Selective oxidation of propene—the allyl radical

The allyl radical, CsHs, is an intermediate in the selective oxidation of propene to acrolein with oxygen, catalysed by bismuth molybdate and iron antimonate [69,91] 

INS has been used to probe the binding of reactants and intermediates to an iron antimonate catalyst [96]. The spectra were assigned with reference to the spectra of compounds of known structure. 

The allyl radical, CH2CH=CH2, may bind through one carbon (a-allyl, 1), through the double bond (r), 2), or through three carbon atoms (ri, 3). The three struetures have distinctive vibrational spectra as shown by model compounds [96,97]. 

The INS spectra of the a-allyl compound allyl iodide, CH2=CHCH2l, and the r -allyl compound di-p-chloro-bis(r] -allylpalladium), [ Pd(Ti -C3H5) 2(p-Cl)2] [94] and the INS below 800 cm of nickel and palladium allyl complexes [97] have been reported. The structure of the palladium complex is shown in Fig. 7.24 [98]. The INS spectra are shown in Fig. 7.25. Peak positions and assignments are in Table 7.15. 

A number of features of the spectra are noteworthy (a) The allyl iodide peak near 140 cm was especially sensitive to the physical state of allyl iodide. This peak was assigned to the fundamental torsional transition of the stable gauche conformer of allyl iodide (v2i) observed in 

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