| 摘要 |
Prodn. of higher (meth)acrylic esters (I) of the formula (CH2=CR2-CO-O-CH2)nR1 (in which R1 is an opt. substd. hydrocarbyl gp. R2 is H or Me. n=1,2,3 or 4) involves the reaction of a Diels-Adler adduct (II) of cyclopentadiene and (meth)acrylic acid or ester with an alcohol of formula (HOCH2)nR1 to a methyl 2-norbornene-5-carboxylate (III) and pyrolysis of (III) to cyclopentadiene and (I).(III) has the formula: Pyrolysis is carried out at 200-500, pref. 350-450 degrees C and 1-20 mbar.Polymerisation during reaction is avoided, in contrast to the ester interchange method. (I) are obtd. in good yields and the cyclopentadiene is recovered almost quantitatively. Pyrolysis is carried out in a vertical heated tube, pref. with addn. of 0.005-0.05% polymerisation inhibitor to (III). After pyrolysis, the prod. is cooled below 25 degrees C.
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