Table I.
Wave Length of Spectral Lines, Concentration Range, and Interfering Lines
Table 111.
Precision of Method Concn. Av.
KO. of
Internal Standard
Element -4.
A.
Si 3050.82
Zn 3075.90
Si 3054.32 Fe 3047.61 Pb 2833.07
Zn 3075.90 zn 3075.90 Bi 2887.98 Bi 2897.98 Zn 3282.33 Z n 3282. 3 3 I3 2897.98
Pb 2663.17
Si 3413.48 '
Concn. Range, P.P.M.
Table II.
Element Copper Sickel Lead
Iron
0 13 0 20 0 46 0.40 1.00 1.50 0.40 0.90 1.30 1.00 3.00 8.0
- _. ~
A. Fe" 3075. 72 Fe" 3075.72
0.2-2.0 0.8-8.0 0.2-6.0 0.1-0.5 0,5-4.0 0 g2.0 0 1-0.8 4.0-15
C u 3247.54 Fc 2483.27 In excess of 10 p.p.111.
Quantity Added, P.P.11.
Interfering Element
c1 12 0 18
0 46 @ .38 1.1
1.45 0 . 30 0.82
1,l5 0 88 2.8 7.6
thoroughly miwd by gentle rotation of the crucible. One drop of the solution is placed on the top of each of the 1/4-inch graphite electrodes, previously treated with 2 drops of redistilled kerosine. This treatment prevents seepage of the solution into the elcctrodps. The treated electrodes are dried nt 130" C. for about 1 hour. It is advisable to keep the coated electrodes in the oven until just prior to use, because of the hygroscopic nature of the sample. The electrode with the sample is transferred to the electrode holder and preburned for 15 seconds nith a 2300-volt arc a t 2.5 amperes. A
:i 0 I:, 0 19 0 48 0 .3 9 c1. 86 1.50 0 38 (1 . !I3 1.20 0.93
2.!1 7.8
80 25 30 30 25
Lead Iron
Range, P.P.M.
Deviation,
0 14 0 50 2.00 0.50 1.50 5.00
i13
e 7
,c
i 6 1.8 1 8
1 8
=t7
Fe" 3 i 1 3 , 1 4 . , .
...
Quantity Found, P.P.11. 2 0 12 0 1s 0 51 0.44 0.93 1.55 0.41 0.86 1.20 1.1 3.1 8.1
Ticlcel
Fen 2832,44
Accuracy of Method
1
Element Detns. Copper 30
-1V.
Sumericd Difference
0 12 0 18 0 48 0.41 0.96 1.50 0.36 0.87 1.18 0.97 2.9 7.8
-0 01 -0 02 1 0 02 i0.01 -0.04 0.00 - 0 04 -0.03 -0.12 -0 03 -0.10 - 0 20
30-second exposure a t 5.0 amperes with a 1.O-nini. arc gap is used. The slit width is 30 microns and the spectra are recorded on a n Eastman 33 plate, which is processed for 5 minutes in a D-19 developer a t 68" F. with continuous agitation. The plates are ealibatcd with a step slit, using a Beckman poiver supply and hydrogen lamp for the light source. After the photographic plate has been processed, the spectrograms are evaluated with the densitometer. The quantities of trace elements are read from the analytical curves, which are constructed by plotting parts per million of the element against the re-
epective element per internal standard log intensity ratios. The \lave lengths of the spectral lines, the concentration ranges used, and the interfering elements are slio\\ n in Table I. RESULTS
To determine the accuracy of the niethod, a knon-n quantity of each deinent n a s added to spectrochemically pure samples of ammonium chloride. The results showing the difference betn een the quantities added and found are listed in Table 11. For quantities less than 1 p.p,m., the agrecnient is within 20.04 p.p.m. Samples of ammonium chloride xei e :iiialyzed 25 or 30 times in order to hnd the precision of the method. The average deviation from each element analyzed is about ilo%, as shou 11 in Table 111. ACKNOWLEDGMENT
The authors wish to express their appreciation to the Pennsalt Chemicals Corp. for permission to publish this article. RECEIVED for review January 14, 1!956. .Iccepted July 18, 1957. Sixth annual Pittsburgh Conference, A1nalyticalChemistry Group, Pittsburgh Section, ;IJIERICAS CHEMICAL SOCIETY, and Spectroscopy Society of Pittsburgh, Pa., March 19%.
X-Ray Diffraction Powder Data of Some Normal Alkyl Dithiol Esters of Sebacic Acid D. A. LUTZ and L. P. WITNAUER €asfern Regional Research loboratory, Philadelphia 1 8, Pa. RICHARD SASIN and GEORGE S. SASIN Drexel lnstitute o f Technology, Philadelphia 4, Pa.
b X-ray diffraction powder data were obtained for n-alkyl dithiol esters of sebacic acid. All the individual compounds can be easily distinguished and identified b y the diffraction data. The esters crystallize in tilted monomolecular layers. Long spacings increase regularly with increase in hydrocarbon 1780
ANALYTICAL CHEMISTRY
chain length, forming two series, one for odd- and one for even-membered series of the alkyl ester groups.
M
of the dithiol esters of longchain fatty acids are solid crystalline materials a t ordinary teniperatures, suitable for characterization by AKT
x-ra) diffraction. In this paper the xray diffraction p o d e r patterns of methyl. u-amyl, n-heptyl, n-octyl, nnonyl, n-decyl, n-undecyl, and n-dodecyl dithiol sebacic esters are reported. EXPERIMENTAL
All the dithiol compounds used were
prepared as recently described (3),with tlie exception of n-undecyl and ndodecyl dithiol sebacate. These tn-o compounds were prepared in the fol1on.ing maiincr. T o 2.4 grams (0.01 mole) of sebacyl chloride in a 100-ml. round-bottomed flask fitted with a reflux coiidenser n a s added 0.022 mole of the appropriate mercaptan and the mixture was allowed to stand overnight. The product then was heatcd on a steam bath for 6 hours. The ditliiol esters were crystallized froiii acetonc until two successive crystallizations showed no increase in the melting point. The yield of n-undecyl dithiol sebacate was 5.0 grams or 91o/c, with a melting point of 67.5' C. The yield of wdodecyl dithiol sebacate was 5.2 g r a m or 91%, n i t h a melting point of 64.56,i" C. A4nalysis: Calculated for C32HN02S2: S, 11 8cL Found: S,12 0 5 Calculated for Ca4Hsa02S2:S, 11 2 5 Found: S,11 GPO Sebncyl chloride, n-dodecyl mercaptan, and n-undecyl bromide nere obtained from Eastman, Aldrich anri Ahtheson, and Colman and Bell, respectively. n-Undecyl bromide n a' converted to n-undecyl mercaptan, boiling point 103-04" C. a t 3 nini., by the method of Urquhart, Gateq, and Connor (4). I n order to obtain the same polymorphic form, the dithiol esters n ere crystallized from acetone a t room teniperature, except that n-hexyl dithiol aebacate was crystallized from acetone at 0" C., because of its low melting point of 29" C. This compound n a s held at 0" C. until after the x-ray diffraction pattern ~\-a$:obtained. Even with these precaution^ the pattern of n-heq-1 dithiol w l m a t e qhon ed that a second pliase n:ie present. Honever, the long yx~ciiigrsoi the polymorphic form fouiid iii the other dithiol csters could lie cwily t1i.t ingui4ied. X-RAY APPARATUS AND TECHNIQUE
X-rny diffraction measuremrnt,s were niade with a Gcineral Elect'ric XRD-3 direct iwoidiiig unit, using aickel-filt e r d C u K a radiation ( A = 1.5105 1.). 1O b m r i d i t , 0.1 O detector slit. highrcwlutioii Soller slit,, 2" per minute scanning spced, 60-inches-per-hour chart speed. lintaar scale, and 2-second time constant. All ,samples r e r e carefull>ground in :in agate mortar to minimize the effccts of orientation. Duplicate s:implcs gave diffraction line? of comparable relative intensities when similarly crystallized, ground, and mounted. The ground samples were gently packcd into tlie r c ( ~ s eof a plastic holder approxiniatcly 1.0 inch long, 0.5 inch wide. and 0.015 inch deep. The intensities of the diffraction lilies rcpor.ted were mrmured as counts per second at, the mimimum height minus counbs per second of tlie background. find then expressed on a relative scale
-
~~~~~~
X-Ray Diffraction Powder Data of Dithiol Sebacic Esters Cl-Clz Aliphatic Mercaptans Dithiol Sebacate
Table I.
Methyl d, A.
1/11
16 98 8 50 5 64 4 84 4 50 4 25 3 59 3 39 2 87 2 83 2 69 2 51 2 42 2 12
0 39 1 00 0 68 0 03 0 04 0 13 0 01 0 09 0 01 0 11 0 01 0 01 0 08 0 01 0 03
1 88
n-Ami 1
25.96 13.06 8.66 6 50 5 20 4 74 4 44 4 33 4 07 3 81 3 72 3 62 3 44 3 39 2 8i 2 90 2 60 2 42 2 36 2.28 2 17 2 08 2 00
0.27 1.00 0.02 0 02 0 10 0 03 0 02 0 04 0 01 0 005 0 10 0 05 0 005 0 003
0 005 0 003 0 03 0 003 0 04 0.003 0.04 0 01 0 005
n-Hept! 1 Ill, 30 44 0 84 15.23 1 00 10 16 0 16 7.62 0 03 6 10 0 12 4.74 0 08 4 48 0 04 4 17 0 02 3 85 0 02 3 81 0 02 3 77 0 03 3 64 0 04 3 39 0 01 3 07 0 01 2 54 0 01 2 42 0 01 2.34 0.02 2.18 0.02 2.08 0.01 n-Octyl
n-Sonyl ____ I/li 34 75 1 00 17 52 0 51 11 70' 0 18 8 70 0 17 7 65 0 01 6 99 0 05 5 84 0 01
33.95 0.0; 17 15 1 00 11 47 0 07 8 58 0 26 6 86 0 19 4 70 0 01 4.29 0.01 4.09 0.02 3.81 0.01 3.61) 0 01 3 44 0 01 2 86 0 02 2 65 0 01 2 45 0 01 2 29 0 13
0 01 0 02 0 01 0 02 0 01
d , A.
I Ii.n-ith the strongcsqt liiic. I , , arbitrarily given a v a l u e i f 1.000 (Table I). The long spacings w r e obtained from oriented s a i n ~ ~ l e s .L-iiground saniules were placed ti a thin hyer on a giass slide and firnilv Dressed to ensure adherence. The "e?;I,osed surface on t h r glfss slides was approximately 0.5 iiirli wide by 0.5 inch long. The values of the long spacings given in Table I1 were obtained from the average of a t least seven orders takcn from the oriented saniplcs. The first order as not included in the average because of the limited n c c u m c j - nitli which it could be measured.
n-Vndecyl I/I, 38.85 1.00 19.65 0.26 13.14 0.18 9.86 0.34 5.63 0.12 4.71 0 08 4.50 O.0i 4.27 0.05 3.95 0.03 3 . 8 0 0.05 3 . 7 5 0.07 3.49 0.18 3.46 0.02 2.42 0.02 2.32 0.01 2.19 0.01 2.07 0.05
d, A.
4 99
0 02
4.73 4.50 4.37 4.23 4.04 3.82
0.03 0.02 0 02 0.01 0.02
3.75
3.63 3.45 3.39 3.18 2 92 2.51 2 43 2 33 2 27 2 19 2 08
d , -1.
0.0;
0.04 0 07
0 01 0 01 0 01 0 01 0 00.;
n-Decyl 38.38 1.00 19.39 0.45 12.89 0.05 7.75
0.05
5.c54
0.04 0 01 0.03 0.01 0.01 0 01 0.01
4.84 4.11 3.69 3.53 2 99 2 i8 2.43 2 29
~
0 01
n-Dodecyl 43.27 1.00 21.64 0.33 14.78 0.03 10 85 0 55 8 66 0 01 7 22 0 01 6 19 0 08 4 82 0 005 4 33 0 01 4 11 0 03 3 94 0 01 3 60 0 01 3 62 0 005 3 31 0 01 2 81, 0 02 2 71 0 01 2.41 0 01 2 29 0 00 1 89 0 004
0 08
~ 11, bL~~~ l spacings ~ of ,,-Alkyl Dithiol Sebacates
Carbon Total .Atoms Carbon in Ester- Atoms in Dithiol -IlW XokSebacnte Group cules Methyl 1 12 5 20 n-Amyl n-Hexvl ci 22 n-Heptyl , 24 8 26 n-Octyl n-Kmi-1 9 28 10 30 n-Dec-1 n-Undecj-1 11 32 12 34 n-Dodecyl r
LongS,pac1I%
A.
17 00 26.00 29.85 30 45 31.35
34.95 38 80 39 40 43 30
RESULTS AND DISCUSSION
The interplanar spacings and relative intensities reported in Table I diol\- that the n-alkyl dithiol esters of eebacic acid can be readily distinguished and identified by the x-ray diffraction data. hIixtures of dithiol sebacates n-itli 7 and 9 carbon atonis and n ith 10 and 12 c:irbon atoms in the alkyl chain w i e c r j stallized together. X-ray diffrnctioii p i t -
terns of these mixtures showed clearly the patterns of both components, one superimposed upon tlie other. In Figure 1, the long spacings of the n-nlkyl dithiol sehacates are plotted against the number of carbon atonis in the ester chain length. TKO parallel straight lilies are obtained, one for the evenmembered and one for the odd-meniVOL. 29, NO. 12, DECEMBER 1957
1781
bered series, which is characteristic of long-chain compounds ( 2 ) . The average increase for each additional carbon atom is approximately 1.12 A. for the dithiol esters of sebacic acid. This is less than the accepted value of 1.27 A. for the projected carbon-to-carbon distance. It appears that the dithiol esters of sebacic acid crystallize .in tilted monomolecular layers, as do the diethyl esters of dicarboxylic acids, containing an even number of carbon atoms in the chain ( I ) , and n-aliphatic thiol derivatives of monocarboxylic acids ( 5 ) . The values of the long spacings reported ( 1 ) for the diethyl esters of dicarboxylic acids, containing an even number of carbon atoms in the acid chain, are approximately 0.2 A. larger than those of the corresponding dithiol esters given in Table 11. This indicates that in both series the compounds crystallize with approximately the same angle of tilt. The dithiol esters containing an even number of carbon atoms in the thiolester groups have long spacings which are slightly greater than those containing an odd number of carbon atoms in the thiol ester group. This is the same as was reported for thiol esters of monocarboxylic acids ( 6 ) . I n general the rererse is true for long-chain aliphatic compounds containing odd and even numbers of carbon atoms in the aliphatic chain ( 2 ) . SUMMARY
X-ray diffraction powder data were obtained for 9 n-alkyl dithiol esters of sebacic acid. All individual compounds can be readily identified and distinguished by the x-ray diffraction data.
45
r--I I
-
40L
s:
30t
a"
I
// //
I
2
0
4
CARBON ATOMS
Figure 1.
0
0
1i
/ / O
/'0 .e /
35
m
/ I
/
I
L
m
I
8 IO ESTER ALKYL
6
IN
12 GROUPS
Long spacings of dithiol esters of sebacic acid
Even number of carbon atoms in each alkyl group in ester Odd number of carbon atoms in each alkyl group in ester
The long spacings increase regularly with increasing ester-chain length forniing an odd and an even series. The n-dialkyl dithiol sebacates crystallize in niononiolecular tilted layers. LITERATURE CITED
(1) Francis, F., Collins, F. J. E . , Piper, S. H., Proc. Roy. SOC.(London) A158, 691 (1937). (2) hlalkin, T., h'ature 127, 126 (1931).
(3) Sasin, R., Weiss, G. S., Wilfond, -4. E., Sasin, G. S., J . Org. Chem. 21, 1304
(1956).
(4)Urquhart, G. G., Gates, J. W., Jr., Connor, R., "Organic Syntheses," Vol. 21, pp. 36-8, New York, Wilev. 1941. ( 5 ) \Titmi&, 1,. P., Lutz, D. A , , Sasin, G. S., Sasin, R., J . Am. Oil Chemists' SOC.34, 71 (1957). RECEIVED for review May 14, 1957. .4ccepted July 16, 1957. Submitted by D: A . Lutz in partial fulfillment of the requirements for the master of science degree at Drexel Institute of Technology. Mention of company or trade names in this paper does not imply endorsement by the U. S. Department of -4griculture over similar concerns or products not mentioned.
Mass Spectrometric Analysis Aliphatic Ethers FRED W. McLAFFERTYl Spectroscopy laboratory, The Dow Chemical Co., Midland, Mich.
b Correlation of the spectra of 25 saturated aliphatic ethers shows the unique usefulness of the mass spectrometer in identification, structure determination, and analysis of such compounds. These mass spectra show marked similarity to the spectra of other compounds with electron-donating functional groups, such as alcohols and amines. Cleavage of the bond alpha to the oxygen atom i s favored to yield the alkyl ion, especially in symmetrical and nonbranched ethers. Beta bond cleavage to give the oxygen-containing ion i s prominent, especially in methyl ethers. Alpha branch1782
8
ANALYTICAL CHEMISTRY
ing favors the cleavage of a beta and opposite alpha bond with rearrangement of a hydrogen atom. Anomalous ions found at one mass unit above the molecular weight are formed by intermolecular recombination. These can b e found with many other types of compounds other than ethers and can be useful in molecular weight determination. Mechanisms for these favored cleavages are proposed.
P
correlations of the mass spectra of saturated aliphatic amines (4-6, 16) and alcohols (9, 18) have shon-n marked similarities, such as the
strong tendency for cleavage a t the beta carbon-carbon bond
R'
It '
R"
R"
to give the positive ion containing the functional group. It has been suggested (17, 18) that these spectral wnilarities are caused bj7 the siniilar
REVIOUB
1 Present address, Eastern Research Laboratory, The DOTT Chemical Co., Framingham, Mass.
