Why is China's C5 fine chemicals sector still dependent on imports?

Why is China's C5 fine chemicals sector still dependent on imports?
China's C5 value chain remains stuck at the low end. Most domestic C5 output is polymerized into petroleum resin, while higher-value derivatives such as n-pentene, 2-pentanone, glutaraldehyde and COC/COP still rely on imports. Isoprene illustrates the gap: rubber and resin applications absorb 77.4% of output, leaving little for flavors, pharmaceuticals and pesticides. Globally, the US and Japan utilize 70-85% of their C5 fractions, with Japan's Zeon the benchmark, building specialty rubber, synthetic flavors, optical films and COC/COP. Chinese firms are only starting to move upstream, with projects like 8,500 t/y pentanone series targeting import substitution, but industrial-scale fine chemical routes remain scarce.