| 摘要 |
<p>In the preparation of isoprene by reacting isobutene with formaldehyde to produce 4,4-dimethyl-m-dioxane in a first stage, and decomposing the dioxane to isoprene and formaldehyde in a second stage, formaldehyde in the effluent streams of either or both of said stages is recovered. The formaldehyde-containing liquids are distilled to separate high boilers; the overhead, which is formaldehyde-rich, is extracted with isobutene feed to the process, whereby the isobutene extracts low boilers from the formaldehyde-containing liquid; and the formaldehyde-containing liquid, having at some point after said distillation been treated with an alkaline material, is subjected to rectification to produce as head product, the recovered formaldehyde.</p> |
