CCL REPORT NO. 304

I FINAL REPORT

ANALYTICAL METHOD FOR ETHYLENE DIBROMIDE

DEPLETION IN AVIATION GASOLINESDD

BY I1

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Aberdeen Proving Ground, Md. 210053 REPORT TITLE

ANALYTICAL METHOD FOR ETHYLENE DIBROMIDE DEPLETION IN AVIATION GASOLINE I4 DESCRIPTIVE NOTES (Type o1 report and inclusive dates)

Final Report5 AUTV;OR(S) (Lost name. first name. initial)

Esposito, George G.

6- REPORT DATE 7o. TOTAL NO OF PAGES 7b NO OF REF S

May 1972 12 ,8o CONTRACT OR GRANT NO. 9a ORIGItNAITORS EPORT NUMBSERS)

AICMS Code No. 502E.11.29500b PROJECT No. CCL #304

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111z U.S. Army Materiel Command

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IS3 ABSTRACT

The measurement of ethylene dibromide depletion in aviation gasoline is oneL-iterion for evaluating the storage stability of coatings used for the corrosionprevention of tanks and containars used for the storage and protection ofmilitary petroleum based hydrocarbons fuels. The standard procedure for thedetermination of ethylene dibromide depletion is time-consuming, requiressoecial equipment, and necessitates extraordinary care in handling. The methoddescribed in this report affords an accurate, uninvolved procedure for measuringethylene dibromide depletion; the procedure is free from hazardous operatingconditions and is highly reproduciblei-

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UNCLASSIFIED

CCL REPORT NO. 304

FINAL REPORT

ANALYTICAL METHOD FOR ETHYLENE DIBROMIDE DEPLETION

IN AVIATION GASOLINE

BY

GEORGE G. ESPOSITO

MAY 1972

AMCMS CODE NO. 502E.11.29500

DEPARTMENT OF THE ARMY PROJECT NO. U

1T062105A329

U. S. ARMYABERDEEN RESEARCH AND DEVELOPMENT CENTER

COATING AND CHEMICAL LABORATORYABERDEEN PROVING GROUND

'ARYLAND 21005

THIS DOCUMENT HAS BEEN APPROVED FOR PUBLIC RELEASEAND SALE; ITS DISTRIBUTION IS UNLIMITED

UNCLASSIFIED

ABSTRACT

The measurement of ethylene dibromide depletion in aviation gasolineis one criterion for evaluating the storage stability of coatings usedfor the corrosion prevention of tanks and containers used for the storage

and protection of military petroleum based hydrocarbons fuels. The stand- iI• ard procedure for the determination of ethylene dibromide depletion istime-consuming, requires special equipment, and necessitates extraordinarycare in handling. The method described'in this report affords an accurate,uninvolved procedure for measuring ethylene dibromide depletion; theprocedure is free from hazardous operating conditions and is highly re-producible. iI I

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TABLE OF CONTENTS

Page No.

ANTITLE PAGE................................................ ii

ABSTRADCTION................................................Ii-A

INTRODUCTION ................................................... 1- 2

DETAILS OF TEST............................................ 2

RESULTSF .................................................. 3

APPENDIX A ............................................... 3

Tables I - I .......................................... 5

DISTRIBUTION LIST ... ...... ............. 6 - 8

DD FORM 1473 ............................................. 9

I

I

i V

I. INTRODUCTION

Many fuel and water resisting protective coatings have been developedto maintain internal corrosion control of cargc tanks of barges, railwaytank cars, tankers, trucks, surface and subsurface tanks. and tankersused for the bulk transportation and storage of a wide variety of militarypetroleum fuels. A number of different types of coatings have provedsatisfactory for this service, and other coatings continue to evolvefrom research and development of new pulymeric materials. A suitablefuel container coating must adequately protect tanks from corrosion,must not react with or contaminate the fuel, and must not be degraded bythe environment.

Current military specifications prescribe requirements for the per-formance characteristics of coatings intended for lining the interiorsurfaces of fuel storage tanks. One of the tests used to determinethe compatibility of protective coatings with hydrocarbon fuel is theethylene dibromide depletion test. Ethylene dibromide is well known asan effective scavenger of lead deposits and at the present time, 3 - 4gms/gallon are blended with aviation gasoline to offset the undesirableeffects of antiknock organolead additives found in aviation gasoline.The test is conducted to determine if any reaction occurs between a coat-ing material and ethylene dibromide in gasoline when they have had inti-mate contact over an extended period of time.

The bromine depletion test described in MIL-STD-1262 (MilitaryStandard Degradation Tests for Fuels and Fuel Container Coatings) con-sists of exposing a coated test panel to aviation gasoline for 35 daysand testing the exposed gasoline and control gasoline for bromine con-tent. A sample of gasoline is added to sodium metal under cryogenic con-ditions followed by various treatments that are necessary for the decom-position of excess sodium and the elimination of interference from addi-tives and impurities in the gasoline. Final measurement is accomplishedby the potentiometric titration of bromides with silver nitrate solution.The procedure must be carefully monitored and extreme caution must beexercised to reduce the hazard of fire.

The procedure developed in this laboratory is based on the reactiondescribed in Fieser and Fieser (1) for the formation of vinyl bromide.

SBrCH 2 CH28r alcohlic KOHBrCH2CH2B )CH 2 =CHBr

Balancing the reaction gives,

BrCH2 CH2 Br + KOH o. CH2 = CHBr + KBr + H20

Since potassium brnmide, one of the products, is easily determined byreaction with silver nitrate, conditions were established which favoredthe quantitative formation of potassium bromide. The proposed procedureis relatively easy to conduct and gives exceptionally good reproducibility.

A gasoline sample is refluxed with alcoholic KOH and potassiumbromide is precipitated quantitatively from solution. The precipitateis washed free of gasoline, dissolved in water, and precipitated as thesilver salt frum an acid solution. The amount of ethylene bromide in theoriginal sample iq calculated from the weight of silver bromide.

I. DETAILS OF TEST

Reagent~s:

1. Alcoholic KOH, IN.Dissolve 65 grams of potassium hydroxide in I liter of absoluteethanol. :'lter immediately before using.

2. Silver nitrate solution, 5%.Dissolve 50 grams of reagent grade silver nitrate in I liter ofdistilled water.

Procedure:

Pipette 100 ml. samples of exposed and unexposed aviation gasolinefo separa:_ 250 ml. flasks with ground glass joints. Treat both samples%, tne 6oiloiwing manner. Add 25 mi. of alcoholic KOH, attach an air con-3:?,ner, and --flt• for 2 hours in a 65 - 70%C. water bath (NOTE 1). Cools-t•e . reoiq -,.rature -nd filter through a dry Gooch crucible con-

t-.ning a nka-" 4f asbestos, was:,ing with benzene. Dry the flask andcrukible at ;"'C. Cool to room temperature and wash the contents of thelaktruhthe crucible into a clean 500 mi. suction flask with about

100 ml. of distilled water. Quantitatively transfer the filtrate to a400 ml. beaker, add 5 ml. of 7.5 N nitric acid, and dilute to 250 ml. withdistifl,.d water. While stirring, slowly add 10 ml. of 5% silver nitratesolution. Heat the solution to 80 - 90°C. and then cool to room tempera-ture. Filter the sample through a tared Gooch crucible containing a matof asbestos; quantitatively wash and transfer precipitate with 1% nitricacid; and finally wash until acid free with distilled water. Dry thecrucible for 1 hour at 125 - 135*C., cool in dessicator, and weigh.

Calculation:

wt. of Br in 100 ml. gasoline = wt. of AgBr x 0.424

t. ue Br in 100 ml. gas. x 37.85grams ethylene dibromide/gallon gasoline =w 0.8507

NOTE 1: Use water bath in a well ventilated hood as the light ends ofgasoline will distill from the sample through the air condenser.

2

77' °

E Ii. RESULTS

Ethylene dibromide was quantitatively blended with unleaded gasolineto give known samples ranging from about I to 6 grams per gallon. Theanalytical results shown in Table I illustrate the high order of repro-ducibility of the method. Theoretical yields were obtained with samplesA and B; however, yields were lower with the smaller samples, C and D.

Low results can be improved by increasing the sample size as shown withSample D. Moreover, ethylene dibromlrda depletion is generally determinedon aviation gasoline containing levels of ethylene dibromide similar toSample B.

' Ethylene dibromide depletion was determined on several tank coatingmaterials; the resuits are shown in Table II. Specifications usuallyallow up to 10% ethylene dibromide depletion.

IV. DISCUSSION

Larger samples would hvve improved the accuracy of the procedurewith fuels containing very low levels of ethylene dibromide, but largesample would have produ,:ed some inherent problems, such as, longer timeto reach reflux tempeiature, larger filtering volume, and increasedvolume of light ends ves,- distilled into the hooded area.

During the early stages of procedure development, potassium bromidewas extracted with water from die gasoline following the alkali treatment.This procedure gave consistently high results and further investigationshowed that some of the additives and impurities, e.g., phenols andsulfides, formed insoluble silver salts which added to the weight ofsilver bromide. By filtering the solution after saponification, theinsoluble potassium bromide was washed free of interfering materialsand subsequent quantitative precipitation of silver bromide was madepossible. The procedure can not be terminated by weighing the potassiumbromide because of the presence of insoluble potassium carbonate saltsthat form during alkali treatment of the sample.

Leaded gasoline for automobiles may contain a chloride lead scavengerin addition to ethylene dibromide. When the procedure was applied directlyto pure ethylene dichloride low results were obtained. Extending the Ireflux time and increasing the reflux temperature, greatly improved theyield for ethylene dichloride; but since a method of analysis for ethyl-ene dichloride was not within the scope of the investigation the studywas not pursued further. However, it is reasonable to believe thatoptimum conditions could be established for the analysis of both ethyl-ene dibromide and ethylene dichloride.

V. REFERENCE

1. Fieser, L. F. and Fieser, Mi., Advanced Organic Chemistry, p. 340,Reinhold Corp., New York (1961).

+ I,

I

APPENDIX A

4

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TABLE I

Determination of Ethylene Dibromide in Aviation Gasoline

g/gallon g/gallonSample P resent Found Recovery

A 6.226 6.319; 6.230 100.7

B 3.113 3.092; 3.092 99.3

C 1.556 m.:42; : .442 92.70 0.933 0.773; 0.770 82.9

0. 933 0. 877; 0. 876 94. O*

*Used 200 mi. of sample.

TABLE I I

Ethylene Dibromide Depletion

EthyleneDibromide

Sample Depletion

A 0.5%

S01.1

C 0.7

:5