Thesis (M.Sc.)--Chulalongkorn University, 1997

Much attention has been paid recently to the development of plastic scintillators for radioactive counting. Initially, scintillator compounds have been employed as a plastic additive but the lift-time of the plastic scintillator was short. Further development followed by co-polymerizing fluorescent molecule with an other non-fluorescent monomer. The synthesis of 4-chloro-5-(3',4'-dinitrophenyl)-2-(4-vinylphenyl) oxazole (which is a novel compound) has been carried out. Its synthesis consists of 8 steps. The oxidation of 3-nitro-4-toluidine afforded 3-nitro-4-nitrosotoluene in 92% yield. Further oxidation gave 3,4-dinitrotoluene in 96% yield. The methyl group was then converted sequentially into the carboxylic acid, acid chloride and aroylcyanide with the yields of 89%, 99% and 84%, respectively. The fifth step was the coupling reaction of the synthesized 3,4-dinitrobenzoyl cyanide with 4-ethyl benzaldehyde to yield 4-chloro-5-(3'4'-dinitrophenyl)-2-(4-ethylphenyl) oxazole (8.2 g). Then the ethyl group was brominated with N-bromosuccinimide (NBS). Finally, the bromoethyl group was converted to the vinyl group. The percent yield of product was (6.4 g) and 0.7 g., respectively. The products were characterized by means of spectroscopic methods. (Fourier Transform Infrared Spectrometry (FTIR) and Nuclear Magnetic Resonance Spectrometer (NMR).