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O. M. E. El-Dusouqui, M. M. Abdelkhalik, A. M. Al-Etaibi, H. H. Dib, N. A. Al-Awadi
Vol 44
4-Methylcinnoline (18a). MS: m/z = 145 (M.+1), C9H8N2
(144.18). H NMR (CDCl3): ꢀ = 2.64 (s, 3H, CH3), 7.10 (t, J =
8.3 Hz, 1H), 7.33 (t, J = 8.3 Hz, 1H), 7.53 (d, J = 8.1 Hz, 1H),
7.75 (d, J = 8.1 Hz, 1H), 8.06 (s, 1H).
thermocouple situated at the center of the furnace. The products
were collected in a U-shaped trap cooled in liquid nitrogen. The
whole system was maintained at a pressure of 2.67 Pa by an
Edwards Model E2M5 high capacity rotary oil pump, the
pressure being measured by a Pirani gauge situated between the
cold trap and the pump. Under these conditions the contact time
in the hot zone was estimated to be ꢁ 10 ms. The different zones
of the products collected in the U-shaped trap were analyzed by
1H NMR, LCMS and GC-MS. Relative and percent yields were
determined from 1H NMR. Identities of compounds obtained
were confirmed by comparison of their 1H NMR with data of
products separated from preparative HPLC.
1
4,6-Dimethylcinnoline (18b).
MS: m/z = 159 (M.+1),
1
C10H10N2 (158.20). H NMR (CDCl3): ꢀ = 2.39 (s, 3H, CH3),
2.50 (s, 3H, CH3), 7.15 (d, J = 8.3 Hz, 1H), 7.43 (d, J = 8.3 Hz,
1H), 7.53 (s, 1H), 7.94 (s, 1H).
6-Chloro-4-methylcinnoline (18c). MS: m/z = 179 (M.+1),
1
C9H7ClN2 (178.62). H NMR (CDCl3): ꢀ = 2.50 (s, 3H, CH3),
7.33 (d, J = 8.5 Hz, 1H), 7.83 (s, 1H), 8.00 (d, J = 8.5 Hz, 1H),
8.44 (s, 1H).
8H-benzo[4',5']imidazo[2',1':5,1]pyrrolo[2,3-c]cinnoline
(23a). MS: m/z = 258 (M.+), C16H10N4 (258.28). 1H NMR
(CDCl3): ꢀ = 6.70 (m, 2H), 7.18 (t, J = 7.5 Hz, 1H), 7.48-7.57
(m, 4H, aromatic H and NH), 7.69 (d, J = 7.8 Hz, 1H), 7.90 (d, J
= 7.8 Hz, 1H), 8.19 (s, 1H).
Acknowledgement. This work was supported by Kuwait
University through research grant # SC01/02 and ANALAB and
SAF grants # GS01/01 and GS03/01.
REFERENCES
5-Methyl-8H-benzo[4',5']imidazo[2',1':5,1]pyrrolo[2,3-c]-
1
cinnoline (23b). MS: m/z = 273 (M.+1), C17H12N4 (272.31). H
NMR (CDCl3): ꢀ = 2.23 (s, 3H, CH3), 6.68-6.70 (m, 1H), 6.92-
7.00 (m, 1H), 7.44-7.55 (m, 4H, aromatic H and NH), 7.70 (d, J
= 8.0 Hz, 1H), 7.91 (d, J = 8.0 Hz, 1H), 8.19 (s, 1H).
5-Chloro-8H-benzo[4',5']imidazo[2',1':5,1]pyrrolo[2,3-c]-
cinnoline (23c). MS: m/z = 293 (M.+1), C16H9ClN4 (292.73). 1H
NMR (CDCl3): ꢀ = 6.63 (d, J = 8.0 Hz, 1H), 7.12 (d, J = 8.0 Hz,
1H), 7.49-7.57 (m, 4H, aromatic H and NH), 7.70 (d, J = 7.64
Hz, 1H), 7.91 (d, J = 7.64 Hz, 1H), 8.19 (s, 1H).
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Kinetic Studies.
For each substrate, first-order rate
coefficients were obtained at regular temperature intervals. Each
rate constant is an average of at least three independent
measurements in agreement to within ± 2%. The reactions for
which the kinetic data were obtained have been ascertained to be
homogeneous, unimolecular, non-catalytic and non-radical
processes. These were carried out in the manner and apparatus
previously described [9]. Arrhenius plots of the data using first
order rate equation: log k (s-1) = log A – Ea kJ mol-1 (2.303 RT)-1
were strictly linear over ꢀ 95% reaction with correlation
coefficient in the 0.99 ± 0.005 range. The log A, Ea values and
the first order-rate constants at 500 K of the six compounds
under investigation are given in Table 1.
Pyrolysis. Flash Vacuum Pyrolysis (FVP). The apparatus
used was similar to the one which has been described in our
recent publications [10,11]. The sample was volatilized from a
tube in a Büchi Kugelrohr oven through a 30 x 2.5 cm horizontal
fused quartz tube. This was heated externally by a Carbolite
Eurotherm tube furnace MTF-12/38A to a temperature of 650
°C, the temperature being monitored by a Pt/Pt-13%Rh
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E. El-Dusouqui, J. Phys. Org. Chem., 12, 654, (1999).
[9] B. J. George, H. H. Dib, M. R. Abdallah, M. R. Ibrahim, N. S.
Khalil, Y. A. Ibrahim, N. A. Al-Awadi, Tetrahedron, 62, 1182-1192,
(2006).
[10] N. Al-Awadi, K. Kaul, O. M. E. El-Dusouqui, J. Phys. Org.
Chem., 13, 499-504, (2000)
[11] Y. A. Ibrahim, N. A. Al-Awadi, M. R. Ibrahim, Tetrahedron,
60, 9121-9130 (2004)
[12] A. Kimbaris, G. Varvounis, Tetrahedron, 56, 9675-9682,
(2000).
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Kaul, J. Chem. Kinet, 32, 402-406, (2001).