Aspirin(3) was synthesized by esterification reaction of salicylic acid(1) with acetic anhydride(2) catalyzed by aluminum dihydrogen tripolyphosphate/loaded sulfur diatomite. The effects of materials ratio[r = n(2) ∶ n(1) ],reaction time,temperature and catalyst amount on the yield of 3were investigated by the single-factor experiments. The results showed that the four main factors influencing the yield of 3 are in the following order: r reaction time reaction temperature catalyst amount. Under the optimum reaction conditions[1 was 50 mmol,the catalyst amount was 5%,r was3. 14,at 81 ℃ for 40 min],the yield was 88. 6%. The yield still reach 83. 3% after reuse for five times of the catalyst
To keep burning, fires require oxygen. Carbon dioxide is used in certain fire extinguishers to put out flames. Explanation: Because magnesium is higher on the reactivity scale than carbon, it is more reactive and eliminates oxygen from carbon dioxide (to give carbon and magnesium oxide).
