METHYLATION OF ANILINE AND ITS DERIVATIVES WITH DIMETHYL CARBONATE
1569
behavior was observed in the reaction of dimethyl
carbonate with p-bromoaniline 6а. Whereas at the use
of the acid catalyst 0.94HY-BS at any concentration of
the catalyst and the reaction time a mixture was
obtained of N-methyl- (6b) and N,N-dimethyl- (6c)
derivatives, in the presence of NaY-BS and 0.72
KNaX-BS selectively formed N,N-dimethyl-4-
bromoaniline 6c (Scheme 6). Similarly the methylation
with dimethyl carbonate proceeded with p-nitroaniline
The reactor was hermetically closed (the ampule
was sealed), and was heated for 1–4 h at 150°С. After
the end of the run the reactor was cooled to
room temperature, opened, the reaction mixture was
filtered through a bed of Al O . Dimethyl carbonate
2
3
was distilled off, the residue was distilled at
atmospheric pressure or in a vacuum, or crystallized
from ethanol.
13
N-Methylaniline (1b). Yield 88%, bp 196°С.
С
7
a: at the use of 0.94HY-BS a mixture was obtained of
NMR spectrum, δ, ppm: 30.53 (NHСН ), 112.17
3
mono-N- (7b) and N,N-dimethyl- (7c) derivatives, and
in the presence of NaY-BS and 0.72 KNaX-BS
compound 7c formed selectively (Scheme 7).
2,6
4
3,5
1
(
С ), 117.12 (С ), 129.10 (С ), 149.42 (C ).
N,N-Dimethylaniline (1c). Yield 90%, bp 194°С.
1
3
С NMR spectrum, δ, ppm: 40.53 (СН ), 112.67
3
Thus we have developed an effective method of the
synthesis of N- and N,N-dimethyl aniline derivatives
applying a reagent of the “green chemistry”, dimethyl
carbonate, with the use of binder-free micro-, meso-,
and macroporous zeolite catalysts with basic
2,6
4
3,5
1
(
С ), 116.12 (С ), 129.01 (С ), 150.68 (C ).
N,4-Dimethylaniline (2b). Yield 71%, bp 110°С
1
3
(30 mmHg). С NMR spectrum, δ, ppm: 20.59 (СН
),
), 112.89 (С ), 129.76 (С ), 130.18
3
3
2
,6
3,5
31.24 (NHСН
(С ), 147.58 (C ).
4
1
(
(
0.72КNaX), neutral (NaY), and acidic properties
0.94НY).
N,N,4-Trimethylaniline (2c). Yield 25%, bp 128°С
1
3
(
4
60 mmHg). С NMR spectrum, δ, ppm: 20.72 (СН ),
3
EXPERIMENTAL
2,6
4
1.23 (NСН ), 113.53 (C ), 126.45 (С ), 130.01
3
(С ), 149.19 (C ).
3
,5
1
1
13
Н and С NMR spectra were registered on a spec-
trometer Bruker Avance-400 (400.13 and 100.62 МHz
N,3-Dimethylaniline (3b). Yield 67%, bp 119°С
1
3
respectively) in СDCl . Mass spectra were measured
(50 mmHg). С NMR spectrum, δ, ppm: 21.33 (СН ),
3
3
6
2
4
on an instrument Shimadzu GCMS-QP2010Plus,
capillary column SPB-5, 30 m × 0.25 mm, carrier gas
helium, ramp from 40 to 300°С (heating rate 8 deg/min),
vaporizer temperature 280°С, ionizing electrons
energy 70 eV. Elemental composition of the samples
was determined on an analyzer Cаrlo Erba 1106.
30.33 (NHСН ), 109.30 (C ), 111.37(C ), 118.95 (С ),
3
5
3
1
128.76 (С ), 138.31 (С ), 149.18 (C ).
N,N,3-Trimethylaniline (3c). Yield 77%, bp 130°С
13
(
4
1
50 mmHg). С NMR spectrum, δ, ppm: 21.10 (СН ),
3
4
6
2
0.27 (NСН ), 109.66 (C ), 112.87 (C ), 115.57 (С ),
3
5
3
1
28.67 (С ), 138.64 (С ), 150.50 (C ).
The reaction progress was monitored and the purity
of compounds obtained was checked by GLC on an
instrument Shimadzu GC-9A, GC-2014, column 2 m ×
N,2-Dimethylaniline (4b). Yield 30%, bp 115°С
13
(
3
1
40 mmHg). С NMR spectrum, δ, ppm: 17.37 (СН ),
3
6
4
2
0.80 (NHСН ), 109.17 (C ), 116.89 (C ), 121.94 (С ),
3
3
mm, stationary phase silicone SE-30 (5%) on the
carrier Chromaton N-AW-HMDS, ramp from 50 to
70°С (heating rate 8 deg/min), carrier gas helium
5
3
1
27.00 (С ), 129.95 (С ), 144.64 (C ).
2
N,N,2-Trimethylaniline (4c). Yield 99%, bp 102°С
1
3
(
47 mL/min).
(30 mmHg). С NMR spectrum, δ, ppm: 17.42 (СН ),
3
5
6
4
4
1
4.27 (NСН ), 118.63 (C ), 122.33 (C ), 127.25 (С ),
3
29.95 (С ), 130.48 (С ), 147.30 (C ).
Binder-free zeolite catalysts 0.72KNaX-BS, NaY-
3
2
1
BS, and 0.94HY-BS were prepared by procedures
6, 7].
[
N-Methyl-2-chloroaniline (5b). Yield 99%, bp
1
3
2
(
1
08‒210°С. С NMR spectrum, δ, ppm: 31.29
Methylation of anilines with dimethyl carbonate.
General procedure. Into a pressure microreactor of
stainless steel of 17 mL capacity or into a glass ampule
6
4
2
NHСН ), 116.64 (C ), 119.07 (C ), 121.17 (С ),
3
5
3
1
28.00 (С ), 129.30 (С ), 142.42 (C ).
(
20 mL) (results of the parallel runs were virtually
N,N-Dimethyl-2-chloroaniline (5c). Yield 55%,
13
identic) was charged 5‒10 wt % of catalyst (0.94HY-
BS, NaY-BS, 0.72KNaX-BS), 100 mmol of aniline or
its derivative, and 400 mmol of dimethyl carbonate.
bp 221°С. С NMR spectrum, δ, ppm: 48.30 (СН ),
3
6
2
4
3
118.2 (C ), 121.7 (C ), 125.34 (С ), 127.70 (С ),
5
1
129.10 (С ), 150.7 (C ).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 52 No. 11 2016