Helvetica Chimica Acta – Vol. 89 (2006)
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sation of secondary amines. Structural investigations of MSA and similar solid acids, as
well as other applications of these systems in various organic reactions, are currently
under investigation.
We gratefully acknowledge partial support of this work by the Yasouj University, Yasouj, Iran.
Experimental Part
General. The amines 1a–14a and all other chemicals were purchased from Merck, Fluka, and
Aldrich. All reactions were monitored by TLC. The products were identified by comparison of their phys-
ical and spectroscopic data with those of authentic samples prepared according to previous methods
[1–7][17]. IR Spectra were recorded on a Jasco 680 FT-IR spectrometer; in cmÀ1
.
1H-NMR Spectra
were obtained on a Bruker DPX-300 apparatus; d in ppm.
Preparation of Molybdate Sulfuric Acid (=Dioxo[bis(sulfato-kO]molybdenum; MSA). To chlorosul-
fonic acid (23.30 g, 0.2 mol) in a 250-ml round-bottom flask immersed in an ice bath, anh. sodium molyb-
date (20.58 g, 0.1 mol) was added gradually. After completion of the addition, the mixture was agitated
for 1 h, which gave rise to crude MSA as a bluish-white solid, which was filtered off and washed with cold
H2O. Yield: 28 g (87.5%).
General Procedure for the N-Nitrosation of Secondary Amines. To a soln. of the amine (2 mmol) in
CH2Cl2 (8 ml), wet MSA (1 mmol; 10% (w/w)) and NaNO2 (2 mmol) were added. The heterogeneous
mixture was stirred at r.t., and the reaction was monitored by TLC (SiO2; hexane/AcOEt). After com-
pletion of the reaction (ca. 15–20 min), the mixture was filtered and washed with CH2Cl2 (4 ml).
Then, anh. Na2SO4 was added to the filtrate, and after 10 min, the mixture was filtered and the
CH2Cl2 was removed on a water bath at 40–508. The products 1b–14b were purified by simple distillation
(Table) and, when necessary, further purified by flash chromatography (SiO2; hexane/AcOEt). Some
physical and spectroscopic data of selected products are given below.
N-Methyl-N-nitrosomethanamine (1b). B.p. 1528. IR: 2850–2950 (CH), 1450 (N=O), 1350 (CÀN),
1375 (Me). 1H-NMR (CDCl3): 2.95 (s, Me); 3.69 (s, Me).
N-Nitrosopyrrolidine (6b). B.p. 2148. IR: 2850–2950 (CH), 1430 (N=O and CH2), 1300 (CÀN), 1050
(NÀN). 1H-NMR (CDCl3): 4.07 (t, 2 H); 3 .3 5t(, 2 H); 1.85 (q, 2 H); 1.89 (q, 2 H).
N-Methyl-N-nitrosoaniline (11b). Solid, decomposing at 708. IR: 3050–3100 (arom. CH); 2900–3000
(aliph. CH); 1500, 1600 (arom. C=C); 1450 (N=O and CH2); 1320 (CÀN); 1050 (NÀN). 1H-NMR
(CDCl3): 7.44–7.51 (m, 5 arom. H); 1.69 (s, Me). 13C-NMR: 30.5 (Me); 141.7; 128.8; 126.6; 118.5.
1,4-Dinitrosopiperazine (12b). Isolated as a mixture of two isomers having either a plane of symme-
try (isomer A) or a C2-axis (isomer B). M.p. 156–1608. IR: 2850–2950 (CH), 1430 (N=O and CH2), 1350
(CÀN). 1H-NMR (CDCl3): 4.50 (s, 4 H of B); 4.40 (t, 4 H of A); 4.60 (s, 4 H of A); 3.83 (s, 4 H of B). 13C-
NMR: 37.2 (A); 40.5 (B); 46.6 (B); 49.2 (A).
2,2’-(Nitrosoimino)diethanol (13b). Solid, decomposing at 2008. IR: 3200–3400 (OH), 2850–2950
(CH), 1100–1350 (CÀO and CÀN), 1450 (N=O and CH2), 1350 (CÀN), 1050 (NÀN). 1H-NMR
(CDCl3): 7.3( s, OH); 4.37 (t, CH2); 4.09 (t, CH2); 3.9 (t, CH2); 3.8 (t, CH2).
N-Nitroso-N-phenylaniline (14b). M.p. 64–668. IR: 3050–3100 (arom. CH); 1500, 1600 (arom. C=
C); 1450 (N=O and CH2); 1300 (CÀN); 1050 (NÀN). 1H-NMR (CDCl3): 7.0–7.3( m, arom. H).
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