Reaction of hexamethyldisilazane with cyclic anhydrides of organic acids: A new route to N-trimethylsilylimides of di- and tetracarboxylic acids

Article abstract of DOI:10.1023/B:RUGC.0000031854.10831.a9

Cyclic anhydrides of di- and tetracarboxylic acids react with hexamethyldisilazane to give the corresponding N-trimethylsilylimides in 90-96% yields. However, cyclic anhydrides of succinic, 4-nitrophthalic, and tetrachlorophthalic acids react differently, giving acyclic trimethylsilyl esters of mono-N-trimethylsilylamides of these acids in 90-93% yields. The ¹H NMR, IR, and mass spectra of the compounds synthesized were studied.

Full text of DOI:10.1023/B:RUGC.0000031854.10831.a9

Russian Journal of General Chemistry, Vol. 74, No. 4, 2004, pp. 545 547. Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 4, 2004,
pp. 596 598.
Original Russian Text Copyright
2004 by Basenko, Voronkov.
Reaction of Hexamethyldisilazane with Cyclic Anhydrides
of Organic Acids: A New Route to N-Trimethylsilylimides
of Di- and Tetracarboxylic Acids
S. V. Basenko and M. G. Voronkov
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, Russia
Received April 18, 2002
Abstract Cyclic anhydrides of di- and tetracarboxylic acids react with hexamethyldisilazane to give the
corresponding N-trimethylsilylimides in 90 96% yields. However, cyclic anhydrides of succinic, 4-nitro-
phthalic, and tetrachlorophthalic acids react differently, giving acyclic trimethylsilyl esters of mono-N-tri-
1
methylsilylamides of these acids in 90 93% yields. The H NMR, IR, and mass spectra of the compounds
synthesized were studied.
It is known [1] that cyclic anhydrides of dicarbox-
ylic acids react with trimethylsilyl(diethyl)aminosilane
[scheme (1)] to give acyclic trimethylsilyl esters of
mono-N,N-diethylamides of the corresponding acids.
O
We found that hexamethyldisilazane reacts with
cyclic anhydrides of dicarboxylic acids differently
[reaction (2)].
HC C(O)SiMe3
HC C(O)NEt2
HC
HC
C
C
O
(1)
O + Me3SiNEt2
O
O
C
C
C
O
R[
]n + (Me3Si)2NH
R[
NSiMe3]n + Me3SiOH
(2)
C
O
I VII
O
n = 1 (I III), 2 (IV VII); R = CH=CH (I), CCl=CCl (II),
(III),
(IV),
CO
CH
(V),
(VI),
(VII).
O
O
O
SiMe3
Cyclic anhydrides of tetracarboxylic acids react
with hexamethyldisilazane similarly to form the cor-
responding N,N -bis(trimethylsilyl)diimides. Reac-
tion (2) is performed by heating to 130 140 C a
mixture of hexamethyldisilazane with an equimolar
amount of a di- or tetracarboxylic acid anhydride with
stirring for 2 3 h, until the anhydride fully dissolves.
The target product precipitates on cooling. Com-
pounds I VI (Tables 1, 2) are yellowish crystalline
substances soluble in the majority of organic solvents.
Compound VII is a viscous liquid.
The new reaction is the simplest route to imides of
di- and tetracarboxylic acids. The yields of N-trimeth-
ylsilylimides synthesized by this route (90 96% in
most cases), their physicochemical constants, and ana-
1070-3632/04/7404-0545 2004 MAIK Nauka/Interperiodica

546
BASENKO, VORONKOV
Table 1. Physicochemical constants and analytical data for N-trimethylsilylimides of di- and tetracarboxylic acids I VII
Found
Calculated
Comp.
no.
Yield,
%
Compound
mp, C
Formula
C
H
C
H
I
II
C2H2(CO)2NSiMe3
C2Cl2(CO)2NSiMe3
C6H4(CO)2NSiMe3
O[C6H3(CO)2NSiMe3]2
CO[C6H3(CO)2NSiMe3]2
42
87
99
98
97
99
99
50.01
35.07
60.32
58.84
6.72
4.10
6.03
5.18
C7H11NO2Si
C7H9Cl2NO2Si
C11H13NO2Si
C22H24N2O5Si2
49.67
35.31
60.24
58.40
6.55
3.81
5.98
5.30
a
III
IV
V
VI
VII
66 67
126 128
120 122
112 115
92 95
b
c
Me3SiOCH[C6H3(CO)2NSiMe3]2
C6H4[OC6H3(CO)2NSiMe3]2
57.69
61.53
6.25
5.04
C26H34N2O5Si3
C28H28N2O6Si2
57.99
61.76
6.31
5.14
a
1
b
1
bp 120 C (1 mm Hg). IR spectrum, , cm : 1700 (C=O), 1295 (C N), 1070 (Si N). IR spectrum, , cm : 1700, 1710 (C=O),
1300 (C N), 1070 (Si N).
c
1
IR spectrum, , cm : 1680, 1720 (C=O), 1070 (Si N).
Table 2. Mass spectra of N-trimethylsilylimides of di- and tetracarboxylic acids R[(CO)2NSi(CH3)3]n, m/z (Irel, %)
R
Ion
a
b
c
g
C2H2
C6H4
C2Cl2
(C6H3)2Od (C6H3)2COe (C6H3)2CH(OSiMe3)f (C6H3O)2C6H4
(n = 1) (n = 1) (n = 1)
(n = 2)
(n = 2)
(n = 2)
(n = 2)
[M]+
[M
169 (1) 219 (1)
154 (44) 204 (100) 222 (67) 437 (100)
96 (48) 146 (2)
131 (64)
237 (1)
452 (9)
464 (1)
449 (57)
538 (5)
523 (20)
465 (4)
544 (13)
529 (84)
475 (6)
Me]+
[M
[M
SiMe3]+
164 (8)
379 (1)
365 (17)
376 (27)
348 (19)
450 (100)
NHSiMe3]+
[M
CO
103 (52) 121 (9)
73 (2) 73 (33)
NHSiMe3]+
[SiMe3]+
73 (58)
73 (33)
73 (100)
73 (100)
73 (100)
a
+
b
+
+
Note: Other ions: 143 (47), 130 (21), 126 (15) [M Me CO] , 75 (100). 160 (74) [M Me CO ] , 77 (4) [C H ] .
2
6 5
+
c
+
+
d
147 (24), 93 (100) [M NHSiMe
2CO] , 88 (41) [Me SiNH] , 75 (21). 424 (2) [M CO] , 393 (8)
3
3
+
+ e
+ f
[M Me CO ] , 323 (4) [M SiMe
2CO] . 246 (2) [M C H (CO) NHSiMe ] . 449 (70), 380 (30),
6 3 2 3
2
3
g
+
360 (16), 351 (12), 287 (18), 220 (18), 96 (16), 94 (15), 75 (30). 490 (4), 400 (9) [M NHSiMe
2CO] ,
3
385 (10), 382 (7), 340 (4), 327 (8), 313 (6), 258 (12), 147 (100).
lytical and spectroscopic (1H NMR, IR) data are given
in Table 1; the mass spectra are given in Table 2.
tron energy 70 eV, Varian-3700 chromatograph, carri-
er gas He, SE-54 phase). The IR spectra were taken
on a Specord IR-75 spectrometer in the range 400
4000 cm (thin films). The H NMR spectra were
measured on a Tesla BS-497 spectrometer (100 MHz,
10 30% solutions in CCl4, internal reference TMS).
However, cyclic anhydrides of succinic, 4-nitro-
phthalic, and tetrachlorophthalic acids do not form
N-trimethylsilylimides in the reaction with hexameth-
yldisilazane. Instead, reaction of type (1) occurs, and
acyclic trimethylsilyl esters of mono-N-trimethylsilyl-
amides of these acids (Me3OOCRCONHSiMe3, VIII
X) are formed. Their yields (90 93%), physicochem-
ical constants, and analytical and spectroscopic (1H,
NMR) data are given in Table 3; the mass spectra are
given in Table 4.
1
1
The chemical shifts are given in the
scale.
Trimethylsilylphthalimide III. A mixture of
29.6 g of phthalic anhydride and 32.2 g of hexame-
thyldisilazane was heated with stirring at 130 140 C
until the anhydride fully dissolved. The reaction
products, trimethylsilanol (17.5 g, 97%) and tri-
methylsilylphthalimide (43.3 g, 99%) were distilled
in a vacuum.
EXPERIMENTAL
The mass spectra were taken on a Varian MAT-212
gas chromatograph mass spectrometer (ionizing elec-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 4 2004

REACTION OF HEXAMETHYLDISILAZANE WITH CYCLIC ANHYDRIDES
547
Table 3. Physicochemical constants and analytical data for O,N-bis(trimethylsilyl) derivatives of dicarboxylic acid
monoamides Me3SiOC(O)RC(O)NHSiMe3 (VIII X)
Found
Calculated
bp,
C
Comp.
no.
Yield,
%
R
(p, mm Hg)
Formula
or mp,
C
C
H
N
Si
C
H
N
Si
a
VIII CH2CH2
96
90
96
110 (1)
63
147 149 (1)
45.90 8.63 5.68 21.42
47.02 6.27 7.40 15.80 C14H22N2O5Si2 47.45 6.21 7.90 15.80
C10H23NO3Si2 46.19 8.81 5.36 21.40
IX
C6H3(NO2)-4b
c
X
C6Cl4
a
20
20
1
d
1.0036, n 1.4525. IR spectrum, , cm : 3418 (N H), 2955 (CH ), 1716 [C(O) O], 1682 [C(O) N], 1450, 1370 (CH ), 1250,
4
4
3
3
b 1
850, 755 (Si CH ), 1055 (Si O).
cm : 3420 (N H), 2960 (CH ), 1728 [C(O) C], 1718 [C(O) N], 1600 (C H ), 1450, 1345 (CH ), 1245, 840, 755 (Si CH ), 1055
(Si O).
H NMR spectrum, , ppm: 0.27 (Me SiO), 0.48 (Me SiNH), 7.58 (C H NO ). IR spectrum, ,
3
3 3 6 3 2
1
3
6
3
3
3
c 1
H NMR spectrum, , ppm: 0.22 (Me SiO), 0.28 (Me SiNH).
3 3
Table 4. Mass spectra of acyclic trimethylsilyl esters of dicarboxylic acid mono-N-trimethylsilylamides Me3OC(O)
RC(O)NHSiMe3, m/z (Irel, %)
R
Ion
a
b
c
C2H4
C6H3NO2
C6Cl4
[M]+
[M
[M
[M
261 (7)
246 (7)
217 (1)
173 (4)
354 (1)
339 (42)
310 (5)
266 (3)
234 (2)
445 (3)
430 (20)
Me]+
CO2]+
NHSiMe3]+
Me
357 (19)
340 (10)
146 (100)
[M
Me3SiOH]+
[Me3SiNHSiMe2]+
146 (70)
144 (17)
73 (100)
146 (100)
[M
CO2SiMe3]+
[Me3Si]+
73 (44)
73 (76)
a
+
b
c
+
Note: Other ions: 231 (2), 130 (15) [M CH CO SiMe ] . 161 (3). 415 (4), 329 (9) [M CONHSiMe ] , 321 (7), 268 (9)
2
2
3
3
+
[Cl C (CO) ] .
4
6
2
The reactions of hexamethyldisilazane with anhy-
drides of other di- and tetracarboxylic acids were per-
formed similarly.
REFERENCES
1. Itoh, K., Sakai, S., and Ishii, Y., J. Org. Chem., 1966,
vol. 31, no. 12, p. 3948.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 74 No. 4 2004