8
ADHIKARI ET AL.
shaped crystals (84% yield) with melting point of 229ꢀC
to 231ꢀC.
4H, NH), 3.07 to 3.03 (t, J = 16 Hz, 2H, CH2CH2), 6.31 to
6.29 (d, J = 8 Hz, 2H, Ar H), 7.35 to 7.33 (d, J = 8 Hz,
2H, Ar H), 10.14 (s, 1H, COOH); 13C NMR (100 MHz,
DMSO-d6) δ: 167.55, 166.88, 152.76, 131.05, 129.87,
117.06, 112.63, 78.82, 21.95, 20.30, 11.07; MS For
C13H16N6O2 (M+H)+: 289.3.
3.4.2 | General procedure for synthesis
of disubstituted 1,3,5-triazine derivatives 3
(a-j)
4-(4-amino-6-(butylamino)-1,3,5-triazin-2-ylamino)
benzoic acid (4c)
0.002 mol of 4,6-dichloro-1,3,5-triazin-2-amine (2) was
dissolved in 5 mL of 1,4-dioxane followed by addition of
0.004 mol of various amines (a-j) and stirred in closed
vessel in microwave synthesizer at 27ꢀC to 31ꢀC, 1 bar
pressure, 15 W power for 10 minutes in the presence of
NaHCO3 as a base. The reaction mixture was dried and
the product was recrystallized with suitable solvent to
afford compounds 3(a-j).
Off-white solid; Yield 66%; Rf 0.5; mp 181ꢀC; FTIR
(cm−1): 3248 (N H stretch, secondary), 3091
(OH stretch, COOH), 2951, 2861 (C H stretch), 1626
(C C stretch), 1536, 1406 (C C aromatic stretch), 1358
(C H aromatic stretch), 1282, 1166 (C N aromatic
1
stretch); λmax 240 nm; H NMR (400 MHz, DMSO-d6) δ:
0.91 to 0.88 (t, J = 12 Hz, 3H, CH2CH3), 1.34 to 1.30 (t,
J = 16 Hz, 2H, CH2CH2), 1.53 to 1.46 (m, 2H,
CH2CH2CH2), 3.29 to 3.20 (m, 2H, CH2CH2CH3), 4.84 (s,
4H, NH), 6.57 to 6.55 (d, J = 8 Hz, 2H, Ar H), 7.65 to
7.63 (d, J = 8 Hz, 2H, Ar H), 9.28 (s, 1H, COOH); 13C
NMR (100 MHz, DMSO-d6) δ: 167.58, 165.29, 152.89,
131.10, 129.85, 117.04, 112.51, 78.74, 30.81, 19.56, 13.71;
MS For C14H18N6O2 (M+H)+: 302.61.
3.4.3 | General synthetic procedure for
title compounds 4(a-j)
In the final step, corresponding to the synthesis of
2,4,6-trisubstituted-1,3,5-triazine derivatives 4(a-j) using
microwave irradiation. To this 0.001 mol of 3(a-j) was
dissolved in 2 mL DMSO followed by addition of excess
of p-aminobenzoic acid (PABA) and was stirred in 10 mL
closed microwave vessel at 100ꢀC, 15 bars pressure and
40 W power for 20 minutes. The desired products 4(a-j)
were recrystallized.
4-(4-amino-6-(2-fluorophenylamino)-1,3,5-triazin-
2-ylamino)benzoic acid (4d)
Off-white solid; Yield 64%; Rf 0.72; mp 204ꢀC; FTIR
(cm−1): 3359 (N H stretch, secondary), 3065
(OH stretch, COOH), 2933, 2833, 2527 (C H stretch),
1596, 1505, 1447, 1413 (C C aromatic stretch), 1247,
1166, 1108 (C N aromatic stretch); λmax 290 nm; 1H
NMR (400 MHz, DMSO-d6) δ: 2.56 (s, 4H, NH), 6.59 to
6.58 (d, J = 4 Hz, 2H, Ar H), 7.22 to 7.06 (m, 4H, Ar H),
7.66 to 7.64 (d, J = 8 Hz, 2H, Ar H), 9.55 (s, 1H, COOH);
13C NMR (100 MHz, DMSO-d6) δ: 167.60, 167.19, 164.80,
164.13, 152.86, 144.23, 131, 129.87, 125.53, 123.78, 118.60,
117.08, 115.14, 112.54; MS For C16H13FN6O2 (M+H)+:
340.31.
4-(4-amino-6-(methylamino)-1,3,5-triazin-2-ylamino)
benzoic acid (4a)
Off-white solid; Yield 59%; Rf 0.46; mp 260ꢀC; FTIR
(cm−1): 3246 (N H stretch, secondary), 3100
(OH stretch, COOH, broad), 2937 (C H stretch), 1590
(N H bend), 1559, 1494 (C C stretch, aromatic), 1341,
1
1241, 1167 (C N stretch, aromatic); λmax 296 nm; H
NMR (400 MHz, DMSO-d6) δ: 2.57 (s, 3H, CH3), 4.65 (s,
2H, 2NH), 4.84 (s, 2H, NH2), 6.53 to 6.50 (d, J = 12 Hz,
2H, Ar H), 7.10 to 7.08 (d, J = 8 Hz, 2H, Ar H), 11.36
(s, 1H, COOH); 13C NMR (100 MHz, DMSO-d6) δ: 167.60,
165.75, 163.51, 152.88, 147.73, 129.90, 114.95, 112.52,
27.26; MS For C11H12N6O2 (M+H)+: 260.65.
4-(4-amino-6-(4-fluorophenylamino)-1,3,5-triazin-
2-ylamino)benzoic acid (4e)
Green solid; Yield 64%; Rf 0.52; mp 150ꢀC; FTIR (cm−1):
3221 (N H stretch, secondary), 3086 (OH stretch,
COOH), 2864 (C H stretch), 1599, 1497, 1413 (C C aro-
matic stretch), 1315 (C H aromatic stretch), 1283, 1217,
1168 (C N aromatic stretch); λmax 230 nm; 1H NMR
(400 MHz, DMSO-d6) δ: 2.57 (s, 4H, NH), 6.63 to 6.61 (d,
J = 8 Hz, 2H, Ar H), 7.16 to 7.04 (m, 4H, Ar H), 7.69 to
7.66 (d, J = 12 Hz, 2H, Ar H), 9.58 (s, 1H, COOH); 13C
NMR (100 MHz, DMSO-d6) δ: 167.53, 167.19, 163.61,
158.95, 151.99, 144.15, 131.08, 129.92, 118.86, 117.76,
114.75, 113.08, 111.09; MS For C16H13FN6O2 (M+H)+:
340.31.
4-(4-amino-6-(propylamino)-1,3,5-triazin-2-ylamino)
benzoic acid (4b)
Off-white solid; Yield 67%; Rf 0.48; mp 154ꢀC; FTIR
(cm−1): 3345 (N H stretch), 3219 (OH stretch, COOH),
2963 (C H stretch), 1597 (N H bend), 1554, 1514 (C C
aromatic stretch), 1372 (C H aromatic stretch), 1242,
1167 (C N aromatic stretch); λmax 273 nm; 1H NMR
(400 MHz, DMSO-d6) δ: 0.65 to 0.62 (t, J = 12 Hz, 3H,
CH2 CH3), 1.37 to 1.27 (m, 2H, CH2CH2CH3), 2.25 (s,