ASTM D5776-07(2012)
(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
SIGNIFICANCE AND USE
This test method is suitable for setting specification, 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.
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 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 the standard. The values given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use. For a specific hazard statement see Section 8.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D5776 − 07 (Reapproved2012)
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.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* D6809Guide for Quality Control and Quality Assurance
Procedures for Aromatic Hydrocarbons and Related Ma-
1.1 This test method determines the amount of bromine-
terials
reactive material in aromatic hydrocarbons and is thus a
E29Practice for Using Significant Digits in Test Data to
measureoftraceamountsofunsaturatesinthesematerials.Itis
Determine Conformance with Specifications
applicable to materials having bromine indexes below 500.
E691Practice for Conducting an Interlaboratory Study to
1.2 This test method is applicable to aromatic hydrocarbons
Determine the Precision of a Test Method
containing no more than trace amounts of olefins and that are
2.2 Other Document:
substantiallyfreefrommateriallighterthanisobutaneandhave
OSHA Regulations, 29 CFRparagraphs 1910.1000 and
a distillation end point under 288°C (550°F).
1910.1200
1.3 In determining the conformance of the test results using
this method to applicable specifications, results shall be
3. Terminology
rounded off in accordance with the rounding-off method of
3.1 Definitions:
Practice E29.
3.1.1 bromine index, n—the number of milligrams of bro-
1.4 The values stated in SI units are to be regarded as the
mine consumed by 100 g of sample under given conditions.
standard. The values given in parentheses are for information
only. 4. Summary of Test Method
1.5 This standard does not purport to address all of the
4.1 The specimen dissolved in a specified solvent is titrated
safety concerns, if any, associated with its use. It is the
with standard bromide-bromate solution. The end point is
responsibility of the user of this standard to establish appro-
indicatedbyafixedend-pointelectrometrictitrationapparatus,
priate safety and health practices and determine the applica-
when the presence of free bromine causes a sudden change in
bility of regulatory limitations prior to use. For a specific
the polarization voltage of the system.
hazard statement see Section 8.
5. Significance and Use
2. Referenced Documents
5.1 This test method is suitable for setting specification, for
2.1 ASTM Standards:
use as an internal quality control tool, and for use in develop-
D1159Test Method for Bromine Numbers of Petroleum
mentorresearchworkonindustrialaromatichydrocarbonsand
Distillates and Commercial Aliphatic Olefins by Electro-
related material. This test method gives a broad indication of
metric Titration
olefinic content. It does not differentiate between the types of
D1193Specification for Reagent Water
aliphatic unsaturation.
D3437Practice for Sampling and Handling Liquid Cyclic
Products
6. Apparatus
6.1 Fixed End Point Electrometric Titration Apparatus—
Any fixed end-point apparatus may be used incorporating a
This test method is under the jurisdiction of ASTM Committee D16 on
high resistance polarizing current supply capable of maintain-
Aromatic Hydrocarbons and Related Chemicals and is the direct responsibility of
ing approximately 10 to 50 µA across two platinum plate
Subcommittee D16.04 on Instrumental Analysis.
Current edition approved Jan. 1, 2012. Published January 2012. Originally
electrodes or a combination platinum electrode and with a
ε1
approved in 1995. Last previous edition approved in 2007 as D5776–07 . DOI:
10.1520/D5776-07R12.
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 AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments,
Standards volume information, refer to the standard’s Document Summary page on 732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http://
the ASTM website. www.access.gpo.gov.
*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 − 07 (2012)
sensitivity such that a voltage change of approximately 500 titrationadd1mLofstarchindicatorsolutionandtitrateslowly
mV at these electrodes is sufficient to indicate the end point to the disappearance of the blue color.
(see Note 1).
7.4 Electronic Standardization of Bromide-Bromate
Solution—Standardize to four significant figures as follows:
NOTE 1—The reagents and techniques may be checked by determining
the bromine index of a 100 mg/kg cyclohexene in heptane. This is
Place 50 mLof glacial acetic acid and 1.0 mLof concentrated
expected to give a bromine index of 18 to 20 mg/100 g sample. Refer to
hydrochloricacid(HCl,spgr1.19)ina500-mLiodinenumber
Test Method D1159 for a list of expected bromine indexes of various
flask.Chillthesolutioninanicebathforapproximately10min
compounds.
with constant swirling of the flask; add 4.00 mL of bromide
6.2 Titration Vessel—A tall form glass beaker of approxi-
bromate solution from the auto buret. Stopper the flask
mately 250-mL capacity or a water jacketed titration vessel of
immediatelyand,shakethecontents,thencoolitinanicebath
approximately 250-mL capacity connected to a refrigerated
for5min.Add4.0mLofpotassiumiodide(KI)tothelipofthe
circulating water bath controlling the temperature at 0 to 5°C.
flask, remove the flask from the ice bath and allow the KI
Apairofplatinumelectrodesspacednotmorethan5mmapart,
solution to slowly flow into the flask by removing the stopper.
shallbemountedtoextendwellbelowtheliquidlevel.Stirring
Shake vigorously, transfer to a chilled beaker and rinse the
shallbebyamechanicalorelectromagneticstirrerandshallbe
flask including stopper with 100 mL of water. Immerse the
rapid but not so vigorous as to draw air bubbles down to the
electrodes into the solution, titrate with standard sodium
electrodes.
thiosulphate (Na S O ) to an end point indicated by a signifi-
2 2 3
6.3 Iodine Number Flasks, glass-stoppered, 500-mL capac- cant change in potential that persists for 30 s (see Note 2).
ity.
NOTE 2—With commercial titrators, a sudden change in potential
indicated on the meter or dial of the instrument as the endpoint is
7. Reagents and Materials
approached. When this change persists for 30 s it marks the end of the
titration. With each instrument, the manufacturer’s instructions should be
7.1 Purity of Reagents—Reagent grade chemicals shall be
followed to achieve the sensitivity achieved in the platinum electrode
used in all tests. Unless otherwise indicated, it is intended that
circuit.
allreagentsshallconformtothespecificationsoftheAmerican
7.5 Potassium Iodide Solution (150 g/L)—Dissolve150gof
Chemical Society where such specifications are available.
potassium iodide (KI) in water and dilute to 1.0 L.
Other grades may be used, providing it is first ascertained that
7.6 Sodium Thiosulphate, Standard Solution (0.10 N)—
the reagent is of sufficiently high purity to permit its use
Dissolve 25.0 g of sodium thiosulphate pentahydrate
without lessening the accuracy of the determination.
(Na S O ·5H O) in water and add 0.02 g of sodium carbonate
2 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
towatershallbeunderstoodtomeanreagentwaterconforming
thoroughlybyshaking.Standardizebyanyacceptedprocedure
to Type III of Specification D1193.
that determines the normality with an error not greater than
7.3 Bromide-Bromate Standard Solution (0.10 N) —
60.0002. Restandardize at intervals frequent enough to detect
Dissolve 10.1 g of potassium bromide (KBr) and 2.8 g
changes of 0.0005 in normality.
potassium bromate (KBrO ) in water and dilute to 1.0 L.
3 6
7.7 Starch Solution —Mill5gofarrow-rootstarchwith3to
Standardize to four significant figures as follows: Place 50 mL
5 mLof water.Add the suspension to 2 Lof boiling water.As
of glacial acetic acid and 1.0 mLof concentrated hydrochloric
apreservative,5to10mgofmercuriciodide(H I)or0.2gof
g 2
acid (HCl, sp gr 1.19) in a 500-mL iodine number flask. Chill
salicylic acid can also be added. Boil for 5 to
...
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