| 摘要 |
Dicarboxylic acids and dicarboxylic acid esters of the formula <IMAGE> wherein both R1 each denote hydrogen, alkyl with 1 to 4 C atoms or phenyl, both R2 each denote hydrogen or alkyl with 1 to 10 C atoms and, if the two R2 each denote hydrogen, the two n represent numbers from 2 to 12 and, if the two R2 each denote an alkyl group with 1 to 10 C atoms, the two n represent numbers from 1 to 12, R3 denotes hydrogen, methyl or ethyl and R4 denotes methyl, ethyl, propyl or isopropyl, are prepared by reacting 1 mol of a 1,1'-methylene-bis-hydantoin of the formula <IMAGE> or its disodium or dipotassium salt with 2 mols of a compound of the formula <IMAGE> wherein Y1 denotes a chlorine or bromine atom. The dicarboxylic acid compounds are characterized by a high stability to heat and therefore very suitable for the manufacture of polycondensates by the melt condensation process.
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