The mercaptosilanw were prepared by the reaction of the sodium salt of the mercaptan with trimethylchlorosilane in hexane (4). RESULTS AND DISCUSSION
The results of analyses by both of these methods for a primmy, a secondary, and a tertiary alkylmercaptosilane and an arylmercaptosilane are shown in Table I. The purities of these compounds are assumed to be greater than 98%. The purest of these would be the tert-butylmercaptosilaiie redistilled three times in a 30-inch, g1:tss-helices packed thermostated column. The analyses may be considered quantitative, except for the values by both methods for the tert-but ylmercaptosilane. Steric hindrance appears to preclude a quantitative determination of the SiSC linkage in the tert-butylmercaptosilane in reasonable lengths of time by 0.04N perchloric acid-catalyzed acetylation. Increaser, in the perchloric acid and acetic anhydride concentrations to 0.15111 and 2 & , respectively, resulted in recoveries o ~ ’only 96.0, 97.7, and 97.9y0 for this same silane over reaction times of 10 minutes, 1 hour, and 21/2 hours. Also, when using the latter, more concentrated acetylating reagent a precipitate similar in nature to those obtained during attenpted assays of the tertiary alkoxysilanes 2,2,4,4,5,5hexamethyl - 1,3 - dioxa - 2 - silacyclopentane ( 5 ) and trimethyl-tert-butoxysilane (6) was noted. Apparently the
Table I.
Analysis of Mercaptosilanes Per cent of theorya
Mercaptosilane Trimethyl-n-butylmercaptosilane
-
Perchloric acidcatalyzed acetylation
Mercuric acetate
98.5 f 0 . 5 98.7 f 0 . 2 86-97“ 99.4 f 0 . 6
99.2 f 0 . 1 98.2 f0 . 1 103.0 f O . l d 100.3 f 0 . 3
Trimethylisopropylmercaptosilane Trimethyl-tert-butylmercaptosilane
Trimethylphenylmercaptosilaneb a Average and average deviation of trinlicate determinations. b N o t previously refirted in the literature, b.p. 72’ C. at 8 mm. Found: C, 59.50; H, 7.80; S, 17.49; Si, 15.42. Calcd.: C, 59.27; H, 7.74; S, 17.58; Si, 15.40. C Six determinations, 3 minutes to 16 hours reaction time. d Dark ppt. formed in methanol-toluene, 400 ml. of 1 : 1 chloroform-butanol used as solvent.
proposed mechanism for steric hindrance in the acetylation of the tertiary alkoxysilane in ( 5 ) holds for the tert-butylmercaptosilane as well. The relatively high assays for the tert-butylmercaptosilane probably result from the rapid acetylation of the tert-butyl mercaptan (2) which is formed during the hydrolysis step in this method. Occlusion of mercuric ions in the mercury mercaptide precipitate (7) is apparently the cause for the 103.0% recovery of the tert-butylmercaptosilane in the mercuric acetate method. This precipitate formed immediately and became very heavy during the titration. The mercaptide precipitates of the other mercaptosilane assays were not very noticeable until a few milliliters before the end point was reached. This method is slightly more precise than the acetylation method because of its very
sharp and stable end point and the use of less concentrated reagents. LITERATURE CITED
( 1 ) Fritz, J. S3., Schenk, G. H., ANAL. CHEM. 31, 1808 (1959). )id., 32, 987 (1960). :under, K. K., Das, M. N., Ibid., 31, ‘8 (1969). (4) Laneer. S. H.. Connell. S.. Wender.‘ I., J. zm. Chem.‘Soc. 23,50 (i958). (5) Magnuson, J., ANAL.CHEM.35, 1487 (1963). (6) Magnuson, J., Silicone Products De-
artment, General Electric Co., WaterF ord. N. y., unwblished results, 1963. . “Quantitative Oreanic (7) Siggia,. S’. Analysis via’ Functional Groups,” 3rd ed., p. 563, Wiley, New York, 1963.
ABE BERGER
J. A. MAQNUSON Silicone Products Department General Electric Co. Waterford, N. Y.
Anion Exchange Characteristics of Elements in Nitric Acid Medium SIR: In anion exchange studies made at this laboratory during the past few years, adsorption of most metal ions from nitric acid solutions of 1M to 14M has been determined and the data have been applied to analytical separations (1, d , 6). The work has now been extended to include the behavior of some 70 elements in acid concentrations ranging down to 0,lM. A strongly basic anion exchanger, Dowex 1 X 10, 200 to 400 mesh, was used throughout. Both column elution and batchwise equilibration were used to determine the distribution coefficients presented in Figure 1. Experimental details and analytical techniques have been described in previous reports (a, 6, 7 ) . Elements found to have a distribution coefficient of less than about one at all acidities were placed in the no adsorption category. Somc:times slight adsorption was found :tt either the low or middle acid range. In some cases a valence change may
have taken place on the resin; as a rule the addition of excess oxidant or reductant to an eluting solution or to a batch was avoided. An exception was neptunium where the tetravalent state was maintained with 0.1M ferrous sulfamate. While Ru(IV) can be adsorbed (S,12, 19) we found that without a holding oxidant most of the ruthenium added to a column broke through early. For Tl(III), the adsorption function shown was somewhat tentative because of possible reduction on the columns. Also Ce(IV), for which excellent absorption has been reported (fd),was eluted about the same as Ce(III), probably owing to a reduction on the columns. For the most part, the adsorptions given in Figure 1 were in satisfactory agreement with those which have been reported in the literature (7), although many of the comparisons can only be qualitative because of variations in physical properties or type of resin used.
Some published values have been included to present the data as completely as possible. Also, Danon and Zamith (5) reported distribution coefficients for Po (IV) ranging from 120 to 90 in nitric acid from 0.8M to 5 M . I n the presence of an effective reductant the adsorption decreased to give a curve similar to that of Bi(II1) in nitric acid. Ichikawa, Urano, and Imai (fa)later found Po(1V) to be only slightly adsorbed. In 7111 acid, Ir(1V) was adsorbed, Se(1V) and Ta(V) were not (IS). For Ge(IV), both negligible adsorption (13, 14) and strong adsorption ( l a ) have been reported. It has been implied that francium and the transcurium elements would not be adsorbed on anion exchange resins from nitric acid solution (10, 1 1 ) . ACKNOWLEDGMENT
The authors appreciate the help of J. J. Hines, R. Krishnamoorthy Iyer, VOL. 36, NO. 6, MAY 1964
1157
m
Am
m
Figure 1.
Removal from solution of elements in 0.1M to 14M nitric acid with strongly basic anion exchange resin
(a), N b V-Bunney et of, (3), James (13), Phillips and Jenkins (15), Prevot et al. (16); (b), Ra Il-Chappin and Sikkeiand ( 4 ) ; (c), Ac Ill-Chappin and SikkeHyde ( 1 0 ) ~(d), Np V, VI-Hardy (8, 9), lchlkawa et al. (121, Taber (181, Wish and Roweil (19)j (e), Pu Ill-Roberts and Brauer (171, Wish and land (4), Raweil (19).
M. A. Essling, J. W. Warton, K. A. Orlandini, G. Jewett, and F. Lawless. LITERATURE CITED
(1) Buchanan, R. F., Faris, J. P., “Radio-
isotopes in the Physical Sciences and Industry,” Vol. 2, p. 361, International Atomic Energy Agency, Vienna, 1962. (2) Buchanan, R. F., Faris, J. P., Orlandini, K. A,, Hughes, J. P., U. S. Atonuc Energy Comm. Rept. TLD-7560,
179 (1958). (3) Bunney; L. R., Ballou, N. E., Pascual, J., Foti, S., ANAL.CHEM.31,324 (1959). (4) Choppin, G. R., Sikkeland, T., p. 60, NAS-NT-3004 (ref. 11). ( 5 ) Danon, J., Zamith, A. A. L., J . Phys. Chem. 61, 431 (1957). (6) Faris, J. P., Buchanan, R. F., 4th Conf., Gatlinburg, Tenn., U. S. Atomic Energy Comm. Rept. TID-7606, 185 (1960).
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ANALYTICAL CHEMISTRY
(7) Faris, J. P., Buchanan, R. F., U. S. At. Energy Comm. Rept. ANL-6811 (1963). (8) Hardy, C. J., “Progress in Nuclear Energy,” F. R. Bruce, J. M. Fletcher, H. H. Hvman. eds.. Series 111. Vol. 2. p. 357, Pergamon, New York,’1958. ‘ (9) Hardy, C. J., Scargill, D., Fletcher, J. M., J . Inorg. Nucl. Chem. 7,.257 (1958). (IO) Hyde, .E. K., “The Radiochemistry of Francium. NAS-NS-3003 (1960). Available from the Office of Technical Services, Dept. of Commerce, Washington. D. C. (11) Hyde, E. K., “The Radiochemistry of Thorium,” NAS-NS-3004 (1960).
----.
Available from the Office of Technical Services, Dept. of Commerce, Washington. D. C. (12) Ichikawa, F., Uruno, S., Imai, H., Bull. Chem. SOC.Japan 34, 952 (1961). (13) James, D. B., J . Znorg. Nucl. Chem. 25, 711 (1963).
(14) Kraus, K. A., Nelson, F., ASTM Spec. Tech. Pub. No. 195 (1956). (15) Phillim, G., Jenkins, E. N., J . Znora. Nucl. Chem. 4, 220 (1957). (16) Prevot, I., Corpel, J., Regnaut, P.. 2nd Intern. Conf. Peaceful Uses A
Atomic Energy Comm. Rept. HW-60552 (1959). (18) Tober, F. W., Proc. 2nd Intern. Conf. Peaceful Uses At. Energy, Geneva 17, 574, United Nations, New York, 1958. (19) Wish, L. Rowell, M., U. S. Naval Radiological! Defense Laboratory, TR117, 1956. J. P. FARIS R. F. BUCHANAN
Argonne National Laboratory Argonne, Ill.
