61. &Mandelic Acid
10
Contributed hy HARRY A. ROSE, Eli Lilly and Co., Indianapolis 6, I d .
OH ~ A - C O O H
Formula Weights per Cell. 8. Formula Weight. 152.14. Density. 1.289 g ram8 per no. (displr&cement);1.300 (x-ray). OPTICAL PROPERTIE3 0.003, Refractive Indexes (Na light; 25" C.), a = 1.526 8 = 1.564 =t0.003, y = 1.620 + 0.003.
*
I
H Strudural Formula for Mandelic Acid OOD crystals of dl-mandelic acid for optical and x-ray study may he obtained from water, ethyl ether, or chloroform. Tablets obtained from water on a microscope slide are shown in Figure 1.
G
IC
IC
/f+ Figure 2. Orthographic Proieotion of dl-Mandelic Acid
Figure 1. Crystals of Mandelic Acid from Water on a Micmsoopic Slide
b
(I
Figure 3.
Crystals of Mandelic Acid from Melt on Microscopic Slide a.
Form
CHYsTAL MORPHOLOGY Crystal System. Orthorhombic. Form and H%hit. The crystals occur as tablets lying on the 010 face. The macropinacoid {loo}and pyramid [ 111 1 may bo men. Goad 100 cleavage. Orthographic projection of a typical crystal (Figure2). Axial Ratio. a:b:e. 0.596:1:0.614, Interfacial Angles (Polar). 111A111 = 46' 18' (x-ray)
x - &DIFFRACTION ~ DATA
Cell Dimensions. a = 9.66 0.05 A.
c = 9.94 =t
+ 0.05 A,; b = 16.20 =t 0.08 A.;
b.
Form11
Optic Axial Angle (Ns. light, 25' C.). 2 (calculated from p and 2 H ) ; 271 = 81" 31 8, and 7 ) . Optic Axial Plane. 100. Sign of Double Refraction. Positive Acute Bisectrix. y = 6. Molecular Refraction ( R ) (N'a light, 25' C.). &% = 1.570. R(calcd.) = 38.6; R(obad.) = 38.7. FUSION DATA.The crystals of mandelic acid obtained by recrystallization from solvents melt in the range 118-119" C. (Kofler hot stage) with considerable sublimation. On cooling,
1680
1681
V O L U M E 2 4 , NO. 10, O C T O B E R 1 9 5 2 t q o crystalline forms are obtained. Form I (Figure 3,a) grows as blades having parallel extinction and a large centered Bra figure and is presumably the same form as is obtained from solvents. The second polymorphic form (Figure 3, b ) grows spontaneously in the melt as rhombs having symmetrical extinction and a profile angle of about 52". Khen growing crystals of form I meet those of form I1 in the presence of the melt, form I grows a t the expense of form 11. On slob%cooling of the melt the entire preparation may be obtained as form I1 with a melting point of 107108'. Form I1 is unstable 1%-ithrespect to form I and on standing overnight converts through a solid-solid phase change. The sublimed crystals occur as form 11. values were obtained X-RAYPOWDER DIFFRACTIOS D ~ T AThese . on &mandelic acid recrystallized from chloroform using chromium radiation with vanadium filter with a camera of 114.59-mm. diameter. A wave-length value of 2.2896 G was used in the calculation?. Form I Index
d
III
8.08 6.36 d . 26 4.83 4.62 4.42 4.26 4.22 4.05 3.88
0.37 0.37 1.00 1.00 0.37 0.63 0.37 0.25 0.50 0.63
020 021 121 200 210 102 112 211 040 122
3.49 3.38 3.18 3.08 2.98
0.37 0.37 0.63 0.06 0.06
141 231,212 222
2.91 2.70 2.52 2.41 2.31
0.25 0.25 0.06 0.25 0.13
... ...
2.197 2.070 1.941 1.910 1.796 1.753
0.06 0.06 0.06 0.06 0.06 0.06
i 42 ...
400
...
,.. ... ...
...
rid-of habit of taking for granted. He then deliberately d i e cards the uncertain even though stubbornly ingrained and tiniehallowed superstructure and starts anew from the solid foundations up, building an entirely new structure from sure facts cemented by strict logic. Such books in which a whole field has heen built anew from bottom to top by original creation are rare and stirring events. This is one of them. Of hydrogen and hydroxyl ions in solution, we know that they originate in the water. For the habitual pattern of thinking in which acids and bases in aqueous solution dissociat'e and thus bring in ions of their on-n, there is no actual basis in fact. K i t h this and similar gratuitous assumptions abandoned, the aut,hor gains complete freedom of thought, and he puts it to masterly use in conquering the intricacies of hydrogen ion concentration, huffering phenomena, polyacidity and polybasicity, acid and base strength, up to systems of any degree of complexity. This he does through matheniatical derivations and developments from a few fundamental rigorously defined notions. The fruits of mathematical treatment in physical sciences, of course, are only as good as the premises; on sound premises, mathematical reasoning cannot possibly go Ivroiig. Aimplereward will be found in the countless eye openers on titrations and precipitation reactions, of paramount interest to the advanced analytical chemist. The interest of the book should extend to all fields dominated by the solutions, as in biology. In omnipresence of aqueous ele~t~rolyte advanced teaching, this book should prove invaluable as an exercise in scientific discipline. In spite of the mathematical character of the book, its reading is not dull. *Itlame or inadequately grounded concepts and arguments, and a t current misconceptions, the author strikes hard and fast and hits above the belt. In a book of this kind, the quality of the typography takes on a great importance. I t is excellent. BATHANEL THON
... ...
Form I1
Optical Society of America
d
HE 37th annual meeting of the Optical Society of rlmerica 4.15 4.04 3.83 3.67 3.32 2.80 2.77
0.13 0.07 0.07 0.13 0.20 0.07 0.13
COSTRIBCTIOSB of crystallographic data for this section should be sent to Walter C. McCrone. Analytical Section, Armour Research Foundation of Illinois Institute of Technology, Chicago 16. 111.
Hydrogen Ion Concentration. New Concepts in a Systematic Treatment. John E. Ricci. xxxvi 460 pages. Princeton Vniversity Press, Princeton, N. J., 1952. Price, $10.00.
+
Among the mass of new books, a very few stand out in that they not only compile and expose existing knowledge and thinking, but throw entirely new light and point ways of approach not heretofore thought of. Once in a while, a scientist of vision and courage, looking a t a field dried up in classic ruts, decides once more to begin a t the beginning. He asks himself, hat is it that we do know for certain from incontrovertible observation, and what is the part that we merely have gotten into the hard-to-get-
was held in Boston, Mass., October 9 to 11, 1952. Abstracts of papers of special interest to analytical chemists are given below.
Spectroscopic Analysis of Organic Polymers in the Glow Discharge. D. P. NORMAN . ~ N DW. W. -4. JOHNSON, Yew England Spectrochemical Laboratories, West Medway, Mass. Organic compounds can be dissociated into free radicals in high current density, low vacuum discharges. The relative intensity of t h e emission spectra of these free radicals is proportional not only t o t h e geometry and electrical constants of t h e discharge tube, but also t o t h e composition and structure of t h e original polymer. T h e band spectra observed are mainly those of t h e well-known diatomic radicals such a s -CH, -CS, -OH, but many new and unlisted bands are observed, particularly in t h e case of sulfur-containing compounds. This technique has proved valuable in empirical studies of t h e curing times and temperatures of commercial polymers, t h e detection and quantitative determination of amino catalysts in plastics, and t h e identification of resin coatings on textiles and paper. Details of t h e application of this spectrographic technique to specific industrial problems in t h e foregoing fields were presented. Korman, .Johnson. and Johnson, A m . Dyestu// R e p t r . , 37, No. 2 5 ; Proc. .4m. d s s o c . Teztile Chem. Colorists, 838-48, (1948), Pearse, R . W .B., and Gaydon, .1. G., Identification of Molecular Spectra," New York, John Wile)- & Sons, 1941.
Further Investigations of Spectroisotopic Analysis of Lithium. J. R . MCNALLY, JR.,G. K . ~ J - E R N EAND R , D. D. S M ~ T H Stable , Isotope Research and Production Division, Oak Ridge National Laboratory, Oak Ridge, Tenn. Recently t h e application of spectroscopy t o t h e determination of isotopic abundances in various synthetic lithium isotope samples was reported [Stukenbroeker, Smith, Werner. and McNally, J . Optical S O C . Am., 42, 383 (1952): 41, 870-4 (1951)l. T h e method is based on t h e intensity evaluation of the Li6 and Li7 isotope components in the
