ANALYTICAL CHEMISTRY
1480 The condensables are particularly suitable for subsequent determination of olefins because hydrogen and carbon monoxide, which interfere with most olefin reagents, are already eliminated. ACKNOWLEDGMENT
The authors express appreciation to R. A. Bourniqur, E’. J. Martin, A. J. Millendorf, and Karl Uhrig for valuable awi+mce in the initial stages of this work. LITERATURE CITED
i l ) Am. Gas Asaoc., New York, “Gas Chemists’ Handbook,” pp. 195-6, 1929. EXG.CHEM., (2) Brooks, F. R., Benjamin, P., and Zahn, V.,IND. AN.4L. ED.,18, 339 (1946). (3) Carnegie Steel Co., Pittsburgh, Pa., “Methods of the Chemists of United States Steel Corporation for the Sampling and Analysis of Gases,” 3rd ed., pp. 36, 39-41, 1927. (4) Cook, F., IXD. EYG.CHEM.,ANAL.ED., 12, 661-2 (1940). 15) Dennis, L. M., and Nichols, M. L., “Gas Analysis.” pp, 240-6, rev. ed., NPWYork, Macmillan Co., 1929.
Francis, A . W.. and Lukasiewirr, S. J., IND.ENG.&EM ASAL. ED.,17, 703 (1945). Gooderham, W.J.,J . SOC.Chem. Ind., 57, 388T-95T (1938). Hoover, C. R., J . Ind. Eng. Chem., 13,770-2 (1921). Lamb, -1.B., Bray. W. C., and Frarer, J. C. W., Ibid.. 12 213-21 (1920). Lawon, A. T.. and IVhittaker, C. Q-., Ind. Eng. Chem.. 17, 31: (1925). McCullough. J . D., Crane, K. A . . and Beckman, A. 0 CHEM.,19, 999 (1947). Manchot, W., and Scherer, O . , Ber., 60B,326-32 (1927). Salsbury, J. M.. Cole. J. W., and Yoe, J. H., ANAL.CHEM..19 66 (1947). Savelli, J. J., Seyfried, W. D., and Filbert, B. M.,IN). F h c . CHEM..ANL. ED.,13, 868-79 (1941). Teaeue. M .C‘., J . Ind. Ena. Chem.. 12, 964-8 (1920). (16) Tropsrh, Hans and Dittrick, E., B r e w & $ - C h e k . ,6, 169 (1925’ (17) Wagner, G., Ostrrr.. Chern.-Ztg.,42, 265-77 (1939). (18) Walker, B. 8.. a n d .Illey, 0. E.. .44nesthesia and d n f d ~ r n k ~ 8, 227-9 119291. (19) White, W.H., ISD. EN^. (:HEM., ASAL.ED.,12, 550 (1940). RECEIVEDM a y 6, 1949. Presented before the Division of Petroleulb So(.rmY. S R ~ Chemistry a t t h e 115th \IPrting of the AVERICAXCHEMICAL Francisco, Calif.
Separation of Polybasic Acids by Fractional Extraction C. S. MARVEL
AND
J. C. RICHARDS, University of Illinois, Urbana, Ill.
Distribution coefficients of a number of mono- and polybasic acids between water and various organic solvents are reported. The solvents are arranged in order of extracting capacity; this order is valid for most of the acids examined. Several polybasic acids have been subjected to fractional extraction procedures to show that the acids distribute themselves among the funnels in approximately the
I
N COSK’ECTIOK’ with a series of structure studies being car-
ried out on GR-S and related copolymers of butadiene, i t was necessary to develop new techniques for separating the polybasic acids of high molecular weight derived by oxidative cleavage of these polymers. Rabjohn, Bryan, Inskeep, Johnson, and Lawson (6) found that distillation of the methyl esters was satisfactory only in the case of the lower members of the dibasic acid series because of the nonvolatility of esters of the acids of higher molecular weight. The separation of nonvolatile materials by fractional extraction is a method that has been developed in the past few years. Craig ( 3 ) has presented an excellent review of the literature in this field, and Bush and Densen ( 2 ) have discussed the principles involved in laboratory-scale fractional extractions. The method has been applied to the separation and identification of the components of mixtures of aliphatic acids by Atchley ( 1 ) and by Sato, Barry, and Craig (7), but in both cases buffered solutions were used and i t was difficult to recover the acids in high yields without contamination. Before attempting to apply the method to the separation of unknown mixtures of acids, the behavior of some known acids in unbuffered extraction systems was investigated. The distribution coefficients of a number of mono- and polybasic acids between water and various organic solvents were determined. After this had been done, fractional extraction procedures were applied to several of these acids to learn whether their distribution among the funnels would check the calculated values.
manner calculated from the known distribution coefficients. Application of the fractional extraction technique to water-soluble acids derived by oxidative cleavage of a butadiene-styrene copolymer results in removal of substantially all the phenylcontaining material from the bulk of the acids as well as in separation of the p-phenyladipic acid that is present. DISTRIBUTION COEFFICIENTS
Because extremely accurate results were not of critical importance in this work, the distribution coefficients were determined iu a simple and rapid fashion. The data obtained, however, are accurate to approximately 3 to 5%. The acids that were soluble in water to the evtent of 1% her? made up in distilled water to a concentration of 1 gram per 100 ml. Two milliliters of this solution were pipetted into a test tube. 10 ml. of water were added, the mixture was shaken, and a 2-ml aliquot was titrated to phenolphthalein end point with 0.010 h’ sodium hydroxide. Ten milliliters of the extracting solvent were added to the test tube, which was stoppered and shaken thoroughly. After the layers had settled, a 2-ml. sample of the water layer was again titrated Mith the same standard alkali. The distribution coefficient, K , was calculated as the quotient of concentration in the water phase (by direct titration) over concentration in the organic phase (by difference). As ratios of less than 1 to 10 or more than 10 to 1 were difficult to estimate accurately, the) were reported as 0.1 and 10, respectively. Acids that were not soluble in water to the extent of 1% could not be handled in this manner. These acids-suberic, azelaic, sebacic, benzoic, and p-phenyladipic-were tested in the following manner. One tenth gram of the acid was dissolved in 100 ml of distilled water and 2 ml. of this solution were titrated with 0.010 N sodium hydroxide to phenolphthalein end point. Ten milliliters of the solution were then extracted with 10 ml. of the extractingsolvent and after the layers had separated, a 2-ml. portion of the water layer was titrated, The value of K was calculated as before. No special effort was made to keep the temperature of the solutions constant; in all cases the temperature of the room was within 2 ” of 26” C. When the extracting liquid was soluhlp i r
V O L U M E 21, NO. 12, D E C E M B E R 1 9 4 9 Table I.
HzU-dknllysolve B HzO-CClr H?O-benzene H~O-CHCII HsO-diisopropyl kctone HzO-butyl acetatr HzO-ethyl ether HzO-methyl isobutyl ketone HnO-ethyl acetate H?O-methyl propyl ketone HnO-methyl ethyl ketone HzO-cyclohexanone HzO-n-butanol 10 signifies equal t o
Citric 10 10 10 10 10 10 10
10 10
in
10
10 6.2
10 10 8.0
4.6
2.8
2.9 2.2
1.1 1.1
Ju-
beric 10 LO 10 10
in 10
>ebaclc BenZOIC 6 5 4.5 3.6 0 62
0.59 0.42 0.27
0.53 0.38 0.34
0.1 0.11 0 1
0.1 0.1 0.1
1,2 0.91
U.83 0.59
0.21 0.16
0.1 0.1
0.1 0.1
2.2
2.3
0.5,5
11.43
4).
12
0.1
0.1
S 4
1.0 0.50 0.91 0.82 0.83 0.31 0.1 signifies equal
0.38 9.21 0.1 0.29 0.14 0.1 0.30 0.12 0.1 t o or leas t h a n 0.1.
I- uriiiic acid Acetic acid Propionir arid
1.4
2.7
0.1 0.1 0.1
__ Distribution Coefficients
H20
n-Butanol Concn." Dil.*
Fu,marl(. 10
.ldipir 10 10 10 10
6.8 3.2
Table 11.
.4cid
8;.-
cinic 10 10 10 10
3.0 1.0 1,i 0.74 3.5 0.85 or greater t h a n 1 0 ;
Hz0 ___-
For t h r i i i w h s i c acids tested, the order r u n ? as follows:
Distribution Coefficients
&Carboxyadipic 10 10
10
148i
Ethyl -4cetate Concn. Dil.
H20 Ether Concn. Dil. 10 10 8 1 8.5 6.0 8 0 4 2 3.9 2 2 2 1 0 91 0.91 0 34 0 , 36 0 14 0 11 0 1 (1. 1
HzO CHCls Concn. Di!.
HzO . . ~. Skellysolve B Conon. Dil.
Oxalic !O 10 10 10 10 10 4.6 5.8 4.0 10 to 10 1 9 4.5 10 hIalqn/c 1.5 I (1 i0 10 2.7 10 3uccinlc 0.83 1.0 10 10 10 0.62 1.5 10 Glutaric 0.59 10 10 10 10 .4dipic 0.36 0 91 0 83 0.31 10 10 10 10 0.38 Pimelic 0 38 0.17 0.15 10 10 10 10 0.16 Suberic 0.12 0 2@ 0.12 0 1 3 8 &.ti 10 10 0.1 0.1 Azelaic 0.1 ( 1 63 0 91 0.1 0 1 6 5 10 0.1 Sebacic 0.1 8-Carboxyadipic 0.83 , , 3.2 . !C 10 10 ., $-Phenyl0 1 , 4.0 . . 1 b ." 0.1 ., adipic 0.1 0.30 ., 0.59 1.1 .. IO . . l o , . Fumaric 10 ... to ... in , 10 Citric 3.5 ... 1.2 1.3 1.7 1.7 3.1 i:8 10 10 10 10 Formic 0.91 0.91 1.5 2.4 10 10 10 10 Acetic 1.5 2 3 10 7.6 10 0.36 0.45 0.45 0.67 5.6 Propionic 0 . 3 6 0.63 1.7 10 10 0.14 0.16 0.18 0.19 0.19 1.2 Butyric 0.22 0.1 0.27 0.48 1.4 3.1 Benzoic 0.1 0.1 0.1 0.1 0.1 a Concentration of acid in water before extraction with an equal volume of solvent, For most acids this was 0.16 weakest to the strongest, is as follows: Skellysolve B (boiling point 60" to 65' C.) Carbon tetrachloride Benzene Chloroform Diisopropyl ketone But) 1 acetate Ethyl ether Methyl isobutyl ketone Ethyl acetate Methylpropjlketone = metha lethylkrtone = cyclohexanone = n-butanol The polybasic acids may also be arranged in a definite order of relative affinity for the aqueous phase, and this order holds true for most of the solvents examined. The order in which the polybasic acids may be arranged, beginning with those which favor the mater layer the most strongly, is as follows: Oxalic acid Citric acid Malonic acid &Carbox>adipic acid Succinic acid Glutaric acid Adipic acid
Fumaric acid Pimelic acid Suberic acid P-Phens ladipir acid Azelaic acid Sebacic acid
, .
..
- .
Butyric acid Benzoic arid
T h r dibrnbution coefficients which M ert. irL tained ale listed in Tables I and 11. Table I in cludei values for thirteen solvents nhich wwt tested u i t h eight acids. I n Table I1 eighteer acids are included and the number of solvrntr ha. been reduced to five, which cover the range of t'x tractive p o a r r adequately. Coefficients o\itninw a t one half the original concentration are ,ilw 111 eluded in Tilhle I1 to shon the effect of concrnirn tion upon the distrihution coefficient. All \ nlur. in Tahlr I are for the more concentrat4 -0111 tioiis. I n examining the data in these tables, thc pul\ basic acids m a t be considered apart fioni tlif monobasic acids, for the distribution coeffirirnr of the former change much more with changes ii the extracting solvent than do those of the latter. I n general, there is little chapge in di. tribution coefficient with a twofold change in cor1 centration in extractions using n-butanol, ethy acetate, or erher, but in the cases of chloroforn and Pkellysolve B the effect of the concentratior change is considerahle. This is probably due ts association of t h r molecules of acid in the Iatti.7 solvents, uhic7h contain too little water to iaturaic the hydrogen bonding capacity of the carbox) groups. The dibasic acids containing an odd number of carbons fit perfectly into the series 0' even-numbered acids despite the so1ubilit.i-differ ence%between the t a o groups.
-
DISTRIBUTIOh OF 4C.105 4MONG THE FUNYEI.3
The two simplest and most aidely used arrangements of iui, iiels in fractional extractions are the "horizontal stage" and the 'vertical stage." Bush and Densen ( d ) have discussed the relative merits of these techniques and concluded t h a t the diagona stage technique is superior. With either arrangement, the operations may be carried out with a series of funnels or with the Craig 4 ) countercurrent distribution machine, if one is available. Ir this laboratory i t has been convenient to replace the seriei of sephlatory funnels with one separatory funnel and a series of flasks By contact of one portion of the lighter solvent u i t h n portions o! the heavier solvent in succession, then contact of the srco~ld lighter layer with the same series of washes, etc., either the cliago. nal or horizontal type of operation may be carried out with t minimum of contamination with stopcock grease. In c a m wherr large volumes of liquids are used, this technique is especial11 advantageous, because it eliminates the necessity of handling nt, merous large sepnratory funnel .
Determining the Vapor Pressure of Petroleum Fractions \ n e w apparatus has been designed and proved practical for deterriiitiiiiy the rapor pressure of approximately 5-grarn samples of pure or mixed h j drocarhons. \ description of the derice and its construction is pi\en; its calibration, limitations, and theoretical consideratiow are discussed. The results ohtairied arcreprodiicihle and in close agreement w i t h thaw determined h? t h r . \ . S . T . \ l . Reid tapor preq-iire method.
T
11 1.; :ippariitus clc.wi,il>c*ti Iirrc.iii \\:is tievelopwl during
it I,('-
that neccwit:i trit :+ r:tpitl, ix~produciblrdrtcwiiiiiittioii of a large range 01 vapoi~pressures on relatively sniall s:tinplrs of gasoline and blends thrrwf. The nelv method wa.q nrcrss:iry tiecausc. t,hcJ .I.S.T.lI. Reid method ( 1 ) rrquirecl consid(~r:thletime as well :IS R I ~amount of material grcater thriri that nhivh w:+savai1:tbl~. Various w p o r pressure determiriatioil ~ 1 x 1 c*rtlures involviiig t,hc, isoteniscopr (n, 0, 10) and other inor(' (~1al)Or:ttl~:q,par:rtus (.4, 7 , si WeTt' c*ollsidc~red,h\11 \vrw 1101 thought :ipplic:il)lc to thr work :it h:ir~d. I r i thc pr(wnt nirthod, the appariituh is ~tatiuii:iryai111 consists of :i \I.utc~r-jiic~kt~t~~ti glass tulw which is one iirni of an open-riitl iiier'r~ui'>' ni:iiioim5trr. Thr 5-nil. smiplv is introtlucwi into the top funnel. portion of the \\-ater-jacvketed sectioii thiuugh :iiviIil~r:~tcd tom is shown in Figure I . This i-onstmt teniprraturc h t t h arid cii,cd:it ioii pump, s:iInple trap, :iiid v:+(*uunipunip used in thr. sj.-tvni shoivii h:i\v twrn omittrd for t h e pui'prw of sinil)lifiratioii, st~:i~~ progruiii c~i~
APPAR
