a t t h e I-nanogram level, and was, therefore, analyzed on column h The inii)uritie. were eluted ac a group in 42 to 57 minutes on column 13. Colu~nn X way not utilized €or the complete beciuie of its poorer reiolution of the indi! idual m a l j zates. Chromatogram. of .ampl> 1 on the t a o column- arc presented in Figure 2. Infrared spectra of compound< 601 and 7 7 3 and iainple I , . before and after chromatographic cleaiiup, are shown in Figure 3. The wnilarity of the purified iam1)le T3 .pectruni and that of ('om1)ound 601 ic ob\ i o u c . but cornliound 7 7 3 I. identified by it. band. a t 1200, 1060, 970. and 662 cnl-'. Inyiection of thrl .pcctra point< out the need for chromatographic cleanuli prior to infrared analy-is. The extraction ( l a t i of samples containing t n o concentrtttion level- of the chlorinated compound. are cornpled in l'ahle 11. I t I\ evidcnt from the data on iamplc A that the extraction efficiencj of the fir5t chamber not exactly reproduced in the othrv chamber\ For e\aini)li., baied on the 97% e\traction effici?nC) obtained for C!oTll]J(Juild 601 by the fir-t e\tractioii clianiber, one nould e\pcct to find 6 0 anti 0 2 1) p.b of coinpound 601, re.pecti\ ~ l y In , the iccond and third e\traction chamber.
The deviation between these and the experimental values probably i p caused by a combination of analytical errors and differences in the estraction efficiency of the respective estraction chambers. These deviations are minor and do not affect the data significantly. A possihle esplanation of the rclatively high values, based upon estraction efficiency, obtained by the third chamber in the case of samlile X and ])robably by the second chamber in the case of sample 1% is a low level analytical interference which becomes significant a t low concentration values. This phenomenon would also esplain the low extraction efficiency obtained in the est'raction of sample 1%. Although the apparatus was limited to the use of only one extraction solvent in these esperimeiits, it can be made much more versatile by the use of different solvents in the estraction chambers and/or by treating the aqueous stream as it passes between chambers. For esample, a basic aqueous stream may be estracted with a nonpolar solvent, such as hexane, in the first estraction chamber and with a more polar solvent, sucah as cthtlr, in the second estraction chamber. Tho stream may then be treattd, for esample, with HCl in passing into the third extraction
chamber, convert'ing organic acid salts to t'heir respective acids, to be est,racted in the nest extraction chamber by an appropriate solvent. The use of such an extraction sequence would extract, \vit,hin limits, compounds according to their structural and,'or chemical characteristics. ACKNOWLEDGMENT
The cooperation of the authorities at, the Rocky Mountain hrsenal in obtaining the saniples, and of Shell Chemical Co., which furnished the reference samples, is gratefully acknowledged. The figures in the paper were prepared by John E. Robertson. LITERATURE CITED
(1) Henderson, C., Pickering, Q. H., Tarzwell, C. M.j Trans. A m . Fisheries Soc. 88,23 (19%). ( 2 ) Phillips, 11. I].> Pollard, G. E , $ Soloway, S. B., J . Agr. Food Chem. 10, 217 (1962). ( 3 ) Rose'n, A. A., Middleton, F. hf., A N A L .CHEM.31, 1729 (1959). (4) Teasley, J. I., Cox, W. S., .I. .4m. U.'ater Irorks .4ssoc. 5 5 , 109.11 (1963). ( 5 ) N'erner, A . E., m'aldichuk, Jlicaliael, AkS.kI,.CHEM. 34, 1674 (1962j. I ~ E C E I ~ EforL )review Xovember 18! 1063. Awept,ed llarch 4, 1964. Publication authorized by the I)irect,or, [ - , S. Geological Survey, Rashingt.on, I). C.
The Determination of dl- and meso-Dibromosuccinic Acids in Aqueous Solutions RAYMOND ANNlNCl and DAVID J. MANZO' Department of Chemistry, Canisius College, Buffalo,
b
A rapid procedure i s described for the analysis of mixtures of dl- and meso-dibromosuccinic acids. The concentration of the acids i s determined polarographically and compared to the amount remaining after 60 minutes in sodium hydroxisde at 25" C. Since only the dl isomer reacts quantitatively during this interval, the final limiting current can b e related directly to the original con'centration of the meso isomer. The concentration of the dl isomer is obtained b y difference.
A.
~II:THOI) was
d w i i ~ dfor the analysis of dilute solutions of dl- and n m o dibromosuc.cinic acids. The polar ogral)hica behavior of the acids has been rqmrtcd ( 2 ) hut, cnfortunately, the half-\vavc~potcntialq (of t,he two isomers UI'C not, sriffiriently wi)arated to allondirccir i)ol:iro,grapliic analy.sii. King and E'efcr (4)h a r e dcveloprd a kinetic method for the a n a l p i of thew two
N. Y.
compounds which is based on the observation that the d l isomer in acid solihon eliminates hydrogen bromide nine time? faster than the meso isomer. .is is the case with many kinetic procedures which do not involve large differences in rate constants, the method is quite lengthy, involves considerable operator time, and its accuracy is questionable es1)ecially when the differtmce in concentration of the two acids is large. I t is quite possible that the method could be improved by determining the total roncentration of the acids directly (polarographic analysis) instead of from a difference titration of the reaction mixture, and using the .single point nwthod of Lee and Kolthoff ( 6 ) . l'he >ubjcct of this paper is an altwnate and inorr satisfactory solution which involves increasing the difference in the rates of dehydrohalogenation as \wll as the ahsolute value of the rate constant.;. This is accomplished by rca d i n g the acids with cxcess base.
I-nder t'he condit'iorw selected, the rll isomer reacts quantitatively in 60 minute? while the'coiicentration of the meso isomer does not, change by more than 1% relative. However, 'a large positive salt effect is observed from these reactions. If the dibioniosuccinic. acids are dissolved in a solution of high ionic strength, a kinetic ~iroportionalityconstant for the rneso iqomer is determined in the sanie niati' EXPERIMENTAL
Reagents. meso - Dibromosuccinic acid (m-DuSAi)wa7 prepared by the addition of bromine to fumaric acid ( 7 ) . .ifter recry~tallizationfrom 50-50 acctone-i )ctroleum hesane, the nrotlurt melted a t 254"-255' C.; reported, 255-6" c'. ( 6 ) . 1 Present address, Chemistrv Department, Kansas State I-niverqitv. 31anhattan, Kan
VOL. 36, NO. 7, JUNE 1964
1343
dl-Dibromosuccinic acid (dl-DBSA) was prepared according to the method of RIcKenzie ( 6 ) . The product which appeared to be contaminat,ed with bromosuccinic acid (identified polarographically) was purified by extraction with ether. The dl-DBSd obtained after evaporation of the ethereal solution proved t o be polarographically pure and kinetically homogeneous. [m.p. 164-165" C.; reported, 166-7" C. ( S ) ] . Stock solutions of each of the above acids were prepared in dist,illed water (4.0 X 10-3AlPto 13.7 X 10-3Jf) and used to make up the mixt'ures shown in Table I. .-ill solut'ions were freshly prepared since the dibromosuccinic acids also undergo dehydrohalogenat,ion in aqueous and acid solutions. The concentration of the dl isomer will decrease by approximately 57c (relative) in 8 hours a t 25" C. Apparatus. Sargent, Model XV Polarograph and a t'hermostated (25" i 0.1" C.) H-type cell equipped with a saturated calomel electrode as reference was connected to the sample side lyith a saturated potassium chloride-3% .$gar bridge. -1number of capillaries have been used for the dropping mercury electrodes (m2iat''6 = 1.31-1.72 1ng.?!3sec. -':z). Procedure. DETERMINATIOX OF
for 15 minut.es. The limiting current was obtained a t -0.3 volt us. the S.C.E. and corrected for that due to supporting electrolyte. The kinetic proportionality constant was then calculated in the following manner (all limiting currents used in the calculations have been corrected for that due to supporting electrolyte).
K=-
id'
&(meso)
The limiting current of the original unreacted solution (id) is usually determined while waiting for the other sample to react. However, it may be also determined a t the end of the analysis (60 minutes) since the dl isomer reacts only to the extent of 0.5% relative in this time. RESULTS AND DISCUSSION
The alkaline elimination of hydrogen bromide from dibromosuccinic acid is a id' = corrected limiting current second-order process, but in the presence after 60-minute reaction of the excess base used in this method with base pseudo first-order kinetics are observed. i d ( m e t S 0 ) = corrected limiting current -1 great simplification in procedure is of the unreacted mesopossible because of the larger difference IlUS.1. in the rate constants for the alkaline AKALYSISOF UNKNOWN SOLUTIOS. dehydrohalogenation. The first-order rat'e constants a t 25" C. for the acid Two 5-ml. aliquots of the unknonn were treated in the same manner as dehydrohalogenation of dl- and mesoabove. The concentration of each DUS.1 are 1 X lo-* minute-' and isomer was then calculated in the 0.09 X lop4 minute-', respectively following manner. ( 3 ) . The second-order rate constants for the two komers in alkaline medium id' at 25" C. and I.( = 0.085 are given in - = id (meso) K Table I. Effect of Ionic Strength on the Rates i d - i d (meso) = i d ( d l ) (3) of Dehydrohalogenation. h large positive salt effect is expected for the id (meso) K I N E T I C PROPORTIOSALITT COXSTANT C(,,,,, = ___ x 20 (4) react'ion of ions of like charge. The FOR meso - DUSh. Two 25-ml. k (meso) variation in rate constant for the two aliquots of 0.1M NaOH were taken isomers is shown in Table I. These at 25' f 2" C. The first was added to a results were obt,ained using KCl to 100-ml. volumetric flask containing a increase the ionic strength of the reac5-nil. aliquot of mso-DBSAIa t the same where temperature. The solution was st,irred tion medium. For highly accurate K = kinetic proportionality conand maintained a t 25" f 2" C. for 60 results the kinetic proportionality constant for the meso isomer minutes when 25 ml. of 0.2M HCl was stant must, be determined in a matrix id = corrected limiting current, added. The second aliquot was acidisimilar to that, containing the sample. a t -0.3 volt, us. S.C.E., of fied with 25 ml. of 0.2M HC1 and added However, a t ionic strength of 0.1 or less undehydrohalogenated alito another 100-ml. volumetric flask the correct,ion amounts to only 1% quot containing a 5-mi. aliquot of mesoid' = corrected limiting current, relative. Ilso, since the mriiple is DBSI. 130th solutions were diluted a t -0.3 volt vs. S.C.E., of diluted six t,imes by the addition of the to volume with distilled water after dehydrohalogenated aliquot base, t,he error encountered by using the the addition of 5 ml. of lYc gelatin i d ( d l j = corrected limiting current, solution. A portion of each solution 1% correction is considerably reduced. contribution from t'he dl was reduced after removing oxygen Effect of Temperature on the Rates isomer by passing nitrogen through the solution of Dehydrohalogenation. The error i d (mesoj = corrected liniit,ing curfound in working a t 23" C. or 27" C. rent, contribution from while using the lYG correction (dethe meso isomer termined a t 25") was found to be k d l and k,,,, = current,-concentration Table I. Effect of Ionic Strength on only 0.2% relative. The dl isomer ratios (&,'e) for the dl Rate Constants of meso- and dl-Diand meso isomers in the has reacted to the extent of 99.91% bromosuccinic Acids same supporting electroeven a t 23" C. and does not interfere k z min. mole-' liter lyte in the final analysis for the meso P meso dl Cdl = concentration of dl-DI3S-I isomer. Thus the temperature need in original solution 0.083 2 . 3 x 10-3 1.65 not be controlled to better than 1 2 " C,,, = concentration of meso0.280 4 9 x 10-3 3.1 c. DUSA in original solu0.978 11.0 x 10-3 Effect of Ionic Strength and Specific tion Salts on the Polarographic CurrentConcentration Ratios. The effect of specific salts and ionic strength on the polarographic behavior of organic Table II. Analysis of Aqueous Solutions of dl- and meso-Dibromosuccinic Acids" compounds has been emphasized in Rel. Concentration, mM error, Re1 std t,he literature ( 1 ) . However, the proTaken % dev, Yo Found Isomer cedure presented here involves a 20-fold -0 9 1 0 11 1 11 2 dl dilution of the original samples, before -0 2 14 0 918 0 920 meso the polarographic analysis step. S o +o 74 2 0 6 78 6 73 dl changes in the current-concentration -0 5 1 0 6 07 6 10 meso ratios were observed in the analysis of dl 0 73 0 65 -9 1 15 7 meso 9 96 10 05 +o 9 0 8 samples up to p = 1.0. Interferences. Interference is exSIXreplicates pected from any species which is ~~
~~~~
5
~~
1344
ANALYTICAL CHEMISTRY
where
polarographically reducible near -0.3 volt u s . S.C.E. where the limiting current is measured. Of the closely related species fumaric, maleic, monobromofumaric, monobromomaleic, and monobromosuccinic acids, only monobromosuccinic acid ( E l i ? = -0.25 volt Z J S . S.C.E.) is cxpected to seriously interfere. However, t’he presence of this impurity is easily detected since in its absence the diffusion current of dibromosuvcinic acid has already reached its plateau and is fairly level in this reTion. Accuracy and ]Precision. ,The method was eva1uatI.d a t three concentration ratios. ‘The results are tabulated in Table 11:. The precision
and accuracy for the determination of t h e meso isomer is somewhat better than for the determination of dlDBSA. This is expected since it is a direct determination while the concentration of the dl isomer is obtained by difference Khereas the method is quite reliable for small concentrations of the meso isomer in the presence of a large amount of the dl isomer the reverse is not true, since the latter analysis involves a small difierence between two relatively large numbers. LITERATURE CITED
(1) Elving,
P. J., Kornyathy, J . C., Van Atta, R. E., Tang, C. S., Rosenthal, I., A 4 CHEM. ~ ~ ~23,. 12118 (1951).
( 2 ) Elving, P. J., Rosenthal, I., l\Zart,in, A. J., J . .4m.C h e m SOC.77, ,5218 (1955). (3) Holniberg, B., J . prakl. C‘heni. 84, 149 ( 1911). ( 4 ) King, I,. C., Fefer, M., Asar.. CHEST, 29, 10.56 (1957). ( 5 ) Lee, T. S., Kolthoff, I. AI., Ann. .Y. Y . i l ~ d SCZ. . 53, 1093 (1951). ( 6 ) McKenzie 4 J., J . ?hem. Soc. 101, 1196 (1912); ’ ~
( 7 ) Ithinesrnith, H. S.,“Organic Synthesis, Collected,” Vol. 2 , p. 177, Wiley, S e w York, 1944.
I~ECEIVEI) for review Sovernber 2GG!1!)63. Accepted Ifarch 26, 1964. This work was supported by the Petroleum Itesearcah Fund-American Chenric*alSociet,y ((;rant Xo. 1049-H ). Pittsburgh Conferenre o n Analytical Chemistry and Applied Spectroscopy, .\larch 1964.
Mic ro dete rmina ti o n of PoIy oxyet hy le ne a nd PoIyoxypropyIene Surface Active Agents JOSEPH LEE WILLIAMS and HORACE D. GRAHAM’ George Washington Carver Foundation, Tuskegee Institute, Ala.
b Polyoxyethylene cind polyoxypropylene surface active agents were quantitatively determined after pyrolysis in the presence of phosphoric acid under a column of scind. The acetaldehyde produced from the former type of compounds and the propionaldehyde produced from the latter, were detected by Rosen’s reagent (sodium nitroprusside and diethanolamine) and the resulting colored complexes measured at !i65 mp and 405 mp, respectively. ,4n inexpensive, easily constructed pyrolysis apparatus is described and optimum conditions for quantitative determination were established. Recovery, based on the ethylene oxide or lsropylene oxide content of the polymlsrs, ranged from 82-94%‘,. All polyoxyethylene and polyoxypropylene compounds tested responded. Spans, fatty acids (except in relatively high concentrations), and other surfactants and compounds which do not contcin the ethylene oxide or propylene oxide units do not respond to the test.
polyoiyethylene and polyo\yl)ropylene surfactants, but by all cationic surfactants, with or without the polyoiyethylene or polyo\ypropylene group. Gatewood and Graham (5) developed a quantitative test for surfactants containing the polyoxyethylene or polyoxypropylene group. .inhydrou. samples of the surfactant were heated
Q
tests for I)Olyosyet hylene and polyoxypropylrne surfactants are few. Those available (1, 6:A‘, I 1 , 15, 16) are essentially modifications of the generally used 1)reciI)itation tests for cationic surfactantb by means of a large anicn (4,11, 13, I ? ) , Thcrrfore, they are g v e n not only by Present address, Ikpartrnent of 13iology, C(il1egeo f Agrirulture and .\lec,h:inic Arts, I-riiversity of Prierto I .proup l(~ii(~ yields propionaldehyde which 1)roducc.q an orange color with t hc rrng.cnt. Icvery type of surfactant coritaini~ipeither t h r polyoxyethylene or I)ol!os\-1)roi).\,lrn~~ groui, ran br detrctrd by Rosen’s method but glycerides interferr with the test. This report i p conwrned with placing Rosrn*s (1’1) qualitative test on a quantitative ba4s. EXPERIMENTAL
Pyrolysis Apparatus.
C o mponent s
of the pyrolysis al)i)aratus (Fiprirc 1 ) are the deli\.rr>. head a n d t h c pychamber. l‘hc tl(1livcry hcad waq made a s follo\v.: a horo~ilirntc glass Claisen head, height 225 m m . . VOL. 36, N O . 7, JUNE 1964
1345
