Diphosphines

A process for preparing the diphosphine of the general Formula I:

• ##STR16## wherein:
• R.sup.2 and R.sup.3 independently from each other represent an alkyl, cycloalkyl, aryl or aryl-alkyl group or an aryl group which is substituted at the aromatic ring with one or more radicals selected from the group consisting of halogen, alkyl and alkoxy,
• R.sup.4 represents an alkylene, cycloalkylene, arylene or aryl-alkylene group or an arylene group which is substituted at the aromatic ring with one or more radicals selected from the group consisting of halogen, alkyl and alkoxy, and
• A is --C(O)--, --S(O)2--, --S(O)--, --C(O)-alkylene-C(O)-- or --C(O)-arylene-C(O)--, the arylene group being optionally substituted at the aromatic ring with one or more radicals selected from the group consisting of halogen, alkyl, cycloalkyl, aryl, oxyalkyl, hydroxy and alkoxy, and the alkylene group being optionally substituted with one or more radicals selected from the group consisting of halogen, alkyl, cycloalkyl, aryl, oxyalkyl, hydroxy and alkoxy, or A is ##STR17## wherein R.sup.6, R.sup.7 and R.sup.8 s independently from each other represent an alkyl, cycloalkyl, aryl or aryl-alkyl group or an aryl group which is substituted at the aromatic ring with one or more radicals selected from the group consisting of halogen, alkyl, cycloalkyl, aryl, oxyalkyl, hydroxy and alkoxy,
• wherein a compound of Formula II:
• ##STR18## wherein R.sup.2, R.sup.3 and R.sup.4 have the meanings as indicated in Formula I, is reacted with a compound of Formula III:
• X--A--X (III)
• wherein A has the meaning as indicated in Formula I and each X independently is halogen, hydroxy or alkoxy or both X together are an anhydride group, the molar ratio between the compound of Formula II and the compound of Formula III being at least 1.7:1.

A polymer composition comprising a thermoplastic polymer and a thermal stabilizing quantity of a diphosphine of the general Formula I:

• ##STR19## wherein:
• R.sup.2 and R.sup.3 independently from each other represent an alkyl, cycloalkyl, aryl or aryl-alkyl group or an aryl group which is substituted at the aromatic ring with one or more radicals selected from the group consisting of halogen, alkyl and alkoxy,
• R.sup.4 represents an alkylene, cycloalkylene, arylene or aryl-alkylene group or an arylene group which is substituted at the aromatic ring with one or more radicals selected from the group consisting of halogen, alkyl and alkoxy, and
• A is --C(O)--, --S(O)2--, --S(O)--, --C(O)-alkylene-C(O)-- or --C(O)-arylene-C(O)--, the arylene group being optionally substituted at the aromatic ring with one or more radicals selected from the group consisting of halogen, alkyl, cycloalkyl, aryl, oxyalkyl, hydroxy, alkoxy and --C(O)--[O--R.sup.4 --P(R.sup.2)(R.sup.3)], and the alkylene group being optionally substituted with one or more radicals selected from the group consisting of halogen, alkyl, cycloalkyl, aryl, oxyalkyl, hydroxy, alkoxy and ##STR20## wherein R.sup.6, R.sup.7, R.sup.8 and R.sup.9 independently from each other represent an alkyl, cycloalkyl, aryl or aryl-alkyl group or an aryl group which is substituted at the aromatic ring with one or more radicals selected from the group consisting of halogen, alkyl, cycloalkyl, aryl, oxyalkyl, hydroxy and alkoxy.