However, the products are different. While propene is formed through elimination, isopropyl chloride is formed through nucleophilic substitution. At 100 • C, in the absence of TOPO, isopropyl chloride had been detected by Arnal and coworkers. Here, we sampled the head space of the decomposition of TiCl 2 (O i Pr) 2 at 250 • C with 2 eq of TOPO, and analyzed the gaseous products quantitatively with gas chromatography (Figure ). We found that i PrCl is formed at a similar rate as the precursor decomposition, confirming the S N 1 mechanism.