Organosilyl isocyanates. Reactions with hydrazine, 1,1-dimethylhydrazine, and 1-methyl-1-[2-(1-methylhydrazino)ethyl]hydrazine and structural and electronic characteristics

Article abstract of DOI:10.1007/s11176-006-0016-0

Reactions of organosilyl isocyanates with hydrazine, 1,1-dimethylhydrazine, and 1-methyl-1-[2-(1-methylhydrazino)ethyl]hydrazine provide a facile synthetic route to urea and previously unknown semicarbazides. Quantum chemistry was used to study the structure and electronic properties of (chloromethyl)- dimethylsilyl isocyanate and (chlorodimethylsilyl)methyl isocyanate and to obtain the thermodynamic parameters of their isomerization.

Full text of DOI:10.1007/s11176-006-0016-0

Russian Journal of General Chemistry, Vol. 75, No. 12, 2005, pp. 1930 1934. Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 12, 2005,
pp. 2021 2025.
Original Russian Text Copyright
2005 by Kirilin, Belova, Knyazev, Lega, Petrov, Chernyshev.
Organosilyl Isocyanates. Reactions with Hydrazine,
1,1-Dimethylhydrazine,
and 1-Methyl-1-[2-(1-Methylhydrazino)ethyl]hydrazine
and Structural and Electronic Characteristics
A. D. Kirilin, L. O. Belova, S. P. Knyazev, A. V. Lega,
M. Yu. Petrov, and E. A. Chernyshev
Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow, Russia
Received January 28, 2005
Abstract Reactions of organosilyl isocyanates with hydrazine, 1,1-dimethylhydrazine, and 1-methyl-1-[2-
(1-methylhydrazino)ethyl]hydrazine provide a facile synthetic route to urea and previously unknown semi-
carbazides. Quantum chemistry was used to study the structure and electronic properties of (chloromethyl)-
dimethylsilyl isocyanate and (chlorodimethylsilyl)methyl isocyanate and to obtain the thermodynamic
parameters of their isomerization.
Previously we studied the reactions of 1,1-di-
methylhydrazine and its trimethylsilyl derivatives with
carbon dioxide [1], carboxylic acid anhydrides [2, 3],
chloro(chloromethyl)dimethylsilane [3], and alkoxy-
dimethylsilanes and silaethylenes [4]. These reactions
not only allowed us to prepare previously unknown
linear and heterocyclic compounds, but also to
find practical application for some of them [5 7].
Proceeding with this research, we established that
hydrazine, 1,1-dimethylhydrazine (I), or 1-methyl-1-
[2-(1-methylhydrazino)ethyl]hydrazine (II) readily
react with organosilyl isocyanates to form previously
unknown semicarbazides.
It is known that organosilyl isocyanates are
aminated similarly to organic isocyanates [8], i.e. via
addition by the double bond, to form silylated ureas
III and IV.
RNHC(O)NHSiMe3
RNH2
Me3SiNCO
III
[Me3SiNHC(O)NH(CH2)6NHC(O)NHSiMe3]
H2N(CH2)6NH2
IV
With diamines, the reaction does not stop on the
formation of disilylureas and gives polyureas as final
products.
could isolate no other products than organic mono-
meric compounds: 1,1-dimethylsemicarbazide (VIIa),
1-(carbamoyl)semicarbazide (VIIb), and 1,1 -ethylene-
bis(1-methylsemicarbazide) (VIII). The formation of
semicarbazides VIIa, VIIb, and VIII in reactions a c
makes it safe to state that the process involves forma-
tion of unstable trimethylsilyl derivatives Va, Vb,
IV
[ (CH2)6NHC(O)NH]n + (Me3Si)2O
+ Me3SiN=C=NSiMe3 + (Me3Si)2NH + NH3.
By involving in this reaction other nitrogen-contain- and VI.
ing compounds that also contain one or two terminal
NH2 groups, such as hydrazine, dimethylhydrazine I,
or dihydrazine II, we expected, like with amines and
diamines, to obtain (trimethylsilyl)semicarbazide V
and polysemicarbazides. However, in all the cases we
Trimethylsilyl isocyanate behaves ambiguously in
reactions with other difunctional nitrogen-containing
compounds. It was previously shown that the reaction
with hydroxylamine hydrochloride [9] readily pro-
1070-3632/05/7512-1930 2005 Pleiades Publishing, Inc.

ORGANOSILYL ISOCYANATES
1931
[Me2NNHC(O)NHSiMe3]
Me2NNHC(O)NH2
Va
VIIa
a
Me2NNH2
H2NNH2
Me3SiNCO
[Me3SiNHC(O)NHNHC(O)NHSiMe3]
H2NC(O)NHNC(O)NH2
b
Vb
VIIb
H2NNC2H4NNH2
Me Me
c
[Me3SiNHC(O)NHNC2H4NNHC(O)NHSiMe3]
Me
H2NC(O)NHNC2H4NNHC(O)NH2
Me
Me
Me
VI
VIII
vides N-[(trimethylsilyl)oxy]urea whose hydrolysis
gives rise to hydroxyurea in a yield of 95%.
H2NNH2 HCl + Me3SiNCO
[Me3SiNHC(O)NHNHC(O)NHSiMe3]
VIIb.
HONH2 HCl + Me3SiNCO
Et3N
H2O
H2NC(O)NHOSiMe3
H2NC(O)NHOH.
(Chlorodimethylsilyl)methyl isocyanate (IX), too,
behaves in a similar way. Regardless of the presence
of two reaction centers, it reacts with 1,1-dimethyl-
hydrazine exclusively by the C=N bond to form (tri-
methylsilyl)urea X that readily converts to semicar-
bazide VIIa.
However, attempted synthesis of 1-[(dimethylsilyl)-
carbamoyl]-4-(trimethylsilyl)semicarbazide (Vb) or
its analog, 1-carbamoylsemicarbazide (VIIb), with
the use of hydrazine hydrochloride failed.
[Me2NNHC(O)NHSiMe3]
VIIa
Me2NNH2
X
Me2NNHCH2SiMe2NCO
ClCH2SiMe2NCO
XI
The absence from the reaction products of com-
pound XI is indicative of an extremely high reactivity
of the isocyanato group. This fact prompted us to study
in more detail certain properties of compound IX.
tion of isomer IXb in the mixture. Moreover, addition
of pyridine, by contrast to data in [9], produces an
only short increase of the faction of (chlorodimethyl-
silyl)methyl isocyanate, and subsequently it becomes
even smaller than before. Evidence for these finding
was obtained from the 1H NMR spectrum (IXa:IXb =
90:10). Such a divergence of our from published data
induced us to perform computer modeling
(GAUSSIAN-98 and HyperChem) of isocyanates IXa
Ammonolyis of (chlorodimethylsilyl)methyl iso-
cyanate (IX), too, involved the isocyanato group only,
and the resulting silylurea XII equally readily con-
verted into urea XIII.
NH3
IX
[ClCH2SiMe2NHC(O)NH2]
H2NC(O)NH2.
IXb, %
Pyridine
20
XII
XIII
16
12
There has been evidence in the literature [9] that
isocyanate IX can exist as a mixture of isomers IXa
and IXb. We examined this issue in more detail.
8
4
150 C
ClCH2SiMe2NCO
OCNCH2SiMe2Cl.
2
4
6
8
10 12 14 16 18 20
Time, h
IXa
IXb, 30%
It was found that prolonged boiling (see figure) of
isocyanate IXa does not appreciably increase the frac-
Change in the concentration of (chlorodimethylsilyl)-
methyl isocyanate (IXb) with time on heating.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 12 2005

1932
KIRILIN et al.
Table 1. Parameters of Me2(ClCH2)Si(N=C=O) and
Me2(CH2N=C=O)SiCl and their isomerization as given by
PM3, B3LYP/6-31G**, and B3LYP/6-311+G** calcula-
tions (GAUSSIAN-98)
sets including diffuse and polarization d and p func-
tions: 6-31G(d, p) and 6-311+G(d, p). Correlation
corrections were included by the B3LYP DFT proce-
dure. The input parameters for the thermodynamic
functions H, S, and G were the following: 298.15 K
(25 C)/1 atm (standard conditions); 323.15 K (50 C)/
B3LYP/
B3LYP/
Parameter
PM3
6-31G** 6-311G** 1 atm, 373.15 K (100 C)/1 atm, 423.15 K (150 C)/
1 atm, 473.15 K (200 C)/1 atm, and 523.15 K
Me2(ClCH2)Si(N=C=O)
1498.5557
(250 C)/1 atm.
1
Eb, kcal mol
d(Si N),
d(N=C),
The optimization of the reagent and product
molecules was performed with higher accuracy with
setting the Tight option. The calculation of normal
mode vibrations and thermodynamic parameters of all
the systems was initiated by the Freq command.
1.761
1.232
1.190
1.737
1.199
1.180
1.740
1.195
1.172
d(C=O),
Si N=C, deg
EHOMO, eV
ELUMO, eV
E, eV
140
178
177
9.612
0.235
9.377
7.608
0.001
7.607
7.887
0.603
7.284
Structure optimization and calculation of thermo-
dynamic functions were performed in the approxima-
tion of isolated molecule in the ground singlet state.
The calculation of the initial and final reaction
products involved control for the absence of ima-
ginary frequencies.
Me2(CH2N=C=O)SiCl
1498.6760
1
Eb, kcal mol
d(Si Cl),
d(C=N),
d(C=O),
2.123
1.258
1.180
2.104
1.206
1.820
2.104
1.198
1.175
C N=C, deg
EHOMO, eV
ELUMO, eV
E, eV
139
140
141
The starting Me2(ClCH2)Si(N=C=O) molecule had
Cs symmetry [the Si N=C=O group is almost linear
9.937
0.186
9.751
7.2539139
0.2957727
7.5496866
7.598
0.697
6.901
H
Me2(ClCH2)Si(N=C=O)
Me2(CH2N=C=O)SiCl
1
H
C
Er, kJ mol
Hr, kJ mol
Sr, kJ mol
Gr, kJ mol
0.120
0.120
0.675
0.454
1.478
0.014
0.023
1.020
50.48
0.479
H
H
1
0.714
1.880
1.276
2.150
0.166
14.27
1
C
Cl
1
O=C=N Si
H
lnK
K
H
C
Concentration of
Me2(CH2N=C=O)
SiCl, %
H
H
Cs
(Si N=C angle 177 178 )] and no imaginary fre-
quencies in all the approximations.
and IXb. As a result, we obtained structural, elec-
tronic, and thermodynamic parameters of these
molecules in the range 25 250 C.
With Me2(CH2N=C=O)SiCl, a Cs molecule cor-
responds to the first-order saddle point on the poten-
tial energy and has an imaginary frequency of
Molecular design and preliminary geometry opti-
mization were performed using the HyperChem
program in the MM+ molecular mechanics and PM3
semiempirical approximations. The main task to be
solved on this step was to find initial geometrical
parameters of the molecules, required for GAUSSIAN-
98 computations. All structures were optimized to
potential energy minima to a gradient accuracy of
Cl
H
C
Si
C
H
C
H
H
H
H
H
H
3
1
no less than 10 kcal 1 mol for the molecular
N
C
mechanics method and 10 kcal 1 mol for the
3
1
PM3 method.
O
The nonempirical calculations were performed by
the RHF procedure with extended split valence basis
Cs
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 12 2005

ORGANOSILYL ISOCYANATES
1933
Table 2. Parameters of the reaction Me2(ClCH2)Si(N=C=O)(CS)
Me2(CH2N=C=O)SiCl(NS) as given by 6-
31G**/B3LYP and 6-311+G**/B3LYP calculations (GAUSSIAN-98)
Temperature, K
Parameter
298.15
323.15
373.15
423.15
473.15
523.15
6-31+G**/B3LYP
a
1
E, kcal mol
H, kcal mol
0.675
0.454
1.478
0.014
0.023
1.020
50.48
1a
0.462
1.503
0.023
0.036
0.970
49.25
0.479
1.553
0.100
0.034
0.894
47.20
0.498
1.599
0.179
0.212
0.838
45.58
0.516
1.640
0.259
0.275
0.795
44.29
0.534
1.675
0.343
0.329
0.760
43.18
S, cal mol 1 K
1
1
G, kcal mol
lnK
K
Concentration of
Me2(CH2N=C=O)SiCl, %
6-311+G**/B3LYP
a
1
1
E, kcal mol
H, kcal mol
0.479
0.714
1.880
1.276
2.150
0.166
14.27
0.708
1.904
1.323
2.057
0.180
15.24
0.691
1.951
1.419
1.911
0.203
16.89
0.673
0.655
2.035
1.618
1.719
0.238
19.26
0.638
2.070
1.721
1.653
0.252
20.13
S, cal mol 1 K
1.996
1.517
1.802
0.222
18.20
1
1
G, kcal mol
lnK
K
Concentration of
Me2(CH2N=C=O)SiCl, %
a
Total energy corresponding to the minimum on the potential energy surface (not related to temperature).
energies of isomeric silyl isocyanates. However,
noteworthy is the fact that, according to the more
precise 6-311+G**/B3LYP calculation, Me2(ClCH2)
Si(N=C=O) (IXa) possesses a higher thermodynamic
stability and prevails in the equilibrium system.
Cl
H
C
Si
C
H
C
H
H
H
C
H
EXPERIMENTAL
H
H
The IR spectra were obtained on a Specord IR-75
instrument in thin films (for liquids) or in mineral oil
N
1
(for solids). The H NMR spectra were recorded on a
Bruker WP-8 instrument (80 MHz), solvent and
internal reference CDCl3.
O
C1
All starting materials and solvents were thoroughly
dried and distilled before use. Synthetic operations,
isolation, and sampling for analysis were carried out
under dry nitrogen. The mixtures and pure com-
pounds were controlled by GLC on a Shimadzu G-8
instrument (1500 3-mm stainless-steel columns
packed with SE-30 on Chromaton N-AW, carrier gas
helium).
1
1
25.8238 cm (B3LYP/6-311+G**) [ 33.3481 cm
(B3LYP/6-31G**)] that relates to A antisymmetric
vibrations that lead to a loss of the Cs symmetry plane
and a decrease of the molecular symmetry to C1.
Calculation of the Me2(CH2N=C=O)SiCl molecule
with C1 symmetry gives a stationary point on the total
potential energy surface, that corresponds to the
potential energy minimum over all the coordinates.
1,1-Dimethylsemicarbazide (VIIa). a. A mixture
of 4.66 g of 1,1-dimethylhydrazine, 8.94 g of tri-
methylsilyl isocyanate, and 50 g of hexane was kept
for 1 h at 60 C. The precipitate was filtered off. Yield
Varied-temperature isomerization thermodynamic
parameters were calculated by including additional
steps with setting required temperature points
(Table 1). The resulting data (Table 2) point to close
1
5.37 g (67%), mp 159 161 C. IR spectrum, , cm :
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 12 2005

1934
KIRILIN et al.
3200 (NH), 1640 and 3440 (NH2). 1H NMR spectrum,
, ppm: 2.92 s (6H, NCH3), 3.71 s (1H, NH), 4.37 s
(2H, NH2). Found, %: C 34.83; H 8.94; N 40.40.
C3H9N3O. Calculated, %: C 34.94; H 8.80; N 40.73.
REFERENCES
1. Sheludyakov, V.D., Kirilin, A.D., Gusev, A.I., Shara-
pov, V.A., and Mironov, V.F., Zh. Obshch. Khim.,
1976, vol. 46, no. 12, p. 2712.
b. A mixture of 6.82 g of compound IX, 9.50 g of
1,1-dimethylhydrazine, and 50 g of hexane was kept
for 1 h at 60 C. The precipitate was filtered off. Yield
9.96 g (61%), mp 160 162 C.
2. Sheludyakov, V.D., Rodionov, E.C., Kirilin, A.D., and
Mironov, V.F., Zh. Obshch. Khim., 1976, vol. 46,
no. 10, p. 2265.
3. Kirilin, A.D., Dokuchaev, A.A., Sokova, N.B., and
Chernyshev, E.A., Izv. Ross. Akad. Nauk, Ser. Khim.,
1999, no. 1, p. 169.
1-(Carbamoyl)semicarbazide (VIIb). A mixture
of 5.37 g of hydrazine, 38.62 g trimethylsilyl iso-
cyanate, and 100 g of hexane was kept for 6 h at 60 C.
The precipitate was filtered off. Yield 27.17 g (62%),
4. Kirilin, A.D., Belova, L.O., Lakhtin, V.G., Lega, A.V.,
Petrov, M.Yu., and Chernyshev, E.A., Zh. Obshch.
Khim., 2005, vol. 75, no. 9, p. 1474.
1
mp 247 248 C. IR spectrum, , cm : 3330 and 1580
(NH2), 3160 (NH), 1680 (C=O). Found, %: C 20.57;
H 5.37; N 47.58. C2H6N4O2. Calculated, %: C 20.34;
H 5.13; N 47.45.
5. Kirilin, A.D., Dokuchaev, A.A., Sokova, N.B., Patske-
vich, A.V., and Chernyshev, E.A., Zh. Obshch. Khim.,
2000, vol. 70, no. 1, p. 51.
1,1 -Ethylenebis(1-methylsemicarbazide) (VIII).
A mixture of 4.07 g of 1,1 -ethylenebis(1-methyl-
hydrazine), 7.94 g of trimethylsilyl isocyanate, and
50 g of hexane was kept for 8 h at 60 C. The preci-
pitate was filtered off. Yield 8.18 g (68%), mp 186
6. Donskoi, A.A., Baritko, N.V., Evseeva, V.A., Zaitse-
va, E.I., Kirilin, A.D., Belova, L.O., Chernyshev, E.A.,
Shapatin, A.S., and Trebukova, E.A., RU Patent
218841, Byull. Izobret., 2002, no. 10.
1
188 C. IR spectrum, , cm : 3430 and 1570 (NH2),
7. Belova, L.O., Cand. Sci. (Chem.) Dissertation, Moscow,
3160 (NH), 1660 (C=O). Found, %: C 35.38; H 7.79;
N 41.01. C6H16N6O2. Calculated, %: C 35.27; H 7.91;
N 41.15.
2003.
8. Kozyukov, V. P., and Mironov, V.F., Organosilyl
Preudohalides and Their Use in Organic Synthesis,
Moscow: NIITEKhim, 1985.
Urea (XIII). Ammonia was passed through a solu-
tion of 30 g of (chlorodimethylsilyl)methyl isocyanate
(IX), and 150 g of chloroform for 1 h at ambient
temperature. Yield 8.67 g (72%), mp 132 133 C.
9. Muzovskaya, E.V., Cand. Sci. (Chem.) Dissertation,
Moscow, 1988.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 75 No. 12 2005