Principal Lines
Xanthotoxin I
41.
Contributed by JOHN KRC, Armour Research Foundation, Illinois Institute of Technology, Chicago 16, 111.
"
HC-C
I1
HC
\o/
c c /\/ NCCH ,
4 A\o/
d 10.08 7.89 6.60 4.97 4.82 4.35 4.14
3.83 3.76 3.56 3.43 3.32 3.22 3.10 2.97 2.88 2.73
L O
,
OCHa Structural Formula for Xanthotoxin
C
of xanthotoxin I can be obtained by erystrtllizaG tion . crystals from ethyl deohol, although benzyl alcohol is the best
I
OOD
solvent for recrystallization on 8. miorascope slide (Figure 1,~). Characteristio crystals from the melt are shown in Figure 1,b. Figure 2 is Bin orthographic projection of a typical orystsl of xanthotoxin I. Xanthotoxin is almost insoluble in cold water and only 0.1% soluble in boiling water. It is only slightly soluble in petroleum ether, freely soluble in chloroform, and less soluble in benzene, alcohol, and ether. Xanthotoxin I1 can be obtained fairly readily on a microscope slide by thoroughly melting a pure sample, followed by chilling on a cold surface. There is no evidence that modification I1 can be formed from solution and it is doubtful that such an unstable form could be crystallized from solution. CRYSTAL MORPEOLOGY Crystal System. Orthorhombic. Form and Habit. Rods and needles elongated along c, showing forms {loo), (0011, [110I,and 1801). Axial Ratio. a;bz = 0.818:1:0.307. Interfacial Angles(Po1ar). 110h 110 = 101'/*'; 1lOA~100= 701,IP ""
.
I/I, 0.02 0.02
2.58 2.54 2.44 2.38 2.30 2.24 2.17
0.04 Very weak 0.02 0.03 0.03 0.06 0.02 0.06 0.03 0.03 Y e w weak 0.06 0.03 Very reilk Very weak
2.05
Very weak 0.05
1 1 -b
1.954 1.896 1.871 1.838 1.781 1.755 1.715 1.673 1.603
C
I
a
IO0
a 1-b
801hsOl = 143". Cleavage. Excellent parallel to 010 and 100. D
d
I/Ir 0.06 0.10 0.62 0.0s 0.06 0.38 0.06 0.09 0.20 0. .57 1.0 Very weak Very weak 0.06 0.26
b
Figure 2. Orthographic Pmjeotion of Typical Crystal of Xanthotoxin I from Ethyl Alcohol
OPTICALPROPERTIES Refractive Indexes (5893 A.; 25°C.). a = 1.698 0.003. 8 = 1.734 * 0.006. y = 1.742 0.006. Optic Axial Angles (5893 A,; 25°C.). 2H = 48'/2". 2V = 43' (calcd. from @ and 2 X ) ; 48' (oalcd. from a, 8, and y). 2E = ca. 82". Dispersion. r > v , very strong. Optic Axial Plane. 001. Sien of Double Refmotion. Neeative. A& Bisectrix. a = a. Extinction. Parallel and symmetrical. Molecular Refraction ( E ) (5893A.; 25°C.). y,sy = 1.724. R (calod.) = 57.1. R (obsd.) = 59.2. FUSIONDATA. Xanthotoxin I melts a t 148' C. with some sublimation and slight decomposition. When cooled just below ita melting point, it crystallizes as highly birefringent rods. If cooled raDidlv to room temnerature. a lower temDerature modification, ;anthotoxin 11, may be obtained, cry&lieing as low f
f
e
X - ~ DIFFRACTION Y DATA Cell Dimensions. a = 12.95 A.; b = 15.83 A.; c Formula Weights per Cell. 4.
=
4.86 A.
Formula Weight. 216. Density. 1.449 (flotation-centrifugation-density b a 1a n c e); 1.440 (x-ray).
390
ANALYTICAL CHEMISTRY
-
The transformation I I1 was not observed. Figure l,c, shows crystals of xanthotoxin I (left) replacing spherulites of xanthotoxin I1 (right). A solution phase transformation I1 --t I can be readily observed a t room temperature by surrounding the crystals with benzyl alcohol in a preparation including both modifications. This preparation is obtained by heating one side of a preparation of modification I1 and immediately cooling to slow the transformation to I. In general, modification I1 transforms entirely to I well below the melting point. ACKNOWLEDGMENT
The author is indebted to R. L. Felton and the Paul B. Elder Co. for the sample of xanthotoxin used in this investigation and for solubility data. COXTRIBUTIOM of crystallographic data for this section should be sent to Walter C. MoCrone, Analytical Section, Armour Research Foundation of Iliinois Inrtitute of Technology, Chicago 16, I11
of organic origin, and mixed goods used in Germany. The treatment of phosphates covers basic slag, superphosphate, Rhenania phosphate, dicalcium phosphate, phosphate rock, bone meal, and new phosphates; that of nitrogen materials covers nitrate, ammonia, and amide nitrogenous products. Descriptions of the various materials, given in appropriate places, include method of production, grade specifications, fineness, and chemical composition shown by typical analyses. The status of fertilizer research in Germany, as of 1948, is discussed, and summarized data on national fertilizer consumption and use are given. The text closes with a discussion of fertilizers as a basis of nutritional improvement, in which are included graphical comparisons of trends in infant mortality, average life span, and cancer death rate with the trend in fertilizer consumption. The author has incorporated in a book of control methods sufficient material of wider interest t o afford a brief coverage of German fertilizer production, evaluation, and use. J. H. C A R 0
Symposia Committee Analytische Chemie der Diingemittel. SiegfTied GerickP. 191 pages. Die Chemische Analyse, Vol. XLIV. Ferdinand Enke, Stuttgart, 1949. Price, paper 95.62, linen $6.19. .4nalytical procedures are described in detail for liming materials, phosphate, potassium, and nitrogen fertilizers, fertilizers
The terms of L. T. Hallett and Beverly L. Clarke on the Committee on Annual Symposia have expired, and Louis Gordon, Syracuse University, and James M. Crowe, ~ A L Y T I C A LCHEW ISTRY, have been appointed in their places. The committee now consists of P. J. Elving, chairman, J. W. Stillman, Edward Wichers, I. 11.Kolthoff, Louis Gordon, and J. M. Crowe.
Fourth Symposium on Analytical Chemistry HE fourth annual Symposium on Modern Methods of Analytical Chemistry was held January 29 to February 1 at the Louisiana State University, Baton Rouge, La. Abstracts of the papers presented are reproduced here.
T
Oscillographic Polarography. P A ~DELAHAY, L Louisiana State University. Methods of Measurement. Single-sweep methods. Multisweep methods Randles-Sevcik equation Causes of error Resistance of the circuit Capacity current Irreversibility Other causes of error (multisweep method) Applications Routine determinations Analyses in the micromolar concentration range Kinetics studies Use of platinum microelectrodes Comparison n-ith conventional polarography Demonstrations Nonmagnetic Radiofrequency Mass Spectrometer. K . H. BENNETT,University of Arkansas. -4 new kind of mass spectrometer has been developed at the National Bureau of Standards in which the masses are separated by velocity rather than magnetic deflections of focused beams. The principles of this new kind of mass spectrometer were presented. This instrument is very different from previous instruments in several. respects. First, it is simpler, more rugged, and much less expensive. Secondly, it is much more sensitive, giving currents a t the collector about 10,000 times as large as those of the more familiar instruments. Thirdly, the instrument does not use slits and because of this absence of slits the instrument can be adapted to a great variety of applications where previous instruments could not be used at all. A number of typical applications where this instrument enjoys unique advantages were mentioned.
Recent work on the development of the instrument has resulted in an improved understanding of the factors determining the resolution and sensitivity. Some recent developments in respect to the ion sources were presented. The various processes which are responsible for background currents were discussed. Polarographic Behavior of Organic Compounds. ELVING, Pennsylvania State College.
PHILIPJ.
Principles of measurement and interpretation Experimental arrangement and conditions: apparatus, sample solution Nature of record obtained: the polarogram Significance of fundamental equations: IlkoviE equation and equation of the wave Current-controlling processes Deduction from experimental data Applicability of polarography to organic com ounds Electroactive functional entities: reducibye, oxidizible, and nonrelative groups Case history: the carbonyl group Effect of substituents in the molecule Current development in organic polarography Study of nature of phenomena involved 1. Buffers, pH, ionic strength 2. Reaction and electrode mechanisms at dropping mercury electrode (oscillographic study) 3. Nature of irreversible reactions 4. Oxidative reactions Use as an investigative tool 1. Applications dependent primarily on id: analysis, reaction rates, etc. 2. Applications dependent primarily on EM: structure, redox potentials, isomerism, etc. 3. Applications dependent on id, 30.6, 12, etc.: equilibria, hydrogen bonding, etc. Effect of experimental conditions (environment) Concentration of reactive species Ionic strength and buffer nature Nature of solvent
