ASTM D5776-99(2006)
(Test Method)Standard Test Method for Bromine Index of Aromatic Hydrocarbons by Electrometric Titration
Standard Test Method for Bromine Index of Aromatic Hydrocarbons by Electrometric Titration
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 500.
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 (550°F).
1.3 The following applies to all specified limits in this standard: For purposes of determining conformance with this standard, an observed value shall be rounded off "to the nearest unit" in the last right hand digit used in expressing the specification limit, in accordance with the rounding off method of Practice E 29.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for informaiton only.
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 and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement see Section 8.
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Designation:D5776–99(Reapproved2006)
Standard Test Method for
Bromine Index of Aromatic Hydrocarbons by Electrometric
Titration
This standard is issued under the fixed designation D 5776; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope* Determine Conformance with Specifications
E 691 Practice for Conducting an Interlaboratory Study to
1.1 This test method determines the amount of bromine-
Determine the Precision of a Test Method
reactive material in aromatic hydrocarbons and is thus a
2.2 Other Document:
measureoftraceamountsofunsaturatesinthesematerials.Itis
OSHA Regulations, 29 CFR paragraphs 1910.1000 and
applicable to materials having bromine indexes below 500.
1910.1200
1.2 This test method is applicable to aromatic hydrocarbons
containing no more than trace amounts of olefins and that are
3. Terminology
substantiallyfreefrommateriallighterthanisobutaneandhave
3.1 Definition:
a distillation end point under 288°C (550°F).
3.1.1 bromine index, n—the number of milligrams of bro-
1.3 The following applies to all specified limits in this
mine consumed by 100 g of sample under given conditions.
standard: For purposes of determining conformance with this
standard,anobservedvalueshallberoundedoff“tothenearest
4. Summary of Test Method
unit” in the last right hand digit used in expressing the
4.1 The specimen dissolved in a specified solvent is titrated
specification limit, in accordance with the rounding off method
with standard bromide-bromate solution. The end point is
of PracticeE29.
indicated by a fixed end-point electrometric titration apparatus,
1.4 The values stated in SI units are to be regarded as the
when the presence of free bromine causes a sudden change in
standard. The values given in parentheses are for information
the polarization voltage of the system.
only.
1.5 This standard does not purport to address all of the
5. Significance and Use
safety concerns, if any, associated with its use. It is the
5.1 This test method is suitable for setting specification, for
responsibility of the user of this standard to establish appro-
use as an internal quality control tool, and for use in develop-
priate safety and health practices and determine the applica-
mentorresearchworkonindustrialaromatichydrocarbonsand
bility of regulatory limitations prior to use. For a specific
related material. This test method gives a broad indication of
hazard statement see Section 8.
olefinic content. It does not differentiate between the types of
aliphatic unsaturation.
2. Referenced Documents
2.1 ASTM Standards:
6. Apparatus
D 1159 Test Method for Bromine Numbers of Petroleum
6.1 Fixed End Point Electrometric Titration Apparatus—
Distillates and Commercial Aliphatic Olefins by Electro-
Any fixed end-point apparatus may be used incorporating a
metric Titration
high resistance polarizing current supply capable of maintain-
D 1193 Specification for Reagent Water
ing approximately 10 to 50 µA across two platinum plate
D 3437 Practice for Sampling and Handling Liquid Cyclic
electrodes or a combination platinum electrode and with a
Products
sensitivity such that a voltage change of approximately 50 mV
E29 Practice for Using Significant Digits in Test Data to
at these electrodes is sufficient to indicate the end point (see
Note 1).
NOTE 1—The reagents and techniques may be checked by determining
This test method is under the jurisdiction of ASTM Committee D16 on
Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of the bromine index of a 100 mg/kg cyclohexene in heptane. This is
Subcommittee D16.04 on Instrumental Analysis.
expected to give a bromine index of 18 to 20 mg/100 g sample. Refer to
Current edition approved June 1, 2006. Published June 2006. Originally
table titled Boiling Range Corrections for Olefins in Test Method D 1159.
approved in 1995. Last previous edition approved in 1999 as D 5776 – 99.
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 AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
the ASTM website. 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401.
*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.
D5776–99 (2006)
6.2 Titration Vessel—A tall form glass beaker of approxi- immediately and, shake the contents, then cool it in a ice bath
mately 250-mL capacity or a water jacketed titration vessel of for5min.Add4.0mLofpotassiumiodide(KI)tothelipofthe
approximately 250-mL capacity connected to a refrigerated flask, remove the flask from the ice bath and allow the KI
circulating water bath controlling the temperature at 0 to 5°C. solution to slowly flow into the flask by removing the stopper.
Apairofplatinumelectrodesspacednotmorethan5mmapart, Shake vigorously, transfer to a chilled beaker and rinse the
shall be mounted to extend well below the liquid level. Stirring flask including stopper with 100 mL of water. Immerse the
shall be by a mechanical or electromagnetic stirrer and shall be electrodes into the solution, titrate with standard sodium
rapid but not so vigorous as to draw air bubbles down to the thiosulphate (Na S O ) to an end point indicated by a signifi-
2 2 3
electrodes. cant change in potential that persists for 30 s (see Note 2).
6.3 Iodine Number Flasks, glass-stoppered, 500-mL capac-
NOTE 2—With commercial titrators, a sudden change in potential is
ity.
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
7. Reagents and Materials
titration. With each instrument, the manufacturer’s instructions should be
followed to achieve the sensitivity achieved in the platinum electrode
7.1 Purity of Reagents—Reagent grade chemicals shall be
circuit.
used in all tests. Unless otherwise indicated, it is intended that
7.5 Potassium Iodide Solution (150 g/L)—Dissolve150gof
all reagents shall conform to the specifications of theAmerican
Chemical Society where such specifications are available. potassium iodide (KI) in water and dilute to 1.0 L.
7.6 Sodium Thiosulphate, Standard Solution (0.10 N)—
Other grades may be used, providing it is first ascertained that
the reagent is of sufficiently high purity to permit its use Dissolve 25.0 g of sodium thiosulphate pentahydrate (Na
2S O ·5H O) in water and add 0.02 g of sodium carbonate
without lessening the accuracy of the determination.
2 3 2
7.2 Purity of Water—Unless otherwise indicated references (Na CO ) to stabilize the solution. Dilute to 1.0 L and mix
2 3
thoroughly by shaking. Standardize by any accepted procedure
to water shall be understood to mean reagent water conforming
to Type III of Specification D 1193. that determines the normality with an error not greater than 6
0.0002. Restandardize at intervals frequent enough to detect
7.3 Bromide-Bromate Standard Solution (0.10 N) —
Dissolve 10.1 g of potassium bromide (KBr) and 2.8 g changes of 0.0005 in normality.
7.7 Starch Solution—Mill5gof arrow-root starch with 3
potassium bromate (KBrO ) in water and dilute to 1.0 L.
Standardize to four significant figures as follows: Place 50 mL to 5 mL of water. Add the suspension to 2 L of boiling water.
As a preservative, 5 to 10 mg of mercuric iodide (H I)or0.2
of glacial acetic
...
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