Sodium azide decomposes exothermically to sodium and nitrogen. Fluoroalkenes polymerize more exothermically than normal alkenes. Trifluoromethanesulfonic acid exothermically reacts with metal carbonates, hydroxides, and oxides. Triflic acid reacts exothermically with alcohols to produce ethers and olefins. In water, alkali perchloratoborates decompose exothermically to form boric acid, perchloric acid, and the perchlorate. Thus, RbO reacts exothermically with water to form rubidium hydroxide. TiCl reacts exothermically with donor solvents such as THF to give hexacoordinated adducts. Lanthanide metals react exothermically with hydrogen to form LnH, dihydrides. Methacrylic anhydride is a liquid which reacts with water exothermically. Like all the alkali metals, sodium reacts exothermically with water. However, above , zirconium metal can react exothermically with water to form free hydrogen gas. Polyester resins are thermosetting and, as with other resins, cure exothermically. It burns quickly and completely in air very exothermically to give nitrogen and water vapour. This enthalpy if released exothermically can in an extreme case cause an explosion. The reaction occurs both rapidly and exothermically, too violently to be used in large-scale manufacturing.