Table 111. Elemental Determination and Compound Analysis of TiB
Ti B
c N 0
79.7% 17.3 0.52 0.25 1.65
Tic Ti02 Bz0, TIN BN TiB TiB2
2,08% 3.20 0.54 1.10 0.00
89.57 2.41
loss was obtained after an alcohol reflux (Table 11) which substantiates the presence of B203in an amorphous form, By determining the amount of TiR2 by x-ray diffraction (18) a value of 10% was obtained, which compares favorably with the results listed. A sample of TiB was also analyzed for compound impurities. The data obtained substantiate the workability of this method to distinguish between the two borides, as shown in Table 111. The conclusions which may be drawn from this investigation are as follows. The cubic phase may be chemically identified. Generally, the major constituents of this phase in decreasing order are Tic, T i S , and TiB. The
reaction of TiOa, and C extends through an intermediate TiC-B203 phase. LITERATURE CITED
(1) Blumenthal) H., ANAL. CHEY. 23,
992 (1951). (2) Brewer, L., Haraldsen, H., J. Electrochem. Soc. 102, 399 (1955). (3) Brewer, L., Sawyer, D. W., Templeton, D. H., Dauben, C. H., 17. S . AEC, Publ. VCRL 610 (1950). (4) Decker, B. F., Kasper, J. S., Acta Cryst. 7, 77 (1954). (5) Ehrlich, P., 2. dnorg. Chem. 1949, n. 2.59
( S i Frank, A . J., ANAL.CHEM.30, 830 (1963). (7) Geach, G. A., Jones, F. O., Second Plansee Seminar, p. 80, Reutte Tyrol, 19.55. (8) Glaser, F. W., J . Metals 4, 391 (1952). (9) Greenhouse, H. AI., Accountivs, 0. E., Sisler, H. H., J . .4m. Chem. Soc. 73, 5086 (1951). (10) Kriege, 0. H., At. Energy Comm. Rept. LA-2306, Chemistry-General, TID-4500,p. 43, 14th Edition (1959). (11) Laboratory Equipment Corp., Instruction Manual for Operation of Oxygen Analyzer, No. 534-300. (12) Laboratory Equipment Corp., Instruction Manual for Oueration of Leco Carbon Determiriator,’ No. 4000A. (13) Nelson, J. A,, Willmore, T. A,, Worneldorph, R. C., J . Electrochem. Soc. 96, 465 (1951).
(14) Nowotny, H., Benesonsky, F., Brukl, C., Schob, O., Monatsh. Chem. 92, 403 (1961). (15) Palty, A . E., JIargonline, H., Nielsen, J. P., Am. Soc. M e t . 46, 312 (1954;. (16) Portnoj, K. I., Samsonov, G. I-., Frolova, K. I., J . r l p p l . Chem. U S S R 33. 577 11960). (17) ‘Post, B., Glaser, F . W., J . Chem. Phys. 20, 1050 (1952). (18),Redmond, J. C., ANAL. CHEM.19, 773 (1947). (19) Roche, 11. A., unpublished reports, National Carbon DeveloDment Laboratory (1961). (20) Rynasiewicz, J., Consalvo, Y. F., TID-7606, 4th Conf., Gatlinburg, Tenn., 1960. (21) Schnwzkopf, P., Kieffer, R., “Cemented Carbides,” p. 103, hlacmillan, Xew York, 1960. (22) Schwarzkopf, P., Kieffer, R., “Refractory Hard Metals,” p. 276, llacmillan, Kew York, 1953. (23) Steinitz, R., Powder Met. Bull. 6, 54 (1951). (24) Tereshko, J. W.,ANAL. CHEM.35, 157 (1963). (25) Tbithey, W. O., Redrnond, J. C., Zbtd., 20, 202 (1948). (26) Treadwell, F. P., Hall, W. T., “Analytical Chemistry,” Vol. 11, p. 574, Wiley, Nem- York, 1956. RECEIVED for review January 22, 1964. Resubmitted January 11, 1965. Accepted February 8, 1965. Presented at the Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Pittsburgh, Pa. 1963.
Correlations and Anomalies in Mass Spectra: Thioesters W. H. McFADDEN, R. M. SEIFERT, and JAN WASSERMAN Western Regional Research laboratory, Albany, Calif.
b The mass spectra of 46 aliphatic thioesters have been investigated. R1COSR2 generally yields the simple bond break ions R1(+) and R’CO+and these define the acid moiety except in the case of octanoates where R1(+) is negligible. Thioesters from acids longer than octanoates were not studied. From n-thiopentanoates and longer acid groups, a cyclic activated complex is formed which favors loss of RZ leading to RICOS+ and a smaller current of parent ions. The common rearrangement ions observed in the mass spectra of the esters R1COOR2 are observed in the mass spectra of thioesters but are less intense and often have little analytical significance. As a result, identification of R2 from weak spectra of higher molecular weight thioesters is difficult. Cyclization of the parent ion results in an important rearrangement reacfrom tion due to loss of -SCHRCHtR~COSCHRCH,(C,H,,+~). In certain favorable cases, this rearrangement can contribute more than 10% of the total ion current, but it generally contributes 2 to 470. Other rearrangement ions not observed in the spectra of ordinary esters (R1COOR2) are noted and discussed. 560
ANALYTICAL CHEMISTRY
S
on vegetable oils and essences involved taking the mass spectra of certain thioesters and related compounds. I n some cases-e.g., methyl thiohexanoate, methyl thioheptanoate, and other esters in hop oil-the unknown mass spectra can be qualitatively determined with ease (Q), but in other cases unknown compounds were erroneously interpreted as thioesters (4). Various unexpected modes of decomposition and rearrangement noted in the spectra of these compounds made a comprehensive study desirable. TUDIES
R2SH
+ (RlCO),O 3 R1COSR2
+ RlCOOH
The thioesters were separated by distillation and purified by gas chromatography on a 20-foot X 3,/8-in~h column which was packed with a stationary phase of SF-9650 silicone fluid or SE-30 silicone gum rubber. Column temperatures were selected to elute the thioester in 30 to 60 minutes. The conditions gave satisfactory separations of the starting materials from the thioesters. The mass spectra did not indicate any significant impurities.
EXPERIMENTAL
Mass Spectra. The mass spectra were obtained from a Bendix TimeOf-Flight mass spectrometer. The electron bombardment was a t 70 e.v. Continuous ionization was used. The external temperature of the ion chamber was 100” C. T h e spectra were scanned from mass 20 to 200 in 25 seconds. Synthetic Methods. Thioesters were prepared from mercaptans by one of the methods described by Wenzel and Reid (22). R2SH or
+ R’COC1
-
R1COSR2
+ HCl
RESULTS
The mass spectral data for the 46 thioesters are presented in Tables I to V as a per cent of the total ion current. Only mass peaks discussed in the text are presented. A complete tabulation of the mass spectral data will be circulated through the ASTN E-14 File of Uncertified Mass Spectra ( I ) . The data are not corrected for the contributions of isotopes. Because of isotopic ions, there are a few cases in which the mass re5olution of the spectrometer was not sufficient to permit
accurate measurement of weak ion currents adjacent to strong ion currents. In these cases, the weak ion current is listed as unmeasurable. Molecular Ion. From the thioacetat'es, thiopropionates, and thiobutyrates, l to 20y0 of the ion current is parent ion. Figure 1 illustrates the decrease of parent ion current with increasing niolecular weight of straight chain esters. At a given molecular weight the parent ion intensity is greater in the order acetates
