A method for the synthesis of stable aryldiazonium salts possessing a 1,1,2,3,3-pentacyanopropenide anion

Article abstract of DOI:10.1016/j.tetlet.2012.08.098

A method for the synthesis of stable aryldiazonium salts possessing an organic 1,1,2,3,3-pentacyanopropenide anion is reported.

Full text of DOI:10.1016/j.tetlet.2012.08.098

Tetrahedron Letters 53 (2012) 5807–5808
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Tetrahedron Letters
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A method for the synthesis of stable aryldiazonium salts possessing a
1,1,2,3,3-pentacyanopropenide anion
⇑
Andrey V. Kachanov , Oleg Yu. Slabko, Vladimir A. Kaminskii
Department of Chemistry, Far Eastern Federal University, Oktyabrskaya St. 27, Vladivostok 690 000, Russia
a r t i c l e i n f o
a b s t r a c t
Article history:
A method for the synthesis of stable aryldiazonium salts possessing an organic 1,1,2,3,3-pentacyanop-
ropenide anion is reported.
Received 11 June 2012
Revised 13 August 2012
Accepted 24 August 2012
Available online 4 September 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Aryldiazonium salts
1,1,2,3,3-Pentacyanopropene
Azo dyes
Malononitrile
Exchange reaction
Aryldiazonium salts have very useful applications in organic
synthesis as well as in industry, in the synthesis of azo dyes.1 Aryl-
diazonium salt formation followed by azocoupling is applied as a
sensitive reaction to nitrite anion (Greass reagent). These salts
may be used as surface initiators of polymerization2 and as light-
sensitive materials3 and most are known to have a low level of sta-
bility. Their stability depends on the aromatic ring substituents
and the nature of the anion. Tetrafluoroborates,4 tosylates,5 and
disulfonimides6 are the most stable salts. The presence of inorganic
anions in these substances decreases or makes dissolution of these
salts impossible in many organic solvents.
Of the organic anions which can stabilise aryldiazonium cations
it is necessary to note the 1,1,2,3,3-pentacyanopropenide anion.
1,1,2,3,3-Pentacyanopropene itself is a strong CH-acid, its strength
being comparable to 12 M sulfuric acid (pKa< ꢀ8.5).7 Earlier several
aryldiazonium salts with this anion were produced.8 However,
they were obtained via an exchange reaction in a diphasic system
of solvents: water–ethyl acetate, from commercially accessible tet-
rafluoroborates. The tetramethylammonium 1,1,2,3,3-pentacya-
nopropenide that is used as a reagent in this patent was also
produced of tetracyanoethylene. We found that the malononitrile
autocoupling reaction9 in the presence of SeO2 made this anion
available.
aryldiazonium chlorides in aqueous medium (Scheme 1).10 Aryldi-
azonium salts in the form of chlorides were produced directly
before the exchange reaction with the appropriate primary aryl-
amines without isolation.11 After the pyridinium 1,1,2,3,3-pentacy-
anopropenide has been added as a hot solution to the reaction
mixture, the precipitation of the aryldiazonium 1,1,2,3,3-pentacy-
anopropenides was observed. The presence of 1,1,2,3,3-pentacya-
nopropenide anion in salts 1–10 was confirmed by IR-spectra—
intensive absorption band in the field of 2200 cmꢀ1 and by 13C
NMR spectra - signals of cyano group 114.2, 114.9, 117.3 and car-
bon atoms at 58.0 (C-10, 30), 135.9 (C-20). These are present in the
spectra of pyridinium 1,1,2,3,3-pentacyanopropenide.
The resulting aryldiazonium 1,1,2,3,3-pentacyanopropenides12
1–10 were sufficiently stable and could be isolated. However, they
can decay spontaneously and be polluted by admixtures, which is
accelerated by heating and sunlight. Depending on the presence of
substituents, the shelf-lives of these aryldiazonium salts can vary
from days to several weeks and more. Salts with electron-acceptor
substituents on the aromatic rings, 7 and 9, were much more stable
than salts with donor substituents, 2 and 3, or without 1. The latter
representatives showed appreciable signs of decomposition within
several hours after isolation, while salts 7 and 9 showed good sta-
bility and could be stored for more than a month below 0 °C.
Highly polluted salt could be purified by reprecipitation from ace-
tone by the addition of diethyl ether.
Herein, a method for obtaining a number of aryldiazonium salts
of 1,1,2,3,3-pentacyanopropene 1–10 was developed via the ex-
change reaction of pyridinium 1,1,2,3,3-pentacyanopropenide with
Aryldiazonium 1,1,2,3,3-pentacyanopropenides readily took
part in azocoupling with phenol or reaction with N,N-dimethylan-
iline with the formation of azocoupling products. Due to the
solubility of these salts, this reaction could be carried out in polar
⇑
Corresponding author. Tel./fax: +7 423 245 7609.
E-mail address: kachanov@chem.dvgu.ru (A.V. Kachanov).
0040-4039/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.08.098

5808
A. V. Kachanov et al. / Tetrahedron Letters 53 (2012) 5807–5808
Scheme 1.
hydrochloric acid (3 ml) and of water (3 ml) and cooled to 0 °C. A solution
0.145 g (2.1 mmol) of NaNO2 in water (1 ml) was added dropwise with stirring
within 1 h. Then, 20 ml of a hot (to 70 °C) aqueous solution of 0.5 g (2 mmol) of
pyridinium 1,1,2,3,3-pentacyanopropenide was added to a reaction mixture,
organic solvents, for example, in acetone. It was not necessary to
apply any additional activation in the azocoupling with N,N-
dimethylaniline. However, the azocoupling with phenol required
the addition of an aqueous solution of alkali. The aryldiazonium
1,1,2,3,3-pentacyanopropenides dissolved in a number of dipolar
aprotic solvents, such as dimethylformamide, dimethylsulfoxide,
and hexamethylphosphotriamide were observed to decompose
with elimination of nitrogen.
In conclusion, we offer a new, simple, and efficient method for
the synthesis of aryldiazonium salts possessing a 1,1,2,3,3-penta-
cyanopropenide anion using aryldiazonium chlorides and pyridini-
um 1,1,2,3,3-pentacyanopropenide by means of exchange reaction
in water solution. The simplicity of the procedure, good yields, and
sufficiently stable products are the main advantages of this
method.
without stopping stirring. As
a result of the exchange reaction the
aryldiazonium 1,1,2,3,3-pentacyanopropenide was precipitated from the
solution. This salt was filtered and was washed with water (3 ꢁ 5 ml). The
salt was dried and purified by reprecipitation from acetone solution (1.0–
1.5 ml) by the addition of diethyl ether (10–15 ml) if necessary.
Compound 1: Yield: 81%, mp P82 °C (dec). IR (KBr): m ;
max 2286, 2203 cmꢀ1 1H
NMR (400 MHz, acetone-d6): d 8.89 (d, J = 7.9 Hz, 2H), 8.42 (t, J = 7.3 Hz, 1H),
8.13 (t, J = 7.6 Hz, 2H); 13C NMR (100 MHz, acetone-d6): d 120.1 (C-1), 132.8 (C-
3, 5), 133.7 (C-2, 6), 142.7 (C-4).
Compound 2: Yield: 88%, mp P91 °C (dec). IR (KBr): m ;
max 2264, 2201 cmꢀ1 1H
NMR (400 MHz, acetone-d6): d 2.67 (s, 3H), 7.91 (d, J = 8.5 Hz, 2H), 8.73 (d,
J = 8.6 Hz, 2H); 13C NMR (100 MHz, acetone-d6): d 23.0 (CH3), 112.3 (C-1), 133.4
(C-3, 5), 133.7 (C-2, 6), 156.6 (C-4).
Compound 3: Yield: 81%, mp P107 °C (dec). IR (KBr): m ;
max 2234, 2203 cmꢀ1 1H
NMR (400 MHz, acetone-d6): d 4.17 (s, 3H), 7.56 (d, J = 9.5 Hz, 2H), 8.79 (d,
J = 9.5 Hz, 2H); 13C NMR (100 MHz, acetone-d6): d 58.2 (CH3), 103.5 (C-1), 118.7
(C-3, 5), 137.1 (C-2, 6), 171.0 (C-4).
Compound 4: Yield: 81%, mp P110 °C (dec). IR (KBr): m ;
max 2264, 2197 cmꢀ1 1H
Acknowledgment
NMR (400 MHz, acetone-d6): d 4.35 (s, 3H), 7.55 (t, J = 7.9 Hz, 1H), 7.79 (d,
J = 8.9 Hz, 1H), 8.33–838 (m, 1H), 8.65 (dd, J = 8.5, 1.5 Hz, 1H); 13C NMR
(100 MHz, acetone-d6): d 59.6 (CH3), 102.5 (C-1), 115.9 (C-3), 124.3 (C-5), 133.2
(C-6), 145.6 (C-4), 164.3 (C-2).
We thank the laboratory of molecular analysis of Far Eastern
Federal University for the technical support.
Compound 5: Yield: 82%, mp P123 °C (dec). IR (KBr): m ;
max 2241, 2205 cmꢀ1 1H
NMR (400 MHz, acetone-d6): d 4.44 (s, 1H), 7.38 (d, J = 9.4 Hz, 2H), 8.69 (d,
J = 9.3 Hz, 2H); 13C NMR (100 MHz, acetone-d6): d 101.5 (C-1), 120.1 (C-3, 5),
137.5 (C-2, 6), 170.6 (C-4).
References and notes
Compound 6: Yield: 60%, mp P118 °C (dec). IR (KBr): m ;
max 2289, 2203 cmꢀ1 1H
1. Hunger, K.; Mischke, P.; Rieper, W. ‘Azo Dyes, Production’, Ullmann’s
Encyclopedia of Industrial Chemistry, Electronic Release; Wiley-VCH: Weinheim,
2007.
2. (a) Iruthayaraj, J.; Chernyy, S.; Lillethorup, M.; Ceccato, M.; Ron, T.; Hinge, M.;
Kingshott, P.; Besenbacher, F.; Pedersen, S. U.; Daasbjerg, K. Langmuir 2011, 27,
1070–1078; (b) Gam-Derouich, S.; Mahouche-Chergui, S.; Truong, S.; Hassen-
Chehimi, D. B.; Chehimi, M. M. Polymer 2011, 52, 4463–4470.
3. Minnesota Mining and Manufacturing Company GB Patent 1041463, 1966;
Chem. Abstr. 1966, 65, 87080.
NMR (400 MHz, acetone-d6): d 8.58 (d, J = 9.0 Hz, 2H), 9.02 (d, J = 9.0 Hz, 2H);
13C NMR (100 MHz, acetone-d6): d 115.9 (C-1), 132.7 (C-3), 133.0 (C-5), 134.1
(C-2, 6), 142.4 (C-4), 164.7 (COOH).
Compound 7: Yield: 84%, mp P119 °C (dec). IR (KBr): m ;
max 2298, 2209 cmꢀ1 1H
NMR (400 MHz, acetone-d6): d 8.88 (d, J = 9.1 Hz, 2H), 9.25 (d, J = 9.1 Hz, 2H);
13C NMR (100 MHz, acetone-d6): d 122.3 (C-1), 127.6 (C-3, 5), 135.8 (C-2, 6),
155.2 (C-4).
Compound 8: Yield: 81%, mp P99 °C (dec). IR (KBr): m ;
max 2287, 2201 cmꢀ1 1H
4. Flood, D. T. Org. Synth. 1943, 2, 295–298.
NMR (400 MHz, acetone-d6): d 2.78 (s, 3H), 8.56 (d, J = 9.0 Hz, 2H), 9.04 (d,
J = 9.0 Hz, 2H); 13C NMR (100 MHz, acetone-d6): d 119.7 (C-1), 131.6 (C-3, 5),
134.4 (C-2, 6), 146.8 (C-4), 196.6 (CO).
5. Filimonov, V. D.; Trusova, M.; Postnikov, P.; Krasnokutskaya, E. A.; Lee, Y. M.;
Hwang, H. Y.; Kim, H.; Chi, K.-W. Org. Lett. 2008, 10, 3961–3964.
6. Barbero, M.; Crisma, M.; Degani, I.; Fochi, R.; Perracino, P. Synthesis 1998, 1171–
1175.
Compound 9: Yield: 79%, mp P120 °C (dec). IR (KBr): m ;
max 2293, 2207 cmꢀ1 1H
NMR (400 MHz, acetone-d6): d 7.38 (s, 2H), 8.51 (d, J = 8.5 Hz, 2H), 9.11 (d,
J = 8.5 Hz, 2H); 13C NMR (100 MHz, acetone-d6): d 120.0 (C-1), 130.1 (C-3, 5),
135.2 (C-2, 6), 155.7 (C-4).
7. Boyd, R. H. J. Phys. Chem. 1963, 67, 737–744.
8. Jinbo, Y. JP Patent 145879, 2005; Chem. Abstr. 2005, 143, 28083.
9. Kaminskii, V. A.; Slabko, O. Yu.; Kachanov, A. V.; Buhvetskii, B. V. Tetrahedron
Lett. 2003, 44, 139–140.
10. Kachanov, A. V.; Kaminskii, V. A.; Slabko, O. Yu. RU Patent 2 379 283, 2010;
Chem. Abstr. 2010, 152, 171017.
11. Grimmel, H. W.; Morgan, J. F. J. Am. Chem. Soc. 1948, 70, 1750.
12. General procedure. Warning: some diazonium salts can be explosive! The
primary arylamine (2.1 mmol) was dissolved in a mixture of concentrated
Compound 10: Yield: 90%, mp P100 °C (dec). IR (KBr): mmax 2237, 2205 cmꢀ1
;
1H NMR (400 MHz, acetone-d6): d 8.03–8.07 (m, 1H), 8.17 (t, J = 8.1 Hz 1H),
8.18–8.22 (m, 1H), 8.50 (d, J =8.3 Hz, 1H), 8.62 (d, J = 8.5 Hz, 1H), 9.05 (d, J = 8.3
Hz, 1H), 9.39 (dd, J = 7.9, 0.9 Hz, 1H); 13C NMR (100 MHz, acetone-d6): d 120.9
(C-1), 122.8 (C-3), 127.6 (C-8), 128.8 (C-9), 131.2 (C-6), 131.8 (C-2), 133.9 (C-7),
134.2 (C-10), 138.6 (C-5), 144.8 (C-4).