| 摘要 |
<p>2,6-dimethyl pyridine 3,5-dicarboxylic acid polyester, for use as heat stabilisers of vinyl chloride polymers or copolymers, made by the known Hantsch synthesis involving (A) condensn. of a aldehyde with a bis-aceto-acetate and ammonia with elimination of water, or (B) condensn. of an aldehyde with a bis-beta-amino crotonate, and elimination of water and ammonia at (C) condensn. of an aldehyde with a bis-beta-amino crotonate and a bis-aceto-acetate with elimination of water, are recovered as a fine powder without purificn. by evaporation of solvent used as reaction medium and drying. The solvent is pref. removed by azeotropic distn. at 100 deg.C. max. and drying is in a fluidised bed with hot air at 100-190 deg.C.. (Reissue of the entry advised in week 9227 based on complete specification).</p> |
