TRANS-2-CARBOXYCINNAMIC ACIDS
2535
1H, CH-COOH), 3.86 (s, 3H, OCH3). 13C NMR (DMSO-d6): 167.52, 167.47, 161.9,
137.7, 122.6 (C), 142.9, 132.9, 121.7, 115.3, 112.5 (CH), 55.6 (CH3). IR[12] (KBr):
ꢂ1
c ¼ 2200–3300 cmꢂ1 (COOH), 1702, 1688 cmꢂ1 (C O), 1637, 1603 cm
=
=
(C C),
1264, 1242, 1208, 1155 cmꢂ1 (C–O).
E-2,5-Dicarboxycinnamic acid (2e). Colorless needles. Mp 273–274 ꢀC (t-
butanol–water, 1:1). 1H NMR (DMSO-d6): 13.19 (s, 3H, COOH), 8.26 (d,
J ¼ 15.6 Hz, 1H, CH¼CH–COOH), 8.21 (s, 1H, H-6), 7.91–8.06 (m, 2H, H-3, H-4),
6.42 (d, J ¼ 15.6 Hz, 1H, CH-COOH). 13C NMR (DMSO-d6): 167.6, 167.2, 166.3,
135.1, 134.6, 133.8 (C), 141.9, 130.6, 130.0, 128.3, 122.3 (CH)ꢂ. 1IR (KBr): c ¼ 2200–
3300 cmꢂ1 (COOH), 1735, 1699, 1670 cmꢂ1 (C O), 1621 cm (C C). Found: C,
56.03; H, 3.34. (C11H8O6) 236.18 requires C, 55.94; H, 3.41.
=
=
E-2-Carboxy-5-carboxymethylcinnamic acid (2f). Colorless needles. Mp
1
210–212 ꢀC (t-butanol–water, 1:1). H NMR (DMSO-d6): 13.11 (s, 2H, COOH),
8.24 (d, J ¼ 15.9 Hz, 1H, CH¼CH–COOH), 8.21 (d, J ¼ 1.1 Hz, 1H, H-6), 8.02
(dd, J ¼ 8.2, 1.1 Hz, 1H, H-4), 7.97 (d, J ¼ 8.2 Hz, 1H, H-3), 6.44 (d, J ¼ 15.9 Hz,
1H, CH-COOH), 3.89 (s, 3H, CH3). 13C NMR (DMSO-d6): 167.5, 167.1, 165.2,
135.2, 134.8, 132.5 (C), 141.7, 130.7, 129.8, 128.1, 122.4 (CH), 52.5 (CH3). IR
ꢂ1
(KBr): c ¼ 2200–3300 cmꢂ1 (COOH), 1735, 1686 cmꢂ1 (C O), 1626 cm (C C),
1149 cmꢂ1 (C–O). Found: C, 57.34; H, 4.14. (C12H10O6) 250.20 requires C, 57.60;
H, 4.03.
=
=
E-5-Bromo-2-carboxycinnamic acid (2g). Cream-colored powder. Mp
176–178 ꢀC (water) (183–185 ꢀC[14]). 1H NMR (DMSO-d6)[14]: 12.97 (s, 2H, COOH),
8.24 (d, J ¼ 15.9 Hz, 1H, CH¼CH–COOH), 7.99 (s, 1H, H-6), 7.80 (d, J ¼ 8.4 Hz, 1H,
H-3 or H-4), 7.67 (d, J ¼ 8.4 Hz, 1H, H-3 or H-4), 6.48 (d, J ¼ 15.9 Hz, 1H, CH-
COOH). 13C NMR (DMSO-d6): 167.4, 167.2, 137.3, 129.9, 125.9 (C), 141.1,
2 ꢁ 132.4, 130.3,ꢂ1122.8 (CH). IR[14] (KBr): c ¼ 2300–3200 cmꢂ1 (COOH), 1683 cmꢂ1
=
=
(C O), 1633 cm (C C).
E-2-Carboxy-5-hydroxycinnamic acid (2h). Mixture with Z-2-carboxy-6-
hydroxycinnamic acid (5h) (4:1) was formed. Brown yellow powder. Mp 240 ꢀC
1
(water) (250–252 ꢀC[13]). H NMR (DMSO-d6): 12.68 (s, 2H, COOH), 10.35 (s, 1H,
OH), 8.40 (d, J ¼ 15.9 Hz, 1H, CH¼CH–COOH), 7.82 (d, J ¼ 8.6 Hz, 1H, H-3),
7.05 (d, J ¼ 2.4 Hz, 1H, H-6), 6.87 (dd, J ¼ 8.6, 2.4 Hz, 1H, H-4), 6.22 (d, J ¼ 15.9 Hz,
1H, CH-COOH). 13C NMR (DMSO-d6): 167.5, 167.3, 160.7, 137.9, 120.9 (C), 143.5,
133.2, 120.9, 116.4, 114.0ꢂ1(CH). IR (KBr): c ¼ 2300–3600 cmꢂ1 (COOH, OH),
ꢂ1
1687 cmꢂ1 (C O), 1624 cm (C C), 1267, 1235 cm (C–O).
=
=
2,4-Dicarboxy-5-hydroxycinnamic acids (2i) and (5i). Mixture of isomers
trans and cis in a ratio of 2:1. Yellow powder. Mp 250 ꢀC (water). IR (KBr):
ꢂ1
ꢂ1
c ¼ 2200–3400 cmꢂ1 (COOH, OH), 1688 cmꢂ1 (C O), 1639 cm (C C), 1234 cm
=
=
1
(C–O). H NMR (DMSO-d6) isomer trans 2i: 11.8 (s, 3H, COOH), 8.39 (s, 1H,
H-3), 8.36 (d, J ¼ 15.9 Hz, 1H, CH¼CH–COOH), 7.29 (s, 1H, H-6), 6.43 (d, J ¼
1
15.9 Hz, 1H, CH-COOH), 4.76 (s, 1H, OH). H NMR (DMSO-d6) isomer cis 5i:
11.8 (s, 3H, COOH), 8.00 (d, J ¼ 9.6 Hz, 1H, CH¼CH–COOH), 7.67 (s, 1H, H-3),
7.27 (s, 1H, H-6), 6.60 (d, J ¼ 9.6 Hz, 1H, CH-COOH), 4.76 (s, 1H, OH). Found:
C, 52.03; H, 3.40. (C11H8O7) 252.18 requires C, 52.39; H, 3.20.