acid solutions. Since then Wilson and others ( 2 , 6, 7) have measured distribution coefficients for plutonium extraction as functions of nitric acid, amine, and plutonium concentrations. Their data indicated highest extraction efficiences a t nitric acid concentrations between 1 and 6Jf and a t amine concentrations above 10%. Wilson (6) had also shown that tertiary amines from tri-n-hexyl to trihuryl all possessed high distribution coefficients for plutonium extraction. On the basis of the above data, a n analytical method was established based on the extraction separation of plutoniun from 431 nitric acid with 5ooj, TKO.4 in xylene. Tantalum is not extracted by TNOA in 4 M nitric acid in the absence of fluoride as Table I stows. Ninety-six per cent of the plutoriium, however, is extracted and more i.han 99% is extracted with 2 contactings. The det,ermination of tantalum is, therefore, made by disolving plutonium in hydrochloric acid, 2,dding nitric acid to oxidize plutonium to IV and to make the nitric acid molarity 4, extracting plutonium into 50y0 T S O A , adding hydrofluoric acid to dissolve tantalum,
and analyzing the aqueous phase for tantalum spectrographically. Spectrographic Analysis. -1fter hydrofluoric acid is added, the aqueous phase is evaporated to dryness to dissolve the tantalum and to eliminate nitric acid which reduces the spectrographic sensitivity. T h e evaporated residue is dissolved in 0.1 -11 hydrofluoric acid a n d transferred to flat-top graphite electrodes. T h e electrodes are dried and analyzed by a Varisource high voltage spark discharge on Kodak 103-0 emulsion. Approximately 2 pg. of tantalum are detected through the extraction and evaporation steps. The range of the method is from 20 to 1000 p.p.m. based on 100 mg. of plutonium. X test of the method with a tantalumnlutonium alloy gave 94% tantalum recovery compared to the make-up value, but some question existed as to the alloy’? homogeneity. .Itest of the method with soluble tantalum made by spiking plutoniurn solutions with tantalum solutions gave 90% recovery. h test of the method with insoluble tantalum made by spiking plutonium solutions with tantalum pentoxide powder and measuring tantalum recovery gravimetrically in the aqueous
phase gave 96y0 recovery. .I relative standard deviation of +=i%for a single measurement mas estimated from the preceding experiments. The data are summarized in Table 11. ACKNOWLEDGMENT
The author expresses hie gratitude to
R. A. Schneider for his many helpful suggestions. LITERATURE CITED
(1) Goldschmidt. B.. et al.. Proc. Intern.
Conf. Peaceful Uses At. Energy, GeneLa,
1966, P/349, T-ol. 9, p. 492, United
Xations (1956). IT. E., Sheppard, J. C., Wilson. -4.S., J . Inoro. ,\-ucl. C’hpm. 12. 32i (1960). ( 3 ) Scribner, B. F.,Mullin, H. I?., G. S. At. Energy Comm. Rept. A-2907 (1945). (4)Sheppard, J. C., U. S . d t . Energy Comm. Rept. HW-51958 (1957). (5) Waterbury, G. R., Bricker. C. E., AKAL.CHEX 29, 14i4 (1957). (6) Wilson, A . d., Prog. S u c l . Energy Ser. 111 Vol. 3 , “Process Cheniistrj-,” p. 211, Pergamon, Oxford, 1961. ( 7 ) Wilson, A. S., c’. S . :It. Energy Comm. Rept. HW-68207 (1961 ).
( 2 ) Keder,
RECEIVEDfor reviet? January 23> 1964. Accepted March 16, 1064. Ilivision of Analytical Cheniistry, 145th Lleeting, ACS, S e w York, September 1963.
Nuclear Magnetic Resonance Spectra-Structure Correlation for Chlorinated Propanes HORACE
F. WHITE
Research and Development Department, Union Carbide Chemicals Co., Division o f Union Carbide Corp., South Charleston, W . Va.
b The proton magnetic resonance spectra of a series of terminal chlorinated 2-chloro- and 2,2-dichloropropanes have been studied. Dilute solution spectra of these molecules are first-order spectra and group assignments are made without difficulty. In addition, the functional group chemical shifts can b e correlated with changing molecular electronegativity to predict group resonances of unavailable molecules. The correlation also demonstrates thct the resonance value depends upon the molecular environment and changes predictably with varying nonadiacsmt substituents.
T
HE: nuclear magnetic resonance spectra of a series of terminal chlorinated 2-chloro- m d 2,2-dichloropropanes have been studied to establish the structure of niateri:tls produced in a photochlorination procedure. This technique was chosen hecause it offered the maximum information from a mininium prior knon-ledge of these
materials. The spectra, when correlated with the number of substituted chlorine atoms, offer a method of predicting the position of resonance peaks for unavailable molecules. This work is an extension to a specific series of propanes of the correlations of electronegativity us. chemical shift established by Gutowsky ( 2 ) and others ( I , 5 ) on simpler molecules. EXPERIMENTAL
The spectra were obtained on a S’arian Model A-60 spectrometer and are of 10% by liquid volume solutions of solute in carbon tetrachloride. -1 few drops of tetramethylsilane were placed in each sample tube for internal standard. Resonance shifts were recorded to the nearest 0.3 cycle and converted to chemical shift in parts per million by the usual method (4). DISCUSSION
The
2,2-Dichloropropane
Series.
From t h e spectra of t h e lowest molecular weight members of this series es-
hibited in Figure 1, it is evident that, there can be no ambiguity as t o the group assignMents of the 2,2-dichloropropane series. The three spectra shown in Figure 1 indicate a slight doanfield shift of the methyl proton resonances with increasing chlorine substitution similar to, but to a much lesser degree than, the downfield shift of the methyl, methylene and methine proton group resonances. These data and those for t h r other molecules of this series are presented in Table I, which also lists the propane substituent electronegativity ( 3 ) of each molecule; this quantity increases by a constant factor of 0.9 electronegativity unit for each chlorine-for-proton substitution, and, hence, is a weful parameter (in this serie?) relating to molecular composition as well as electrical environment. Figure 2, then, graphically de1)icts the data of Figure 1 and Table I. Several lipear and nonlinear correlations are shown. Several appects of this figure should be emphasized: VOL. 36, NO. 7, JUNE 1964
1291
4 Figure 1.
NMR spectra of the 2,2-dichloropropanes
2.2- MCHLOROPROPANE ( CH~CCIZCHJ)
The linear nature of the CH, variation The almost linear variations among the four molecular series-i.e., CH3 + CH, + C H in
1,2,2
-
CH,Cli-CCl;CC13 The nonlinearity of the CHI and C H variations The surprising point a t 4.29 p.p.m., 4.5 C1 atoms (20.85 electronegativity units), that relates the CH3 to CH resonances through a center of inversion. One might have expected the inversion point, should it, exist, to occur in the center of the methylene variation. N o explanation is offered for either the point or its location; its existence aids the analysis.
TRICHLOROPROPANE
(CH3CCI,CH,CI)
I
Table I.
Structure
Observed Chemical Shifts for Chlorinated Propanes
Sum of substituent electronegativitya 18.6 19.5 20.4 20.4 21.3 21.3 22.2
Methyl
Chemical shift* Methylene
2.21 2.23 2.33 ...
. . ,
4.04 , . .
CH;ClCCl;-CHzCi 4.17 CHzC1-CClz-CHClz , . . 4.30 CHa-CClz-CCl3 2.53 ... CHClz-CClz-CHClz ... . . , C1 = 3.0, H = 2.1. a Pauling’s electronegativities. * Parts per million to lower fields from tetramethylsilane internal standard.
Methine ... ...
6.03 ... 6.27 ...
6.35
As can be seen from Figure 2, resonances of two molecules are predicted; thus some points have changed from triangles to circles as the molecules have been acquired. The 2-Chloropropane Series. The N M R spectra of the molecules of the 2-chloropropane series are somewhat more complicated, as indicated by Figure 3, than the spectra of the 2,2dichloropropane series. This arises because the central proton interacts with the terminal ones, and the introduction of a n asymmetric center may lead to a significant nonequivalence of the terminal protons, particularly the terminal methylene protons. In Figure 3, the group resonance assignments for the terminal protons of the 2-chloro- and 1,1,2-trichloropropanes are obvious; the methylene terminal proton assignment for 1,2dichloropropane is not so obvious. The resonance a t about 4.0 1l.p.m. (shown enlarged) can be reduced to an ABC pattern (4) that is readily analyzed. Such an analysis offers an additional argument for the validity of the assignment as well as an aid to the separate assignments for the methylene and methine resonances. The data of Figure 3 are, then, summarized with those from two other molecules in Table 11. The peak positions recorded in this table and in Figure 4 are the algebraic mean of the individual line positions and not the probably preferred intensity weighted
4 Variation of proton chemical shift in Figure 2. CHzCI,CCIzCH,CI, PROTON CHEMlCAL SHIFT (PARTS PER MILLION FROM TETRAMETHYLSILANE)
1292
ANALYTICAL CHEMISTRY
x + y = 3 = m + n Observed resonances A Predicted resonance
0
niean or band moment positions. These positions, being experimental values, are also the averages of the various shifts arising from the different molecKO attempt has been ular forms. made to sort the spectra to a given constant molecular geometry. The various correlations for this molecular series derived from Table I1 are presented in Figure 4. Here again, there are both linear and curved correlations and many predicted resonance values. The curves were prepared from the resonance values of five molecules and from the fact that the methyl and methine resonances of the 2,2-dichloropropane series are related through an inversion center. For the 2-chloropropane series, the inversion point was established a t 3.77 p.p.m., 3.50 chlorine atoms, by extrapolating the methyl resonance to 1.73 1i.p.m. for CH3CHClCC13 and adding the appropriate resonance shift increment to the methine resonance of 1,1,2-trichloropropane for each terminal chlorine addition, as indicated by the mirror image of the methyl variation. The predicted variations among the four molecular series are not straight lines; these nonlinear variations are again most probably the result of instrumentally averaging the chemical shifts from more than one molecular orientation. Future plans include an investigation of these molecules a t various elevatcd teruixraturps
2:CHLOROPROPANE (CH3CHClCH3 1
1Ic
I
h
1.2- DICHLOROPROPANE
I
.-
8
I
ao
1
I
a
8
NMR
Figure 3.
spectra of the 2-chloropropane3
,:..,
I
,
70 6.0 5.0 4.0 3.0 20 CHEMICAL SHIFT (PAFITS PER MILLION PARAMAGNETICALLY TETRAMETHYLSILANE, INTERNAL STANDARD)
1.0 FROM
6 5 1.73 PPM (CH3CHCl CCI 3) 4
&
3 . ;;
rigure 4.
variarion
OT
proron cnemicai snin
CH,CI,CHCICH,CI,
-
,
-
,
r -I L v = 9 = m l ..I ~
I,
\Cd3
Observed resonances 0 Terminal protons 0 Iniernol protons Predickd A Resonances Correlations
‘1.5
RESONANCES ?O
---
Table
Structure Carbon NO.,^ 1
2
3
Sum of substituent electronegativity*
II.
Observed
NMR
3.0
4.0 5.0 PROTON CHEMICAL SHIFT (MRTS PER MILLION PARAMAGNETICALLY FROM TETRAMETHYLSILANE)
6.0
Parameters for 2-Chloropropanes
Chemical shiftc - Terminal protons
Methyl
Methylene
Methine
Internal proton
Coupling constantsd J2,3(cis)
J112
CIIICHClCHI 17.7 1.50 ... ... 4.13 6.4 CHsCHClCHzCl 18.6 1.62 3.61 ... 4 10 6.5 CHaCHClCHClZ 19.5 1.69 ... 5.83 4.32 6.6 CHzClCHClCH2Cl 19.5 ... 3.87 , . . 4.20 CClaCHClCHzCl 21.3 ... 4.57 , . . 3.79 ... Sumbering system reverse of chemical nomenclature, but consistent with spectroscopic system. * Pauling’s electronegativities. C1 = 3.0, H = 2.1. Parts per million paramagnetically from tetramethylsilane internal standard. Cycles per second. 0 Spectra not analyzed for coupling constants.
JB.l(tranr)
JS.3’
6.4 4.3 3.8
6.4 8.9 3.8
... 10.8
9.3
12.0
2.1
VOL. 36, NO. 7,JUNE 1964
...
1293
in an effort to obtain uniform molecular geometry or constant geometric distribut ion.
and stimulating discussions during the course of this investigation.
ACKNOWLEDGMENT
(1) Alley, S. K., Jr., Scott, R. L., J . Chem. Eng. Data 8, 117 (1963). ( 2 ) Meyer, L. H., Gutowsky, H. S., J . Phys. Chem. 57, 481 (1953). ( 3 ) Pauling, L., “Sature of the Chemical Bond,” p. 58, Cornell University Press, Ithaca, S . Y., 1940.
Schneider, W. G., Bernstein, H. J., “High-R&solution Nuclear Magnetic Resonance, pp. 87, 130, McGraw-Hill, New York, 1959. ( 5 ) Smith, T. S., Smith, E. A., J . Phys. ( 4 ) Pople, J. A.,
LITERATURE CITED
The author thanks Verner Schomaker and E. €3. Whipple for helpful criticisms in the preliminary manuscript, and V. A. Yarborough for his continuing interest
Chem. 63, 1701 (1959).
RECEIVED for review January 28, 1964. Accepted March 25, 1964. Division of Analytical Chemistry, 144th Meeting, ACS, Los Angeles, Calif., April 1963.
Mass Spectra of Diary1 Sulfones SEYMOUR MEYERSON Research and Development Department, American Oil Co., Whiting, Ind. HARALD DREWS’ and ELLIS K. FIELDS Research Department, Amoco Chemicals Corp., Whiting, Ind.
b The mass spectra of 2 4 diaryl sulfones have been measured. These spectra are sensitive not only to differences in molecular weight but also to structural differences among isomers. Correlation with molecular structure furnishes a basis for deducing
A
EARLIER study of reactions of phenyl alkyl sulfones under electron impact (24) suggested that mass spectrometry might be applicable for determining diaryl sulfones. This tech’ Present address, Stauffer Chemical Co., Richmond. Calif.
structural features when pertinent reference spectra are not available, and also suggests decomposition paths underlying the spectra. Mass-spectral analysis of the product mixture obtained by sulfonating toluene has revealed all six possible isomeric sulfones.
N
Table 1.
Partial Spectra of
Positions of methyl groups Kone
2
2,5
2,2’
2,3’
2,4’
3,3‘
3,4’
4,4’
246
246
246
100 0
100 0
100 0
Molecular weight 218
P P less 15 17 18 64 65 66 79 80 81 Ar ’ Ar Ar ’0 ArO Ar ’SO ArSO Ar’SO?
232
246
246
246
2 46
Normal peaks
Ion
Mass
100 0 ArSOzAr ’ ArS02Ar’ less 0.04 CHI 0.17 OH 0.17 Hz0 6.49 SO? 14.5 SOZH 17.3 SO& 1 88 SOZCHJ 0 i2 SOtCH4 0 10 SOZCH~ 4 55 ArSOz Ar ‘SO2 384 ArSO Ar’SO 3.10 ArO Ar’O+ +
100 0
100 0
100 0
100 0
100 0
48.6 24.5 56.8 10.1 45.4 143
2 56 2 21 6 97 6 45 67 4 55.6 1.48 112 124 4.81
2.34 33.0 63.0 7.03 31.6 98.4 35.6 37 5 53 4 1 33 3 75 10 5 23 4 27.4 9.60 85.7 166 4.44
40 5 75 7 2 97
1.49 13.2 46.4 36.4 57.2 119 168. 46 4 81 2 2 32
3.28 32.9 91.2 9.15 41.9 141 74.1 40 5 82 9 3 25
21 1
52 7
83 2
1.16
1.83
+
+
+
+
+
+
Ar
+
Ar‘+ ArSO2 Sensitivity at mass Pb
190 7.43
0.97 14.7 52.4 15.8 56.9 97.7 12 1
22 S
90 5
0.27 0.24 0.13 3.12 4.86 0.83 8.10 10 2 ‘ 15 7 1 55 210
11.7
19.0
305
0.17 0.15 0.28 3.19 3.90 0.83 5.67 6 73 11 7 2 57 323
la
Q
13.6
0.25 0.18 0.13 3.54 4.66 0.67 6.80 8 78 14 2 2 36
4.48
50.4
37.8
LI
212
199
209
126
131
128
a
4.06
4.06
3.79
8.62
9.38
9.35
1.98
...
...
...
Metastable peaks
Transition denoted ...
1.03
1.42
0.56 0.82 0.95 0.64 1.05 ... ( P less 66) ( P less 66) -. ... ... ... 1.12 0.86 0.77 0.74 ... ( P less 8 1 ) + 1.49 ... ... ... ... ... 0.94 0.70 P + .-,ArSO+ ... 0.23 P + -. Ar’SO+ ... 0.29 0.94 2.16 2.11 1.93 1.29 1.30 P -r ArO +d Ar ’-containing ion not distinguishable from corresponding Sr-containing ion. Expressed in scale divisions of peak height per 1% liquid volume, corrected to instrumental conditions at which sensitivity n-hexadecane at m/e 57 is 20.0. +
+
+
1294
ANALYTICAL CHEMISTRY
...
1.13 1.15
of
