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190 Chapter 7
7.4.2 Hydrogenation of PNP to PAP
The catalytic aqueous-phase in-situ hydrogenation of PNP to PAP using NaBH4 as a
hydrogen source was carried out in a 100 cm 3 batch reactor at room temperature (298K),
ambient pressure and 1300 min -1 stirring speed. Figure 7.28 depicts the catalytic
experimental setup. In the typical catalytic experiment, 5.0 cm 3 of an aqueous solution of
NaBH4 (0.60 mmol dm −3 ) were added to 45.0 cm 3 of an aqueous solution of PNP (0.18
mmol dm −3 ). The reaction was started by introducing 5.0 mg of the catalyst. PNP
concentration changes were monitored via online UV-vis spectroscopy (AvaSpec-3648,
optical path length: 5 mm) at a wavelength of 400 nm (see Figure 7.29). The initial
reaction rate (r0) was calculated by assuming a zero order reaction from the linear
decrease of PNP concentration after the addition of the catalyst.
Figure 7.28. Experimental setup for aqueous-phase in-situ hydrogenation of PNP to PAP with
NaBH 4 as hydrogen source using an online UV-vis spectrometer. Figure is provided by M. Al-Naji.