The rates of thermal and photochemical reactions of butyraldehyde with NO2 were measured. The thermal rate constant was determined to be 107•4 exp (-12,400/ RT) lm-1 sec-1. The rate constant for the reaction of oxygen atoms with butyraldehyde was determined to be 1.5 X 10s lm"1 sec-1 at 25°C. These results are close to those for the lower-molecular-weight aldehydes and indicate that they may all be treated by means of one general mechanism. 530 (1973).

Structure–activity relationships in heterogeneous catalysis demand the development of original preparation routes to create catalyst sets with extended surface properties. Pure zirconia is a bifunctional catalyst which shows a high versatility in acid‐base catalysis. The present work aims to synthesize a set of zirconia catalysts with various acid–base reactivities. It proposes a new route to prepare pure zirconia using sodium alginate, a low‐cost biosourced polymer. This zirconia phase is compared to samples obtained from two more conventional preparation routes, precipitation and sol‐gel. Upon calcination (500–900 °C), the alginate‐derived zirconia maintains a high specific area, which can be explained by the high dispersion of the zirconyl species in the ionogel precursor. Moreover, the three types of catalysts have distinct acid–base properties, as shown by CO2 adsorption and catalysis (methylbutynol model reaction). The alginate‐derived ZrO2 has a higher and more stable amphoteric reactivity than the phases obtained by precipitation and sol‐gel, which can be rationalized by a higher level of Lewis acid‐base pairs.