发明授权
US4831136A Oxatellurazolium and oxatellurazinium compounds 失效
氧杂八唑鎓和氧杂碲化合物

Oxatellurazolium and oxatellurazinium compounds
摘要:
Compounds containing an aromatic ring portion fused with a tellurazolium or derivative tellurazole, tellurazoline (including tellurazolinylidene), or tellurazolinium ring portion are disclosed together with processes and intermediates for their preparation. With properly selected pendant groups these tellurazolium and derivative compounds can be usefully employed as dyes, antifoggants or stabilizers, nucleating agents, latent image keeping addenda, or speed or contrast altering addends in silver halide photographic systems.
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