Epichlorohydrin → Potassium Chloride
反応式
[C:1]([O:6][CH2:7][CH:8]([OH:11])[CH2:9][Cl:10])(=[O:5])[C:2]([CH3:4])=[CH2:3].[OH-].[Na+].[OH-].[K+:15].C(C1OC1)Cl>O>[C:1]([O:6][CH2:7][CH:8]1[O:11][CH2:9]1)(=[O:5])[C:2]([CH3:4])=[CH2:3].[Cl-:10].[K+:15][C:1]([O:6][CH2:7][CH:8]([OH:11])[CH2:9][Cl:10])(=[O:5])[C:2]([CH3:4])=[CH2:3].[OH-].[Na+].[OH-].[K+:15].C(C1OC1)Cl>O>[C:1]([O:6][CH2:7][CH:8]1[O:11][CH2:9]1)(=[O:5])[C:2]([CH3:4])=[CH2:3].[Cl-:10].[K+:15]
A feed with 3-chloro-2-hydroxypropyl methacrylate (CHPMA), epichlorohydrln, and minor amounts of by-products (GMA and heavies such as polymer by-product materials) flows into an epoxidation reactor to which aqueous alkali metal hydroxides such as sodium hydroxide (NaOH) or potassium hydroxide (KOH) and additional epichlorohydrin are added. KOH reacts with CHPMA to form glycidyl methacrylate to (GMA), water, and potassium chloride (KCl). Sodium hydroxide may be used in place of KOH, but a higher GMA yield is obtained using KOH. Preferable reaction conditions are: starting molar epichlorohydrin/CHPMA ratio of 6.0 or higher (most preferably 9.0), molar KOH/CHPMA ratio of 0.8-1.5 (most preferably 1.1, temperature of 40-80 degrees centigrade (most preferably 60-65 degrees Centigrade), and a pressure of less than atmospheric (typically 150-200 mm Hg absolute). Preferably, KOH is added as a 40-60 weight per cent solution in water. A vapor stream removed from the epoxidation reactor is fractionated and the overhead epichlorohydrin/water stream is condensed and allowed to separate into two liquid phases. The heavier (organic) phase is returned to the fractionation tower as reflux and from the bottom of the fractionation tower to the epoxidation reactor. (See FIG. 7 and previous description thereof). The aqueous phase is sent forward in the process in the same manner as previously described for the epoxy process to serve as wash water which removes the last traces of KCl from the GMA product before the epichlorohydrin is stripped and the product recovered.
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