Claims
- 1. A purification process of crude methacrylamide by recrystallization from an aqueous methacrylamide solution obtained by neutralizing methacrylamide sulfate with a basic compound, comprising the steps of conducting crystallization by adjusting the hydrogen ion concentration of the aqueous methacrylamide solution to between pH 8 and pH 13, separating methacrylamide crystal, adjusting 5% or more by weight of the resulting mother liquor to between pH 1 and pH 5, separating precipitated insoluble matter, and recycling the thus-treated mother liquor to the neutralization step.
- 2. The purification process of claim 1 wherein from 10 to 80% by weight of the mother liquor is adjusted to between pH 1 and pH 5.
- 3. The purification process of claim 1 wherein from 10 to 80% by weight of the mother liquor is recycled to the neutralization step and from 90 to 20% by weight of the mother liquor is recycled to a dissolution step of crude methacrylamide.
- 4. The purification process of claim 1 wherein the pH of the mother liquor is adjusted to between pH 1 and pH 5 by using mineral acid selected from the group consisting of sulfuric acid and hydrochloric acid.
Priority Claims (2)
Number |
Date |
Country |
Kind |
2-152710 |
Jun 1990 |
JPX |
|
2-168374 |
Jun 1990 |
JPX |
|
Parent Case Info
This application is a continuation of application Ser. No. 07/712,109, filed Jun. 7, 1991, now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (2)
Number |
Date |
Country |
2063529 |
Jul 1971 |
DEX |
7006747 |
Nov 1970 |
NLX |
Continuations (1)
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Number |
Date |
Country |
Parent |
712109 |
Jun 1991 |
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