CRYSTALLOGRAPHIC DATA
81. Erythromycin and Some of Its Derivatives HARRY A. ROSE, Lilly Research Laboratories, Indianapolis, Ind.
T
H E crystallographic data reported here (Tables I and 11) were obtained for identification purposes and to determine the molecular Feight in the course of the chemical investigation of erythromycin. The free base, two salts, and two other derivatives were used for the determination of the molecular xeight, giving an average value of 736. This compares very favorably with the values 733.9 t o 735.9 calculated from the formula CnHb--egSOla, which is based on analytical results. The chemistry of erythromycin has been discussed by Flynn et al. (1). Erythralosamine is a degradation product of erythromycin obtained by mild acid hydrolysis of the free base. The molecular formula of this compound is thought to be Cz9H4gNOa.Desosamine hydrochloride hydrate is obtained by hydrolysis of erythromycin in 61V hydrochloric acid. The molecular formula of this compound is thought to be CsH1,N03.HC1. The sample of desosamine hydrochloride used in this study had a melting point range of 135' to 140'. The acetone solvate and the chloroform solvate of erythro-
System rh. rh.
Erythromycin N-oxide
rh.
0,N-Dicarbethoxy des-N-methylerythromycin Erythralosamine
rh.
Blades elong. /I e
mon.
100 blades elong.
11
a
B
Y
1.512
1.523 1.492
1.532 1.516
...
...
...
...
1.484
...
0,N-Dicarbethoxy des-N-methylerythromycin Erythralosamine
a'
COXTRIBCTIONS of crystallographic data for this section should be sent to Walter C. hIcCrone, Analytical Section, Armour Research Foundation of Illinois Institute of Technology, Chicago 16, Ill.
b showing 110
Refractive Indices, 5893 A , : 25' C.
Erythromycin oxalate dihydrate Erythromycin N-oxide
(1) F l y n n , E. H., Sigal, M. V., Wiley, P. F., a n d Gerson. K.. to be published.
Form and Habit Water gives 010 tablets with 120 and 021; and 100 blades elong.11 e Acetone-water gires prisms elong. 11 c showing 110 and 011. Methanol-ether gires blades elong.11 a showing 011.
Erythromycin oxalate dihydrate
Compound Erythromycin dihydrate
LITERATURE CITED
Crystallographic Data for Some Erythromycin Derivatives
Table I. ComDound Erythromycin dihydrate
mycin readily lose solvent on exposure to air and are converted t o a powder. The crystals for which unit cell dimensions are given Fere those used in the determination of the molecular weight. The orientation of the unit cell and its relative dimensions were checked on single crystal patterns a i t h rotation around one or more crystallographic axes. The powder data Fere obtained m-ith a camera having a diameter of 114.6 mni. using chromium radiation and a vanadium pentoxide filter. A wave-length value of 2.2896 A. was used in the calrulations
.. (in 100) = 1.501
1,506 (whitelight)
, ,
Interfacial .4ngles, Polar (x-ray) 120 A 120 = 021 A021 = 110 A 710 = 011A011 = 011 A j i l = 101 A 101 = 110 a i i o = 011 aCJl = 101 A 101 = B = 91: 47' 011 A 011 =
44' 42' 42' 30' 66' 46: 76'22 66' 44,' 88' 56 102O 42' 5 l 0 12: 124' 56
22.56 10.71
Optic Axid Angle, 2 V
Orientation
(from P B Y )
100
a = c
(-)84"
010
Y = c
(+)60° (from =BY)
...
...
001 010
.. .... (approx.)
a = b
( -)60°
UAC
(+)30" (approx.)
26' (in acute 8)
900 44'
Cell Dimensionst -4. , a b C 9.70 47.17 9.17 17.95 16.34 14.42 15.97 19.97 13.15 20.76 13.61
Optic Axial Plane
Formula Weights per Cell, Z 4
10.81 10.85
4
Formula Weight (X-Ray) 772.8 862.6
Density (Displ.) 1.225 1.209
Melting Point, C. 134-138 161 (dec.)
4
757.6
1.213
228-229
4 2
861.2 548.5
1.132 1.155
200-205 204-209
Table 11. X-Ray Diffraction Powder Data d , A.
11.84 9.01 8.57 7.26 6.73 6.40 6.12 5.43 5.05 4.99 4.60 4.42 4.25 4.12 4.00 3.90 3.78 3.39 3.30 3.16 2.99 2.90
Erythromycin Dihydrate I/Il hkl 0.10 0.50 1.00 0.10 1.00 0.20 0.40 0.30 0.40 0.30 0.30 0.20 0.20 0.20 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10
040 011,120 02 1 041 150 121 160 151 180 081 190,230 181 0, 10, 1; 1, 10, 0
Erythromycin Acetone Solvate d , A. 1/11 0.05 17.1 0.80 14.5 1.00 13.5 0.30 11.0 0.50 9.96 0.30 6.66 0.50 7.77 0.05 7.22 6.64 0.05 0.20 5.84 0.10 4.95
... ... ,..
938
Erythromycin Chloroform Solvate d , A. 1/11 18.1 14.4 9.43 7.50 5.76 4.76 4.35
0.25 0.50 1.00 0.50 0.25 0.13 0.13
Erythromycin Oxalate Dihydrate d , A. I/II hkl 12,94 11.33 9.63 9.23 6.95 8.08 7.63 7.10 6.71 6.40 5.86 6.41 4.99 4.60 4.70 4.50 4.26 4.14 3.80 3.52 3.27
0.50 0.25 0.13 0.25 0.13 0.63 0.25 0.38 0.25 0.25 1.00 0.25 0.25 0.38 0.38 0.25 0.36 0.25 0.13 0.13 0.06
110 011,101 111 020 200 210 201 211 012 220 22 1
...
... ... ...
400
... . .
...
...
...
V O L U M E 2 6 , NO. 5, M A Y 1 9 5 4
939 Table I1 (Continued)
Erythromycin N-oxide
d , A. 11.04 10.15 9.01 8.44 8.00 7.40 7.03 6.51 6.21 5.80 5.52 5.08 4.78 4.61 4.44 4.27 4.17 4.00 3.83 3.71 3.51 3.38 3.32 2.89 2.81
1/11 0.50
1.00 0.30 0.20 0.20 0.10 0.10 0.30 0.50 0.10 0.20 0.20 0.20 0.20 0.20 0.05 0.05 0.20 0.10 0.10 0.05 0.05
0.10 0.05 0.05
h kl 011 101 111 120 200 210 121 002 220,012 112 131 310 311 032 132 013,240 330 400 401,123, 142 420 212 303
O,.V-Dicarbethoxy des-iV-methylerythromycin d , A. I/Il hkl 110 15.36 0.53 020 0.67 11.18 01 1 9.67 1 .oo 111 8.83 0.67 201 7.50 0.33 211 7.10 0.33 230 0.13 6.08 320 5.85 0.07 040 0.13 5.67 012 5,25 0.27 112 0.13 5 09 022 0.07 4.80 420 0.13 4.72 212 0.07 4.62 251 0.13 4.47 430 4.27 0.07 510 0.07 4.10 0.13 232 4.00 060 0.07 3.71 422 3.54 0.07 360 3.25 0.07
Ethylmethylpicrate as a Reagent for Barium .IN
hkl 100
Desosamine Hydrochloride d , A. 1/11 8 30 0.50 7 36 0.38 0.50 6 05 0.13 5 87 0.13 5 63 0.13 4 84 1.00 4 39 4.24 0.38 0.25 4 10 0.25 3.76 0.06 3.64 0.25 3 51 0.63 3.42 0.13 3.10 0.13 2.83 0.06 2.77 2.62 0.06 2 58 0.06
'
OOL
101 011 111 201 002, e20 102 02 1 12i
...
...
...
... ... ...
SCIENTIFIC COMMUNICATION
u
d , A. 13,61 10 77 8.49 7.61 6.56 5.67 5.37 4 99 4.81 4.49 3.91 3.82 3.32 3.27
Erythralosamine I/Il 0.13 0.53 0.33 0.27 1.00 0.13 0.27 0.53 0.13 0.20 0.07 0.03 0.07 0.07
exploratory investigation of the properties of certain
I-trinitrophenols as analytical reagents, we have observed that '
3-ethyl-5-methyl-2,4,6-trinitrophenol (hereafter called ethylmethylpirric acid for short) has considerable promise as a precipitation reagent for barium. For its practical application as a reagent, a saturated aqueous solution of its sodium salt appears to be more useful than the acid itself, and a preliminary study of the value of the reagent in this form is here reported. Keither this acid nor any of its salts appears to have been previously reported. The following simple method for synthesizing ethylmethylpicric acid was found to he satisfactory. Add 10 grams of 1,3,5-ethylmcthylphenol (Eastman Kodak Co.) to 50 grams of 95% sulfuric acid and heat to 60" C. Cool to about 5' C. and add 70% nitric acid with constant stirring a t such a rate that the temperature does not rise above 15" C. Dropaise addition is advisable a t the beginning. Continue adding the nitric acid until a total of 35 grams has been added. Allow to stand overnight and then pour the reaction mixture on an equal volume of cracked ice. Filter off the insoluble material, preferably on a suction filter, and dissolve it in narm ethyl alcohol. Add 10% potassium hydroxide to the solution until no more precipitate forms. Filter off the potassium salt and dissolve it in hot water. Add 38% hydrochloric acid dropwise with constant stirring until no more precipitate forms. Filter off the precipitate, dissolve it in 95% ethyl alcohol for recrystallization, and dry the final product at room temperature. The yield should be about 90%. For the preparation of 100 ml. of a saturated solution of the sodium salt, place 3 grams of the dried acid in 75 ml. of water and slowly add 10% sodium hydroxide until the pH of the mixture as measured with the glass electrode becomes 7 . Dilute to 100 ml. and use the clear supernatant liquid. Analyses of the barium salt precipitated in water solution at room temperature and dried a t various temperatures up to 100" C. showed that it has the formula Ba(COH*N307)Z.H20. Its theoretical barium content is 19.70%. This salt loses its water of hydration a t higher temperatures, and a t 150' C. the rate of loss is easily observable. The dehydration is accompanied by a marked change of color from yellow to dark orange.
In spite of the appreciable solubility of this barium salt in water (0.12 gram per 100 ml. at 25' C.), its precipitation is practically quantitative if a sufficient excess of reagent is used. Satisfactory results have been obtained gravimetrically for barium alone, for barium in the presence of an equal amount of calcium by single precipitation, and for barium in the presence of an equal amount of strontium or potassium by double precipitation. This reagent seems especially convenient for the rapid spectrophotometric determination of amounts of barium up to about 15 mg. The following procedure has been developed and tested. Adjust the concentration of the neutral barium solution contained in a 100-ml. beaker to about 2 mg. per ml. Add 15 ml. of reagent and allow the mixture to stand a t room temperature for half an hour. Remove the supernatant liquid with a filter stick and wash Ti-ith successive small portions of ethyl ether, or with ethyl ether saturated with barium ethylmethylpicrate, until the washings become colorless. Dissolve the precipitate in about 50 ml. of warm water, cool the solution, and transfer it to a 100-ml. volumetric flask with the aid of successive small portions of water. Dilute to the mark, mix, and use the solution directly for measurement when the amount of barium is small, or for further dilution when the amount of barium is high. Results of test determinations by the above procedure are shown in Table I. The instrument used was a Beckman spectrophotometer, Model DU, with a 1.00-cm. cell. The measurements were made at 390 mp. That there is a well defined maximum at about this point is shown by the data in Table 11. These measurements were made on a barium ethylmethylpicrate solution having a concentration of 4.98 mg. per 100 ml. contained in a 1.00-cm. cell. The relationship between light absorption and concentration was found to be closely proportional for solutions of this salt.
Table I.
No.
Spectrophotometric Estimation of Small Amounts of Barium
Degiee of Dilution of Original Solution of Precipitate None None None 2 . 5 times 2 . 5 times 2 . 5 times 5 times 10 times
Absorbancy 0.206 0,620 0.650 0.510 0.830 0.820 0.670 0.900
Barium Taken, Mg.
0.3 1.0 1.0 2.0 3.0 3.0 5.0 13.9
'
Barium Found, hlg. 0.3 0.9 1.0 1.9 3.1 3.1 5.0 13.6
Difference Error, Mg.
0.0 -0.1 0.0 -0.1 fO. 1 fO. 1 0.0 -0.3
