Process for the synthesis of alpha-olefin polymerization procatalysts

A process for the synthesis of a Ziegler Natta procatalyst, the process comprising the following steps:

• (a) first treating a mixture of magnesium alkoxides with a mixed solvent of TiCl4 and chloro benzene in the presence of ethyl benzoate to form a first stage product;
• (b) treating the first stage product with a used mixed solvent of TiCl4 and chlorobenzene to form a second stage product;
• (c) treating the second stage product with a recovered mixed solvent of TiCl4 and chlorobenzene to form a third stage product;
• and
• (d) washing the third stage product with hexane comprising recycled hexane;
• wherein, the mixed solvent left at the end of step (c) is used in step (b), and the solvent left at the end of step (b) is used in step (a), the recovered mixed solvent added in step (c) is obtained by treatment of effluent from step (a) with benzoyl chloride so as to convert contaminant of formula TiCl3OR in the effluent to an addition complex which is precipitated, filtered off and hydrolyzed to recover ethyl benzoate and to form Ti(OH)4 as a side product, the ethyl benzoate being recycled for use in step (a) and the hexane being recycled to step (d).