Infrared Spectra of Nicotine and Some of Its Derivatives C. R O L A N D E D D Y and A B N E R EISNER Eastern Utilization Research Branch, Agricultural Research Service,
Ultraviolet spectrophotometry has been used for the identification and characterization of tobacco alkaloids and related substances, but the ultraviolet spectra cannot be used to distinguish among alkaloids having equivalent degrees of conjugated unsaturation. Infrared spectra are presented in this paper for nicotine and five related alkaloids. These spectra are quite different for compounds having identical ultraviolet curves. Rapid and unambiguous identification of any one of these alkaloids is possible by comparison of the spectrum of an unknown with these infrared curves. The absence of an N-H stretching vibration in the spectrum of myosmine suggests that the accepted structure of this alkaloid is incorrect.
N
Table I.
Wave No., K.
1916 2960
PER
WAVELENGTH,
'
1
1
1
'
1
1
'
'
spo 1
1
'
1
1
1
1
'
Nicotine 715 1025 1117 1191 1418 1478 1577 1592 1912 2970
Nornicotine 714 1026 1125 1190 1427 1479 1577 1592 1914 2970
Nicotyrine
Pyridine ( 2 ) 703 1030
..
.. 1482 1572 1583 1923 2960
tine and nornicotine, whose ultraviolet spectra are essentially identical, show pronounced differences in the infrared, the most prominent being the stretching band a t 3294 kaysers (1). In general, those alkaloids having nitrogen-hydrogen groups show this pronounced band near 3300 K., while the band is absent in the tertiary-nitrogen alkaloids. One seeming exception is myosmine, which shows no band in the 3300 K. region, even in the solid state as a mineral-oil mull. This raises the question once more of the structure of myosmine. Although the accepted formula is I, it has been suggested (7, 8) that there may be tautomeric equilibrium with structure 11. Some of the chem-
WAVES
1000
Myoarnine 707 1025 1118 1193 1414 1473 1567 1591 1915 2967
Metanicotine
sh
nicotyrines derived from them as dehydrogenation products have been prepared a t this laboratory in a state of high purity. Their ultraviolet spectra were presented and discussed in earlier papers (S, 9). The infrared spectra of six of these alkaloids are presented in this paper. Although the ultraviolet spectra were not capable of distinguishing among the various alkaloids possessing equivalent degrees of conjugated unsaturation, the infrared spectra are distinctive and allow unambiguous identification of any one of these alkaloids. In particular, nico-
4 1100 ~ l 0 0 " ~ " " " "
Philadelphia 18, Pa.
Infrared Bands Common to All Six Alkaloids, with Pyridine Bands for Comparison
Dihydrometanicotine 713 1025 1127 1186 1420 1476 1572
ICOTINE, nornicotine, and some of the myosminss and
WAVES
U. S. Department o f Agriculture,
CENTIMETER
MICRONS
PER C E N T I M E T E R
8 00
1
I
1
1
700 1
I
1
COMPOUND
DIHYDROMETAN ICOTINE 80
SOURCE AN0 PURITY EASTERN REQIONAL RES. LAB. 95-100 %
18
/-
60
f
I
B
7
A
I
40
STATE
LIOUID
TEMPERATURE 1 -P U R E
LIQUID
25.C
0.03mrn.
8 - 2 4 . 1 W L . I N CCI,
20
I
0; 9.0
0.41mm
LABORATORY USOA- BAIC
I025 9.5
, 10.0
EASTERN REGIONAL R E S L A B P W I L A D E L P H I b 18. PA
10.5
11.0
11.5
12.0
12.5 WAVELENOTW,
13.0
13.5
14.0
MICRONS
Figure 1. Infrared Spectrum of Dihydrometanicotine
1428
14.5
150
5000
4000
2.0
2.5
I100
3000
3.0
3.5
4.0
1000
100-'"~1."'!
4.5
5.0
1 1 1 1 ' 1 1 1
'
PER
CENTIMETER 1500
5.5
6.5
6.0
1400
I
1
7.5
8.0
8.5
9.0
95
700 I
I
I I00
1200
1300
7.0
800
900
I
I
I
I
I
I
I
I
I
f-
7
80
WAVES 2000
2500
1
M E T A N ICOT IN E
B A
SOURCE
AND
PURITY
E I S T E R N REGIONAL R E S L A B
1 '
60
I
h B ' STLTE
795
I023
LIOUID
CELL
40
A
LENGTH
967
Z 9.0
9.5
/%TAL
J
10.0
10.5
707
11.5
12.0
12.5
2.0
2.5
I100
3.0
2000
2500
3.5
4.0
4.5
5.0
900
1000
13 5
13.0
14.0
14.5
15.0
MICRONS
Infrared Spectrum of Metanicotine WAVES PER
3000
US DA-BAlC E A S T E R N REGIONAL RES L A B
I 11.0
Figure 2.
4000
I N CCI,
I
906
WAVELENGTH,
5000
OlOmn
A - PURE LIQUID 0-593G'L
i I
30'C
TEMPERITURE
5.5
CENTIMETER 1500
6.0
6.5
1400
7.0
7.5
800
700 I
I
I
I
j
I
PA I\.
40
j
I/
! I
I
1200
1300
8.0
. I Ai I
8.5
9.0
COMPOUND
MYOSMINE SOURCE
AND
PURITY
E A S T E R N REGIONAL R E S L A 0
99-100 X ST4TE
SOLUTION
TEMPERATURE
1-52 I GIL
,
9.5
t
8 - 5 3 5
20
I100
GlL
IN IN
30' C
CCL. ACETONE
I
1
USDA-BAIC EASTERN REGlON4L RES L 4 B
707
0 go
95
100
105
110
115
120
125
WAVELENGTH,
Figure 3.
130
135
140
145
150
MICRONS
Infrared Spectrum of Myosmine
1429
WAVE LENGTH.
Figure 4.
MICRONS
Infrared Spectrum of Nicotine
SOURCE 4 N D P U R I T Y E A S T E R N REGIONAL
1
98-100% STATE
LIQUID
TEMPERATURE
25.C
4 - P U R E LIQUID,
OlOmm
8-363W L I N C C I . . 041mm
E A S T E R N REGIONAL RES L A B P H I L A D E L P H I A 18, PA.
I WAVELENGTH,
1430
Figure 5.
MICRONS
Infrared Spectrum of Nicotj-rine
I
V O L U M E 26, NO. 9, S E P T E M B E R 1 9 5 4
1431 NAVES PER
5000
4000
3000
2500
CENTIMETER
1400
I500
2000
I100
I200
1300
d
1618
20.
at w 0
0 20
25
30
35
40
45
a z
50
55
+ c
65
60
WAVELENGTH,
75
70
80
85
90
95
MICRONS
z
a K c
I
I
I
I
I
I
I
I
I
I
I
I
B
8 C
80.
1
1040
NORNlCOTl N E
c 8
902
SOURCE
4ND PURITY
EASTERN REGIONAL RES L A 0
1
I
60.
\I
809
1026
40
\f
20 /\
ObA
\
1
ical reactions of myosmine ( 4 ) can also be interpreted in terms of 11. Absence of a nitrogen-hydrogen band in the infrared suggests that the predominant tautomer in the equilibrium is I1 rather than the accepted structure. Witkop (11) has also called attention to the 1621 K. band as a possible C=N vibration in the 5membered ring. Its much greater strength in myosniine than similar bands in metanicotine and nicotyrine suggests a C==X rather than a C=C linkage.
TEMPERATURE CELL L E N G T H
30.C O10mrn
A-PURE LIQUID 0 - 5 2 2 G / L I N CCI.
USDA-0AIC EASTERN REGIONAL R E S L A 0 P H I L A D E L P H I A 18, PA
Beckman IR-2 spectrophotometer, using the slit-drive mechanism suggested by Shreve and Heether (6). The transmittances were obtained by the method of Willis and Philpotts (IO). Figures 2, 3, 4, and 6 were obtained with a Beckman IR-3 spectrophotometer, which records transmittance directly and has considerably higher resolution. Sodium chloride prisms were used in both instruments. The term “kayser” (K.) is used in this paper as a unit of wave number, as recommended by the Joint Commission for Spectroscopy (1 ). ACKNOWLEDGMENT
I
I1 Table I lists the major bands common to all six of these alkaloids, together with some of the bands of pyridine ( 2 ) . Since the pyridine ring is common to all of these alkaloids, it is to be espected that many of their vibrational frequencies should correspond with pyridine frequencies. N o simple assignment of bands to the five-membered ring in these alkaloids can be made from this small number of compounds. Although Pleat, Harley, and Wiberley ( 5 )have proposed using the 13.966-micron(716 K.) band of nicotine for analytical purposes, Table I shows that a band near this location is characteristic of all these alkaloids containing the pyridine ring. This band corresponds to the strongest fundamental vibration of the pyridine spectrum ( 2 ) . EXPERIMENTAL
Methods of preparation and purification of these compounds have been described (9). Figures 1 and 5 were obtained with a
The authors gratefully achnowledge the assistance of Jane R. Willis, Mary-Anne Morris, and Henry 8. Walens in obtaining and processing the infrared spectra. LITERATURE CITED (1) Bakker, C. J.. J . Opt. SOC. Amer., 43, 410 (1953). ( 2 ) Corrsin, L., Fax, B. J., and Lord, R. C., J . Chem. Phys., 21, 1170 (1953). (3) Haines, P. G., and Eisner, A, J. Am. Chem. SOC.,72, 1719 (1950). (4) Haines, P. G., Eisner, A., and Woodward, C. F., Ibid., 67, 1258 11945). ~, Pleat, G. B., Harley, J. H., and Wiberley, S. E., J . Am. Pharm. Assoc., 40, 107 (1951). Shreve, 0. D., and Heether, M . R., A x . 4 ~ CREM., . 22,836 (1950). SpLth, E., and Mamoli, L., Ber., 69B, 757 (1936). Spath, E., Wenusch, A., and Zajic, E., Ibid., 69B,393 (1936). Swain, hI. L., Eisner, .4.,Woodward, C . F., and Brice, B. A,, J . Am. Chem. Soc., 71, 1341 (1949). Willis, H. A., and Philpotts, 4 . R., Trans. Faraday Soc., 41, 187 (1945). Witkop, Bernhard, private communication. ~
C I V E D for
.
review March 11, 1954. Accepted June 7, 1954.
