherwise indicated references to water shall be understood to mean reagent water conforming to Type
III I or II of Specification D1193.
Available from U.S. Government Printing Office Superintendent of Documents, 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
www.access.gpo.gov.
Reagent Chemicals, American Chemical Society Specifications,ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, 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. Pharmacopeial Convention, Inc. (USPC),
Rockville, MD.
D5776 − 21
7.3 Bromide-Bromate Standard Solution (0.10 N) —Dissolve 10.1 g of potassium bromide (KBr) and 2.8 g potassium bromate
(KBrO ) in water and dilute to 1.0 L. Standardize to four significant figures as follows: Place 50 mL of glacial acetic acid and 1.0
mL of concentrated hydrochloric acid (HCl, sp gr 1.19) in a 500-mL500 mL iodine number flask. Chill the solution in an ice bath
for approximately 10 min and with constant swirling of the flask, add from a 50-mL50 mL buret 40 to 45 mL 45 mL of bromide
bromate solution, estimated to the nearest 0.01 mL, at a rate such that the addition takes between 90 and 120 s. 120 s. Stopper the
flask immediately, shake the contents, place it again in the ice bath, and add 5.0 mL of potassium iodide (KI) solution in the lip
of the flask. After 5 min remove the flask from the ice bath and allow the KI solution to flow into the flask by slowly removing
the stopper. Shake vigorously, add 100 mL of water in such a manner as to rinse the stopper, lip, and walls of flask, and titrate
promptly with the standard sodium thiosulphate (Na S O ) solution. Near the end of the titration add 1 mL of starch indicator
2 2 3
solution and titrate slowly to the disappearance of the blue color.
7.4 Electronic Standardization of Bromide-Bromate Solution—Standardize to four significant figures as follows: Place 50 mL of
glacial acetic acid and 1.0 mL of concentrated hydrochloric acid (HCl, sp gr 1.19) in a 500-mL500 mL iodine number flask. Chill
the solution in an ice bath for approximately 10 min with constant swirling of the flask; add 4.00 mL of bromide bromate solution
from the auto buret. Stopper the flask immediately and, shake the contents, then cool it in an ice bath for 5 min. Add 4.0 mL of
potassium iodide (KI) to the lip of the flask, remove the flask from the ice bath and allow the KI solution to slowly flow into the
flask by removing the stopper. Shake vigorously, transfer to a chilled beaker and rinse the flask including stopper with 100 mL of
water. Immerse the electrodes into the solution, titrate with standard sodium thiosulphate (Na S O ) to an end point indicated by
2 2 3
a significant change in potential that persists for 30 s (see Note 2).
NOTE 2—With commercial titrators, a sudden change in potential indicated on the meter or dial of the instrument as the endpoint is approached. When
this change persists for 30 s it marks the end of the titration. With each instr
...