Reaction of aldehydes with hydrazine in the system sulfur-alkali

Article abstract of DOI:10.1023/A:1022512723467

Dissolution of sulfur in the system hydrazine hydrate-alkali leads to strong activation of hydrazine, so that the latter readily reacts at room temperature with aldehydes of the aromatic and thiophene series to give the corresponding aldehyde azines in high yield. The mechanism of activating effect of sulfur is discussed.

Full text of DOI:10.1023/A:1022512723467

Russian Journal of Organic Chemistry, Vol. 38, No. 10, 2002, pp. 1498 1500. Translated from Zhurnal Organicheskoi Khimii, Vol. 38, No. 10, 2002,
pp. 1551 1553.
Original Russian Text Copyright
2002 by Russavskaya, Grabel’nykh, Levanova, Sukhomazova, Deryagina.
Reaction of Aldehydes with Hydrazine
*
in the System Sulfur Alkali
N. V. Russavskaya, V. A. Grabel’nykh, E. P. Levanova,
E. N. Sukhomazova, and E. N. Deryagina
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
fax: (3952)356046; e-mail: admin@irioch.irk.ru
Received February 1, 2002
Abstract Dissolution of sulfur in the system hydrazine hydrate alkali leads to strong activation of hydrazine,
so that the latter readily reacts at room temperature with aldehydes of the aromatic and thiophene series to give
the corresponding aldehyde azines in high yield. The mechanism of activating effect of sulfur is discussed.
Aromatic aldehyde azines are obtained by reactions
of aldehydes with hydrazinium salts or hydrazones
derived from various carbonyl compounds, which are
carried out in alcohol, dry benzene, or polyphosphoric
acid at 100 C [1 4]. Aldehyde azines of the thiophene
series were prepared only from 2-thiophenecarbalde-
hyde and 5-trimethylsilyl-2-thiophenecarbaldehyde by
heating them with hydrazine hydrate in anhydrous
alcohol under reflux. However, the yield of the corre-
sponding azines did not exceed 60% [5].
In continuation of our studies on reactions of sulfur
solutions with electrophilic reagents in basic reducing
systems, we examined such reactions with aldehydes
of the aromatic and thiophene series. Formaldehyde
and paraformaldehyde are known to react with the
above sulfur solutions to give poly(methylene poly-
sulfides) [6]. We found that no sulfurization of sub-
stituted benzaldehydes or thiophenecarbaldehyde
derivatives occurs in the system sulfur hydrazine
hydrate sodium hydroxide. Instead, hydrazine effec-
tively reacts with aldehydes Ia Ih at room tempera-
ture, affording the corresponding aldehyde azines
IIa IIh. The reaction is complete almost instantly,
and the yield of products II reaches 86% (Scheme 1).
The reaction conditions and product yields are given
in Table 1. Aldehyde azines II on the basis of thio-
phenecarbaldehyde derivatives were synthesized for
the first time (Table 2). They were characterized by
1
1
IR and H NMR spectra. The H NMR spectral param-
eters of IIa IIh are given in Table 3.
The activating effect of sulfur in this reaction may
be explained as follows. Sulfur reacts with alkali to
give sulfide anions which are solvated by hydrazine
with formation of a complex with charge separation.
Thus a solution of sulfur in the system hydrazine
hydrate alkali is a complex reagent like III which
reacts with aldehyde. The hydrazine molecule strongly
activates sulfide ions, e.g., as shown in Scheme 2. The
reaction of complex III with aldehyde could involve
Scheme 1.
Scheme 2.
R = Ph (a), 2-ClC H (b), 4-ClC H (c), 2-thienyl (d),
6
4
6
4
5
-chloro-2-thienyl (e), 5-(2-thienyl)-2-thienyl (f), thieno-
2,3-b]thiophen-2-yl (g), 5-(2-thienylthio)-2-thienyl (h).
[
_
*
___________
This study was financially supported by the Russian Founda-
tion for Basic Research (project no. 00-03-32810).
1
070-4280/02/3810-1498$27.00 2002 MAIK Nauka/Interperiodica

REACTION OF ALDEHYDES WITH HYDRAZINE
1499
Table 1. Reactions of aldehydes Ia Ih with hydrazine in the system sulfur sodium hydroxide
Amounts of reactants, g (mol)
Aldehyde
Yield of II
no.
S
NaOH
N H H O
H O (ml)
RCHO (I)
g
%
2
4
2
2
Ia
Ia
Ia
Ib
Ic
Id
Ie
If
3.84 (0.12)
3.2 (0.1)
0.96 (0.03)
1.28 (0.04)
3.84 (0.12)
4.0 (0.1)
3.05 (0.05)
2.0 (0.05)
1.3 (0.033)
4.0 (0.1)
5.0 (0.1)
25.0 (0.5)
12.0 (0.4)
1.66 (0.033)
5.0 (0.1)
30
10.6
21.1
12.7
4.66 (0.033)
14.0
1.76 (0.0156)
2.0
1.6
1.68 (0.01)
0.004 (0.98)
(0.1)
(0.2)
(0.12)
8.4
11.7
9.2
1.5
11.6
1.3
1.7
1.3
1.4
0.5
86
56
74
33
84
76
86
82
84
52
a
a
10
30
5
3
3
(0.1)
0.5 (0.0156) 0.6 (0.0156) 3.0 (0.06)
0.45 (0.014)
0.3 (0.009)
0.32 (0.01)
0.64 (0.02)
0.56 (0.014)
0.3 (0.0075) 1.0 (0.02)
0.4 (0.01)
0.6 (0.015)
1.0 (0.02)
(0.014)
(0.008)
Ig
Ih
1.0 (0.02)
0.8 (0.015)
3
5
a
2
-Aminoethanol was used instead of alkali solution.
Table 2. Melting points and elemental analyses of aldehyde azines IIa IIh
Found, %
Comp.
Calculated, %
mp,
C
Formula
no.
C
H
S
N
Cl
C
H
S
N
Cl
IIa
IIb
IIc
IId
IIe
IIf
85
70 72
81.75 5.82
59.85 3.78
12.43
C H N
4 12 2
80.77 5.77
60.60 3.60
60.60 3.60
13.46
10.00 25.60
10.00 25.60
1
10.69 25.74 C H N Cl
10.14 25.90 C H N Cl
1
4
10
2
2
2
205 207 59.62 3.99
151 152 54.66 3.51 29.26 13.36
148 149 41.53 1.69 22.50
191 192 56.65 3.38 33.01
14 10 2
C H N S
0 8 2 2
54.55 3.64 29.09 12.73
1
9.75 24.00 C H Cl N S
41.52 2.06 22.16
56.25 3.12 33.33
50.60 2.41 38.55
48.21 2.68 42.86
9.69 24.57
1
0
6
2 2 2
6.96
8.40
6.45
C H N S
7.29
8.43
6.25
1
8 12 2 4
IIg
IIh
195
125
49.22 2.32 37.89
47.64 2.41 41.56
C H N S
14 8 2 4
C H N S
8 12 2 6
1
intermediate generation of the corresponding thioalde-
hyde which reacts with hydrazine at a higher rate than
does initial aldehyde [7]. Probably, activated sulfide
ions favor cleavage of the carbonyl bond to give
carbocation which is subjected to attack by hydrazine.
Complex formation between hydrazine and sulfide
ions was also presumed by us in the reactions of thiols
and disulfides with dihaloalkanes in the system hydra-
zine hydrate alkali [8]. Moreover, all reactions of
alkyl halides with sulfur solutions in the system
hydrazine hydrate alkali occur under mild conditions
and require no heating; by contrast, they are accom-
panied by heat evolution (unlike sulfur reactions with
alkyl halides in aqueous alcoholic solutions of
alkalies) [9, 10]. These data also support our assump-
tion that activation of sulfur or its derivatives in
basic reductive systems (hydrazine hydrate alkali
among these) involves generation of complexes.
Depending on the electrophile nature, complexes like
III can act as either thionating or aminating agent.
Apart from aqueous alkali, we also used 2-amino-
ethanol to dissolve sulfur [11]. In this case, the molar
ratio sulfur 2-aminoethanol hydrazine hydrate was
1:0.5:5 or 1:1.5:15. The latter ensured a greater
yield of benzaldehyde azine (IIa) from benzaldehyde
(Ia). However, the reaction occurred only on heating
at 75 C for 2 3 h. Probably, the activation of hydra-
zine in complex III is weaker in the absence of
alkali metal cation.
Thus dissolution of sulfur in the system hydrazine
hydrate alkali considerably activates hydrazine via
complex formation with sulfide ions. The developed
procedure ensures effective reactions of hydrazine
with various aldehydes to obtain practically important
aldehyde azines. The products are monomers and
starting compounds for preparation of various hetero-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 10 2002

1
500
RUSSAVSKAYA et al.
Table 3. 1H NMR spectra of aldehyde azines IIa, IIb,
and IId IIh
The IR spectra of II contain an absorption band at
600 cm 1 due to stretching vibrations of the C N
1
bond. The physical constants of previously known
compounds IIa IIc were reported in [4], and of
compound IId, in [5].
Reaction of benzaldehyde with hydrazine in the
system sulfur 2-aminoethanol. Sulfur was dissolved
in the system hydrazine hydrate 2-aminoethanol
Chemical shifts , ppm
Comp.
no.
CH N
Haroma
IIa
IIb
2.71 s 7.88 m (m-H), 7.52 7.50 m (p-H, o-H)
9.02 s 8.21 8.19 m (o-H), 7.43 7.24 m (p-H,
m-H)
(molar ratio 0.03:0.4:0.05), the solution was heated
for 2 3 h at 80 85 C and cooled to room temperature,
and benzaldehyde (Ia) was added. The reaction was
accompanied by heat evolution, but the product did
not separate from the solution. The mixture was
heated for 2 h at 75 C, and benzaldehyde azine (IIa)
precipitated (Table 1).
IId
8.84 s 7.78 d (5-H), 7.62 t (4-H), 7.20 d
(3-H)
IIe
IIf
8.55 s 7.15 d (4-H), 6.92 d (3-H)
8.6 d 7.28 m
IIg
IIh
8.76
8.53
7.54 m
7.24 m
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General procedure for preparation of aldehyde
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sulfur, and hydrazine hydrate (molar ratio 1:1:1) was
prepared in a three-necked flask equipped with
a stirrer, reflux condenser, thermometer, and adapter
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 38 No. 10 2002