Process for the preparation of isoprene from isobutene and formaldehyde
Abstract
Abstract ISOPRENE IS PREPARED BY REACTING IN A FIRST STATE ISOBUTENE OR A C4-HYDROCARBON MIXTURE WHICH CONTAINS ISOBUTENE WITH AN AQUEOUS FORMALDEHYDE SOLUTION AT A MOLAR RATIO OF ISOBUTENE TO FORMALDEHYDE OF FROM 1:1 TO 1:2 IN THE PRESENCE OF FROM 0.01 TO 1.5% BY WEIGHT OF ORTHOPHOSPHORIC ACID, BASED ON THE QUANTITY OF AQUEOUS FORMALDEHYDE, AT A TEMPERATURE IN THE RANGE OF 90* C. TO 180* C.; SEPARATING THE REACTION MIXTURE PRODUCED INTO AN ORGANIC PHASE WHICH CONTAINS 4,4-DIMETHYL-M-DIOXANE AND AN AQUEOUS PHASE; EVAPORATING THE AQUEOUS PHASE TO REMOVE THE BY-PRODUCTS AND PHOSPHORIC ACID DISSOLVED THEREIN; FEEDING TOGETHER, IN A SECOND STAGE THE 4,4-DIMETHYL-M-DIOXANE FORMED AND THE BY-PRODUCTS WHICH CONTAIN PHOSPHORIC ACID OBTAINED ON EVAPORATION OF THE AQUEOUS PHASE, IN THE LIQUID STATE INTO A REACTOR WHICH IS OPERATED AT 200* C. TO 400* C.; AND RETURNING THE FORMALDEHYDE SOLUTION OBTAINED FROM THE DECOMPOSITION REACTION OF THE SECOND STAGE WHICH CONTAINS PHOSPHORIC ACID TO THE FIRST REACTION STAGE.
Inventors
- 👤 P Losacker
- 👤 W Schwerdtel
- 👤 W Swodenk
Bibliographic Details
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