CRYSTALLOGRAPHIC D A T A
83. Reserpine and 84. Reserpic Alcohol Hydrate Contributed by HARRY A. ROSE, Eli Lilly & Co., Indianapolis 6, Ind. 83.
RESERPINE
CRYSTALMORPHOLOQY Crystal System. Monoclinic. Form and Habit. Blades and needles elongated parallel to b and lying either on the orthopinacoid {loo) or basal pinacoid { 001 ) . Crystals sometimes show the clinodome [ 011 ) and the hemipyramid { 111) . The blades are usually terminated by the clinopinacoid { 010). Axial Ratio. a : b : c ,= 1.654:1:1.537 (x-ray). Beta Angle. 115' 8 . Cleavage. Good, parallel to 010. X-RAYDIFFR.4CTION DATA Cell Dimensions. a = 14.57 A., b ='8.81 A., c = 13.54 .4. Formula Weights per Cell. 2 (2.009 calculated from x-ray data). Formula Weight. 608.7 (calculated 611.3 (x-ray). Density. 1.298 grams per1cc. (flotation); 1.293 grams per cc. (x-ray).
in
HOH,C-()-OH
T
HE chemistry and determination of structure of reserpine,
the new sedative and hypotensive principle of the Indian medicinal plant, Rauwolfia serpentina, have been reported in the literature ( I S ) ; however, no report has previously been made concerning the crystallography of the compound. The x-ray data given here were used to determine the molecular weight of the compound before the structure had been determined. Reserpine can be recrystallized from acetone, methanol-water, or methanol-chloroform solution. The methanol-chloroform combination results in blades suitable for crystallographic work. Reserpic alcohol can be obtained by reduction of reserpine with lithium aluminum hydride in tetrahydrofuran as a solvent. The crystals used for this work were obtained from aqueous tetrahydrofuran. All x-ray powder diffraction data were obtained using a camera 114.6 mm. in diameter and chromium radiation with vanadium pentoxide filter. A wave-length value of 2.289 A. was used in the calculations.
f -b
H' ---------__
07-0
I
-b
OCHI Structural Formulas for Reserpine and Reserpic Alcohol Hydrate
bllS'8'
C
I
I
C
c C
Figure 1. Orthographic Projection of Reserpine
1245
x
Figure 2. Orthographic Projection of Reserpic Alcohol Hydrate
OPTICALPROPERTIES Refractive Indices (5893 A., 25" C.). a = 1.51. 1.51, 4 13 = 1.568 + 0.002,+= ~ 1.687 & 0.004. Optic Axial Angle. 2V = (+)SO" (est.). Optic Axial Plane. 010. Acute Bisectrix. y. Extinction. y A a = 13" in acute 6. FCSION BEHAVIOR.Reserpine melts with decomposition a t 26465" C. 84.
RESERPlC ALCOHOL HYDRATE
CRYSTALMORPHOLOGY Crystal S stem. Orthorhombic. Form a n B Habit. Orthorhombic prisms elongated parallel to c showing the prism { 110) and orthodome [ lor}. Axial Ratio. a : b : c = 0.687:1:0.334.
ANALYTICAL CHEMISTRY
1246 Interhcial Angles (Polar). 101 d 101 = 51" 50' (x-ray). 110 A 110 = 68'58'. (x-ray). X-RAYDIFFRACTION DATA Cell Dimensions. a = 14.38 A.; b = 20.94 A.; c = 6.99 A. Formula Weights per Cell. 4 (3.983 calculated from x-ray data). Formula Weight. 404.5 (calculated for Cz2HsoOaN2. H,O); 402.8 (x-ray). Density. 1.271 grams per cc. (flotation); 1.276 grams per cc. (x-ray). OPTICALPROPERTIES Refractive Indices (5893 A,, 25' C.). 01 = 1.548 Z!Z 0.003, 6 = 1.620 rt 0.003, y = 1.670 ;t 0.003. Optic Axial Angle. 2V = (-)76" 24' (calculated from 01, p, and y). Optic Axial Plane. 001. Acute Bisectrix. cy = a. FUSION BEHAVIOR.Reserpic alcohol hydrate melts with decomposition a t 216-17" C.
Reserpic Alcohol Hydrate Powder Data d
6 00 5 82 3 42 5 01 4 89 4.65 4.56 4.43 4.02 3.97 3.76 3.64 3 32 2.27
1/11
hkl
d (Calcd.)
1 00 0 10 0 10 0 10 0 20 0.20 0.40 0.20 0.20 0.20 0.40 0.10 0.10 0.40
111 02 1 121 230, 201 03 1 131 22 1 320 23 1 330 321 250 022 251
6.02 5.81 5 40 5 01, 5 01 4 94 4.67 4.52 4.36 4.07 3.95 3.76 3 62 3.32 3.21
ACKNOWLEDGMENT
Reserpine Powder Data d 13 14 12 22 7 44 7 19 5 73
d (Calcd ) 13 11 12 18 7 48 7 14 5 70
The author wishes to thank Sorbert Xeuss for the samples on u hich these data were obtained and for information concerning the chemistry of the compounds.
40
hkl 100 00 1 101 011 111
5.34 5.02 4.78 4.49 4.21
0.40 0.40 0.60 0.60 0.40
210 012 102 103 112
5.26 5.01 4.80 4.45 4.21
(1) Dorfman, L.,et al., Helv. Chim. Acta, 37, 59 (1954). (2) Neuss, N.,Boaz, H. E., and Forbes, J. W., J . A m . Chem. SOC., 75, 4870 (1953) (3) I b i d . , 76, 2463-7 (1964).
4.18 3.71 3.56 3.47
0.20 0.40 0.40 0.20
02 1 20'' 4oi 103
4 15 3.74 3.57 3.48
COSTRIBUTIONS of crystallographic d a t a for this section should be sent to Walter, C. McCrone, Analytical Section, Arrnour Research Foundation of Illinois Institute of Technology, Chicago 16, Ill.
1/11
0 0 0 1 0
40 40 20 00
LITERATURE CITED
SCIENTIFIC C O M M U N I C A T I O N
Precipitation from Homogeneous Solution by Controlled Cation Release
P
RECIPITA4TIONfrom homogenous solution ( 3 , 4,8-10) is usuallybrought about by slow release of anions in a solution containing a metal ion. The literature on this subject was revien-ed by Willard ( 8 ) in 1950. Controlled release or generation of cations for purposes of precipitation from homogeneous solution has been reported only twice, by Heyn and Schupak (6) and by Willard and Yu (11). Heyn and Schupak released barium from bdrium Versenate complex in a sulfate solution by slow acidification of the solution. Willard and Yu precipitated the basic iodate of cerium, CeZ(IO3)iOH.rHzO, by slowly oxidizing cerium(II1) t o cerium(1V). The Heyn method is limited to those metals whose precipitates remain relatively insoluble in acid solution. The Willard method is limited t o oxidizable cations. In addition t o the controlled release of anions and cations, Gordon and Shaver ( 5 )used the complexing power of ethylenediaminetetraacetic acid t o obtain selective separation of precipitates with proper temperature and p H adjustments. Beck ( 1 ) ha< also reported the separation of rare earths using acidification of nitrilo-triacetate complexes but did not specifically apply it t o preripitation from homogeneous solution. This communication reports the precipitation from homogeneous solution of hydrated ferric oxide by a gradual release of ferric ion t o a solution whose pH remains nearly constant. Ferric ion is first complexed with Versene ( 2 ) in a solution of p H 3.0 t o 3.2. The Versene is then slowly destroyed with hydrogen peroxide over a period of about 1 hour. Comparisons of particle size, sedimentation volume, drying, and final ignition weights have been made between hydrated feriic oxide formed by the gradual release of ferric ions and hy-
h a t e d ferric oxide formed by the gradual increase of the hydroxyl ioii (9,10). Other oxidizing agents-namely, ammonium persulfate and sodium hypochlorite-were tried and found too vigorous. Sodium bromate is satisfactory, but its use is limited to acid solution. Precipitation of Hydrated Ferric Oxide by Destruction of IronVersene Complex. The rate of oxidation of Versene by hydrogen peroxide was studied by mixing Versene with hydrogen permide a t various p H values. After suitable time intervals, the remaining Versene was titrated ( 7 ) with calcium chloride solution and Eriochrome Black T indicator. Experiments a t 70" t o 80" C. indicated complete oxidation of 50 ml. of 0.05M Versene reagent by 15 m]. of 3% hydrogen peroxide in about l hour. I n the presence of ferric iron, the oxidation of the Versene is slower. However, by increasing the concentration of hydrogen peroxide sufficiently, the oxidation could be brought about a t lower temperatures. The following conditions may be used for the controlled oxidation of the iron-Versene complex: Dissolve about 0.5 gram of ferrous ammonium sulfate hexahydrate in 25 ml. of 0.05M Versene solution and dilute to 100 ml. Add 20 grams of ammonium chloride, warm t o 30' C., and adjust the pII to 3.0 with 0.01X hydrochloric acid and 0.01N sodium hydroxide. Add 10 ml. of 30% hydrogen peroxide, and allow the solution to stand a t room temperature for 1 hour. Rising bubbles of oxygen provide sufficient stirring. The reaction is complete in about 1 hour. (Although the necessity for warming the solution in order to complete the reaction was not shown, the suspensions were warmed a t 90' t o 95" C. for 1 hour.) Kash the precipitate several times with hot, 3% ammoniam nitrate until chloride free, filter on S. and S. No. 589 white iibbon paper or on a Gooch crucible with a fine asbestos mat. For other amounts of iron, the quantities of hydrogen peroxide
