clean, dry, inert liquids which are insoluble in DzO are suitable. Among those used are hexane, benzene, amyl acetate, and carbon tetrachloride. Thus far, all reactive samples encountered have exchanged in less than */z hour of shaking. Among the materials analyzed, the only one found which exchanges, but not rapidly, Tyas the extremely highly hindered structure present in 2,6-di-tert-butyl-4-methylphenol described in Table I. I n one month 4-methyl-2-pentene did not eschange measurably. I n the case of materials which emulsify easily, gentle shaking or centrifugation may be necessary to obtain a clear D20 phase. After the exchange is complete and the two phases have separated, the absorbance of the DzO phase is measured a t 2.97 microns and corrected for cell blank and residual DzO absorption. The active hydrogen content of the sample is calculated as described above, remembering that the volume of the sample being analyzed is only the volume of the D2O phase in the case of insoluble materials. I n these two-phase systems one can correct for incomplete exchange due to statistical distribution a t equilibrium of the exchanging hydrogen bet\yeen the D20 and the parent molecules. If the magnitude of the isotope effect is known, a n appropriate correction can be applied. Such corrections are possible because the exchanging molecule is not present in the DzO phase but remains in the organic phase and the partial compensation due to unreacted molecules present in the equilibrium mixture is not acting in these samples. Although the active hydrogen of Some
DzO-insoluble solids apparently will exchange completely, it is desirable first t o dissolve the solid in a suitable solvent. Those solvents mentioned above have been used successfully, although many others would be just as satisfactory. Once the sample is in solution, the analysis is performed as described above for insoluble liquid samples. Because most solvents contain small amounts of water, a blank determination should be run, by the same procedure, using the same amount of solvent and D20, but with no sample. Errors D u e to Presence of HzO. Because of t h e hygroscopicity of DzO i t is necessary t o be extremely careful in t h e preparation and handling of both D20 and samples t o prevent including water from t h e sample or from atmospheric water vapor. One per cent of water in a sample of molecular weight 100 containing one active hydrogen per molecule will introduce a n error of over 10%. To obtain an accurate active hydrogen figure, exclusive of water, it is often necessary to use a suitable drying procedure or to obtain a separate water determination and calculate the correction. Results of Known Samples. The results obtained from analysis of known compounds are shown in Table I. The analyses were performed on Model 21 Perkin-Elmer instruments using a n 0.025-mm. cell in t h e case of water-soluble compounds and a n 0.05-mm. cell for t h e water-insoluble ones. The modified base line technique described above was used; a solvent blank was also used where t h e water-insoluble materials were in a solvent.
CONCLUSIONS
I n general, a determination is accurate t o h2Yc of the amount of active hydrogen present, while repeatability is somewhat better. As little as 0.005 ’ active hydrogen can be deterweight % mined with no method modification. Determinations may be made in about ‘/z hour per sample a t a fairly low cost. DzO costs approximately 50 cents per gram, and 1to 5 grams are ordinarily used for each sample.
LITERATURE CITED
(1) Blout, E. R., Lenormant, W., J . Opt. SOC.Am. 43,1093 (1953).
(2) Broida, H. P., Morowitz, H. J., Selgin, M., J . Research h’utl. Bur. Standurds 52,293 (1954). (3) Gaunt, J., Analyst 79, 580 (1954). (4) Gaunt, J., Spectrochim. Acta 8, 57 (1956). (5) Gore, R. C., Barnes, R. B., Peterson, E., ANAL.CHEM.21,382 (1949). (6) Jones, J. H., Hall, M. A., “NearInfrared Determination of H20 in DgO. Application to Determination of n’ater of Crystallization and Readily Exchangeable Hydrogen in Organic and Inorganic Compounds,” Pittsburgh Conference on ilnalytical Chemistry and Applied Spectroscop March 1956. ( 7 ) Mitchell, John, Jr., dilthoff, I. M., Proskauer, E. S., Weissberger, A., “Organic Analysis,’’ Vol. I, Chap. 1, 3, 4; Vol. 11, Chap. 4, Interscience, New York, 1953 and 1954. (81 Morowitz. H. J.. ChaDman. XI. W.. Arch. Biochem. Bidphys. 5 6 , 110 (1955): (9) Potts, W. J., Wright, X., ANAL. CHEM.28,1255 (1956). (10) Trenner, N. R., Arison, B. H., Walker, R. JT., Ibid., 28, 530 (1956). \
,
RECEIVEDfor review June 3, 1959. Accepted March 23, 1960.
Twenty-one New X-Ray Diffraction Powder Patterns H. G. NORMENT,l P. 1. HENDERSON,2 and R. L. SOUTH3 Callery Chemical Co., Callery, Pa.
A collection of 21 standard x-ray diffraction powder patterns, mostly of boron compounds, is presented. The data have been collected by both diffractometer and Debye-Scherrer methods.
I
THE COURSE of several years of analysis by x-ray diffraction in this laboratory, many powder patterns have been obtained which are not included in existing reference compilations. The best of these data are presented here as well as a brief description of the source of the compounds and their preparation (when this information is not restricted),
x
796
ANALYTICAL CHEMISTRY
purification, and method of intensity measurement. Unit cell parameters are given where these are available. Except where specifically mentioned, the powder patterns have not been checked against the single crystal data. The Bragg d-spacings and intensities are found in Table I. APPARATUS AND TECHNIQUES
When sufficient sample was available, the patterns were measured with the Xorelco Geiger counter diffractometer using standard procedures ( I S ) . Nickel filtered C U R , radiation was used. The intensities reported are peak heights
above background, so scaled that the most intense line is given a value of 100. Samples were finely powdered by a Wig-L-Bug vibration grinder. All diffractometer patterns were checked against 114.6-mm. Debye-Scherrer films for completeness and accuracy of dvalues. 1 Present address, Diffraction Branch, Optics Division, U. S. Saval Research Laboratory, Washington 25, D. C. 2 Present address, Graham Research Laboratories, Jones and Laughlin Steel Co., Pittsburgh, Pa 3 Present address, Department of Chemistry, Western Reserve University, Cleveland, Ohio
Bis(acetonitrile)decaborane, BioHiz(CH8CN 19 2.61 39 4 . 3 25 2.48 3 3.43 E 3.20 13 2.37 34 2.29 25 3.00 48 1.82 32 2.83 14 1.77 100 2.74 1.72
8.9 7.1
6.5 5.7 5.0 4.5
- -
Boric Acid, 6.0 88 2.83 7-4 7 2.65 4.5 2 2.56 4.2 3 2.49 4.0 2 2.28 3.45
