Propanol, aeration

The phosphorescence of a 5 X lO" M solution of biacetyl in de-aerated 2-propanol at room temperature could be quenched completely by 1 a,d,e (10 8 M) 84). In all three cases, the corresponding photoreduction products 2a,d,e emerge from analogous preparative scale biacetyl sensitized runs. Since 2e is also formed, steric hindrance to hydrogen abstraction from solvent cannot be too effective when a (probably longer-lived) triplet is populated, whereas it might be effective in the direct photolysis ot 1 e 88) where isomerisation competes with reduction probably in the (short-lived) singlet state. 

The effect of calcination temperature on photocatalytic activities of HyCOM Ti02 for mineralization of acetic acid under aerated conditions50 and dehydrogenation of 2-propanol under deaerated conditions9) have also been examined and are shown in Figs. 3.8 and 3.9, respectively. 

A careful heat treatment under aerated condition has been performed for Hombikat UV100 Ti02 powder (Sachtleben Chemie, GmbH). The crystal structure of the powder remains anatase below 800°C. For ESR measurements, Ti02 powder sealed under vacuum in a sample tube was irradiated with a 500 W mercury lamp through a band-pass glass filter. In order to examine the reactivity of the samples, 1 atm of air, 45 Torr of 2-propanol vapor, or 20 Torr of water vapor was introduced into the sample tubes. 

Subbaraman and Santappa found that with de-aerated solutions the rate equation for the oxidation of 2-butanol is the same as that found by Ball et al. for the oxidation of 2-propanol in the absence of oxygen, i.e. equation (19). 

In figure 4 measured mean bubble sizes are shown for the aeration of xylene and propanol by nitrogen. The measurements took place in a column of 225 mm diameter. The measuring height was 850 mm above the gas distributor, which was formed as a sieve tray with different hole diameters. It can be seen, that the... 

Figure 4. Sauter mean bubble diameter as a function of gas linear velocity for the aeration of xylene and propanol...

In the iodometric method of OOH concentration determination, a known weight of polymer sample (1-2 g) should be cut into the smallest possible pieces and refluxed for 30 min in a mixture of 2-propanol (8 ml), glacial acetic acid (2 ml) and sodium iodide (0.5 g). Sometimes it is recommended that the cut pieces of polymer be allowed to swell for 18-24h in a given solvent, e.g. chloroform before adding glacial acetic acid and sodium iodide. Instead of 0.5 g solid sodium iodide 1-2 ml of a freshly prepared de-aerated 5% solution... 

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