Yththeoretical yield — stoichiometric ceiling (MT/MT)Yprpractical yield — real selectivity & losses (MT/MT)t/tolefin per MT finished product (= 1/Ypr) — inverted viewmolmolar intensity — olefin molecules per product unitolf%olefin-derived share of product mass — the tightness readcomonco-monomer — second monomer built into the chaincoreactco-reactant — consumed in synthesis, not polymerisedroleend product · or intermediate (→ feedstock for…)The t/t vs olf% gap is your co-feed exposure gauge. Styrene (t/t 0.29, olf 27%) and cumene (t/t 0.37, olf 35%) look like heavy olefin consumers per tonne shipped, but ~two-thirds of that tonnage is benzene — a styrene or cumene trip is really a benzene signal first. PVC is the same with chlorine. Contrast PE / PP / BR where t/t ≈ 1.0 and olf ≈ 100%: pure olefin pull, tonne for tonne.
mol = 1 almost everywhere is the quiet headline. Nearly every major derivative eats one olefin molecule per product unit, so the wild mass-multiplier spread (0.20 for ABS up to 2.12 for PVC) is entirely an MW-and-co-feed artefact, not a difference in how hard each pulls on olefin molecules. The only exceptions — LAO (~2.5 ethylene/chain) and 2-EH (2 propylene/molecule) — are where one product molecule consumes several olefin molecules.
ACN is the sideways-cascade flag. Intermediate off propylene, it then re-enters three C4 rows (ABS, NBR) and acrylic fibre as a co-monomer — so a propylene-ACN squeeze transmits straight into the butadiene rubber complex. Likewise: SAP demand routes almost entirely through C3→acrylic acid, and Nylon 6,6 through C4→adiponitrile — single-sector end-markets that move the parent olefin.