Metal catalyst-free amination of 2-chloro-5-nitrobenzoic acid in superheated water

Article abstract of DOI:10.3184/174751912X13524831206251

A series of N-arylanthranilic acid derivatives were synthesised by amination of 2-chloro-5-nitrobenzoic acid with various arylamine in superheated water with potassium carbonate as base. Good yields were achieved within 2-3 h at 150-190 °C. The results indicated that this metal catalyst-free method is a simple, environmentally-friendly and efficient synthesis of N-phenylanthranilic acid derivatives. Furthermore, it will work with an alkylamine and phenol.

Full text of DOI:10.3184/174751912X13524831206251

726 RESEARCH PAPER
DECEMBER, 726–728
JOURNAL OF CHEMICAL RESEARCH 2012
Metal catalyst-free amination of 2-chloro-5-nitrobenzoic acid in
superheated water
Cong Lan, Zhi-Ning Xia*, Zheng-Hua Li and Rong-Hui Liang
College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, P. R. China
A series of N-arylanthranilic acid derivatives were synthesised by amination of 2-chloro-5-nitrobenzoic acid with
various arylamine in superheated water with potassium carbonate as base. Good yields were achieved within 2−3 h
at 150−190 °C. The results indicated that this metal catalyst-free method is a simple, environmentally-friendly and
efficient synthesis of N-phenylanthranilic acid derivatives. Furthermore, it will work with an alkylamine and phenol.
Keywords: N-arylanthranilic acids derivatives, 2-chloro-5-nitrobenzoic acid, superheated water, synthesis
N-Arylanthranilic acid derivatives are versatile compounds
with various pharmacological activities, such as antibacterial,
anti-inflammatory, antimalarial and anticancer activities.1–3
For example, flufenamic and mefenamic acids are widely used
as powerful analgesic and nonsteroidal anti-inflammatory
drugs for the treatment of osteoarthritis, rheumatoid arthritis
and other painful musculo-skeletal illnesses. Furthermore,
they are possible candidates for the treatment of neurodegen-
erative and amyloid diseases.4–6 Therefore, the synthesis of
compounds containing an anthranilic acid moiety has recently
received attention.
Results and discussion
The reaction conditions of 2-chloro-5-nitrobenzoic acid with
aniline were optimised in superheated water for 2 hours and
the results are given in Table 1. Firstly we examined the effect
of temperature. The results showed that the best yield was
obtained at 150 °C (Table 1, entry 3). Secondly the proportion
of reactants was investigated. The optimum yield was obtained
when the ratio of 2-chloro-5-nitrobenzoic acid to aniline was
1:2, Finally, the effect of different amounts of potassium
carbonate was examined. The best result was obtained using
0.5 equiv. of potassium carbonate per mole of 2-chloro-5-
nitrobenzoic acid (Table 1, entry 3). However, if the reaction
time was reduced to 1 h using the previously optimum condi-
tions, the yield decreased to 58% (Table 1, entry 9).
The optimum reaction conditions for the synthesis of N-
substituted 5-nitroanthranilic acid derivatives in superheated
water involved the use 0.5 equiv. of potassium carbonate,
2 equiv. of amine to 1 equiv. of 2-chloro-5-nitrobenzoic acid
and heating the mixture at 150 °C for 2 h. This procedure was
used for the coupling of 2-chloro-5-nitrobenzoic acid with dif-
ferent arylamines. The results are listed in Table 2. According
to the differences in the reactivity of the arylamine, the
temperature was raised to 170 °C or 190 °C in order to reduce
the reaction time for some reactions. Good yields were obtained
in the examples when the aromatic ring of the arylamines pos-
sessed an electron-donating group (Table 2, 3b−d, 3h), except
for 2,3-dimethyl substituted arylamine which afforded a yield
of 55% (Table 2, 3i). This is probably due to steric hindrance.
Electron-withdrawing substituents on the aromatic ring
decreased the yields (Table 2, 3e−g). This is due to the low
reactivity of the starting materials. When, the amination proce-
dure was applied to hindered substrates, they coupled poorly
and gave only low yields of the product, even at elevated tem-
perature. For example, 2,6-dimethylaniline and 2,4,6-trimeth-
ylaniline gave the corresponding products in yields of 34% and
46% within 3 h at 190 °C, respectively (Table 2, 3j, 3k).
Traditionally, the most widely used strategy for the synthe-
sis of N-arylanthranilic acids derivatives is the coupling of
anilines and o-halobenzoic acid derivatives with a palladium
or copper catalyst.7–9 However, the requirement for organic
solvents, long reaction times, high temperatures, catalysts
and tedious procedures for purifying the products, hampered
the application of these methods. Ultrasonic and microwave
irradiation have been successfully utilised in the synthesis of
N-arylanthranilic acids derivatives.10,11 For example, Rolando
and his co-workers12 have studied the reaction of 2-chloroben-
zoic acids and aminothiazoles or aminobenzothiazoles under
ultrasonic irradiation using copper catalysis, and the results
show that the yields were enhanced and the reaction time
13
was reduced. Younis and his co-workers used microwave
irradiation to synthesise N-substituted 5-nitroanthranilic acid
derivatives without a catalyst nor solvent and obtained yields
up to 99% within 5−30 min at 80−120 °C.
In the past decade, the superheated water has emerged as
an efficient, clean, economic and environmentally friendly
medium for organic synthesis.14–17 Superheated water pos-
sesses some unique properties including the fact that it is
cheap, naturally abundant and nontoxic, and it can simultane-
ously play the role of solvent, reactant and catalyst.17,18 It has
been applied in various reactions such as hydration,19 reduc-
tion,20 catalytic oxidation,21 alkylation,22 the Heck coupling,23
the Suzuki reaction24 and the Claisen rearrangement.25
In the present work, we have synthesised the N-phenylan-
thranilic acid derivatives without a catalyst by the amination
of 2-chloro-5-nitrobenzoic acid in superheated water with
potassium carbonate as base (Scheme 1).
Table 1 The reaction of 2-chloro-5-nitrobenzoic acid with
aniline under different reaction conditionsa
Entry
Ratio of 1/2a Temp/°C T/h K2CO3/mmol Yield/%b
1
2
3
4
5
6
7
8
9
1:2
1:2
1:2
1:2
1:1
1:3
1:2
1:2
1:2
110
130
150
170
150
150
150
150
150
2
2
2
2
2
2
2
2
1
1.5
1.5
1.5
1.5
1.5
1.5
0
52
67
88
83
69
90
78
74
58
3
1.5
Scheme 1
a Reaction conditions: 2-chloro-5-nitrobenzoic acid (3 mmol),
water (2 mL).
* Correspondent. E-mail: chem_lab_cqu@yahoo.com.cn
b Isolated yield.

JOURNAL OF CHEMICAL RESEARCH 2012 727
Table 2 Synthesis of N-arylanthranilic acid derivatives in
94% yield (Table 3, 3q). When o-chlorobenzoic acid was
the reactant, the yield was only 30% for 3 h under 190 °C
(Table 3, 3r) due to the absence of the activating nitro group
in the para-position. This showed that a nitro group on the
aromatic ring of the benzoic acid was necessary for high yields
of the desired products.
In summary, a simple, metal catalyst-free, environmentally-
friendly and efficient amination procedure for synthesis of N-
substituted 5-nitroanthranilic acid derivatives in superheated
water has been developed in the present study. Several target
products were obtained in excellent isolated yields by the
coupling of 2-chloro-5-nitrobenzoic acid with arylamines.
Additionally, the present method has many advantages, such
as the absence of organic solvents or metal catalysts and it can
be applied to an alkyl amine and to phenol.
superheated water without catalysta
Entry
Ar
Temp./°C Time/h Products Yield/%b
1
2
C6H5
2-CH3C6H4
3-CH3C6H4
4-CH3C6H4
2-ClC6H4
150
170
150
150
170
150
150
150
170
190
190
2
3
2
2
3
2
2
2
3
3
3
3a
3b
3c
3d
3e
3f
3g
3h
3i
88
75
78
76
44
56
60
76
55
34
46
3
4
5
6
3-ClC6H4
7
4-ClC6H4
8
4-C2H5OC6H4
2,3-diCH3C6H3
2,6-diCH3C6H3
2,4,6-triCH3C6H2
9
10
11
3j
3k
a Reaction conditions: 2-chloro-5-nitrobenzoic acid (3 mmol),
arylamine (6 mmol), potassium carbonate (1.5 mmol), water
(2 mL).
b Isolated yield.
Experimental
All starting materials were purchased from commercial sources and
used without further purification. All reactions were carried out in the
Teflon lined heated reactor. Melting points were measured using
an uncorrected micro-melting point X-4 apparatus. IR spectra were
recorded as KBr discs on a Shimadzu IRAffinity-1 spectrometer. All
1H NMR spectra were recorded on Bruker 500 MHz spectrometer in
DMSO-d6 using TMS as an internal standard. High resolution mass
spectrometric (HRMS) data of some compounds were obtained using
AB (Applied Biosystems) Qtar elite.
In further experiments, to investigate the scope of this syn-
thetic method, the procedure was applied to coupling reactions
with different reactants (Scheme 2) and the results were listed
in Table 3. Firstly the reaction of benzylamine and naphthyl-
amine with 2-chloro-5-nitrobenzoic acid was investigated and
the expected compounds were obtained with the yields of 90%
and 70%, respectively (Table 3, 3l, 3m). It was then utilised in
the reaction of n-butylamine and 2-chloro-5-nitrobenzoic acid.
The reaction proceeded smoothly and the expected product
was obtained in 91% isolated yield (Table 3, 3n). Moreover,
the reactions of oxygen and sulfur-based nucleophiles with 2-
chloro-5-nitrobenzoic acid were also investigated. Thiophenol
gave the desired product in 87% yield (Table 3, 3o), but phenol
gave the relevant product in 38% yield for 3 h at 190 °C
(Table 3, 3p).
Amination of 2-chloro-5-nitrobenzoic acid in superheated water;
general procedure
A mixture of 2-chloro-5-nitrobenzoic acid (3 mmol), arylamine
(6 mmol), anhydrous potassium carbonate (1.5 mmol) and distilled
water (2 mL) were placed in a teflon inner call having a volume of
10 mL an oven. The mixture was heated in a drying oven for the time
and temperatures listed in Table 2 and Table 3. After the reactor was
cooled to room temperature, the reaction mixture was basified to pH
12 with aqueous NaOH. Then it was filtered and the filter residue was
washed with distilled water (3×20 mL). The aqueous layer was acidi-
fied with aqueous HCl to pH ≤ 3. The product was precipitated in the
acidic medium. The precipitated solid was filtered off, washed with
distilled water (3×20 mL) and re-crystallised from ethanol/water to
give the desired product with the yields listed in Tables 2 and 3.
5-Nitro-2-(phenylamino) benzoic acid (3a): M.p. 253−254 °C (lit.13
251−253 °C). FT-IR (KBr) νmax: 3449, 3327, 3065, 2922, 1678, 1614,
1597, 1578, 1500, 1342, 1254 cm−1; 1H NMR (DMSO-d6, 500 MHz):
7.13 (d, J = 9.50 Hz, 1H, ArH), 7.27 (t, J = 7.00 Hz, 1H, ArH), 7.37
(d, J = 7.50 Hz, 2H, ArH), 7.48 (t, J = 8.00 Hz, 2H, ArH), 8.18 (dd,
J = 9.00 Hz, 3.00 Hz, 1H, ArH), 8.72 (d, J = 2.50 Hz, 1H, ArH), 10.38
(s, 1H, NH), 13.89 (s, 1H, COOH).
Finally, the importance of the electron-withdrawing nitro
group was also studied. When the nitro group was in the ortho-
position and the carboxyl group was in the para-position of the
chlorobenzene and it coupled with aniline, the reaction gave a
5-Nitro-2-(2-tolylamino)benzoic acid (3b): M.p. 258−260 °C. FT-
IR (KBr) νmax: 3447, 3310, 3063, 2859, 1663, 1609, 1584, 1501, 1441,
1338, 1248 cm−1; 1H NMR (DMSO-d6, 500 MHz): 2.20 (s, 3H, CH3),
6.72 (d, J = 9.50 Hz, 1H, ArH), 7.25−7.28 (m, 1H, ArH), 7.30−7.35
(m, 2H, ArH), 7.39 (s, J = 7.00 Hz, 1H, ArH), 8.15 (dd, J = 9.50 Hz,
3 Hz, 1H, ArH), 8.72 (d, J = 2.5 Hz, 1H, ArH), 10.24 (s, 1H, NH),
13.85 (s, 1H, COOH). 13C NMR (DMSO-d6, 500 MHz) δ = 17.38,
110.29, 112.87, 125.67, 126.72, 127.13, 128.44, 129.37, 131.25,
133.58, 136.17, 136.55, 152.99, 168.73. HRMS calcd. for
C14H13N2O4[M + H+]: 273.0870; found: 273.0869.
Scheme 2
Table 3 Synthesis of different substituted benzoic acid
derivativesa
Entry R1
R2
HXR3
Temp. Time Products Yield
/°C
/h
/%b
5-Nitro-2-(3-tolylamino)benzoic acid (3c): M.p. 268−269 °C. FT-
IR (KBr) νmax: 3449, 3318, 3103, 2920, 1665, 1603, 1576, 1531, 1491,
1333, 1242 cm−1; 1H NMR (DMSO-d6, 500 MHz): 2.34 (s, 3H, CH3),
7.09−7.17 (m, 4H, ArH), 7.35 (t, J = 7.50 Hz, 1H, ArH), 8.17 (d, J =
9.00 Hz, 1H, ArH), 8.71 (s, 1H, ArH), 10.35 (s, 1H, NH), 13.89 (s, 1H,
COOH). 13C NMR (DMSO-d6, 500 MHz) δ = 20.86, 110.74, 113.22,
120.90, 124.42, 126.47, 128.41, 129.27, 129.52, 136.42, 137.99,
139.36, 152.36, 168.66. HRMS calcd. for C14H13N2O4[M + H+]:
273.0870; found: 273.0859.
1
COOH NO2
150
2
3l
90
2
3
4
5
6
7
COOH NO2
COOH NO2
170
150
150
190
150
190
2
2
2
3
2
3
3m
3n
3o
3p
3q
3r
70
91
87
38
94
30
COOH NO2 C6H5SH
COOH NO2 C6H5OH
NO2 COOH C6H5NH2
5-Nitro-2-(4-tolylamino)benzoic acid (3d): M.p. 263−264 °C (lit.26
262°C). FT-IR (KBr) νmax: 3509, 3317, 1924, 2857, 1676, 1585, 1516,
1423, 1317, 1246 cm−1; 1H NMR (DMSO-d6, 500 MHz): 2.34 (s, 3H,
CH3), 7.04 (d, J = 9.50 Hz, 1H, ArH), 7.26 (q, J = 9.00 Hz, 4H, ArH),
8.15 (dd, J = 9.50 Hz, 3.00 Hz, 1H, ArH), 8.71 (d, J = 2.50Hz, 1H,
ArH), 10.29(s, 1H, NH), 13.84 (s, 1H, COOH).
COOH
H
C6H5NH2
a Reaction conditions: benzoic acid derivatives (3 mmol), amine
or phenol (6 mmol), potassium carbonate (1.5 mmol), water
(2 mL).
b Isolated yield.

728 JOURNAL OF CHEMICAL RESEARCH 2012
2-(2-Chlorophenylamino)-5-nitrobenzoic acid (3e): M.p. 263−
265 °C (lit.27 273−275 °C). FT-IR (KBr) νmax: 3449, 3279, 2922, 2853,
5-Nitro-2-(phenylthio)benzoic acid (3o): M.p. 225−227 °C (lit.30
227 °C). FT-IR (KBr) νmax: 3468, 3099, 2868, 1692, 1595, 1564, 1510,
1
1684, 1593, 1502, 1437, 1341, 1251 cm−1; H NMR (DMSO-d6,
1
1340, 1252 cm−1; H NMR (DMSO-d6, 500 MHz): 6.87 (d, J =
500 MHz): 6.99 (d, J = 9.50 Hz, 1H, ArH), 7.33 (t, J = 7.50 Hz, 1H,
ArH), 7.46 (t, J = 8.00 Hz, 1H, ArH), 7.61 (d, J = 8.00 Hz, 1H, ArH),
7.65 (d, J = 8.00, 1H, ArH), 8.21 (dd, J = 9.50 Hz, 2.50 Hz, 1H, ArH),
8.74 (d, J = 2.50 Hz, 1H, ArH), 10.57 (s, 1H, NH), 13.85 (s, 1H,
COOH).
2-(3-Chlorophenylamino)-5-nitrobenzoic acid (3f): M.p. 272−
274 °C (lit.13 274−276 °C). FT-IR (KBr) νmax: 3468, 3310, 3098, 3019,
1684, 1612, 1587, 1497, 1342, 1319, 1234 cm−1; 1H NMR (DMSO-d6,
500 MHz): 7.20 (d, J = 9.50 Hz, 1H, ArH), 7.32 (d, J = 8.00 Hz, 1H,
ArH), 7.35 (d, J = 8.00 Hz, 1H, ArH), 7.47 (t, J = 8.00 Hz, 2H, ArH),
8.21 (dd, J = 9.50 Hz, 2.50 Hz, 1H, ArH), 8.71 (d, J = 3.00 Hz, 1H,
ArH), 10.35 (s, 1H, NH), 13.94 (s, 1H, COOH).
2-(4-Chlorophenylamino)-5-nitrobenzoic acid (3g): M.p. 287−
288 °C (lit.27 285 °C). FT-IR (KBr) νmax: 3450, 3316, 3072, 2980,
1670, 1597, 1585, 1508, 1337, 1242 cm−1; 1H NMR (DMSO-d6, 500
MHz): 7.13 (d, J = 9.50 Hz, 1H, ArH), 7.40 (d, J = 9.00 Hz, 2H, ArH),
7.51 (d, J = 8.50 Hz, 2H, ArH), 8.18 (dd, J = 9.00 Hz, 3.00 Hz, 1H,
ArH), 8.71 (d, J = 2.50 Hz, 1H, ArH), 10.32 (s, 1H, NH), 13.92 (s, 1H,
COOH).
2-(4-Ethoxyphenylamino)-5-nitrobenzoic acid (3h): M.p. 198−
200 °C (lit.13 199−201 °C). FT-IR (KBr) νmax: 3449, 3306, 3073, 2926,
1676, 1589, 1526, 1502, 1335, 1250, 1130 cm−1; 1H NMR (DMSO-d6,
500 MHz): 1.34 (t, J = 7.00 Hz, 3H, CH3), 4.05(q, J = 7.00 Hz, 2H,
CH2), 6.90 (d, J = 9.50 Hz, 1H, ArH), 7.01 (d, J = 8.50 Hz, 2H, ArH),
7.26 (d, J = 8.50 Hz, 2H, ArH), 8.14 (dd, J = 9.50 Hz, 2.50 Hz, 1H,
ArH), 8.70 (d, J = 3.00 Hz, 1H, ArH), 10.20 (s, 1H, NH), 13.80 (s, 1H,
COOH).
9.00 Hz, 1H, ArH), 7.58−7.60 (m, 3H, ArH), 7.62−7.64 (m, 2H, ArH),
8.20 (dd, J = 9.00 Hz, 2.50 Hz, 1H, ArH), 8.65 (d, J = 2.50 Hz, 1H,
ArH), 13.95 (s, 1H, COOH).
5-Nitro-2-phenoxybenzoic acid (3p): M.p. 161−162 °C (lit.31 155−
156 °C). FT-IR (KBr) νmax: 3428, 3082, 2851, 1690, 1616, 1577, 1514,
1
1477, 1348, 1260 cm−1; H NMR (DMSO-d6, 500 MHz): 7.02 (d,
J = 9.00 Hz, 1H, ArH), 7.15 (d, J = 7.50 Hz, 2H, ArH), 7.28 (t,
J = 7.50 Hz, 1H, ArH), 7.49 (t, J = 8.00 Hz, 2H, ArH), 8.34 (dd,
J = 9.00 Hz, 2.50 Hz, 1H, ArH), 8.60 (d, J = 3.00 Hz, 1H, ArH), 13.59
(s, 1H, COOH).
3-Nitro-4-(phenylamino)benzoic acid (3q): M.p. 260−261°C (lit.32
262 °C). FT-IR (KBr) νmax: 3335, 3088, 2816, 1686, 1626, 1568, 1531,
1
1497, 1288, 1217 cm−1; H NMR (DMSO-d6, 500 MHz): 7.13 (d,
J = 9.50 Hz, 1H, ArH), 7.30 (t, J = 7.50 Hz, 1H, ArH), 7.37 (d,
J = 7.50 Hz, 2H, ArH), 7.48 (t, J = 8.00 Hz, 2H, ArH), 7.93 (dd,
J = 9.00 Hz, 2.00 Hz, 1H, ArH), 8.64 (d, J = 2.00 Hz, 1H, ArH), 9.81
(s, 1H, NH), 13.01 (s, 1H, COOH).
2-(Phenylamino)benzoic acid (3r): M.p. 181−182 °C (lit.33 181−
183 °C). FT-IR (KBr) νmax: 3485, 3337, 3042, 2889, 1663, 1582, 1514,
1435, 1261 cm−1; 1H NMR (DMSO-d6, 500 MHz): 6.78 (t, J =
9.50 Hz, 1H, ArH), 7.30 (t, J = 7.50 Hz, 1H, ArH), 7.37 (d, J =
7.50 Hz, 3H, ArH), 7.34−7.40 (m, 3H, ArH), 7.91 (dd, J = 9.00 Hz,
1.50 Hz, 1H, ArH), 9.64 (s, 1H, NH), 13.08 (s, 1H, COOH).
We thank the Ministry of Science and Technology of China
(No.2010DFA32680) and the Fundamental Research Funds
for the Central Universities (No. CDJXS11232242) for
financial support.
2-(2,3-Dimethylphenylamino)-5-nitrobenzoic acid (3i): M.p. 266−
268 °C (lit.13 262−264 °C). FT-IR (KBr) νmax: 3470, 3310, 3071, 2859,
1659, 1607, 1580, 1499, 1443, 1337, 1242 cm−1; 1H NMR (DMSO-d6,
500 MHz): 2.09 (s, 3H, CH3), 2.31 (s, 3H, CH3), 6.59 (d, J = 9.50 Hz,
1H, ArH), 7.14−7.22 (m, 3H, ArH), 8.13 (dd, J = 9.50 Hz, 2.00 Hz,
1H, ArH), 8.72 (d, J = 2.50 Hz, 1H, ArH), 10.21 (s, 1H, NH), 13.80
(s, 1H, COOH).
Received 16 August 2012; accepted 13 October 2012
Paper 1201466 doi: 10.3184/174751912X13524831206251
Published online: 5 December 2012
2-(2,6-Dimethylphenylamino)-5-nitrobenzoic acid (3j): M.p. 236−
238 °C. FT-IR (KBr) νmax: 3450, 3325, 3101, 2954, 1668, 1641, 1574,
1495, 1330, 1238 cm−1; 1H NMR (DMSO-d6, 500 MHz): 2.12 (s, 6H,
CH3), 6.18 (d, J = 9.50 Hz, 1H, ArH), 7.04 (s, 2H, ArH), 8.12 (dd,
J = 9.00 Hz, 2.50 Hz, 1H, ArH), 8.72 (d, J = 2.50 Hz, 1H, ArH), 9.97
(s, 1H, NH), 13.72 (s, 1H, COOH). 13C NMR (DMSO-d6, 500 MHz)
δ = 17.65, 109.76, 112.25, 127.54, 128.56, 128.62, 129.57, 135.28,
135.73, 135.94, 153.48, 168.64. HRMS calcd. for C15H15N2O4[M +
H+]: 287.1026; found:287.1025.
2-(Mesitylamino)-5-nitrobenzoic acid (3k): M.p. 233−234 °C. FT-
IR (KBr) νmax: 3450, 3345, 2922, 2857, 1672, 1609, 1578, 1499, 1439,
1248, 1128 cm−1; 1H NMR (DMSO-d6, 500 MHz): 2.07 (s, 6H, CH3),
2.29 (s, 3H, CH3), 6.17 (d, J = 9.00 Hz, 1H, ArH), 7.23 (s, 3H, ArH),
8.10 (dd, J = 9.50 Hz, 2.00 Hz, 1H, ArH), 8.71 (s, 1H, ArH), 9.89 (s,
1H, NH), 13.55 (s, 1H, COOH). 13C NMR (DMSO-d6, 500 MHz) δ =
18.07, 21.02, 110.54, 112.84, 129.71, 129.74, 130.06, 133.15, 135.90,
137.37, 137.25, 158.61, 168.66. HRMS calcd. for C16H17N2O4[M +
H+]: 301.1183; found:301.1183.
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2-(Benzylamino)-5-nitrobenzoic acid (3l): M.p. 239−241 °C (lit.13
239−241 °C). FT-IR (KBr) νmax: 3471, 3336, 3096, 2866, 1668, 1583,
1547, 1502, 1443, 1335, 1248 cm−1; 1H NMR (DMSO-d6, 500 MHz):
4.64 (d, J = 6.00 Hz, 2H, CH2), 6.84 (d, J = 9.50 Hz, 1H, ArH),
7.27−7.30 (m, 2H, ArH), 7.35−7.38 (m, 4H, ArH), 8.13 (dd, J =
9.00 Hz, 2.50 Hz, 1H, ArH), 8.66 (d, J = 2.50 Hz, 1H, ArH), 9.19 (t,
J = 5.50 Hz, 1H, NH), 13.55 (s, 1H, COOH).
10 M.L.D. Palacios and R.F.P. Comsom, Synth. Commun., 2003, 33, 1771.
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Commun., 2006, 63, 271.
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1853.
13 Y. Baqi and C.E. Müller, J. Org. Chem., 2007, 72, 5908.
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2004, 6, 250.
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1702.
2-(Naphthalen-1-ylamino)-5-nitrobenzoic acid (3m): M.p. 251−
252 °C (lit.28 247−249 °C). FT-IR (KBr) νmax: 3449, 3306, 3094, 3057,
1668, 1607, 1578, 1526, 1499, 1333, 1240 cm−1; 1H NMR (DMSO-d6,
500 MHz): 6.69 (d, J = 9.50 Hz, 1H, ArH), 7.57−7.64 (m, 4H, ArH),
7.89 (d, J = 8.00 Hz, 1H, ArH), 7.97 (t, J = 7.00 Hz, 1H, ArH), 8.06
(dd, J = 7.50 Hz, 1H, ArH), 8.10 (dd, J = 9.50 Hz, 3.00 Hz, 1H, ArH),
8.77 (d, J = 3.00 Hz, 1H, ArH), 10.69 (s, 1H, NH), 13.97 (s, 1H,
COOH).
2-(Butylamino)-5-nitrobenzoic acid (3n): M.p. 186−188 °C (lit.29
180 °C). FT-IR (KBr) νmax: 3492, 3356, 3108, 2930, 2870, 1665, 1610,
1
1582, 1487, 1331, 1244 cm−1; H NMR (DMSO-d6, 500 MHz): 0.92
(t, J = 7.50 Hz, 3H, CH3), 1.38 (q, J = 7.50 Hz, 2H, CH2), 1.60 (quint,
J = 7.00 Hz, 2H, CH2), 3.33 (q, J = 6.50 Hz, 2H, CH2), 6.90 (d,
J = 9.50 Hz, 1H, ArH), 8.16 (dd, J = 9.50 Hz, 3.00 Hz, 1H, ArH), 8.63
(d, J = 3.00 Hz, 1H, ArH), 8.77 (s, 1H, NH), 13.47 (s, 1H, COOH).