REACTION OF POLYNITROTOLUENES WITH PHTHALIC ANHYDRIDE
1247
acetic acid was refluxed for 2 h. The mixture was
cooled to 20 C, and the precipitate was filtered off.
The filtrate was diluted with 20 ml of distilled water
to isolate an additional amount of the product. The
combined precipitates were washed with 3 4 portions
of water and cold ( 0 C) methanol (2 3 ml). Yield
3.44 g (83%); slightly colored crystals, mp 235 C
(from acetone); published data [4]: mp 236 C.
VIII was isolated as bright yellow lustrous crystals;
yield 0.08 g (40%), mp 213 214.5 C (from acetone).
1H NMR spectrum (acetone-d6), , ppm: 2.60 s (3H,
Me), 3.89 s (3H, COOMe), 7.65 7.75 m (4H, Harom
,
in o-MeOCOC6H4), 8.56 s and 9.0 s (2H, 3-H, 5-H),
9.7 br.s (1H, NH). Found, %: C 54.26; H 3.85;
N 12.59. C15H13N3O6. Calculated, %: C 54.38;
H 3.93; N 12.69.
N-(2-Methyl-5-nitrophenyl)phthalimide (Va)
and N-(4-methyl-3-nitrophenyl)phthalimide (VI)
(regioisomeric mixture; molar ratio 2:3) were syn-
thesized by the procedures described in [4, 6]. H
NMR spectrum of Va, , ppm: 2.63 s (3H, Me),
6-Nitro-2,4-bis(phthalimido)toluene (IX). A solu-
tion of 2.54 mmol of amine VII and 2.54 mmol of
phthalic anhydride in 5 ml of N,N-dimethylaniline
was refluxed for 2.5 h. The mixture was cooled to
18 20 C and acidified with dilute (1:6) hydrochloric
acid to pH 1 2 ( 22 ml). After 1 h, the orange precip-
itate was filtered off and repeatedly washed with
water. Yield 0.42 g (39%, calculated on the taken
amine VII); colorless crystals, mp >300 C (decomp.;
the product was twice recrystallized from acetone).
1H NMR spectrum, , ppm: 2.15 s (3H, Me), 7.95
8.02 m (8H, Harom, phthalimide), 8.55 s and 8.56 s
(2H, 3-H, 5-H). Found, %: C 64.74; H 3.16; N 9.94.
C23H13N3O6. Calculated, %: C 64.64; H 3.07; N 9.83.
1
7.73 s (1H, 3-H), 7.98 br.s (4H, Harom, phthalimide),
8.15 s (1H, 4-H), 8.38 s (1H, 6-H). 1H NMR spectrum
of VI, , ppm: 2.32 s (3H, Me), 7.73 s (1H, 5-H),
7.98 br.s (4H, Harom, phthalimide), 8.29 br.s (1H,
6-H), 8.38 s (1H, 2-H).
2-Amino-4,6-dinitrotoluene (VII). a. A solution
of 1.53 mmol of phthalimide Vb in 50 ml of benzene
containing 0.44 ml of 85% aqueous hydrazine was
refluxed for 5 h. The mixture was cooled, and the
precipitate was filtered off and washed with benzene.
The solvent was distilled off from the filtrate under
reduced pressure (water-jet pump). The dark yellow
residue was dissolved in 20 ml of methanol, unreacted
initial phthalimide Vb was filtered off, and the filtrate
was heated under reflux for 15 min with charcoal.
The solution was filtered, the filtrate was evaporated
to a volume of 0.5 ml, and the precipitate was fil-
tered off. Yield 0.18 g (60%); yellow crystals,
mp 170 171 C (from ethanol); published data [10]:
Reaction of amine VII with phthaloyl chloride.
a. To a solution of 2.54 mmol of amine VII in 5 ml
of N,N-dimethylaniline at 18 20 C we added drop-
wise an equimolar amount of phthaloyl chloride
(0.37 ml), and the mixture was refluxed for 2.5 h.
It was then cooled to 18 20 C, acidified with dilute
(1:6) hydrochloric acid, and left overnight. The
precipitate was filtered off and repeatedly washed with
water and with two 2-ml portions of methanol. We
thus isolated 0.23 g (31%) of N-(3-amino-2-methyl-
5-nitrophenyl)phthalimide (XI) as bright yellow crys-
1
mp 175 176 C. H NMR spectrum, , ppm: 2.20 s
1
(3H, Me), 6.12 br.s (2H, NH2), 7.67 s and 7.72 s
(2H, 3-H, 5-H).
b. A solution of 61.6 mmol of compound I and
17.2 mmol of FeCl3 in 120 ml of methanol was heated
to 60 C, and 21 ml of a 64% aqueous solution of
N2H4 and 70 ml of glacial acetic acid were added.
The mixture was stirred for 2 h at 60 C, cooled, and
tals with mp 270 271 C (from acetone). H NMR
spectrum, , ppm: 1.95 s (3H, Me), 5.7 br.s (2H,
NH2), 7.4 s and 7.63 s (2H, 4-H, 6-H), 7.9 7.95 m
(4H, Harom in phthalimide). [M]+. 297. Found, %:
C 60.67; H 3.64; N 14.05. C15H11N3O4. Calculated,
%: C 60.61; H 3.73; N 14.14. M 297.
b. Amine VII, 2.54 mmol, was dissolved in 25 ml
diluted with water, and the precipitate was filtered of boiling toluene, an equimolar amount of phthaloyl
off. Yield 8.6 g (71%), mp 172 C (from ethanol). IR
spectrum (KBr), , cm : 3420, 3350 (NH2). Found,
%: C 42.40; H 4.00; N 20.90. C7H7N3O4. Calculated,
%: C 42.60; H 3.50; N 21.31.
Methyl 2-(2-methyl-3,5-dinitrophenylcarba-
moyl)benzoate (VIII). A solution of 0.6 mmol of
phthalimide Vb and a small amount of K2CO3 (on
the tip of a spatula) in 30 ml of methanol was kept
for 30 min at 18 20 C. The solvent was removed
under reduced pressure (water-jet pump, 18 20 C),
and the residue was washed with 3 4 portions of
water and two 1-ml portions of methanol. Compound
chloride (0.37 ml) was added, 5.1 mmol (0.71 ml) of
triethylamine was added dropwise, and the mixture
was refluxed for 40 min. It was cooled to 18 20 C,
and the precipitate was filtered off and washed with
toluene (2 3 ml). The filtrate was evaporated under
reduced pressure (water-jet pump), and the residue
was twice recrystallized from acetone. Yield of Vb
0.3 g (36%). For 1H NMR spectrum of Vb, see above.
4-Nitro-2,6-bis(phthalimido)toluene (X). A solu-
tion of 10.4 mmol of phthalimide XI and 20.9 mmol
of phthalic anhydride in 5 ml of glacial acetic acid
was refluxed for 35 min. The mixture was cooled, and
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 9 2001