Gas-phase thermolysis of benzotriazole derivatives: Part 1 - Synthesis of α-N(1)- and N(2)-benzotriazolyl ketones and kinetics and mechanism of their gas-phase pyrolysis

Article abstract of DOI:10.1002/poc.717

1-(Benzotriazol-1-yl)propan-2-one (1) and 3-(benzotriazol-1-yl)butan-2-one (2), and their respective phenyl analogues 2-(benzotriazol-1-yl)-1- phenylethanone (3) and 2-(benzotriazol-1-yl)-1-phenylpropan-1-one (4), together with 1-cyanobenzotriazole (5) and 1-(benzotriazol-2-yl)propan-2-one (6), were synthesized and then subjected to gas-phase thermolysis. The products of complete pyrolysis of 1-4 were found to be aniline in addition to either 2-substituted indoles or 2,3-disubstituted indoles. The kinetics of the gas-phase thermal elimination reactions of the present compounds were also studied, the first such investigation on benzotriazoles. The Arrhenius preexponential factor (A/s^-1) and activation energy (E_a/kJ mol^-1) are, respectively: 10.03 and 156.7 for (1), 9.93 and 158.0 for (2), 12.68 and 169.9 for (3), 9.45 and 144.4 for (4) and 15.40 and 163.6 for (5). Compound 6 appeared to have isomerized by a thermally allowed 1,5-group migration into 1 prior to thermolysis. The results of the kinetic and product analysis are rationalized with reference to a mechanism involving extrusion of a stable (N₂) molecule and formation of a reactive 1,3-biradical intermediate, which in turn rearranges into the final products of reaction. 2004 John Wiley & Sons, Ltd.

Full text of DOI:10.1002/poc.717

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY
J. Phys. Org. Chem. 2004; 17: 267–272
Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/poc.717
Gas-phase thermolysis of benzotriazole derivatives:
part 1—synthesis of a-N(1)- and N(2)-benzotriazolyl
ketones and kinetics and mechanism of their
gas-phase pyrolysis
Hicham H. Dib, Nouria A. Al-Awadi,* Yehia A. Ibrahim and Osman M. E. El-Dusouqui
Chemistry Department, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait
Received 8 April 2003; revised 10 June 2003; accepted 18 July 2003
ABSTRACT: 1-(Benzotriazol-1-yl)propan-2-one (1) and 3-(benzotriazol-1-yl)butan-2-one (2), and their respective
phenyl analogues 2-(benzotriazol-1-yl)-1-phenylethanone (3) and 2-(benzotriazol-1-yl)-1-phenylpropan-1-one (4),
together with 1-cyanobenzotriazole (5) and 1-(benzotriazol-2-yl)propan-2-one (6), were synthesized and then
subjected to gas-phase thermolysis. The products of complete pyrolysis of 1–4 were found to be aniline in addition
to either 2-substituted indoles or 2,3-disubstituted indoles. The kinetics of the gas-phase thermal elimination reactions
of the present compounds were also studied, the first such investigation on benzotriazoles. The Arrhenius pre-
exponential factor (A/sꢀ 1) and activation energy (Ea/kJ molꢀ1) are, respectively: 10.03 and 156.7 for (1), 9.93 and
158.0 for (2), 12.68 and 169.9 for (3), 9.45 and 144.4 for (4) and 15.40 and 163.6 for (5). Compound 6 appeared to
have isomerized by a thermally allowed 1,5-group migration into 1 prior to thermolysis. The results of the kinetic and
product analysis are rationalized with reference to a mechanism involving extrusion of a stable (N2) molecule and
formation of a reactive 1,3-biradical intermediate, which in turn rearranges into the final products of reaction.
Copyright # 2004 John Wiley & Sons, Ltd.
KEYWORDS: benzotriazolyl ketones; pyrolysis; gas phase; kinetics; mechanism
INTRODUCTION
Preparative and mechanistic investigations on BT com-
pounds have been extended to thermolysis reactions. Gas-
phase pyrolysis, mostly flash vacuum pyrolysis (FVP), has
been reported for BT and its N-aryl, heteroaryl, alkyl,
arylmethyl, acetyl, benzoyl, aroyl and alkenyl derivatives
and related compounds.10–21 However, no kinetic investi-
gation has so far been carried out on the gas-phase
pyrolysis of benzotriazoles. The present study on com-
pounds 1–6 (Fig. 1) is believed to be the first effort in this
field. Optimization of reaction conditions in FVP and
pyrolysis using static reactors in order to facilitate struc-
ture–reactivity correlations is normally achieved by con-
trol of reaction temperature, reactant pressure and
residence time. However, thermolytic reactions using
static reactors afford longer residence times, which could
in turn lead to complete pyrolysis.22,23
The effect of temperature in FVP reactions of N(1)-
benzotriazolyl compounds is illustrated by the thermolysis
of 1-benzoyl- and 1-acetylbenzotriazoles.10,20 At rela-
tively higher reaction temperatures, these substrates gen-
erate benzoxazoles in higher yields. The mechanisms
suggested for the pyrolysis of the benzoyl and acetyl BT
compounds and several other related benzotriazoles in-
volve extrusion of N2 and formation of 1,3-biradicals and/
or carbenes as reactive intermediates.5,20
Benzotriazole (BT) and its derivatives constitute an
important class of heterocyclic compounds with a wide
range of synthetic, industrial and biological applica-
tions.1–5 The theoretical and experimental aspects of
the chemistry of these compounds have recently been
reviewed.5 Significantly, the BT group provides a novel
and versatile synthetic auxiliary based mainly on its
thermal and chemical stability, and the ease with which
it can be removed and re-introduced during synthesis.4–9
Further, the BT moiety is also unique in its capacity to act
as an electron-donating or -withdrawing group.9 Both
N(1)- and N(2)-BT derivatives are known, and in reac-
tions where the two isomers are formed simultaneously
they could be separated readily by chromatographic or
other means. It is instructive, however, to note that
theoretical and experimental studies describe the N(1)-
isomer as the more aromatic and thermodynamically
more stable structure.5
*Correspondence to: N. A. Al-Awadi, Chemistry Department, Kuwait
University, P.O. Box 5969, Safat 13060, Kuwait.
E-mail: nouria@kuc01.kuniv.edu.kw
Contract/grant sponsor: Kuwait University; Contract/grant numbers:
SC01/99; GS01/01; GS03/01.
Copyright # 2004 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2004; 17: 267–272

268
H. H. DIB ET AL.
the reactor were 0.06 mbar and 900 s respectively, for all
the substrates. The pyrolyzates of 1 and 3 consisted of
either 2-methylindole (from 1) or 2-phenylindole (from 3)
and aniline. The latter was also identified alongside
indoles in the products of pyrolysis of other BT deriva-
tives.14–19 The synthesis of the indole derivatives from 1
and 3 corresponds to loss of N2 and O fragments, and the
results of mass spectrometric and NMR studies are
compatible with the formation of 2-methyl- and 2-pheny-
lindole from 1 and 3, respectively. Similarly, substrate 2
and 4 pyrolyzed to give 2,3-dimethylindole and 3-methyl-
2-phenylindole, respectively, in addition to aniline.
The formation of these 2-substituted indole derivatives
from 1 and 3 could be explained by the mechanistic
pathway presented in Scheme 1. This starts by the initial
extrusion of N2 to give the corresponding biradical, which
through radical rearrangement then gives the aziridine
diradical, oxirane diradical and oxaziridinoindole. The
latter upon extrusion of oxygen followed by a 1,5-H shift
gives the 2-substituted indole derivatives; similar extru-
sion of atomic oxygen has been reported.28
Figure 1. Substrates studied
RESULTS AND DISCUSSION
Synthesis of isomeric N(1)- and N(2)-
a-benzotriazolyl ketones
Compounds 1 and 3 were obtained by heating under
reflux benzotriazole with the ꢀ-haloketones in toluene or
DMF for several hours. In agreement with literature
reports,5 the reaction of benzotriazole with ꢀ-chloroace-
tone did not give benzotriazol-1-yl ketone (1) exclusively,
but also the benzotriazol-2-yl ketone isomer (6) was
formed alongside as a minor product. The two isomers
were separated by fractional crystallization from etha-
nol.24,25 Simultaneous formation of analogous N(1)- and
N(2)-isomers has been observed in the synthesis of many
benzotriazole derivatives.5 N(1) regioselectivity is, how-
ever, achieved in the present work and elsewhere when
the reactions are carried out in absence of base and/or
heating under reflux in dry toluene.26,27 Heating under
reflux, however, often requires a prolonged reaction time.
The possibility of the initial formation of 3-substituted
indoles followed by thermal rearrangement into the 2-
substituted derivatives via a series of 1,5-sigmatropic
shifts of hydrogen and substituents has been excluded
based on the following facts:
1. The 3-substituted derivatives could not be detected
among the reaction products from 1 and 3.
2. The 3-substituted indole compounds prepared at high
temperature from FVP of 1-vinylbenzotriazole deriva-
tives have been isolated without rearrangement.18,19,29,30
3. Pyrolysis of 4 gave 3-methyl-2-phenylindole but no
trace of the isomeric 2-methyl-3-phenylindole. This is
strong evidence in support of the proposed mechan-
ism, and it excludes the initial formation of the
isomeric indole derivative which subsequently rear-
ranges thermally.
Reaction products and mechanism
The temperature used to ensure complete gas-phase
pyrolysis of 1–6 was 390, 400, 320, 370, 210 and
450 ꢁC respectively. The pressure and residence time in
4. Thermal rearrangement of 3-phenyl- and 3-methylin-
doles into the 2-isomeric derivatives has only been
reported in the presence of Lewis acid catalysts.31,32
The methylindole isolated from the pyrolysate of the
1
N(2)-isomer 6 gave mass and H NMR spectra identical
with 2-methylindole obtained from the N(1)-isomer 1.
These results suggest that 6 is first converted into its more
stable isomer 1 by a thermally allowed 1,5-migration of
the ketone moiety, which then pyrolyzed as shown in
Scheme 1. Similar rearrangements have been reported.5 It
is important to note also that the aromatic sextet of the
benzene ring is maintained through the reaction pathway
postulated for the extrusion of N2 and O.
Kinetics and structure–reactivity correlations
The rates of reaction of the ꢀ-benzotriazolyl ketones 1–5
were measured over the temperature range 60 ꢂ 9 K to
J. Phys. Org. Chem. 2004; 17: 267–272
Scheme 1. Formation of 1,3-biradical and its further
reaction from N(1) radical centre
Copyright # 2004 John Wiley & Sons, Ltd.

GAS-PHASE THERMOLYSIS OF BENZOTRIAZOLE DERIVATIVES
269
Table 1. Rate coeffecients and Arrhenius parameters of ꢀ-benzotriazolyl ketones 1–5
Substrate
T (K)
104k (sꢀ1
)
Log [A (sꢀ1)]
10.03 ꢂ 0.11
Ea (kJ molꢀ1
)
k500K (sꢀ1
)
1
579.65
591.05
602.75
614.65
626.55
639.15
648.55
597.75
610.25
622.85
636.05
647.85
661.85
533.95
543.85
554.60
564.95
575.45
585.25
580.75
590.95
599.65
609.25
620.65
638.85
441.75
453.35
465.55
477.15
0.8170
1.565
2.723
5.353
9.208
16.75
25.99
1.252
2.660
5.130
7.197
14.74
28.83
1.065
2.383
5.200
10.45
16.87
32.01
2.908
4.846
7.403
11.72
20.60
43.26
1.12
156.7 ꢂ 1.34
4.591 ꢃ 10ꢀ7
2
3
4
5
9.934 ꢂ 0.31
12.68 ꢂ 0.47
9.452 ꢂ 0.12
15.39 ꢂ 0.44
158.0 ꢂ 3.64
169.9 ꢂ 5.02
144.4 ꢂ 1.38
163.60 ꢂ 3.85
2.674 ꢃ 10ꢀ 7
8.592 ꢃ 10ꢀ 6
2.322 ꢃ 10ꢀ 6
1.996 ꢃ 10ꢀ 2
3.38
11.24
28.53
ensure reliable activation parameters.23,33,34 The upper
limits of the reaction temperatures afforded nearly com-
plete pyrolysis (94 ꢂ 4%) of the substrates under study.
Thermal decomposition of 1–5 gave reproducible first-
order rate constants. The rate constants given in Table 1
represent an average of three values in agreement to
within ꢂ 2%. The Arrhenius plots showed correlation
coefficients of 0.998 ꢂ 0.001. A typical plot, which is
linear over >90% reaction, is depicted in Fig. 2 for
1-(benzotriazol-1-yl)propan-2-one (1), with a correlation
coefficient of 0.999. The values obtained for the pre-
exponential factor (log A ¼ 9–15 sꢀ1), and the energy of
activation (Ea ¼ 144–170 kJ molꢀ1) are in the range ex-
pected for homogeneous unimolecular gas-phase thermal
elimination reactions.35,36 The data on log A, the energy
of activation and rate coefficients at 500 K are summar-
ized in Table 1.
carbene intermediate stabilized by extended ꢁ-conjuga-
tion with the C N multiple bond. It has already been
—
—
—
reported that ꢁ-conjugated biradicals have much longer
lifetimes than non-conjugated biradicals, a result attrib-
uted to the greater structural stability of the biradical due
to conjugation.37 In addition, substituents further removed
from the free radical/carbene centres would be expected to
have less pronounced effects on the stability of the
proposed reactive intermediate, and hence less effect on
molecular reactivity.
The present results lend support to this analysis. Com-
pound 3 was found to be ca 19-fold more reactive than 1.
A plausible mechanism which is proposed to account
for both the kinetics and reaction product of gas-phase
thermolysis of the present BT compounds involves initial
extrusion of a stable N2 fragment leading to a reactive 1,3-
biradical intermediate (Scheme 1). The most reactive
substrate in the present series is 1-cyanobenzotriazole
(5), with a rate constant 2.3 ꢃ 103–7.5 ꢃ 104 times higher
than for the ꢀ-benzotriazolyl ketones 1–4. Structurally,
compound 5 is distinguished from the keto benzotriazoles
1–4 in that thermal extrusion of N2 from the former
compound results in the formation of a 1,3-biradical/
Figure 2. Arrhenius plot for pyrolysis of 1-(benzotriazol-
1-yl)propan-2-one (1)
Copyright # 2004 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2004; 17: 267–272

270
H. H. DIB ET AL.
This difference is attributed to the presence of the elec-
tron-withdrawing phenyl group in 3 and the electron-
donating methyl group in 1. A similar but lower rate
factor of ca 4 induced by the same spectral difference is
obtained on comparing the reactivities of substrates 4 and
2. Rate reduction factors of ca 2–4 ascribed to the
presence of an additional methyl group is also observed
when the rate constants of 1 and 3 are compared with
those of 2 and 4. It is to be noted that although the phenyl
and methyl groups would be expected to exert, respec-
tively, ꢁ-conjugative and inductive/hyperconjugative in-
teractions with the carbonyl function of the benzoyl and
acetyl moieties of substrates 1–4, the moieties are not
themselves in direct conjugation with the free radical/
carbene centres of the intermediates generated during
pyrolysis.
with anhydrous sodium sulfate, filtered and the ether was
then evaporated to give a pale-yellow, viscous liquid.
Further purification by vacuum distillation (b.p.
118–120 ꢁC at 1.4 ꢃ 10ꢀ2 mbar) produced the pure sub-
strate. The compound was obtained as pale-yellow,
viscous liquid (65%). MS: m/z ¼ 189 (Mþ .). IR (KBr):
ꢂ~ ¼ 3366 cmꢀ1 (NH), 1601 cmꢀ1 (CO). 1H NMR
(CDCl3): ꢃ ¼ 1.94 (d, J ¼ 7.2 Hz, 3H, Me), 2.03
(s, 3H, Me), 5.58 (q, J ¼ 7.2 Hz, 1H, CH), 7.41–7.46
(m, 2H, Ar-H), 7.53 (t, J ¼ 7.6 Hz, 1H, Ar-H), 8.12
(d, J ¼ 8.4 Hz, 1H, Ar-H). 13C NMR (CDCl3): ꢃ ¼
15.86, 26.60, 64.11, 109.85, 120.84, 124.76, 128.38,
132.86, 146.79, 203.67. Anal.Calcd for C10H11N3O
(189): C, 63.48; H, 5.86; N, 22.21. Found: C, 63.45; H,
5.98; N, 21.52%.
2-(Benzotriazol-1-yl)-1-phenylpropan-1-one. (4). A mix-
ture of 2-bromopropio phenone (10.75 g, 0.05 mol) and
1H-benzotriazole (5.95 g, 0.05 mol) in DMF (50 ml) was
heated under reflux for 24 h. The solid obtained was then
crystalized from ethanol as brown crystals (75%), m.p.
102 ꢁC. MS: m/z 251 (Mþ .). IR (KBr): ꢂ~ ¼ 3352 cmꢀ1
(NH), 1684 cmꢀ1 (CO). 1H NMR (CDCl3): ꢃ ¼ 2.01
(d, J ¼ 7.2 Hz, 3H, Me), 6.74 (q, J ¼ 7.2 Hz, 1H, CH),
7.35 (td, J ¼ 0.9, 7.3 Hz, 1H, Ar-H), 7.44 (t, J ¼ 8.1 Hz,
2H, Ar-H), 7.46 (t, J ¼ 8.1 Hz, 1H, Ar-H), 7.56 (dd,
J ¼ 0.9, 8.3 Hz, 2H, Ar-H), 8.02–8.07 (m, 3H, Ar-H).
13C NMR (CDCl3): ꢃ ¼ 16.69, 59.82, 110.82, 120.68,
124.52, 128.17, 129.19, 129.39, 132.45, 134.55, 147.01,
194.29. Anal.Calcd for C15H13N3O (251): C, 71.70; H,
5.21; N, 16.72. Found: C, 71.93; H, 5.32; N, 16.68%.
EXPERIMENTAL
General. Melting-points were determined on
a
Shimadzu–Gallenkamp apparatus and are uncorrected.
Elemental analysis was by means of a LECO CHNS-932
elemental analyzer. NMR spectra were measured using a
Bruker DPX 400 MHz superconducting spectrometer and
FT-IR measurements were performed with a Perkin-
Elmer 2000 FT-IR system. Mass spectrometric analysis
was carried out on a VG-Autospec-Q high-performance
three-sector GC/MS/MS system and the instrument for
HPLC was an Agilent 1100 series LC/MSD with API-ES/
APCI ionization.
Both kinetic and reaction product analyses were con-
ducted using a Chemical Data System (CDS) custom-
made pyrolyzer comprising an insulated aluminium alloy
block fitted with a platinum resistance thermocouple
connected to a Comark microprocessor thermometer for
reactor temperature read-out. The temperature of the
reactor was controlled by means of a Eurotherm 093
precision temperature regulator. HPLC analysis of kinetic
runs was carried out on: (a) a Waters HPLC system
(Model 515 pump, Model 2487 UV detector; and (b) a
Metrohm HPLC system (Model 709IC pump, Shimadzu
SPD 10AV UV detector).
1-(Benzotriazol-2-yl)propan-2-one (6). This compound,
which is an isomer of (1), was obtained serendipitously
in the reaction mixture during the preparation of com-
pound (1). The mixture was separated by fractional
crystallization from ethanol into pure 1 and 6. Compound
6 was obtained as white crystals (10%), m.p. 120 ꢁC. MS:
m/z 175 (Mþ.). IR (KBr): ꢂ~ ¼ 3447 cmꢀ1 (NH),
1
1731 cmꢀ1 (CO). H NMR (CDCl3): ꢃ ¼ 2.18 (s, 3H,
Me), 5.54 (s, 2H, CH2), 7.45 (dd, J ¼ 6.5, 3.1 Hz, 2H,
Ar-H), 7.91 (dd, J ¼ 6.5, 3.1 Hz, 2H, Ar-H). 13C NMR
(CDCl3): ꢃ ¼ 27.43, 65.18, 118.61, 127.37, 145.37,
200.20. Anal.Calcd for C9H9N3O (175): C, 61.70; H,
5.18; N, 23.99. Found: C, 62.13; H, 5.22; N, 23.79%.
Procedure for synthesis of compounds 1, 3 and 5. 1-
(Benzotriazol-1-yl)propan-2-one (1), 2-(benzotriazol-
1-yl)-1-phenylethanone (3) and 1-cyanobenzotriazole
(5) were prepared and characterized as described in the
literature.26,27,38
Pyrolysis of compounds 1–6 and general procedure for
product analysis. The apparatus used for this purpose is
the same pyrolysis unit as used for kinetic studies. Each
of the substraters (0.2 g) is introduced into the reaction
tube, cooled in liquid nitrogen, sealed under vacuum and
placed in the pyrolyzer for 900 s at a temperature com-
parable to that used for complete pyrolysis in the kinetic
studies. The contents of the tube were then analysed by
NMR and LC–MS and yield was determined by HPLC
with a reference sample. The spectral data for the
3-(Benzotriazol-1-yl)butan-2-one (2). 3-Chlorobutanone
(10.6 g, 0.1 mol) was heated under reflux with 1H-benzo-
triazole (11.9 g, 0.1 mol) in toluene (250 ml) for 130 h.
The solvent was then removed under vacuum and the
reaction product was washed with 10% NaOH and
extracted with diethyl ether. The ethereal layer was dried
Copyright # 2004 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2004; 17: 267–272

GAS-PHASE THERMOLYSIS OF BENZOTRIAZOLE DERIVATIVES
271
pyrolysates were compared with their reference spectra
(2-methylindole,39 2,3-dimethylindole,40 2-phenylin-
dole,41 3-methyl-2-phenylindole40 and aniline42).
2-Methylindole, m/z 131; 1H NMR (CDCl3), ꢃ 2.47 (s,
1H, CH3), 6.24 (d, J ¼ 0.8 Hz, 1H, CH), 7.07–7.15 (m, 2H,
Ar-H), 7.31 (d, J ¼ 7.8 Hz, 1H, Ar-H), 7.54 (d, J ¼ 7.6 Hz,
1H, Ar-H), 7.87 (br s, 1H, NH); 13C NMR (CDCl3), ꢃ
14.32, 100.97, 110.78, 120.21, 120.21, 121.50, 129.63,
135.64, 136.61.
2,3-Dimethylindole, m/z 145; 1H NMR (CDCl3), ꢃ 2.16
(s, 3H, CH3), 2.17 (s, 3H, CH3), 7.17–7.30 (m, 3H, ArH
and NH), 7.56–7.60 (m, 2H, ArH); 13C NMR (CDCl3), ꢃ
8.62, 11.60, 107.29, 110.30, 118.16, 119.26, 121.10,
130.07, 130.91, 135.50.
ance of the substrate with respect to the internal standard
as follows.
An aliquot (0.2 ml) of each solution containing the
substrate and the internal standard was pipetted into the
reaction tube, which was placed in the pyrolyzer for 6 min
under non-thermal conditions. A sample was then ana-
lyzed using the HPLC probe with the UV detector at a
wavelength of 256 nm, and the standardization value (A0)
was calculated. Several HPLC measurements were ob-
tained with an accuracy of ꢄ2%. The temperature of the
pyrolysis block was then raised until ꢅ10% pyrolysis was
deemed to have occurred over 900 s. This process was
repeated after each 10–15 ꢁC rise in the temperature of the
pyrolyzer until ꢄ90% pyrolysis took place. The relative
ratio of the integration values of the sample and the
internal standard (A) at the pyrolysis temperature was
then calculated. A minimum of three kinetic runs were
carried out at each 10–15ꢁC rise in the temperature of the
pyrolyzer to ensure reproducible values of A. Treatment of
the kinetic data has been detailed elsewhere.33,34,43
2-Phenylindole, m/z 193; 1H NMR (CDCl3), ꢃ 6.86 (d,
J ¼ 2, 1H, CH), 7.16 (t, J ¼ 8.1 Hz, 1H, ArH), 7.23
(t, J ¼ 8.1 Hz, 1H, ArH), 7.36 (t, J ¼ 8.2 Hz, 1H, ArH),
7.43–7.50 (m, 3H, Ar-H), 7.65–7.71 (m, 3H, Ar-H), 8.36
(br s, 1H, NH); 13C NMR (CDCl3), ꢃ 100.57, 111.47,
120.86, 121.26, 122.95, 125.74, 128.31, 129.62, 129.84,
132.95, 137.38, 138.45.
1
3-Methyl-2-phenylindole, m/z 207; H NMR (CDCl3),
Acknowledgement
ꢃ 2.52 (s, 3H, CH3), 7.18–7.61 (m, 9H, ArH), 8.06 (br s,
1H, NH); 13C NMR (CDCl3), ꢃ 9.89, 108.97, 110.94,
119.23, 119.77, 122.56, 127.77, 128.02, 128.80, 130.00,
131.62, 134.31, 136.17.
Aniline, m/z 93; 1H NMR (CDCl3), ꢃ 3.67 (s, 2H, NH),
6.75 (d, J ¼ 7.6 Hz, 2H, Ar-H), 6.86 (t, J ¼ 7.6 Hz, 1H, Ar-
H), 7.25 (t, J ¼ 7.6 Hz, 2H, Ar-H); 13C NMR (CDCl3), ꢃ
146.4, 129.2, 118.4, 115.0.
This work was supported by Kuwait University through
research grant SC01/99 and ANALAB and SAF grants
GS01/01 and GS03/01
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