We varied the amount of TOPO, taking either 2, 4, or 11.4 equivalents (the latter is a synthesis in pure TOPO without octadecane as co-solvent), see Figure . While the data for 2 equivalents is well described by a straight line (apparent zero order kinetics), the data in pure TOPO (11.4 eq.) is perfectly fitted with a single exponential (first order kinetics). The data for 4 equivalents is intermediate and are not well described by either function. We thus analyzed the initial rate, which increases with the TOPO amount (see Table ). This can be rationalized by considering the transition state of the first step in an E1/S N 1 mechanism (the formation of the carbocation). According to the Hammond postulate, the transition state of such an endothermic reaction should reflect the structure of the products. Given that the reaction solvent (octadecane) is highly nonpolar, the build-up of charge is unfavorable.