The present invention relates to a process for preparing of phosphorus-containing dicarboxylic acids of the formula (I) ##STR1## where R.sup.1 and R.sup.2 are identical or different and are each a straight-chain or branched alkyl radical having from 1 to 8 carbon atoms, a cycloaliphatic radical having 5 or 6 carbon atoms in the ring, an unsubstituted or substituted aryl radical having from 6 to 10 carbon atoms, or R.sup.1 and R.sup.2 form, with inclusion of the phosphorus atom, a ring having from 5 to 8 members, and m and n are each, independently of one another 0 or 1, by reacting a compound of the formula (II) ##STR2## where R.sup.1, R.sup.2 and m are as defined above, with fumaric acid, maleic acid or itaconic acid in the presence of a saturated aliphatic monocarboxylic acid having a total of from 1 to 5 carbon atoms as solvent at from 100.degree. to 200.degree. C. under atmospheric pressure or superatmospheric pressure.
本发明涉及一种制备含
磷二
羧酸的方法,其
化学式为(I),其中R^1和R^2相同或不同,分别为具有1至8个碳原子的直链或支链烷基基团,具有5或6个碳原子的环脂基团,具有6至10个碳原子的未取代或取代的芳基基团,或R^1和R^2与
磷原子形成含有5至8个成员的环,m和n各自独立地为0或1,通过将化合物(II)与
富马酸、
马来酸或顺
丁二酸在100℃至200℃的大气压或超大气压下,在具有1至5个碳原子总数的饱和脂肪族一
羧酸作为溶剂的条件下反应得到。