A polymerization process comprising: halogenating, in the presence of a substituted 1,2-phenylene aromatic diester, particles of a MagTi procatalyst precursor having a particle size D50 from 19 microns to 30 microns to form particles of a procatalyst composition having a particle size D50 from 19 microns to 30 microns, wherein D50 is the median particle diameter such that 50% of the sample weight is above the stated particle diameter; first contacting, under first polymerization conditions, propylene and optionally one or more first comonomers with a catalyst composition comprising the particles of the procatalyst composition in a first polymerization reactor to form an active propylene-based polymer; and second contacting, under second polymerization conditions, the active propylene-based polymer with at least one second comonomer in a second polymerization reactor to form a propylene impact copolymer; wherein (a) the substituted 1,2-phenylene aromatic diester has the structure wherein R 1 -R 14 are the same or different; each of R 1 -R 14 may be independently selected from a hydrogen, substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof, provided that at least one of R 1 -R 14 is not hydrogen; and (b) the active propylene-based polymer has a melt flow rate greater than 100 g/10 min as measured in accordance with ASTM D 1238, 2.16 kg, 230°C. halogenating, in the presence of a substituted 1,2-phenylene aromatic diester, particles of a MagTi procatalyst precursor having a particle size D50 from 19 microns to 30 microns to form particles of a procatalyst composition having a particle size D50 from 19 microns to 30 microns, wherein D50 is the median particle diameter such that 50% of the sample weight is above the stated particle diameter; first contacting, under first polymerization conditions, propylene and optionally one or more first comonomers with a catalyst composition comprising the particles of the procatalyst composition in a first polymerization reactor to form an active propylene-based polymer; and second contacting, under second polymerization conditions, the active propylene-based polymer with at least one second comonomer in a second polymerization reactor to form a propylene impact copolymer; wherein (a) the substituted 1,2-phenylene aromatic diester has the structure wherein R 1 -R 14 are the same or different; each of R 1 -R 14 may be independently selected from a hydrogen, substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof, provided that at least one of R 1 -R 14 is not hydrogen; and (b) the active propylene-based polymer has a melt flow rate greater than 100 g/10 min as measured in accordance with ASTM D 1238, 2.16 kg, 230°C. (a) the substituted 1,2-phenylene aromatic diester has the structure wherein R 1 -R 14 are the same or different; each of R 1 -R 14 may be independently selected from a hydrogen, substituted hydrocarbyl group having 1 to 20 carbon atoms, an unsubstituted hydrocarbyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a heteroatom, and combinations thereof, provided that at least one of R 1 -R 14 is not hydrogen; and (b) the active propylene-based polymer has a melt flow rate greater than 100 g/10 min as measured in accordance with ASTM D 1238, 2.16 kg, 230°C.