Reaction of organosilicon derivatives of 1,1-dimethylhydrazine with methyl iodide

Full text of DOI:10.1007/s10631-005-0012-7

Doklady Chemistry, Vol. 400, Part 2, 2005, pp. 17–20. Translated from Doklady Akademii Nauk, Vol. 400, No. 4, 2005, pp. 483–486.
Original Russian Text Copyright © 2005 by Voronkov, Gostevskii, Shainyan, Rakhlin, Mirskov, Makarova.
CHEMISTRY
Reaction of Organosilicon Derivatives
of 1,1-Dimethylhydrazine with Methyl Iodide
Academician M. G. Voronkov, B. A. Gostevskii, B. A. Shainyan,
V. I. Rakhlin, R. G. Mirskov, and O. S. Makarova
Received October 27, 2004
The reactions of haloalkanes with 1,1-dimethylhy- CHCl3, or CH2Cl2 even under long heating to 100°ë.
drazine (DMH) give 1,1-dimethyl-1-alkylhydrazonium The reaction easily proceeds in acetonitrile but still
salts, which possess practically valuable properties does not give the expected (Me3Si)2NN+ Me3 I– salt.
[1−3]. Similar reactions of organosilicon derivatives Instead, the cleavage of the Si–N bond by the acetoni-
of DMH have not been studied. To study these reac- trile molecule proceeds almost quantitatively:
tions, we synthesized organosilicon DMH deriva-
(Me3Si)2NNMe2 + MeI + MeCN
Me2NNHSi(Me)2Si(Me)2NHNMe2 (3), (Me3Si)2NNMe2
[Me3SiNHNMe3]+I– + Me3SiCH2N.
tives: Me3SiNHNMe2 (1), (EtO)3SiNHNMe2 (2),
(4), and (Me3Si)(Cl3Si)NNMe2 (5).
Compounds 1–3 were prepared by reactions of the
corresponding triorganylchlorosilanes with DMH in
ether [4]. Previously, compounds 4 and 5 were prepared
by the reaction of lithiated 1,1-trimethyl-2-triorganyl-
silylhydrazines with chlorosilane according to the fol-
lowing pattern [5]:
We suggested that this reaction gives intermediately
1,1,1-trimethyl-2,2-bis(trimethylsilyl)hydrazinium
iodide [(Me3Si)2NHNMe3]+I–, which is a good silylat-
ing agent able to silylate CH-acids. To verify this
assumption, we studied the reactions of compound 4
with MeI, phenylacetylene, and trimethylpropargyloxy-
silane. However, these reactions do not proceed in
nonpolar solvents, while, in acetonitrile, only
[Me3SiNHNMe3]+I– and Me3SiCH2CN were isolated.
Not even traces of silylation products of the acetylene
CH bond were detected by GLC with reference com-
pounds. Therefore, the reaction mechanism requires
further investigation.
R3SiNLiNMe2 + R13 SiCl
(R3Si)(R13 Si)NNMe2.
We developed a method for the synthesis of 4 and 5
in yields of up to 80% by the reaction of 1 with trior-
ganylbromosilanes in the presence of triethylamine:
Et3N
–Et3NH+Br
R3SiNHNMe2 + R13SiBr
(R3Si)(R13Si)NNMe2,
The reaction of DMH with Me3SiCl differs qualita-
tively from its reaction with MeI and other primary
alkyl halides. Whereas methylation involves the Me2N
group, silylation involves the NH2 group. The reaction
route may be influenced by the steric factor. Indeed,
branched organyl halides (isopropyl iodide, picryl chlo-
ride, 2,4-dinitrochlorobenzene) do not quaternize
DMH but yield 1,1-dimethyl-2-organylhydrazines [6].
However, the formation of sterically strained
(Me3Si)2NNMe2 in the reaction of 1 with Me3SiBr indi-
cates that the reaction pathway is determined by not
only steric but also electronic factors. To elucidate the
reasons for the different behaviors of DMH toward
alkylation and silylation, we carried out calculations for
the reactants and the reaction products using the
MP2/6-31G(d) method, which gives the most chemi-
cally reasonable charges on atoms [7]. The Mulliken
charges, the electrostatic charges, and the degrees of local-
ization of the HOMO on the nitrogen atoms in DMH and
compounds 1 and 4 are summarized in Table 1.
R = Me; R1 = Me, Cl.
The reactions of organosilicon DMH derivatives
with MeI were carried out in evacuated glass tubes in
ether or acetonitrile. Compounds 1–3 readily react with
MeI to give products in almost quantitative yields:
R3SiNHNMe2 + MeI
[R3SiNHNMe3]+I–,
2
R = Me, EtO.
[Me2NNHSiMe2]2
+ MeI
[Me3N+NHSiMe2]22I–.
The reactions of compounds 4 and 5 with MeI fol-
low an unexpected route. Compound 5 does not react
with MeI in low-polarity solvents or acetonitrile. Com-
pound 4 also does not react with MeI in ether, THF,
Calculations for MeCl and Me3SiCl attest that silyl-
ation is largely dictated by charge control, while alkyl-
ation is under orbital control. This is indicated by the
Favorsky Institute of Organic Chemistry,
Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
0012-5008/05/0002-0017 © 2005 Pleiades Publishing, Inc.

18
VORONKOV et al.
Table
Contributionofnitrogen
AOs to the HOMO
Molecule
Atom
Mulliken charge
Electrostatic charge
H2N1–N2Me2
N1
N2
N1
N2
N1
N2
C
–0.647 (0.012)*
–0.393
–0.799 (–0.071)
–0.135
5.0%
53.7%
34.7%
18.6%
11.4%
47.2%
Me3SiN1H–N2Me2
–0.738 (–0.403)
–0.384
–0.757 (–0.394)
–0.188
1
2
**
(Me3Si)2N –N Me2
–0.830
–0.711
–0.401
–0.184
MeCl
–0.536 (0.103)
1.079
–0.096 (0.205)
0.922
Me3SiCl
Si
* The values in parentheses are the charges on heavy atoms summed with the charges on their bonded hydrogen atoms.
** HF/6-31G(d) calculations.
4 toward MeI is due to the decreased basicity of the N2
atom, as indicated by its less pronounced pyramidality
compared with both DMH and compound 1.
relatively small positive charge of the methyl group in
the MeCl molecule and the great positive charge on the
silicon atom in Me3SiCl. This means that DMH should
be alkylated at the N2 atom, whose atomic orbitals
The best localization of the HOMO on the N2 atom
make the greatest contribution to the HOMO, while in the DMH molecule is due to the electron-donating
silylation of DMH should be directed at the N1 atom,
having the greatest negative charge. According to the
calculation for the isomeric H2NN+Me3 and
effect of the two methyl groups, while that in molecule 4
is due to the low basicity of the N1 atom in the planar
NNSi2 fragment. The molecule of 1 retains the pyrami-
dality of N1, but the pyramidality of N2 decreases,
resulting in some equalization of the contributions of
these atoms to the HOMO. Therefore, to interpret the
direction of methylation of compound 1, we carried out
the HF/6-31G(d) calculation of the isomeric
Me3SiNHN+Me3 and Me3SiN+HMeNMe2 cations (the
MP2/6-31G(d) calculation would be impracticable due
to the large size of the system). In this case, methylation
at N2 proves to be more favorable, although the differ-
ence between the methylation energies (3.85 kcal/mol)
is smaller than that for DMH (for DMH, this value is
6.05 kcal/mol at the HF/6-31G(d) level).
MeN+H2NMe2 cations, the methylation at the N2 atom
is 7.9 kcal/mol more favorable than that at the N1 atom.
Upon consecutive introduction of Me3Si groups to the
N1 atom, the negative charge on this atom and the Mul-
liken charge difference increase, ∆q(N1M – NM2 ) =
0.254, 0.354, 0.429, while the electrostatic charge and
the charge difference decrease, ∆q( N1el – Ne2l ) = 0.664,
0.569, 0.527. Nevertheless, in all cases, N1 bears a
much greater negative charge than N2. The reaction of
compound 4 with a second Me3SiCl molecule is subject
to charge control and also involves the N1 atom. The
contributions of the N1 and N2 AOs to the HOMOs of
the calculated molecules (Table 1) are markedly differ-
ent. For DMH and compound 4, the HOMO is mainly
localized on the N2 atom, while, for compound 1, the
contribution of the N1 AO is almost twice that of the N2
AO. These differences might be due to the change in the
EXPERIMENTAL
1H and 29Si NMR spectra were recorded on a Bruker
DPX-400 instrument operating at 400 and 80 MHz,
respectively, for 10–20% solutions in CDCl3, CD3CN,
or DMF-d7 using Me4Si as the internal standard.
GLC analysis was performed on a Tsvet-500 chro-
atom pyramidality upon the introduction of Me3Si matograph with a heat conductivity detector using 3 m ×
4 mm glass columns, the Inerton-super 0.125–0.150 mm
sorbent impregnated with 10% PMS-1000, and helium
as the carrier gas.
groups into DMH. The Me3SiN fragment is stabilized
via conjugation of the nitrogen lone pair with the Me3Si
group, resulting in flattening of the pyramid, i.e., in an
increase in the sum of angles around the N1 atom from
322.4° for DMH to 351.8° for compound 1 and 359.2°
for the nearly planar NNSi2 fragment in 4. The sum of
1. Synthesis of Organosilicon Derivatives
of 1,1-Dimethylhydrazine
the bond angles around N2 varies as 330.1°, 330.7°, and
342.3° in the same series; i.e., the hybridization of nitro-
gen does not change on introduction of the first Me3Si
group but markedly changes after the introduction of
the second Me3Si group. Thus, the lack of reactivity of
1.1. Trimethyl(2,2-dimethylhydrazino)silane 1.
A solution of DMH (192 g, 3.2 mol) in 250 mL of
anhydrous ether was charged into a three-necked flask
equipped with a stirrer, a dropping funnel, a reflux con-
denser, and a calcium chloride tube. The solution was
DOKLADY CHEMISTRY Vol. 400 Part 2 2005

REACTION OF ORGANOSILICON DERIVATIVES
19
cooled to 7°ë and Me3SiCl (167 g, 1.6 mol) was added
dropwise. The reaction mixture was stirred for 1 h at
room temperature and for 1 h at reflux. The precipitate
was collected on a Schott filter and washed with anhy-
drous ether. The combined filtrates were concentrated
and the residue was distilled to give 113 g (86%) of
2. Reactions of Organosilicon Derivatives
of 1,2-Dimethylhydrazine with MeI
2.1. A mixture of compound 1 (5 g, 0.037 mol), MeI
(5.3 g, 0.037 mol), and 30 mL of anhydrous ether was
kept in an evacuated glass tube for 1 h and the precipi-
tate was filtered off, washed with anhydrous ether (2 ×
10 mL), and dried in vacuum to give 9.2 g (89%) of
[Me3N+NHSiMe3]I–, mp 158°ë. 1H NMR (CD3CN), δ,
ppm: 0.313 (s, 9H, Siëç3), 3.50 (s, 9H, NCH3), 5.86 (s,
compound 1, bp 96–101°ë, n2D0 1.4016 (lit.: bp 100°ë,
n2D0 1.4018 [4]).
1H, NH). 29Si NMR (CD3CN), δSi, ppm: 8.86.
1.2. Triethoxy(2,2-dimethylhydrazino)silane 2
was prepared in a similar way using DMH (6.43 g,
0.27 mol) and (EtO)3SiCl (26.6 g, 0.13 mol) in 50 mL
of anhydrous ether. This gave 15 g (50%) of compound 2,
2.2. A mixture of compound 2 (4 g, 0.017 mol), MeI
(2.69 g, 0.019 mol), and 20 mL of CH3CN was placed
into a glass tube; warming-up to 50°ë was observed.
The mixture was heated for 4 h at 90°ë. The volatile
compounds were recondensed into a clean glass tube at
0.5 mm Hg. The remaining crystalline material was
washed with anhydrous ether (2 × 40 mL) and dried at
0.5 mm Hg to give 4.4 g (97%) of the salt
[(EtO)3SiNHN+Me3]I–, mp 121–124°ë (in an evacu-
ated capillary). 1H NMR (CD3CN), δ, ppm: 1.25 (t, 9H,
ëç3C), 3.60 (s, 9H, NCH3), 3.95 (q, 6H, CH2O), 6.51
(s, 1H, NH). 29Si NMR (CD3CN), δSi, ppm: –76.98.
bp 65–70°ë (5 mm Hg), n2D0 1.4025. 1H NMR (CDCl3),
δ, ppm: 1.23 (t, 9H, CH3C), 2.44 (s, 6H, CH3N), 3.86
(q, 6H, CH2).
For C8H22Si1N2O3 anal. calcd. (wt %): C, 43.04; H,
9.86; N, 10.31; Si, 13.00.
Found (wt %): C, 43.17; H, 9.88; N, 10.23; Si, 13.03.
1.3. 1,1,2,2-Tetramethyl-1,2-(2',2'-dimethylhy-
drazino)disilane 3. A mixture of 1,1,2,2-tetramethyl-
1,2-dichlorodisilane (8.2 g) and DMH (13 g) in 60 mL
of anhydrous ether was heated in an evacuated glass
tube for 5 h at 90°ë. The precipitate was filtered off and
washed (2 × 50 mL) with anhydrous ether. The com-
bined filtrates were concentrated and the residue was
distilled in vacuum to give 7.3 g (69.4%) of compound 3,
2.3. A mixture of compound 3 (3.1 g, 0.013 mol),
MeI (5 g, 0.044 mol), and 20 mL of CH3CN was placed
into an evacuated glass tube. The reaction mixture
warmed up to 50°ë and a crystalline precipitate formed.
After 1 h, the crystals were filtered off and washed with
anhydrous CH3CN (2 × 10 mL) to give 6.4 g (93%) of the
salt I–[Me3N+NH(Me)2SiSi(Me)2HNN+Me3]I–, mp
1
bp 75°ë (10 mm Hg), n2D8 1.4484. 1H NMR (CDCl3), δ,
ppm: 0.14 (s, 12H, SiCH3), 2.00 (s, 2H, NH), 2.37 (s,
12H, NCH3). 29Si NMR (CDCl3), δSi, ppm: –10.91.
156°ë (in an evacuated capillary; decomp.). H NMR
(DMF-d7), δ, ppm: 0.19 (s, 12H, CH3C), 3.51 (s, 18H,
NCH3).
2.4. A mixture of compound 4 (5 g, 0.024 mol), MeI
(6 g, 0.042 mol), and 15 mL of CH3CN was heated in
an evacuated glass tube for 30 h at 100°ë. The volatile
compounds were recondensed into a clean glass tube at
0.5 mm Hg. The residue was washed with anhydrous
ether (2 × 10 mL) and dried in vacuum to give 5.3 g
(80.8%) of the salt [Me3N+NHSiMe3]I– as yellowish
crystals, mp 158°ë (decomp.). The 1H NMR spectrum
is identical to that given in Section 2.1. Vacuum frac-
tionation of the condensed liquid fraction gave 2.2 g
(92%) of Me3SiCH2CN, bp 71°ë (30 mm Hg), n2D0
1.4213 (lit.: bp 82–84°C (54 mm Hg), n2D0 1.4203 [8]).
1.4. 1,1-Bis(trimethylsilyl)-2,2-dimethylhydrazine 4.
A mixture of compound 1 (14 g, 0.1 mol), Me3SiBr
(15 g, 0.09 mol), Et3N (10 g, 0.09 mol), and 100 mL of
anhydrous ether was heated in an evacuated glass tube
for 100 h at 90°ë. The precipitate was filtered off and
washed with anhydrous ether (2 × 50 mL). The com-
bined filtrates were concentrated and distilled in vac-
uum to give 16.8 g (84%) of compound 4, bp 63°ë
(13 mm Hg), n2D0 1.4360 (lit.: bp 67°ë (12 mm Hg),
n2D0 1.4390 [5]).
1.5. 1-Trimethylsilyl-1-trichlorosilyl-2,2-dimethyl-
hydrazine 5. A mixture of compound 1 (20 g,
0.151 mol), BrSiCl3 (32.4 g, 0.151 mol), Et3N (17 g,
017 mol), and 80 mL of anhydrous ether was heated in
an evacuated glass tube for 10 h at 90°ë. The precipitate
was filtered off and washed with anhydrous ether (2 ×
50 mL). The combined filtrates were concentrated and
distilled to give 23.1 g (57.5%) of compound 5, bp
Heating of a mixture of compound 4 (5 g, 0.024 mol)
and MeI (6 g, 0.042 mol) in 15 mL of THF, ether,
CH2Cl2, or CHCl3 in an evacuated glass tube for 54 h at
100°ë did not result in the formation of a precipitate.
GLC of the reaction mixture showed only the starting
compounds, which were recovered unchanged by dis-
tillation.
2.5. Reaction of compound 4 with MeI in the pres-
ence of terminal acetylenes. A mixture of compound 4
(5 g, 0.024 mol), MeI (6 g, 0.042 mol), and a terminal
acetylene derivative (0.05 mol) in 15 mL of a solvent
was heated in an evacuated glass tube for 30 h at 95°C.
92−95°ë (10 mm Hg), n2D0 1.4688. 1H NMR (CDCl3),
29
δ, ppm: 0.34 (s, 9H, SiCH3), 2.77 (s, 6H, CH3N). Si
NMR (CDCl3), δSi, ppm: –66.15 (SiCl3), 10.80
(SiCH3).
DOKLADY CHEMISTRY Vol. 400 Part 2 2005

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VORONKOV et al.
2. Lopyrev, V.A., Dolgushin, G.V., and Laskin, B.M., Ross.
Khim. Zh., 2001, vol. 14, no. 5–6, pp. 149–156.
Phenylacetylene or trimethylpropargyloxysilane was used
as the acetylene derivative, and CCl4, CH2Cl2, CHCl3, and
CH3CN were used as solvents. In the first three solvents,
the reaction does not proceed, the starting compounds
being recovered unchanged. In acetonitrile, the reaction
gives Me3CH2CN and [Me3N+NHSiMe3]I– in an almost
quantitative yield within 20 h. According to GLC analysis
with reference compounds, products of triple bond silyla-
tion are not formed even in trace amounts.
3. Kochkina, E.N., Belobrzhetskaya, M.K., and Lokteva, N.V.,
Zh. Prikl. Khim. (S.-Peterburg), 1999, vol. 72, no. 12,
pp. 1964–1970.
4. Fomina, A.N., Cand. Sci. (Chem.) Dissertation, Irkutsk:
Irkutsk Inst. of Chem., 2002.
5. Wannagat, U. and Brandstaffer, V., Monatsh. Chem.,
1966, vol. 97, p. 976.
ACKNOWLEDGMENTS
6. Kirichenko, V.V., Koshokova, A.V., and Drozdetskii, A.G.,
This work was supported by the Presidium of the
Siberian Division of the RAS, project no. 114.
Zh. Org. Khim., 1987, vol. 23, no. 10, pp. 2100–2104.
7. Foresman, J.B. and Frisch, A., Exploring Chemistry with
Electronic Structure Methods, Pittsburgh: Gaussian,
Inc., 1996.
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1. Lopyrev, V.A., Dolgushin, G.V., and Voronkov, M.G.,
Zh. Prikl. Khim. (S.-Peterburg), 1998, vol. 71, no. 8,
pp. 1233–1248.
8. Prober, M., J. Am. Chem. Soc., 1956, vol. 78, no. 10,
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DOKLADY CHEMISTRY Vol. 400 Part 2 2005