nadium, tantalum, niobium, iron, and titanium. The oxides of these elements are analyzed after their chemical separation from ore, metal, or liquid samples. The instrument is programmed for medium and high concen trations, and correction factor systems are used to correct for interelement effects. Speed of analysis, instrumental sensitivity, analytical accuracy, and precision are excellent. I n 1959, 10,OOO element determinations (including
LITERATURE CITED
trace range concentrations), an average of 800 determinations per month, were made.
(1) Kemp, J. W., ANAL.CHEM.28, 1838 (19.56). \----,.
(2) Mitchell, B. J., Ibid., 30, 1894 (1958). (3) Liebhafsky, H. A,, PfeifTer, H. G., Zemany, P. D., IM., 27, 1257 (1955).
ACKNOWLEDGMENT
The author thanks the members of the x-ray group for their assistance in instrumental calibration and statistical evaluation, and H. J. O’Hear and the members of his chemical group for their preparation of standards and samples.
RECEIVEDfor review August 7, 1959. Resubmitted April 28, 1960. Accepted August 3, 1960. Presented in part at the 10th Annual Symposium on Spectroscopy, Chicago, Ill., June 1, 1959.
Some Physical Characteristics of the 2,4Dinitrophenylhyd razine and Semicarbazide Derivatives of Three-Carbon Carbonyls J. C. UNDERWOOD and HARRY G. LENT0 Eastern Regional Research laboratory, Eastern Utilization Research and Development Division, Agricultural Research Service, United States Department o f Agriculture, Philadelphia 7 8, Pa.
b A means of identifying the shortchain hydroxyaldehydes and ketones resulting from the alkaline degradation of hexoses was needed, and the literature was found lacking in data which permit the differentiation of these compounds (acetol, dihydroxyacetone, glyceraldehyde, hydroxypyruvaldehyde, and methylglyoxal). The 2,4dinitrophenylhydrazine and semicarbazide derivatives of these trioses were therefore prepared, purified, and characterized by the determination of their elemental composition, melting points, and ultraviolet and infrared spectral absorptions.
I
N A STUDY (12) of the intermediates
involved in the color and flavor formation in maple sirup, it became necessary to identify a number of short-chain aldehydes and ketones resulting from alkaline degradation of sugars. Examination of the literature revealed that the formation of the 2,4dinitrophenylhydrazine (DPH) derivatives of carbonyl compounds has been a n excellent means of separating and identifying even very small quantities of aldehydes and ketones. Data on the derivatives of the three-carbon carbonyls related to the alkaline brehkdomn products of hexose sugars were limited (7, 8, 11). Reich and Samuels (IO) described the reaction products of D P H with the simple carbonyl compounds, acetol, methylglyoxal, glyceraldehyde, and dihydroxyacetone, but their physical data !$ere not complete. This is especially true with respect to the ultraviolet and infrared absorption data. Although semicarbazide has been 1656
ANALYTICAL CHEMISTRY
the five compounds (acetol, methylglyoxal, glyceraldehyde, dihydroxyacetone, and hydroxypyruvaldehyde) just five DPH derivatives can be formed. Acetol, glyceraldehyde, and dihydroxyacetone form different hydrazones. The pyruvaldehyde dinitrophenylosazone is formed from methylglyoxal, acetol, dihydroxyacetone, and glyceraldehyde. I n addition, glyceraldehyde, dihydroxyacetone, and hydroxypyruvaldehyde form another dinitrophenylosazone,-namely, hydroxypyruvaldehyde dinitrophenylosazone. Further, only two semicarbazide derivatives of these five carbonyl compounds were found useful-i.e., those of acetol and methylglyoxal. Therefore, those derivatives that serve to differentiate the five carbonyls are characterized in this study. They are:
used to form derivatives of carbonyl compounds (5-5, 9), it has had limited usage since it does not react as readily as DPH. Many of the semicarbazones are so soluble that amounts of material needed for identification are not obtained. The D P H derivatives of acetol and methylglyoxal, however, do not adequately serve to differentiate between the two compounds. The semicarbazide derivatives are much better for this purpose. This paper presents data on the physical characteristics of some of the D P H and semicarbazide derivatives of acetol, glyceraldehyde, methylglyoxal, dihydroxyacetone, and hydroxypyruvaldehyde which will help to identify these compounds in the presence of each other.
Acetol dinitrophenylhydrazone Glyceraldehyde dinitrophenylhydrazone Dihydroxyacetone dinitrophenylhydrazone Methylglyoxal dinitrophenylosazone
EXPERIMENTAL
Preparation of Derivatives.
Table
I.
From
Melting Points and Spectral Absorption Data
Melting MethaPooint, nol c. Sol(Cor.) vent0
Absorption Data, Mp Maxima Minima
Acetol hydrazone
128
A
B
355, 2559, 226 517, 432, 255s, 224
290 494, 390
Methylglyoxal osazone Hydroxypyruvaldehyde osazone Acetol semicarbazorie Methylglyoxal semicarbazone a A, acidic; B, basic.
303 276-7 193 256-7
A A A A
432, 270 430, 396, 250s, 225 286 225
288 296 225
2 , 4 - D l N ITROPHENYLHYDRAZONES ACETOL
0 LY C E R A L D E HY DE
W V
z a tI v)
z a
a I-
a?
w
HO-C
V
z
a
I
m 0
250
300
I
I
I
350
4 00
4
I
I
-C-
I
I
1
3
4
s
C=O
I
6 WAVE
I
I
I
7 8 9 IO L E N G T H , MICRONS
1
1
12
1
L
15
ADIHYDROXYACETO I Figure 2. Infrared curves of 2,4-dinitrophenylhydrazones of acetol, dihydroxyacetone, and glyceraldehyde
200 200
300 WAVE
400 LEkGTH.
phenylhydrazones could be formedfrom acetol, dihydroxyacetone, and glyceraldehyde. They were found t o have sufficiently different characteristics to differentiate one from t h e other. Table I shows t h a t t h e melting point of the acetol hydrazone will readily distinguish i t from t h e other two. Also, the ultraviolet absorption curves in Figure 1 show that the principal absorption maximum for dihydroxyacetone is at 362 mu, higher than the 355 and 353 for acetol and glyceraldehyde, respectively. This difference of absorbance maximum for dihydroxyacetone is due to the influence of the two OH groups on carbon atoms adjacent to the carbonyl group. This, also, caused increased absorbance which was reflected in a higher e (molar absorptivity) value for dihydroxyacetone than for acetol or glyceraldehyde. I n
6 00
500
mp
Figure 1 , Absorbance curves of 2,4-dinitrophenylhydrazones of acetol, glyceraldehyde, and dihydroxyacetone Top. In acidic methanol Bottom. In alkaline methanol
Hydrotypyruvaldehyde dinitrophenylosazone Acetol semicarbasone Methylglyoxal disemicarbazone The DPH derivatives were prepared according to the procedures of Allen ( I ) and Brady ( 2 ) except that impure derivatives were chromatographed on silicic acid. The semicarbazide derivatives were made by the method described by Kamm (6). The elemental analyses of these derivatives were in agreement with theoretical values. Physical Measurements. Corrected melting points were determined on both a Fisher hot stage a n d a n aluminum block apparatus. T h e values are listed in Table I. T h e ultraviolet absorption spectra were run in absolute methanol from 210 to 600 mp using a Cary recording spectrophotometer. Table I lists the data from these measurements. The infrared absorption moperties were determined using potassium bromide disks of the compounds in a Pcrkin-Elmer spectrophotometer, Model 21. These are recorded as Figure 2 . DISCUSSION OF RESULTS
Hydrazones. From the five compoiiniis studied only three 2,G-dinitro-
I
I
I
GLYOXAL
W 0
z a
1.0
m a v) 0
m
a
\
/
0 200
2 50
'0
300
WAVE LENGTH,
mp
Figure 3. Absorbance curves of semicarbazones of and methylglyoxal
acetol
VOL. 32, NO. 12, NOVEMBER 1960
1657
addition, the absorption at the 250, mp wave length point is a more definite peak for glyceraldehyde than for acetol and dihydroxyacetone. The aldehyde carbonyl gives a sharper absorption at this point than the ketone carbonyl. The infrared absorption curves (Figure 2) did not show any highly significant differences for these compounds. I n the 3- and 9-micron region the dihydroxyacetone curve shows additional absorption bands which differentiate it from acetol and glyceraldehyde. The acetol curve shows a much more significant band a t 13.8 microns than those for glyceraldehyde or dihydroxyacetone. Semicarbazones. Only two semicarbazide derivatives were made and characterized from the five compounds-Le., the acetol and methylglyoxal semicarbazones. These have distinctly different physical properties and furnish an excellent means of differentiating acetol and methylglyoxa!. As shown in Table I, the melting points of the two compounds are 192--4O C. for acetol semicarbazone and 256-7' C. for methylglyoxal disemicarbazone. The ultraviolet absorption curves (Figure 3) have absorption maxima a t widely different points, acetol a t 225 mp and methylglyoxal a t 286 mp.
Osazones. T h e five compounds produce just two osazones which are usually designated as the pyruvaldehyde dinitrophenylosazone and the hydroxypyruvaldehyde dinitrophenylosazone. T o have the compounds involved in this study distinctly different in name, the alternate term methylglyoxal has been used for pyruvaldehyde. The osazone derivative does not contribute much toward the identification of the five carbonyls because the methylglyoxal dinitrophenylosazone may be formed from any of them. However, the hydroxypyruvaldehyde derivative can be made from only three-those containing two hydroxyl groups (glyceraldehyde, dihydroxyacetone, and hydroxypyruvaldehyde). As the melting points of the two osazones are significantly different, a partial separation of the five carbonyls can be made on this basis. A C K N O WLEDGMENl
The authors express their appreciation to B. il. Brice for interpretation of the ultraviolet absorption data, to Anne Smith for making the ultraviolet measurements, t o Carl Leander and Roland Eddy for obtaining and interpreting the infrared data, and to Ruth Kelly
for the elemental analyses of the compounds. LITERATURE CITED
(1) Allen, C. F. H., J. Am. Chem. SOC. 52, 2955 (1930). (2) Brady, 0. L., J. Chem. SOC.(London) 1931, 756. f3) Coulson. D. M..Anal. Chim. Acta 19, 284 (1958). ' (4) Davison, W. H. T., Cristie, P. E., J , C h m . SOC.(London) 1955,3389. (5) Eistert, B., Haupter, F., Chem. Ber. 91, 2703 (1958). (6) Kamm, Oliver, "Qualitative Organic I
,
Analysis," 2nd I
(8) Neuberg, C., Strauss, E., Arch. Bzochem. 7,211 (1945). (9) Kodzu, R., Matsui, K., Bull. Chem. SOC.Japan 10, 122 (1935). (10) Reich, H., Samuels, B. K., J . Ow. Chem. 21, 68'(1956). (11) Strain. H. H.. J . Am. Chem. SOC. . 57, 758 (1935). ' (12) Underwood, J. C., Lento, H. G., Jr.. Willits. C. 0.. Food Research 21. 589 (195G).' '
'
RECEIVED for review February 5, 1960. Accepted June 23, 19GO. Fifteenth paper in a series on maple sirup. The mentior of commercial names in this paper does not constitute a recommendation Of these items over others of similar nature.
Absorption Spectra of Molten Fluoride Salts Solutions of Praseodymium, Neodymium, a n d Samarium Fluoride in Molten Lithium Fluoride J. P. YOUNG and J. C. WHITE Analytical Chemisfry Division, Oak Ridge National laboratory, Oak Ridge, Tenn.
b Spectra are presented for solutions of praseodymium, neodymium, and samarium fluoride in molten lithium fluoride a t a temperature of approximately 900" C. These data are discussed and compared to similar resul?s which have been obtained in other molten salts and aqueous sobtions. Molar absorptivities for selected major absorbance peaks of these rareearth spectra are also given.
I
shown. These spectra were obtained using the Cary recording spectrophotometer, Model 14M, equipped with the high-temperature cell assembly as described in a previous report (6). The molten salts were confined in the form of a pendent drop. The ability t o obtain these spectra demonstrates the capability of this technique for confining corrosive solutions such as molten fluoride salts at very high temperatures in a windowless container.
N A PREVIOUS PUBLICATION ( 7 ) the
authors presented the absorption spectra of several metal fluorides dissolved in a molten lithium fluoridesodium fluoride-potassium fluoride mixture a t temperatures ranging from 500" t o 650" C. In this report the qpectra of praseodyniium, neodymium, and samarium fluorides dissolved in molten lithium fluoride (m. p. 848' C.) are 1658
ANALYTICAL CHEMISTliY
EXPERIMENTAL
Apparatus and Reagents. The hightemperature cell assembly (6) was used to obtain the spectra; the molten fluoride samples were contained as a pendent drop in a platinum tube, 1.0 cm. in length and 0.44-vm. diameter (6, 7 ) > a t approximately 999' C;. This temperatu:? wa5 obtained within 45
minutes by passing a current of 8 amperes a t a voltage of 40 volts to the heater circuit, which consisted of quartz plate5 wound with 20-mil platinum wire. The temperature of the pendent, drop of lithium fluoride was determined either by direct measurement of t'he drop with a platinum-platinum rhodium thermocouple (0' C. cold junction) w!iich v;ns spot-welded to the skin of the platinum tube sample container, or by e proportionality relationship in which the furnace block temperature, measured by a Chromel-Alumel thermocouple, was compared to the illensured tempcratuie of the drop. Ana!)-ticsl reagent-grade lithium fiuuride "as used in thP prepiratioi: of the samples. Tile pure rare-earth salts praseodymium fiuoride, neodyrniuni fluoride, and saniariuin fluoridc, wvrre prepared at the Oak Ridge Natiozal La!,oratory. Procedure. The melts w x e pre-
