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New polymer syntheses, 79. Hyperbranched poly(ester‐amide)s based on 3‐hydroxybenzoic acid and 3,5‐diaminobenzoic acid

1995; Wiley; Volume: 196; Issue: 6 Linguagem: Inglês

10.1002/macp.1995.021960604

1521-3935

Hans R. Kricheldorf, Gerd Löhden,

Synthesis and Characterization of Heterocyclic Compounds

Abstract The reaction of 3‐acetoxybenzoyl chloride ( 4 ) with N,N ′, O ‐tris(trimethylsilyl)‐3,5‐diaminobenzoic acid ( 5 ) proceeds by highly selective and almost quantitative acylation of both amino groups. The resulting 3,5‐bis(3‐acetoxybenzamido)benzoic acid ( 6a ), or its silylated derivative ( 6b ), was polycondensed in bulk. The silylated monomer yielded the higher molecular weights. The condensation of 3,5‐diacetoxybenzoyl chlorides with diamines containing aliphatic protons yielded acetylated tetraphenols which served as “star centers” for polycondensation. The polycondensation of silylated 3,5‐bis(3‐acetoxybenzamido)‐benzoic acid ( 6b ), with these “star centers” yieled in turn hyperbranched star polymers. The feed ratio of monomers and “star centers” allows the control of the molecular weight. 1 H NMR spectroscopy of these hyperbranched star polymers was used to determine the average degree of polymerization ( DP ) and the average degree of branching ( DB ). 1 H and 13 C NMR spectroscopy also revealed that all polycondensations involve a significant extent of ester‐amide interchange reactions.