Synthesis and Characterization of New Azo-Schiff Bases and Study Biological Activity of Some These Compounds

Introduction Schiff bases are compounds which prepared by the condensation of aldehyde or ketone with primary amines(1-3). Schiff bases are used in the synthesis of some industrial, bioactive and inorganic compounds(45). The compounds including good fungicdal activity(6), Anticancer(7-9), antibacterial (10-12), antifungal (13,14), antiinflammatory(15-17)and herbicidal activities(8). Azo compounds are widely used as dyes and pigments. Another application is analytical chemistry. On the other hand azo compounds shown biological activities containing antibacterial(18). Schiff bases and azo compounds are important structures in the medicinal and pharmaceutical fields(19). Experimental Melting points were taken on astuart Melting points apparatus. FTIR spectra were recorded on Schimadzu 8000 serise. 1HNMR were run on abruker, Ultra shield 300 MKz, Switzear land using TMS as interenal standard and CDCl3 as solvent. UvVis spectra were recorded on Shimadzu Uv-1700. C.H. N analytical were recorded on a Eurovectro, EA 3000A, Italy. * Corresponding author at: University of Baghdad College of Science, Iraq.E-mail address: A-Synthesis Azo compound Diazonium salt (2) was prepared according to a reported method(20). Treatment of compound (2) with 2-hydroxy benzaldehyde gave compound (3), scheme (1). Azo aldehyde (3) could also be purified in 80% yield by recrystallization from warm ethanol. BSynthesis new derivatives The compound (3) treatment with different aromatic amines containing 3 drops of glacial acetic acid were heated under reflux in absolute ethanol for (3-10h), yielded the azo Schiff bases 4(a-h) in excellent yields (scheme 2). Results and discussion Eight new azo-Schiff bases were prepared in excellent yields via the condensation of different aromatic amines with new azo compounds(20). The diazonium compound was treatment with salicylaldehyde gave the azo compound (3) scheme (1) which was purified by recrystallization from ethanol. Treatment of compound (3) with different aromatic amines, in refluxing absolute ethanol yielded the new azo Schiff bases (Scheme 2, Table 1). The reactions are followed by (TLC), (Benzene:MeOH). New compounds were identified by their melting points, elemental analysis, IR spectra, UV spectra and 1HNMR spectra. FTIR spectra(21) shown disappearance of (NH2) absorption bands at 3160, 3280 cm-1 and the appearance of (C=O) absorption band at (166o) cm-1. Also FTIR was used to confirm the structure of new compounds 4(a-h) no PISSN 1991-8941 E-ISSN 2706-6703 Journal of University of Anbar for Pure Science (JUAPS) Open Access 2010,(4), (3 ) :34-38 35 absorption band corresponding to (C=O) group was observed in the FTIR spectra of the new compounds. New bands at (15901630) cm-1due to (C=N) group, (Table 2). The UV spectra of new azo-Schiff bases shown absorption maxima at (260-295) nm due to the (π→π∗), and another absorption maxima at (305-360) nm due to the (n-→π∗). Table (4). In the 1HNMR spectra signals (6.3-8.5) ppm due to aromatic protons of new compounds (4b, 4d and 4e), (8.1-8.6) ppm belonging to the (N=CH) group of compounds (4a, 4d and 4e) and (10.1-10.6) ppm for (-OH) group of compounds were observed. These signals represent more characteristic evidence for the formation of these compounds. Anti bacterial Activity The new compounds were tested against one strain each of a gram positive and two gram negative. The test results presence in Tables (6) and (7), some new compounds were active against tested and another compounds are no active. All compounds are no active where used (1×10-5M), but active in the concentrations : 1×10-4 M and 1×10-3M see Tables (6) and (7). Table (1): Physical data for new Schiff bases NO. M.F M.Wt (gm /mole) M.P C Yield % Rf Time (hrs) (4a) C34H28N6O2 552 220 72 0.68 24 (4b) C32H22N6O2Cl2 593 253 78 0.81 12 (4C) C36H28N6O4 608 266 68 0.71 10 (4d) C32H22N8O6 614 269 62 0.59 10 (4e) C32H22N6O2Br2 682 272 75 0.76 10 (4f) C32H22N6O2Cl2 593 243 80 0.56 8 (4g) C34H28N6O2 552 260 66 0.62 8 (4h) C28H18N10O2 528 251 64 0.65 6 Table (2): Analytical data for some new Azo Schiff bases Comp. No. M.wt (g/mol) Found (calc) % C H N (4a) 552 73.62 (73.91) 4.89 (5.07) 15.02 (15.21) (4c) 608 70.89 (71.05) 4.25 (4.60) 13.62 (13.81) (4d) 614 62.13 (62.54) 3.24 (3.58) 17.98 (18.24) (4h) 528 63.12 (63.63) 2.99 (3.40) 26.30 (26.51) Table (3): FTIR spectra for some new Azo – Schiff bases