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Assignment of Thiatriazole Structure to
So-called Azidodithiocarbonates
Sir: Recent on the chemistry of 5-substituted amino-1,2,3,4-thiatriazoles,I, has led to a reexamination of the structures of the products obtained by the condensation of azide ion with carbon disulfide previously designated in the literature4 as azidodithiocarbonates, 11.
/s\
N
S
C-NHR
I1
II
N-N
I
//
N1-C
\
SR XI XI1 'R = H ) IV 'R = Ce.€&C&)
The reaction of sodium azide with carbon disulfide by the method of Smith, Wilcoxon, and Browne5 followed by acidification of the concentrated aqueous solution led to the precipitation of pale yellow crystals which, after drying over phosphorus pentoxide, displayed all of the thermal and chemical properties for the compound designated5 as azidodithiocarbonic acid, 111. I n a similar manner, benzoylaxidodithiocarbonate, IV, was prepared by the method of Audrieth, Johnson, and BrowneG which showed all of the thermal and chemical properties previously describede for that designation. The infrared spectra of I11 and IV were taken in saturated chloroform solutions, against chloroform, using a Perkin-Elmer Model 21-A DoubleReam Infrared Spectrophotometer. Table I summarizes the absorption frequencies obtained. The most important observation arising from this study is the complete absence of the azido group, -N3, absorbance in the infrared spectra of I11 and IV. Recent studies8 have confirmed the strong absorbance for the azido group which occurs with great consistency close to 2130 cm.-l This intense N=N asymmetric stretching absorption is so strong and so little altered by environmental (1) E. Lieber, E. Oftedahl, C. K.Pillai, and R. D. Hites, J . Org. Chem., 22, 441 (1957). ( 2 ) E. Lieber, C. N. Pillai, and R. D. Hites, Can. J~ Chem., 35, 832 (1957). (3) E. Lieber and C. K. Pillai, J. Org. Chem., 22, 1054 (1957). ( 4 ) L. F. Audrieth, Chem. Revs., 15, 169 (1934). (5) G . B. L. Smith, F. Wilcoxon, and A. W. Browne, J . Am. Chem. Soc., 45, 2604 (1923). (6) L. F. Audrietb, J. R. Johnson, and A. W. Browne, J . Am. Chem. SOC.,52, 1928 (1930). (7) L. 5. Bellamy, The Infrared Spectra of Complex Molecules, Methuen and Company, Ltd., London, 1954. ( 8 ) E. Lieber, C. N. R. Rao, T. S. Chao, and C. W. W. Hoffman, Anal. Chem., 29, 916 (1957).
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22
groups as to make its absence in an infrared spectrum a guarantee that the compound under scrutiny is free of this structural group. For this reason the ideas previously presented in the literature4* for the so-called axidodithiocarbonates, 11, 111, and IV, are in need of revision. TABLE I SUMMARY AND ASSIGNMENTS OF INFRARED ABSORPTIONS Frequency (Cm. -1) AzidodithioBenzoylcarbonic azidodithioacid carbonate (111) (IV) 3030 3005 2533 Absent 1590
Absent Absent Absent
1470
1450 1333 1180' 1100 1000 900
Assignmentsa
1680
1590b
1333 Absent 1100 Absent 900
a Based on data summarized by Bellamy.7 This is exhibited as a doublet. ' This is exhibited as a very broad doublet with strong absorption. Heterocyclic ring configuration.
An analysis of the infrared spectral data, Table I, coupled with the chemical properties of I11 and IV previously reported616 suggests that these compounds are derivatives of 1,S,S,4-thiatriazole. On this basis we have assigned structure V, 4H,1,2,3,4thiatriazoline-5-thione (which may be abbreviated to thiatriazolinethione), and VI, 4-benzoyl-1,2,3,4thiatriazoline-5-thione (which may be abbreviated to 4-benzoylthiatriazolinethione),to the products previously designated as I11 and IV, respectively: /5, N
/s\
c=s
I1
I1
I
N-NH
C=S
N
I
N -N-COC6Hj
v
VI
The choice of structures V and VI over the alternate tautomeric thiol forms, VI1 and VIII, were /S\
N
C-SH
II
N-N VI1
I1
/S\
C-S-COGHS
N
il
N-N
II
VI11
dictated by the spectra and, especially in the choice
DECEMBER
1957
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of VI, by degradative and kinetic e v i d e n ~ e . ~The ~ ~ J ~ These studies are continuing and will subchemical and kinetic evidences further indicates a sequently be reported upon in detail. Acknowledgment. The authors are indebted to the widely disparate structural alteration for the socalled alkyl azidodithiocarbonates over that of 'the Research Corp. and the Eli Lilly Co. for research so-called acyl azidodithiocarbonates. This evidence grants which made these studies possible. points to the structure, IX, for the alkyl azidodithioDEPARTMENTS OF CHEMISTRY EUQENE LIEBER carbmates: AND THE C. N. PI= DEPAULUNIVERSITY
/s,
C-SR
N
II
Ii
N-N
ARMOUR RESEARCH FOUNDATION J. RAMACWNDRAN OF THE ILLINOIS INSTITUTE RALPHD. HITES OF TECHNOLOQY CHICAQO 14,ILL.
Received July 30, 1957 IX
X a f i = CH,)
The Hunsdiecker Reaction of Optically Active These structures easily explain the fact that the Silver trans-Cyclobutane-l,2-dicarboxylate alkyl azidodithiocarbmates invariably fomied nomnal thiocyanates while the acyl axidodithiocarbmates Sir: yield isothioyanates: In view of recent interest in the mechanism of the RSCSNa +RSCN + Ns + S brominative decarboxylation (Hunsdiecker reRCOSCSNs +RNCS + Nz + S action) of cyclic 1,2-di~arboxylates,~ we wish to Audrieth, Johnson, and Brownee suggested that in make a preliminary report of an experiment which the case of the acyl derivative (R=CJ&) the further elucidates the stereochemistry of that renormal thiocyanate is first formed as an intermediate action. It has been shown that brominative deand immediately undergoes rearrangement to the carboxylations of cis- and trans-cyclobutanedicarboxylate2 and of cis- and trana-cyclohexanedicarisothiocyanate: boxylatel lead to the corresponding trans-1,Z RCOSCN +RCONCS dibromocycloalkanes. Abell' had pointed out that Unfortunately not much is known about the above these results may be explained in terms of the usual interconversion. However, the literature'' indicates free-radical mechanism ( R C O A p R C 0 2 B w R --t that this is not an easy process. On the other hand, RBr)a either by a steric effect in the addition of a by the assignment of structures X and VI, the mode bromine atom to radical I or by the intermediacy of a bridged radical, 11, which would yield transof ring rupture indicated dibromide if the ring opened with inversion of configuration. A third possibility is that radical 111, U.
X
VI
produces all of the degradation products without the need of postulating a rearrangement of n m L to an iso-thiocyanate in the case of the benzoyl derivative. The indicated mode of ring rupture is exactly the same as described for the 5-substituted amin0-1,2,3,4-thiatriazoles,~J I.
I
111
W
I1
IV
formed in the first phase of the decomposition of the bishypobromite, might decompose to the cycloolefin, IV, which could then add bromine by an (9) It is interesting to note thatxm early as 1922,Oliveri- ionic mechanism. Mandala, Cazz. d i m . ad.,52, 11, 139 (1922)in a general Reaction paths involving I1 or IV would almost discussion on the addition of hydrazoic acid to systems con- necessarily give racemic trans-dibromocycloalkane: taining adjacent double bonds had postulated that the addition of HN, to CSn could lead to structures 111,V, and whereas a stepwise, sterically controlled, stereoVI1 but rejected V and VI1 in favor of I11 on the basis of specific introduction of bromines by way of I11 and degradative evidence. I could give optically active product from optically (10) The absence of the SH stretching vibration between active trans-dicarboxylate. 26004500 cm.+ coupled with the strong absorbancies for
I
I
C=S; - N - C 4 ; and -N-C(=O)(Table I) were decisive. Studies in this laboratory show that the very strong absorbance at 900 ern.-' can be taken a8 indicative of a heterocyclic -N-S-Cgrouping. (11) H. E. Williams, Cyanogen Compounds, Edward Arnold and Co., London, 2nd ed. 1948,p. 321.
(1) P. I. Abell, J . Org. Chem., 22, 769 (1957). (2) E. R. Buchman, J. C. Conly, and D. R. Howton,
N6onr-244/XI Tech. Rept., California Institute of Technology, 1951, p. 90; cf. E. Vogel, Fortschr. chem. Forsch., 3,430 (1955). (3) R. 0.Johnson and R. K. Ingham, Chem. Revs., 56, 219 (1956).
