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Part-IResults and Discussion3.5. Spectral Discussion3.5.1. 2-Chloromethylthieno[2,3-d]pyrimidinesThe 2-chloromethylthienopyrimidines are colorless to buff white colored solid, with highmelting points generally above 200 o C. These compounds are soluble in mixture ofchloroform and methanol and hot DMF and practically insoluble in methanol, hexane orethanol.Infra red (IR) spectra:IR spectra of 2-chloromethylthienopyrimidines exhibit bands of medium faint intensityaround 3200-3100 cm -1 due to asymmetric and symmetric N-H stretching vibrations.Intense absorption bands observed in all these spectras around 1680-1650 may be due toN-H deformation vibrations. The IR spectra of some compounds exhibited a strongabsorption band around 1730-1720 cm -1 due to C=O stretching. Stretching due to C-Clwas observed between 760-730 cm -1 (Table-8).The 1 H NMR spectra:The 1 H NMR spectra of 2-chloromethylthienopyrimidines were taken in CDCl 3 . All thecompounds showed characteristic peaks corresponding to the protons of different groupsand functionalities in the molecules. The 2-methylene protons of the chloromethyl linkageappear downfield as a singlet at around 4.4 to 4.6 ppm. Since this methylene group isattached to electronegative atom, the proton signal appear downfield than the normalposition. The NH proton present in all the compounds at the 3 position of the pyrimidinering is observed as a singlet between 10 to 13 ppm. All the aromatic protons present in themolecules were observed as a multiplet at around 7-8 ppm (Table-8).The Mass Spectra:The fragmentation pattern of the synthesized compounds 2-chloromethylthienopyrimidines,under electron impact ionization has also been studied. It is veryinteresting and many prominent fragment ion peaks are revealed in the mass spectra ofthese compounds. The mass spectrum of 2-chloromethyl-5,6,7,8-tetrahydrobenzo(b)thieno[2,3-d]pyrimidin-4(3H)-oneIIi was clearly showing the molecular ionpeak (a) 255 m/e, which is the base peak as well. The major mode of fragmentation isloss of chloride ion to give daughter ion (b) m/e 219. The molecular ion (a) also loses101