Isoprene prodn. from formaldehyde and isobutylene or tert. butanol - using sulphamic acid or amino-aryl-sulphonic acid as catalyst

摘要

In the prodn. of isoprene (I) by reacting HCHO with isobutylene (II) and/or t.-butyl alcohol (III) in the liq. phase at 200 degrees C in the presence of a catalyst (IV), (IV) is H2NSO3-H or an aromatic ammonium cpd. (IVa) or condensed ammonium cpd. (IVb) of the naphthalene series with a sulpho gp., of the formula (IVa) or (IVb) (where R1 and R2 are H, alkyl, aryl, alkylaryl or aralkyl. In (IVa), the sulpho gp. can be in the o-, m- or p-position) or their reaction prods. with HCHO. The catalyst is less aggressive than usual, does not react with unsatd. synthetic prods., has a high b.pt. and is resistant to hydrolysis. The process technology can be simplified and the yield increased. In an example, a mixt. of HCHO soln., (III) soln., (II) and sulphanilic acid was heated 30 mins. at 130 degrees C and 35 mins. at 180 degrees C, in a sealed ampoule, then chilled. The (I) yield was 74.0 mole % w.r.t. HCHO.