NOTES
159G
Vol. GO
0 chemical shift, 6, versus mole fraction of acid using II water as a reference substance. Details of this R-P-F investigation will be reported later. In Table I, the shifts recorded under series A were AFV obtained using a single cell with four to six different where placements of the indicated sample cell in the turR R’ bine spinner. The deviations, d, recorded in this serMethyl isopropyl ies of measurements are the average deviation of a Methyl pinacolyl ((Iij single observation for the several values recorded Ethyl isopropyl (111) for the chemical shift as the indicated cell was conMethyl cyclohexyl (IV) secutively repositioned in the turbine spinner. In of the physical properties of I and I11 have series B, the same solution was placed in the annu- Some been reporteda2 lus of each of the indicated cells and the recorded In the work described herein, the distribution of shifts are the average of several measurements with the compounds I-IV between water and various the cell in the same position in the turbine spinner. solvents was determined a t room temperature (25-29’). TABLE I CHEMICAL SHIFT$OF SULFURIC ACIDSOLUTIONS IN TERMS Experimental
MILLIGAUSS AND 6 = 106 ( H r - H c ) / H , USINGCONCENReagents.-The phosphonofluoridates were synthesized TRIC CYLINDER SAMPLE CELLS by the Organic Branch and analyzed by the Analytical Mole Research Branch of the Chemical Warfare Laboratories. fraction Elemental analysis indicated that the compounds were of Of HmSOi Cell x 108 a no. highpurity, L e . >95%. Stock solutions of the phosphonod8 AH AH fluoridates were made up daily either in distilled water and Series A the pH of the solution adjusted to 5.5-5.7 to minimize 2.38 5 0.68 f O 05 0.013 1 0 . 0 0 1 hydrolysis* or in one of the organic solvents to be tested. The organic solvents used herein were purified. according ,014 0.72 6 i .03 .a01 to standard procedures.‘ Water-saturated organic solvents 4.79 ,019 5 0.96 i .05 i .001 and organic solvent-saturated water were used in the dis0.84 .08 .017 f ,002 tribution studies to minimize errors due to volume changes. 6 6.87 ,024 1.23 i .04 5 f .001 The preparation of the solvents was accomplished by .026 f .04 i .001 agitation of mixtures of water and the solvent for approxl1.30 6 mately one hour on a Burrell-Wrist-Action shaker, centri.032 9.85 5 f .07 f .001 fugation and separation. 1.63 .028 f .002 1.40 i .OS 6 The following reagents were used for analytical determinations. Series B a. Phosphate buffer, 0.05 M pH 8.7: pre ared by mixing 29.5 0.0894 $0.002 loom!. of 1 M KH2P04, 100 ml. of 1 M &OH and 1 liter 1 4.54 +0.126 5 4.47 .os .OS80 ,001 of distilled water, adjustin6 to pH 8.7 with saturated NaOH a?d diluting to 2 liters with distilled water. 7 .OS75 .001 solution, 4.44 .02 b. o-Tolidine reagent: 1%aqueous solution of o-tolidine .OS45 - .002 dihydrochloride 8 4.29 - .13b (stored under refrigeration and used a t any .0855 - .001 temperature up to room temperature.) 4.34 - .08 9 c. Sodiuw perborate reagent: 1.25% aqueous solution .0871 10 4.42 .00 .000 of sodium perborate (prepared daily). .OS65 - .001 B. Procedure.-Known volumes 11 4.39 - .03 of solvent and water 12 .0875 .001 were pipetted into a glass-stoppered graduated cylinder. 4.44 .02 .0870 Av. f .001 A very small volume of solution containing the phos hono4.42 f .06 fluoridate was pipetted into the cylinder. The sofutions a H , is the magnetic field intensity necessary to obtain resonance absorption at a fixed frequency for the reference were shaken VigOrOUEly for at least one minute (preliminary compound, namely, water. H , is the field intensity required work showed that equilibrium was established in 15 seconds) for observing resonance absorption in the system under and allowed to separate. Aliquots of the two phases were investigation, namely, sulfuric acid solutions. These withdrawn and analyzed for phosphonofluoridate concentracells might be discarded. but are included in the table to tion colorimetrically by a modification of the o-tolidine perborate method for estimation of phosphonofluoridates.* indicate the maximum deviations observed. The modification allowed us to use one standard curye to determine the concentration of the phosphonofluoridate for either the organic or aqueous phase. A description of a typical experiment on one solvent pair will illustrate the THE DISTRIBUTION OF SOME technique. Calibration Curve .-Known quantities of the phosphonoPHOSPHONOFLUORIDATES BETWEEN fluoridate, varying from zero to 536 mg. (in either water or ORGANIC SOLVENTS AND WATER chloroform), were , added to a series of glass-stoppered graduated cylinders, each containing 40 ml. of acetone, 4 BY ROBERTW. ROSENTHAL, REUBENPROPER AND JOSEPH ml. of buffer, 2 ml. of o-tolidine reagent and sufficient EPSTEIN chloroform or water so that the final solution contained 3 ml. of chloroform and 10 ml. of water exclusive of water Chemical Warfare Laboratories, Army Chemical Center, Mariland from the aqueous reagents (these latter volumes were Received July 69, lS66 varied from solvent pair to solvent pair). A homogeneous resulted. Three ml. of perborate solution was then In connection with other work carried out in these solution added to each cylinder and the intensity of color measured laboratories, it was considered desirable to deter- after 20 minutes in a Klett-Summerson photoelectric with a OF
*
+
+
+
+
+
+
1
mine the distribution of some phosphonofluoridates (I-IV)I between organic solvents and water. The four compounds studied had the formula (1) These compounds are sufficiently toxic that one should observe extreme care in working with them.
(2) C. E. Redemann, et al., J . A m . Chem. Soc., 7 0 , 3604 (19481. (3) J. Epstein and V. E. Bauer, Pittsburgh Conference on Analytical Chemistry and Applied Spectroaaopy, February 27-March 2, 1950. (4) L. Fieaer, “Esperimenta in Organic Chemistry.’ ’ 2nd Edition, D. C. Heath and Company, New York, N. Y., 1941.
i
0
NOTES
Nov., 1956 No. 42 filter. The colorimetric readings (corrected for blanks) were plotted against mg. of phosphonofluoridate. Analyses .-In the analysis for phosphonofluoridate in the chloroform phase, one ml. of this phase was added to a cylinder containing 40 ml. of acetone, 4 ml. of buffer, 2 ml. of o-tolidine reagent, 2 ml. of chloroform and 10 ml. of water. For the aqueous phase, 10 ml. was added to a cylinder containing 40 ml. of acetone, 4 ml. of buffer, 2 ml. of o-tolidine and 3 ml. of chloroform. The concentration in each phase was determined by comparison of the net colorimetric readings with the calibration curve.
Results The results of a typical experiment, zlix., the determination of the distribution coefficient (solvent/ water) of I between chloroform and water, are given in Table I. DATAFOR
Run
1
2 3 4 5 6
1597
which also includes the number of runs made for each determination and the standard deviation from the mean. Discussion An attempt was made t o correlate the distribution coefficients between I and various organic solvents with Hildebrand and Scott's "solubility parameter."6 (This quantity, b, which has been identified with the internal pressure of a liquid has been useful in predicting the solubility of one liquid in another.) In general the closer the b-values of two liquids, the greater the mutual solubility.6 The b of I was calculated to be 9.04 from the equation
= ( A H v - RT)'lZ TABLE I V, DETERMINATION OF THE DISTRIBUTION OF I BETWEEN CHLOROFORM AND WATER where H v is the heat of vaporization of 2 5 O . ' VO!. Phosphono- . VI was calculated from the molecular weight and
THE
ratio Total (I), CHCls/ pg. Hs0
4474: 4474 4474 8948 8948 8948
1:lO
1:7 1:5 1:7 1:5 1:lO
fluoridate recovered CHCla, HnO, Recovery, pg.
Pg.
%
K
3346 3890 3890 7550 8150 6860
1070 823 636 1670 1350 2230
98.6 105.4 101.0 103.0 105.8 101.5
31.4 33.0 30.6 31.7 30.2 30.7
-
Av. 31.2
Per cent. recovery (100 X wt. phosphonofluoridate found by analysis/nominal weight phosphonofluoridate) was calculated for each experiment and values of 100 i 5% were usually obtained. A summary of the K's obtained is given in Table 11,
A comparison of the differdensity of I a t ences between values ef bsolvent (using Hildebrand's values6 or calculated from literature values of A H ) and b~ with the K's of I between eight of these solvents and water shown in Table 111. TABLE 111 SOLUBILITY PARAMETERS (a) OF VARIOUSORGANICSOLVENTS AND DISTRIBUTION COEFFICIENTS (K) OF I" BETWEEN THESE SOLVENTS AND WATER i Ab,
Solvent
a,,l.,..t aI - aSolvant
K
9.15 0.11 2.08 Benzene 8.60 0.44 0.84 Carbon tetrachloride n-Heptane 7.00 2.04 0.20 9.50 Chlorobenzene 0.46 1.94 TABLE I1 Nitrobenzene 10.0 0.96 2.51 10.45 1-Nitropropane 1.41 4.70 DISTRIBUTION COEFFICIENTS OF PHOSPHONOFLUORIDATES BETWEEN ORGANIC SOLVENTS AND WATER (T = 25-29') Chloroform 9.30 0.26 31.2 No. sym-Tetrachloroethane 8.23 0.81 17.6 Comof Distribution pound Solvent run8 coe5oient Stand dev. " a* = 9.M. I Chloroform 31.2 6 0.61 For the non-polar liquids shown in Table 111, sym-Tetrachloroethar le 2 17.6 1.5 (Le., benzene, carbon tetrachloride and n-heptane) 1-Nitropropane" 4.70 6 0.29 there is qualitative agreement between the pre1,4-Dichlorobutane 5 .06 2.68 diction of distribution and the observed coefficient, Nitrobenzene" 2.51 6 .28 ie., K increases as A a decreases. Large deviations l12-Dibromoethane 2.25 5 .12 are found for sym-tetrachloroethane and chloroBenzene 2.08 .04 6 form, two materials capable of hydrogen bonding. Chlorobenzene 1.95 .12 4 A comparison of the K values for the CCL and Tributyl phosphate 1.82 .04 ti CHC18-water systems suggests that hydrogen Carbon tetracbloride 0.84 6 .06 bonding may be an important factor in determining n-Heptane 0.20 3 .Ol the solubility of I in organic solvents. Moreover, Perfluorodimethyla comparison of coefficients of I between halogencyclohexane 6
