No abstract

2-Azetidinone (2b-e) and some unexpected azet-2(1H)-one derivatives (3b-f) were synthesized in two steps from the substitution of 2-aminobenzothiazole and different substituted aromatic aldehydes. Firstly, the Schiff bases were prepared via reaction of different 2-aminobenzothiazoles with different aromatic aldehydes. Second step was the formation of corresponding 2-azetidinone and some unexpected azet-2(1H)-one analogues by cyclocondensation of the Schiff bases with chloroacetyl chloride and phenoxy acetyl chloride in the presence of triethylamine. The chemical structures of the newly synthesized compounds were confirmed by FTIR, 1 H NMR, 13 C NMR, HMQC, elemental analysis and mass spectroscopic analysis.

Melting points (m.p.) were determined using a Gallenkamp apparatus, infrared (FT-IR) spectra were recorded using pressed KBr discs in a Perkin Elmer Spectrum 100 FT-IR spectrophotometer (U.S.A), and 1 H NMR and 13 C NMR spectra were recorded using Bruker DPX FT NMR (500 MHz) and (125 MHz) spectrometers at 298 K (Germany). Chemical shifts are given in δ (ppm) relative to TMS (DMSO-d 6) as the internal standard. Elemental analyses were obtained using an Elementar Analsensysteme GmbH vario MICRO CHNS (Turkish Technical and Scientific Research Council Laboratories, Ankara, Turkey). TLC was performed on pre-coated silica gel plates (Merck 60, F254, 0.25 mm). The organic solvents used were of HPLC grade or were purified by a standard procedure. All reagents were of commercial quality or were purified before use.

Abstract. Bilateral comparison of calibration factor of microwave power sensor was carried out between National Metrology Institute of Turkey (TÜBİTAK UME) and National Measurement and Calibration Center at Saudi Standards, Metrology and Quality Organization of the Kingdom of Saudi Arabia (SASO NMCC). In this comparison, TÜBİTAK UME was pilot laboratory and supplied the travelling standard with N type connector. Nine different frequency points at 0 dBm power level were determined for this comparison in prepared technical protocol. Each participant used their own measurement standards and applied the direct comparison transfer method at comparison. There is a good agreement between TÜBİTAK UME and SASO NMCC results.

The acid dissociation constants (K a ) of eight novel biologically active benzothiazole Schiff bases were determined by UV-vis spectroscopic technique at 25 ± 0.1 °C. The calculated acidity constants, pK a values , were evaluated in structure elucidation and protonation -deprotonation mechanisms. The prototropic tautomerism was also studied.