Distillation: processes – separatory – With measuring – testing or inspecting – Of temperature or pressure
Reexamination Certificate
2005-09-20
2005-09-20
Manoharan, Virginia (Department: 1764)
Distillation: processes, separatory
With measuring, testing or inspecting
Of temperature or pressure
C203S017000, C203S078000, C203SDIG009, C564S216000
Reexamination Certificate
active
06946060
ABSTRACT:
A method to purify N,N-dimethylacetamide (DMAc) from an aqueous solution containing acetic acid as a contaminant. Two fractional distillation columns are arranged in a series. The solution containing the contaminant is provided to the first column with a temperature profile to result in acetic acid partitioning into the overhead water. The material remaining in the bottom portion of the first column is recycled to the first column and also provided into a second column, whereby DMAc free of acetic acid contamination is recovered, and remaining DMAc and acetic acid are returned to the first column for further separation. The method uses standard fractional distillation procedures and equipment, thus eliminating the need for more complex extractions and/or chromatographic separations.
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Mallinckrodt Inc.
Manoharan Virginia
Wood Herron & Evans L.L.P.
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