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The paper describes thermal and chemical cyclodehydration studies of bismaleamic acids prepared by reacting 4,4′‐diaminodiphenyl methane (DADPM), 4,4′‐diaminodiphenyl ether (DADPE), and 3,3′‐diaminodiphenyl sulfone (DDS) with maleic anhydride and 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride. Thermal cyclisation was carried out by heating the bismaleamic acids at 120 – 140°C for 1 – 4 h. Chemical cyclisation was carried out by treating the bismaleamic acids with NaOAc/Ac2O to give bismaleimides BTM, BTE, and BTS, respectively. The products of thermal and chemical cyclisation were characterized by determination of acid number. Percentage conversion of bismaleamic acid to imide was found to be higher at higher temperatures for the same duration of thermal treatment. Elemental analysis and acid number indicated incomplete cyclisation of bismaleamic acid on thermal treatment. IR spectra of samples confirmed the disappearance of amide groups on cyclodehydration. In DSC traces of bismaleamic acids a broad endothermic peak due to imidization reaction was observed. Thermogravimetric analysis of uncured and isothermally cured samples was carried out in nitrogen atmosphere. Improvement in thermal stability was observed on curing.

Some 1-fluoroaryl-1,3-diketones were prepared by treatment of methyl 1-fluoroaryl ketone with ethyl acetate, ethyl fluoroacetate or ethyl pentafluoropropionate in the presence of sodamide which were characterized in the form of their copper chelates. 1-Substituted-aryl-1,3-diketones (1a-h) in turn on treatment with uranyl acetate afforded corresponding ORDER REPRINTS bis(1,3-diketonato) dioxouranium(VI) (3a-f). Bis(1,3-diketonato)dioxouranium(VI) (3a-f) when subjected to electrophilic bromination or nitration reactions yielded bis(2-bromo-1,3-diketonato)dioxouranium(VI) (4a-e) and bis(2-nitro-1,3diketonato)dioxouranium(VI) (5a-e), respectively. The bonding mode of the ligands to the uranium ion has also been determined from IR and 1 H NMR spectral studies. 156PATHAK ET AL. ORDER REPRINTS 170PATHAK ET AL.

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