A Convenient procedure for the preparation of bis(dialkylamino) malononitriles

Article abstract of DOI:10.1055/s-0029-1218852

N,N,N⁺⁺,N⁺⁺-Tetraalkylchloroformamidinium chlorides react with trimethylsilyl cyanide without solvent to give bis(dialkylamino) malononitriles, which can be distilled off from the reaction mixture in vacuo. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-0029-1218852

SHORT PAPER
2703
A Convenient Procedure for the Preparation of
Bis(dialkylamino)malononitriles
es is Tiritiris, Willi Kantlehner*a,b
a
P
I
reparat
o
B
is(di
a
nm alononitri ln
a
Institut für Organische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany
Fakultät Chemie/Organische Chemie, Hochschule Aalen, Beethovenstr. 1, 73430 Aalen, Germany
Fax +49(7361)5762250; E-mail: willi.kantlehner@htw-aalen.de
b
Received 18 March 2010; revised 20 April 2010
Table 1 Formation of Bis(dialkylamino)malononitriles 3
Abstract: N,N,N¢,N¢-Tetraalkylchloroformamidinium chlorides re-
act with trimethylsilyl cyanide without solvent to give bis(dialkyl-
amino)malononitriles, which can be distilled off from the reaction
mixture in vacuo.
1
2
1 2
R R N
R R N
CN
CN
+
X
3
4
3
4
Cl–
R R N
R R N
3
Key words: iminium salts, N,N,N¢,N¢-tetraalkylchloroformamidin-
ium chlorides, trimethylsilyl cyanide, bis(dialkylamino)malononi-
triles
1
2
X = Cl
a X = CN
R
1
= R = R3 = R4 = Me
2
Entry R1
R2
R3
R4
Method Product Yield
%)
a
(
Compounds with a captodative substituent pattern very
1
often show surprising chemical properties. Bis(dialkyl-
1
Me
Me
Me
Me
A
B
C
3a
43
72
85
b
amino)malononitriles 3 are compounds of this type.
Some time ago we showed that bis(dimethylamino)malo-
nonitrile (3a) can be used for the preparation of ketene
aminals, 1,3-bis(N,N,N¢,N¢,N¢¢,N¢¢-hexamethylguanidini-
um)substituted 1,2,3-tricyanoprop-2-en-1-ides, 1,4-di-
2
3
4
5
6
7
8
9
Et
Et
Et
Et
B
B
B
B
C
C
C
C
3b
3c
3e
3f
83
76
89
64
81
77
70
77
(CH
)
(CH )
2 4
2
4
methylpiperazine-2,2,5,5-tetracarbonitrile,
N,N,N¢,N¢-
(CH2)5
(CH ) O(CH )
(CH )
2 5
tetramethylcyanoformamidinium salts, and dimethylam-
monium salts of 5,5¢-dicyanomethylenedibarbituric acid.
2
(CH ) O(CH )
2 2 2 2
2
2
2 2
Bis(dimethylamino)malononitrile (3a) was prepared for
the first time by the reaction of N,N,N¢,N¢-tetramethyl-
chloroformamidinium chloride (1a) with copper(I) cya-
nide. The complex thus obtained, which was not
specified, was decomposed with aqueous potassium cya-
Me
Me
Et
Me
Pr
Pr
3g
3h
3i
Me
Et
Bu
Pr
Bu
Pr
3
Et
Et
Bu
Bu
3j
nide solution to give 3a in 43% yield. The reaction of
N,N,N¢,N¢-tetramethylcyanoformamidinium chloride (2a)
a
Starting from 1, unless otherwise indicated. Method A: Ref. 3, X =
O; Method B: Refs. 2 and 4, X =
with potassium cyanide in a two-phase system water/di-
4
Cl; (1) CuCN, MeCN; (2) KCN, H
Cl, CN; KCN, Et O–H O; Method C: this work, X = Cl; TMSCN, no
2
ethyl ether also afforded 3a in 72% yield. Bis(dialkyl-
2
2
amino)malononitriles 3a–f were similarly prepared by
this procedure directly from N,N,N¢,N¢-tetraalkylchloro-
solvent (–TMSCl).
b
Starting from 2a.
formamidinium chlorides 1b–f and potassium cyanide in
2
6
4–89% yields. Recently we have found that the reaction
The N,N,N¢,N¢-tetraalkylchloroformamidinium chlorides
a,g–j were prepared according to already described
of trimethylsilyl cyanide with the salts 1a,g–j without sol-
vent gives easy access to bis(dialkylamino)malononitriles
1
2,5
procedures from the corresponding ureas and phosgene
in acetonitrile. By subsequent removal of the solvent the
solid chlorides 1 were obtained and used without further
purification in the reactions with trimethylsilyl cyanide.
3
a,g–j (Table 1). In contrast, the reaction of trimethylsilyl
cyanide with salts 1 in acetonitrile resulted in dark brown
to black polymeric products.
According to this procedure symmetrically substituted
malononitriles such as 3a, and unsymmetrically substitut-
ed malononitriles, such as 3g–j, can be prepared in 70–
All reactions were performed in dry glassware with magnetic stir-
ring and exclusion of moisture. Trimethylsilylcyanide and
N,N,N¢,N¢-tetrasubstituted ureas were prepared according to
known procedures. H and C NMR spectra were recorded on a
Bruker Avance 500 spectrometer. The refractive indices were deter-
mined using a Zeiss Abbe refractometer.
6
8
5% yields.
7
1
13
SYNTHESIS 2010, No. 16, pp 2703–2704
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x.
x
x
.
2
0
1
0
Advanced online publication: 29.06.2010
DOI: 10.1055/s-0029-1218852; Art ID: T06610SS
Georg Thieme Verlag Stuttgart · New York
©

2
704
I. Tiritiris, W. Kantlehner
SHORT PAPER
1
Bis(dialkylamino)malononitriles 3; General Procedure
H NMR (500 MHz, CDCl ): d = 0.90–0.93 (t, J = 7.4 Hz, 6 H,
3 3 2
3
To solid N,N,N¢,N¢-tetraalkylchloroformamidinium chloride 1 (0.2
mol) in a 2-necked flask equipped with a reflux condenser and dry-
ing tube (CaCl ) was added cautiously at 0 °C excess Me SiCN (59
CH ), 1.15–1.18 (t, J = 7.4 Hz, 6 H, CH ), 1.56–1.61 (m, 4 H, CH ),
2.70–2.73 (m, 4 H, NCH ), 2.86–2.91 (m, 4 H, NCH ).
2
2
2
3
13
C NMR (125 MHz, CDCl ): d = 11.6 (CH ), 13.3 (CH ), 21.7
3
3
3
g, 0.6 mol). On subsequent warming, an exothermic reaction oc-
curred at r.t. and the chloride 1 dissolved. Then the mixture was
(
CH ), 43.3 (NCH ), 52.2 (NCH ), 79.8 (C ), 112.9 (CN).
2 2 2 q
MS (EI, 70 eV): m/z = 236.2 [M]+.
magnetically stirred for 10–12 h at r.t. The Me SiCl formed and the
3
excess Me SiCN were removed under reduced pressure (20 Torr).
3
Anal. Calcd for C H N (236.36): C, 66.06; H, 10.23; N, 23.70.
1
3
24
4
The residue was distilled in vacuo through a 25-cm Vigreux column
with fractionation. The malononitriles 3 are colorless liquids when
freshly distilled, and after some time become yellow-to-orange col-
ored.
Found: C, 65.94; H, 10.06; N, 23.63.
(
Dibutylamino)(diethylamino)malononitrile (3j)
Yield: 77%; bp 98–100 °C/0.013 mbar; n = 1.4491.
20
D
1
H NMR (500 MHz, CDCl ): d = 0.92–0.95 (t, J = 7.4 Hz, 6 H,
3
Bis(dimethylamino)malononitrile (3a)
3
CH ), 1.30–1.35 (m, 4 H, CH
1.51–1.55 (m, 4 H, CH ), 2.73–2.76 (m, 4 H, NCH ), 2.85–2.90 (q,
2 2
3
), 1.15–1.18 (t, J = 7.4 Hz, 6 H, CH
3
2
),
Yield: 85%; bp 89–90 °C/40 mbar (Lit. 75 °C/16 mbar);
2
0
4
20
n
= 1.4359 (Lit. n = 1.4360).
D
D
J = 7.4 Hz, 4 H, NCH2).
1
H NMR (500 MHz, CDCl ): d = 2.45 [s, 12 H, N(CH ) ].
3
3 2
13
C NMR (125 MHz, CDCl ): d = 13.2 (CH ), 13.9 (CH ), 20.4
3
3
3
1
3
C NMR (125 MHz, CDCl ): d = 39.2 (NCH ), 81.6 (C ), 110.0
3
3
q
(CH ), 30.5 (CH ), 43.3 (NCH ), 50.5 (NCH ), 79.8 (C ), 112.9
2
2
2
2
q
(
CN).
(
CN).
MS (EI, 70 eV): m/z = 152.1 [M]+.
MS (EI, 70 eV): m/z = 264.2 [M]+.
Anal. Calcd for C H N (152.20): C, 55.24; H, 7.95; N, 36.81.
Found: C, 55.18; H, 7.93; N, 36.62.
7
12
4
Anal. Calcd for C H N (264.41): C, 68.14; H, 10.67; N, 21.19.
15 28 4
Found: C, 67.95; H, 10.53; N, 21.09.
(
Dimethylamino)(dipropylamino)malononitrile (3g)
2
0
Yield: 81%; bp 64–65 °C/0.013 mbar; n = 1.4461.
Acknowledgment
D
1
H NMR (500 MHz, CDCl ): d = 0.90–0.93 (t, J = 7.3 Hz, 6 H,
3
We thank the Bundesministerium für Bildung und Forschung der
Bundesrepublik Deutschland for financial support (BMBF Projekt:
Neuartige ionische Flüssigkeiten als innovative Reaktionsmedien
für die Technische Organische Chemie, FKZ 01 RI 05175).
CH ), 1.57–1.62 (m, 4 H, CH ), 2.44 [s, 6 H, N(CH ) ], 2.71–2.74
3
2
3 2
(
m, 4 H, NCH2).
1
3
C NMR (125 MHz, CDCl ): d = 11.6 (CH ), 21.6 (CH ), 39.2
3
3
2
(NCH ), 52.5 (NCH ), 81.1 (C ), 111.4 (CN).
3
2
q
MS (EI, 70 eV): m/z = 208.1 [M]+.
References
Anal. Calcd for C H N (208.30): C, 63.43; H, 9.68; N, 26.90.
1
1
20
4
(
1) Stella, L.; Janousek, Z.; Merényi, R.; Viehe, H. G. Angew.
Chem., Int. Ed. Engl. 1978, 17, 691; Angew. Chem. 1978, 90,
Found: C, 63.23; H, 9.65; N, 26.81.
7
41.
(
Dibutylamino)(dimethylamino)malononitrile (3h)
(
(
2) Kantlehner, W.; Greiner, U. Liebigs Ann. Chem. 1990, 965.
3) Arnold, Z.; Svoboda, M. Collect. Czech. Chem. Commun.
1977, 42, 1175.
(4) Kantlehner, W.; Greiner, U. Synthesis 1979, 339.
(5) Kantlehner, W.; Haug, E.; Mergen, W. W.; Speh, P.; Maier,
T.; Kapassakalidis, J. J.; Bräuner, H.-J.; Hagen, H. Liebigs
Ann. Chem. 1984, 108.
6) (a) Voronkov, M. G.; Roman, V. G.; Maletina, E. A.
Synthesis 1982, 277. (b) Kantlehner, W.; Haug, E.; Mergen,
W. W. Synthesis 1980, 460.
2
0
Yield: 77%; bp 86–88 °C/0.013 mbar; n = 1.4473.
D
1
H NMR (500 MHz, CDCl ): d = 0.92–0.95 (t, J = 7.4 Hz, 6 H,
3
CH ), 1.29–1.36 (m, 4 H, CH ), 1.51–1.57 (m, 4 H, CH ), 2.44 [s, 6
3
2
2
H, N(CH ) ], 2.74–2.78 (m, 4 H, NCH ).
1
3
2
2
3
C NMR (125 MHz, CDCl ): d = 13.9 (CH ), 20.5 (CH ), 30.4
3
3
2
(
CH ), 39.1 (NCH ), 50.5 (NCH ), 81.1 (C ), 114.4 (CN).
2 3 2 q
(
MS (EI, 70 eV): m/z = 236.2 [M]+.
Anal. Calcd for C H N (236.36): C, 66.06; H, 10.23; N, 23.70.
13
24
4
Found: C, 66.10; H, 10.14; N, 23.76.
(7) Kantlehner, W.; Edelmann, K.; Gissel, A.; Scherr, O.;
Vetter, J.; Wezstein, M.; Ziegler, G.; Mezger, J.; Iliev, B.
Acta Chim. Slov. 2009, 56, 612.
(
Diethylamino)(dipropylamino)malononitrile (3i)
Yield: 70%; bp 84–86 °C/0.013 mbar; n = 1.4478.
2
0
D
Synthesis 2010, No. 16, 2703–2704 © Thieme Stuttgart · New York