Co-extraction techniques for separating and purifying butadiene and isoprene from a C4 hydrocarbon mixture including butadiene and a C5 hydrocarbon mixture including isoprene are provided. In an exemplary embodiment, a system includes a dimerization heat exchanger, a C5 purification column; an extraction zone including a mainwasher column, a rectifier column and an afterwasher column; a distillation zone; a degassing zone; and an isoprene finishing column. The system can further include a C5 washer column, an absorption column, and a distillation column.