| 摘要 |
1,271,474. Acyclic alcohols and esters. COMPAGNIE FRANCHISE DE RAFFINAGE. 7 May, 1970 [8 May, 1969], No. 22156/70. Heading C2C. [Also in Division C5] In a reaction sequence to produce diolefins having a tertiary carbon atom (see Division C5), the following preliminary steps occur: (1) an alpha-glycol or alpha-epoxide is mono-esterified with a monocarboxylic acid or anhydride thereof, and (2) the monoester is pyrolysed to give an olefinic alcohol, which is the diolefin precursor. The following sequence, including preparation of the starting material, is given for ultimate isoprene production: (a) isopentane is oxidized in air to its hydroperoxide; (b) the hydroperoxide is reacted with isoamylene to give either methyl- 2,3-epoxybutane or, if water is present, methyl butane-2,3-diol; (c) the epoxide or diol is esterified with acetic acid in the presence of FeCl 3 to give methylbutane-2,3-diol monoacetate; (d) the monoacetate is pyrolysed at 500-600‹ C. to give corresponding olefinic alcohols together with acetic acid which may be recycled; and (e) the olefinic alcohols are dehydrated to isoprene. In step (b) tertiary amyl alcohol is also produced, and can be dehydrated to isoamylene which is re-used. |
