General method for the synthesis of acylhydrazones AH1- AH7
The respective hydrazide (0.3 g, 1 eq), 3-hydroxybenzaldehyde (1 eq) and concentrated HCl (2 drops) were stirred in etanol (20 mL) at 20–25°C for 8 h. The acylhydrazones were obtained as crystaline solids after vacuum filtration and recrystallization with hot ethanol.
N'-[(1E)-(3-hydroxyphenyl)methylene]benzohydrazide (AH1, C14H12N2O2):
Yellowish solid; yield 91%; melting point: 195–196°C. 1H NMR (200 MHz, DMSO-d6) d 11.78 (s, 1H, NH), 9.61 (s, 1H, OH), 8.37 (s, 1H, N = CH), 7.91 (d, 2H, H-2’ and H-6’, J = 5.6 Hz), 7.61–7.50 (m, 3H, H-3’, H-4’, H-5’), 7.27–6.82 (m, 4H, H-2, H-4, H-5 and H-6); 13C NMR (50 MHz, DMSO-d6) d 163.5 (C = O), 158.1 (C-3), 148.3 (N = CH), 136.0 (C-1), 133.9 (C-1’), 132.1 (C-4’), 130.3 (C-5), 128.9 (C-3’and C-5’), 128.0 (C-2’ and C-6’),119. 2 (C-6), 117.9 (C-4), 113.0 (C-2). 4-chloro-N'-[(1E)-(3-hydroxyphenyl)methylene]benzohydrazide (AH2, C14H11Cl N2O2):
White solid; yield 85%; melting point: 221–223°C.IR (ATR) ῡmax/cm-1 : 3277 (v N-H), 3099 (v C-H ar), 1647 (v C = O), 1560 (v C = N), 1275 (v C-O); 1H NMR (200 MHz, DMSO-d6) d 11.82 (s, 1H, NH), 9.59 (s, 1H, OH), 8.34 (s, 1H, N = CH), 7.91 (d, 2H, H2’ and H-6’, J = 6.12 Hz), 7.58 (d, 2H, H-3’ and H-5’, J = 6.12 Hz), 7.23–6.80 (m, 4H, H2, H-4, H-5 and H-6); 13C NMR (50 MHz, DMSO-d6) d 161.4 (C = O), 157.1 (C-3), 147.6 (N = CH), 136.0 (C-1), 134.9 (C-4’), 131.6 (C-1’), 129.3 (C-5), 129.0 (C-2’ and C6’), 128.0 (C-3’ and C-5’), 118.3 (C-6), 117.0 (C-4), 112.1 (C-2). MS (ESI) m/z calcd for C14H11ClN2O2 (M + H)+ : 275.05, found 274.96.
N'-[(1E)-(3-hydroxyphenyl)methylene]-4-nitrobenzohydrazide (AH3, C14H11N3O4):
Light gray solid; yield 86%; melting point: 255–256°C.IR (ATR) ῡmax/cm-1 : 3280 (v NH), 3051 (v C-H ar), 1661 (v C = O), 1605 (v C = C ar), 1560 (v C = N), 1518 (v NO2), 1348,2 (v NO2), 1282 (v C-O); 1H NMR (200 MHz, DMSO-d6) d 12.04 (s, 1H, NH), 9.61 (s, 1H, OH), 8.36 (s, 1H, N = CH), 8.34 (d, 2H, H-3’ and H-5’, J = 6.3 Hz), 8.13 (d, 2H, H-2’ and H-6’, J = 6.3 Hz), 7.26 (m, 4H, H-2, H-4, H-5 and H-6); 13C NMR (50 MHz, DMSO-d6) d 161.5 (C = O), 156.7 (C-3), 150.5 (C-4’), 139.5 (C-1’), 135.7 (C-1), 130.9 (C-2’ and C-6’), 129.6 (C-5), 124.6 (C-3’ and C-5’), 120.1 (C-6), 118.2 (C-4), 113.6 (C-2).MS (ESI) m/z calcd for C14H11N3O4 (M + H)+ : 286.07, found 286.00.
4-hydroxy-N'-[(1E)-(3-hydroxyphenyl)methylene]benzohydrazide (AH4, C14H12N3O3):
Light brown solid; yield 72%; melting point: 255–258°C.IR (ATR) ῡmax/cm-1 : 3200 (v N-H), 3051 (v C-H ar), 1619 (v C = O), 1585 (v C = N), 1236 (v C-O); 1H NMR (200 MHz, DMSO-d6) d 11.61 (NH), 10.22 (OH), 9.69 (OH), 8.31 (N = CH), 7,79 (d, 2H, H2’ and C-6’, J = 8.5 Hz); 13C NMR (50 MHz, DMSO-d6) d 164.5 (C = O), 162.3 (C-4’), 159.8 (C-3’), 147.9 (N = C), 137.4 (C-1), 132.1 (C-5), 131.4 (C-2’ and C-6’), 125.5 (C1’), 121.8 (C-6), 119.6 (C-3’ and C-5’), 116.7 (C- 4), 114.3 (C-2).MS (ESI) m/z calcd for C14H12N2O3 (M + H)+ : 257.08, found 256.99.
N-(4-{[(2E)-2-(3-hydroxybenzylidene)hydrazino]carbonyl}phenyl) benzamide (AH5, C21H17N3O3):
Light gray solid; yield 91%; melting point: 284–286°C.IR (ATR) ῡmax/cm-1 : 3423 (v O-H), 3319 (v N-H), 3242 (v N-H), 3079 (v C-H ar), 1651 (v C = O amide), 1633 (v C = O hydrazone), 1511 (v C = N), 1296 (v C-O); 1H NMR (200 MHz, DMSO-d6) d 11.77 (s, 1H, CONHN = C), 10.54 (s, 1H, OH), 9.66 (s, 1H, CONHAr), 8.38 (s, 1H, N = CH), 8.00-6.82 (m, 13H, Harom); 13C NMR (50 MHz, DMSO-d6) d 166.2 (C = O), 162.9 (C = O), 158.0 (C-3), 147.8 (N = C), 142.7 (C-1’), 136.0 (C-1), 135.0 (C-1’’), 132.2 (C-4’’), 130.2 (C-3’ and C-5’), 128.8 (C-3’’ and C-5’’), 128.4 (C-4’), 128.1 (C-2’’ and C-6’’), 119.8 (C-2’ and C-6’), 119.1 (C-6), 117.7 (C-4), 112.9 (C-2).MS (ESI) m/z calcd for C21H17N3O3 (M + H)+ : 360.13, found 360.06.
4-[(4-{[(2E)-2-(3-hydroxybenzylidene)hydrazino]carbonyl}phenyl)amino]-4- oxobutanoic acid (AH6, C18H17N3O5):
Light gray solid; yield65%; melting point: 232–234°C. IR (ATR) ῡmax/cm-1 : 3400 − 2400 (v O-H carboxylic acid), 3322 (v N-H), 3242 (v N-H), 3051 (v C-H ar), 1706 (v C = O carboxylic acid), 1665 (v C = O amide), 1644 (v C = O hydrazone), 1522 (v C = N), 1181 (v C-O); 1H NMR (200 MHz, DMSO-d6) d 12.10 (s, 1H, COOH), 11.66 (CONHAr); 10.22 (CONHN = C), 9.59 (s, 1H, ArOH), 8.33 (N = CH), 7.85 (d, 2H, H-2’ and H-6’, J = 8.5 Hz), 7.69 (d, 2H, H-3’ and H-5’, J = 8.5 Hz), 7.25–6.78 (m, 4H, H-2, H-4, H-5 and H-6); 2.58–2.44 (m, 4H, H-2’’, H-3’’); 13C NMR (50 MHz, DMSO-d6)d 173.3 (C-4’’), 170.1 (C-1’’), 161.9 (CONHN), 157.1 (C-3), 146.9 (N = C), 141.8 (C-1’), 135.2 (C-1), 129.3 (C-3’ and C-5’), 128.0 (C-5), 126.9 (C-4’), 118.2 (C-6), 117.6 (C-2’ and C-6’), 116.8 (C-4), 112.0 (C-2), 30.64 (C-2’’), 28.17 (C-3’’).MS (ESI) m/z calcd for C18H17N3O5 (M + H)+ : 356.12, found 356.01.
N'-[(1E)-(3-hydroxyphenyl)methylene]isonicotinohydrazide (AH7, C13H11N3O2):
Yellowish solid; yield 93%; melting point: 268–269°C. IR (ATR) ῡmax/cm-1 : 3474 (v OH), 3397 (v N-H), 3099 (v C-H ar), 1668 (v C = O), 1561 (v C = N), 1287 (v C-O); 1H NMR (200 MHz, DMSO-d6) d 12.69 (s, 1H,NH), 9.04 (s, 1H, OH), 9.03 (d, 2H, H-2’, H-6’, J = 9.63 Hz), 8.54 (s, 1H, N = CH), 8.36 (d, 2H, H-3’, H-5’, J = 9.63 Hzs), 7.30–6.78 (m, 5H, H-2, H-4, H-5, H-6, OH); 13C NMR (50 MHz, DMSO-d6)d 159.9 (C = O), 154.7 (C-3), 150.4 (C-2’ and C-6’), 146. 2 (N = C), 145.3 (C-4’), 136.1 (C-1), 129.3 (C-5), 123.8 (C-3’ and C-5’), 119.2 (C-6), 118.1 (C-4), 113.0 (C-2).MS (ESI) m/z calcd for C13H11N3O2 (M + H)+ : 242.09, found 241.98.