P-Toluidinyl radical

Figure 2. Frontier electron density distribution for the p-toluidinyl radical...

In order to interpret the results for MDI-PUE and TDI-PU, the laser flash photolysis measurements of several model systems were performed. The transient spectra of the p-toluidinyl radical, recorded upon laser flash photolysis (Aex=248 nm) of p-toluidine (1.4 X 10 M in THF), has a distinct maximum at approximately 310 nm and a broad, diffuse absorbance above 400 nm (Figure 3). The results for p-toluidine are in agreement with previously reported spectra for anilinyl type radicals (12.13). Comparing the transient spectra for p-toluidine with TDI-PU and MDI-PUE, it is quite obvious that the p-toluidinyl radical in THF (Figure 3) is essentially identical to the 300-330 nm and > 400 nm portions of the transient spectra of MDI-PUE and TDI-PU in Figures 1 and 2. 

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