Catalysts for preparing ultra high molecular weight polyethylene (UHMWPE)

A process for preparing a bi-dentate pro-ligand comprising:

• providing a 2-methoxynaphthalene of formula II:
• reacting the 2-methoxynaphthalene of formula II with R2X′ in the presence of a first base, wherein X′ is a leaving group,
• wherein R2 is independently selected from an unsubstituted or substituted aryl or cycloalkyl group having from 1 to 12 carbon atoms, or from Z(R9)3 wherein Z is an atom selected from Group 14 of the Periodic Table and each R9 is independently selected from a hydrogen, substituted or unsubstituted aryl, alkyl or cycloalkyl group having from 1 to 12 carbon atoms, with the restriction that R2 is a bulky group, at least as sterically bulky as tert-butyl, and
• wherein R3, R4, R5, R6 and R7 are each independently selected from hydrogen, alkyl, cycloalkyl or aryl group comprising from 1 to 12 carbon atoms, a halogen, or a silyl group, wherein two or more of said groups can be linked together to form one or more rings, to obtain a compound of formula III:
• reacting the compound of formula III with an electrophilic bromine source to obtain a compound of formula IV:
• reacting the compound of formula IV with acylchloride R1COCl in the presence of a second base to obtain a compound of formula V′:
• wherein R1 is an unsubstituted or substituted aryl, alkyl, or cycloalkyl group comprising from 1 to 12 carbon atoms, a halogen, or a silyl group;
• deprotecting the compound of formula V′ in order to obtain a compound of formula VI:
• condensation of the compound of formula VI with an amine R8—NH2 in the presence of catalytic amounts of an acid, optionally in the presence of tetraethyl orthosilicate or titanium tetrachloride, to obtain compounds of formula I and its tautomeric form I′, being a bidentate pro-ligand:
• wherein A is nitrogen.