Synthesis , Characterization and Antibacterial Activity of New Chalcones Derived from New Aldehyde ; 4-[ 5-( 4 `-tolyl )-1 , 3 , 4-thiadiazole-2-yl ] benzaldehyde

New chalcones of -{ y hi di z e-y he y e ee substituted phenyl have been prepared from condensation of a new of 4-[5-(4`-tolyl)1,3,4-thiadiazole-2-yl] benzaldehyde (which is synthesized by the reaction of 2amino-5(4`-tolyl) -1,3,4-thiadiazole and benzaldehyde) with 3or 4substituted acetophenones in alkaline medium. The physical, CHNS analysis and spectral data of the synthesized compounds were determined. The biological activity evaluated of new compounds showed that many of these compounds possess antibacterial activity.


Experimental
Chemicals: All chemicals were supplied by fluka, GCC, merek and Aldrich chemicals Co.
Techniques: : FTIR spectra were recorded (by KBr discs) on a Shimadzo (Ir prestige -21) ¹HNMR spectra were examined by: Bruker , model: ultra shield 300 MHz , origin : Swi ze d d e e ed i DMSO s s ve m δ uses TMS s i e standard were made in Al-al Bayt University, Jordan .Hot-Stage, Gallen Kamp melting point apparatus was used for determined (uncorrected) melting points.UV spectra of solutions were performed on CECL 7200 England Spectrophotometer using CHCl 3 as a solvent.Elemental analysis (C.H.N.S) were carried out by a Perkin-Elmer model 2400 instrument.The purity of the synthesized compounds was determined using thin layer chromatography (the spots were observed using employing iodine chamber).

General procedures
The compounds [I] , [II] and [III] a-f were synthesized via Scheme 1.

Synthesis of chalcones [III] a-f
Equi-molar quantities of different 4-substituted acetophenone (0.01mol) and aldehyde[II] (0.01 mol) were dissolved in 20mL of alcohol.Sodium hydroxide solution (0.02mol) was added slowly (and the mixture becomes cold), then the mixture was poured onto 400mL of ice water with stirring.The precipitate obtained was filtered after kept in refrigerator for 24 hrs.washed and re-crystallized from chloroform .

Results and Discussion
2-Amino-1,3,4-thiadiazole derivatives was synthesized from condensation of tuloic acid with thiosemicarbazide in POCl 3 .The FTIR absorption spectrum gives two bands at 3258cm -1 , 3180 cm -1 related to NH 2 group, 3020cm -1 for CH aromatic, peak at 1628cm -1 due to C=N of thiadiazole ring , para substituted in benzene ring indicated by a good bending band at 813cm -1 .The UV-VIS s ec sc y exhibi ed λ max at 296.5 nm.
The new aldehyde[II] was synthesized from reaction of 2-amino-1,3,4-thiadiazole with bezaldehyde in a preoperative conditions .FTIR spectrum of this compound showed a good  No.
7302 Ibn Al-Haitham Jour.for Pure & Appl.Sci.Vol. 30 (3) 2017 stretching band at 1692 cm ˉ dueto aldehydic carbonyl and two vibration bands at 2750 cm ˉ and 2820 cm ˉ for C-H aldehydic stretching.The UV-VIS s ec sc y exhibi ed λ max at 294.5 nm. 1 HNMR spectrum (in DMSO) of synthesized [II](Figure 2), showed a signal sh δ d ub e s be wee δ 6.9 -7.71)ppm due to the eight aromatic protons and a singlet signals at δ .0 m due h ee s f CH 3 group.By claisen-schmidt condensation of aldehyde[I] and 3-or 4-substituted acetophenone using base catalyzed followed by dehydration led to produce new chalcones [III].The structural assignments of the chalcones [III] a-f based on C.H.N.S analysis and their spectral data (FTIR, UV and ¹HNMR spectroscopy).The FTIR specta indicated the disappearance of two bands which could be attributed to asymmetric and symmetric stretching vibration of CH of aldehydic group, besides, two peaks appearance around (1638-1635)cm ˉ and around (1628-1610)cm ˉ due to of C=O, C=C (CH=CH) stretching vibrations, respectively.The 1 HNMR of chalcone [III] b (Figure 3) showed the following features: two pairs of doublet in the region δ8.7-8.49ppm which could be attributed to two protons of CH=CH group.doublet of d ub e s si g e d i e e ed i he egi δ7.-7.86 ppm due to twelve protons of benzene rings having different substituents at positions 3-or 4-, a sharp signal appearance in he s ec um δ .69m due h ee s f CH 3 group.The 1 HNMR of chalcone [III] f sh wed he f wi g fe u es: w i s f d ub e i he egi δ8.-8.26 ppm which can be attributed to two protons of CH=CH group, three d ub e s e ed i he egi δ7.0-7.94ppm due to twelve protons of benzene rings having different substituents at positions I,4.A s he s ec um sh w w e ks s sh sig s δ .7 m d b d sig δ 6.24ppm for three protons of CH 3 group and one proton of NH 2 group, respectively.