Isopropyl Alcohol can react with AIR and OXYGEN over time to form unstable peroxides that can explode. Isopropyl Alcohol forms explosive mixtures, when heated, with ALUMINUM.
At higher temperatures, yeast grows more quickly, and fermentation is more vigorous. This causes the yeast to create by-products which spoil the flavour of the beer. The most common by-products generated when you ferment beer too warm are esters and fusel alcohols.