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Methylene Chloride as a Reagent for Cyclizations with SO3 as HCl Trapping Agent.

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GBb. S. Nirz. H . Pnrlnr. F. Korre. ;bid. 4. 251 (19751: d) S. Gab. J .
Sdiniitrrr. H.-W Thamm, H. Parlar, F . Kortr, Nature (London) 270,
331 (1977).
[S] A . W Castleman, Jr., University of Colorado, Boulder, Col., personal
communication.
[6] W Roth, Hoechst AG, Frankfurt, personal communication.
[7] C. Hubrich, C. Zetzsch, F. Stuhl, Ber. Bunsenges. Phys. Chem. 81, 437
(1977).
[S] Catalyst: COEX 0.3 (Dr. E. Durrwachter DODUCO KG, D-6920 Sinsheim), 150°C.
CAS Registry numbers:
( I a ) , 14986-54-0; ( 1 b ) , 421-85-2; ( 2 a ) . 30277-57-7; ( 2 b ) , 66183-94-6;
methylene chloride, 75-09-2
[l] H . W Roesky, M . Diehl, H . Fuess, J . W Bats, Angew. Chem. 90, 73
(1978); Angew. Chem. Int. Ed. Engl. 17, 58 (1978); H . W Roesky, M .
Aramaki, ibid. 90, 127 (1978) and 17, 129 (1978). respectively.
Contamination of Amines with N - N i t r o s a m i n e s [ * * l
Methylene Chloride as a Reagent for Cyclizations with
SO3 as HCl Trapping Agent["]
By Herbert W Roesky, Minoru Aramaki, and Lothar
Schonfelder [*I
Owing to its inertness, methylene chloride is usually
employed as solvent and not as reactant. To our knowledge
methylene chloride has hitherto not been observed to react
with amides or amines at room temperature with concomitant
loss of hydrogen chloride. We have now found that such
reactions can indeed readily take place in the presence of
sulfur trioxide as HCI trapping reagent. When fluorosulfonamide ( 1 a ) or trifluoromethane sulfonamide (1 b ) is allowed
to react with "SO3in CH2C12"the corresponding 1,3,5-tris(sulfony1)-I,3,5-triazacyclohexane (2) and chlorosulfonic acid are
formed.
3 RSO2NHz
+
3 C H z C l 2 + 6 SO3
-
SOzR
(2a). R
(2b), R
= F
= CF3
The products ( 2 a ) and (2b) are crystalline white products,
m. p. 217 and 21 1"C, respectively. The six-membered ring
structure of the molecules manifests itself in the spectroscopic
data: The mass spectrum of (2a) shows the molecular ion
at m/e=333 (3 %) along with fragments at 222 ( F S O Z N C H ~ ) ~
20 %, 111 FSO'NCH' 20 %, 113 FS02NHCH3 100 %. 19FNMR: 6 = - 54.8, quintet; 'H-NMR: S = 5.5, quartet,
JHF=1.5 Hz. The mass spectrum of (2 b) likewise shows a
trimer at m/e=483 with a relative intensity of 2 %. The "FNMR spectrum shows only one signal, 6 = 77.6 (rel. CFC13
ext.)"].
Experimental
SO3 (0.3 mol) is added dropwise to a suspension of (1 ,I
(0.1 mol) in methylene chloride (0.25 mol). A weakly exothermic
reaction takes place with formation of a white precipitate.
After 24 hours' stirring, excess CH2C12 and SO3 are removed
by evaporation in a vacuum and the solid product isolated
by filtration. ( 2 a ) can be purified by recrystallization from
a mixture of CH3CN and CC14, ( 2 b ) from CH3CN; yields:
75 % and 42 % respectively.
Received: March 6, 1978 [Z 948 IE]
German version: Angew. Chem. 90,382 (1978)
p] Prof. Dr. H. W. Roesky, M. Aramaki ['I,
L. Schonfelder
Anorganisch-chemisches Institut I der Universitat
Niederurseler Hang, D-6000 Frankfurt am Main 50 (Germany)
['I Permanent address: Central Glass Co., Ltd., Tokio (Japan).
[**I This work was supported by the Deutsche Forschungsgemeinschaft.
Angew. Chem. lnt. Ed. Engl. 17 (1978) No. 5
By Bertold Spiegelhalder, Gerhard Eisenbrand, and Rudolf
~reus.sriiniin'1
During studies on trace analysis of carcinogenic nitrosamines in the environment['], we have discovered that commercially available secondary and tertiary amines are contaminated with the corresponding nitrosamines. Concentrations
in samples from'various manufacturers varied between 0.03
and 53.0mg/kg. The results of 35 determinations are shown
in Table 1. Only in exceptional cases were other nitrosamines
present; presumably, their occurrence is due to contamination
with other amines.
Table 1 . Contamination ofsecondary and tertiary amines with the corresponding dialkyl-N-nitrosamine.
Amine investigated
Concentration
[mg/kgl
Dimethylamine solution
Dimethylamine hydrochloride
Diethylamine
Dipropylamine
Diisopropylamine
Dibutylamine
Diisobutylamine
Dipentylamine
Dihexylamine
Piperidine
Pyrrolidine
Triethylamine
0.65-17.3
0.21
0.1-7.3
1.9-13.0
0.25-0.39
0.3-2.95
8.35
0.31-2.6
0.4
1.6-2.1
3.65-53.0
0.03 [c]
X [a]
6.72
1.78
1.34
1.4
25.65
n [b]
6
i
6
2
6
1
3
1
2
4
1
[a] R=average value from several samples. [b] n=number o f samples from
different sources. [c] Diethylnitrosamine.
For analysis, a sample of the amine (0.5-1 g) is steam
distilled at reduced pressure. After acidification with 2 N
H2S04,thedistillate isextracted with dichloromethane. Nitrosamine could be separated from the concentrated extract by
gas chromatography (5 m steel column, 1/8'' id., 13 % Carbowax 20 M TPA on Gas Chrom Q, oven temp. 205°C)
and determined with a nitrosamine-specific chemiluminescence detector (TEA detector)['] (sensitivity better than
0.0001 mg/kg). The identity of the nitrosamines was confirmed
on combination of gas chromatography and high-resolution
mass spectrometry (Varian MAT 311A) at a resolution of
R = 15OOO by precision measurement of the mass of the molecular ion.
The occurrence of even slight amounts of the extremely
carcinogenic nitrosamine~[~I
in commercial material make protective measures imperative during their handling, especially
in view of their volatility. Just a single dose of 1.25 mg/kg
body weight produces malignant tumors in ratsr4].Moreover,
the nitrosamines can appear in the reaction products of such
amines, e. g. in drugs and pesticide^'^]. Hence safety precautions
p] Prof. Dr. R. Preussmann, Dr. B. Spiegelhalder, Dr. G. Eisenbrand
Institut fur Toxikologie und Chemotherapie,
Deutsches Krebsforschungszentrum
Im Neuenheimer Feld 280, D-6900 Heidelberg 1 (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft.
367
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methylene, reagents, cyclization, agenti, chloride, so3, hcl, trapping
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