Method for purifying the azeotropic fraction generated during the synthesis of N,N-dimethyl aminoethyl acrylate
AssigneeArkema France
InventorsJean-Michel Paul, Coralie Graire, Audrey Riehl
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Abstract
The invention relates to a method for producing N,N-dimethylaminoethyl acrylate by the transesterification reaction of an alykl acrylate by N1N-dimethylaminoethanol, and more particularly relates to a method for purifying the azeotropic fraction generated during said reaction, thereby enabling the recycling thereof on the alkyl acrylate production unit. The aim of the method of the invention is in particular to remove the acetaldehyde and the dialkoxyethane contained in the azeotropic fraction, either by the direct distillation of the azeotropic fraction or by the distillation of the aqueous phase resulting from the water scrubbing of the azeotropic fraction.
Claims11
A method for purifying an azeotropic fraction generated during the synthesis of N,N-dimethyl aminoethyl acrylate of formula:
- H2C=CHCOOCH2CH2N(CH3)2
- by transesterification of an alkyl acrylate of formula CH2=CH—COOR1 by N,N-dimethyl aminoethanol,
- wherein R1 represents a methyl or ethyl radical;
- said method comprising:
- distilling transesterification reaction products in a first distillation column in communication with a transesterification reactor to yield an azeotropic fraction comprising:
- an alkyl acrylate,
- a lower alcohol, R1OH, formed during the reaction, and
- by-products comprising acetaldehyde and dialkoxyethane of formula CH3CH(OR1)2;
- (a) distilling the azeotropic fraction in a second distillation column to yield:
- a minority acetaldehyde-rich overhead product comprising alkyl acrylate, lower alcohol, most of the acetaldehyde, and traces of the dialkoxyethane, and
- a low-acetaldehyde main fraction comprising alkyl acrylate, lower alcohol, most of the dialkoxyethane, and traces of the acetaldehyde;
- removing said acetaldehyde-rich product, and
- recovering said low-acetaldehyde main fraction at the bottom of the second column;
- or
- (b) distilling the azeotropic fraction directly in the first distillation column,
- removing the acetaldehyde-rich product, and
- drawing off the low-acetaldehyde main fraction via a side stream from the first column;
- and
- recycling the low-acetaldehyde fraction to a synthesis process for alkyl acrylate comprising reaction of acrylic acid and lower alcohol.
A method for synthesis of N,N-dimethyl aminoethyl acrylate of formula:
- H2C=CHCOOCH2CH2N(CH3)2
- comprising:
- transesterifying an alkyl acrylate of formula CH2=CH—COOR1 with N,N-dimethyl aminoethanol,
- wherein R1 comprises a methyl or ethyl radical;
- purifying an azeotropic fraction generated during the transesterification step,
- wherein said purifying step comprises:
- distilling the azeotropic fraction in a distillation column to yield:
- a minority acetaldehyde-rich overhead product comprising alkyl acrylate, lower alcohol, most of the acetaldehyde, and traces of the dialkoxyethane, and
- a low-acetaldehyde main fraction comprising alkyl acrylate, lower alcohol, most of the dialkoxyethane, and traces of the acetaldehyde,
- removing said acetaldehyde-rich product, and
- recovering said low-acetaldehyde main fraction;
- and.
- recycling the low-acetaldehyde main fraction to an alkyl acrylate production unit.
A method for purifying an azeotropic fraction comprising:
- (i) reacting alkyl acrylate of formula CH2=CH—COOR1 with N,N-dimethyl aminoethanol to yield reaction products comprising N,N-dimethyl aminoethyl acrylate,
- wherein R1 represents a methyl or ethyl radical;
- (ii) distilling the reaction products to yield an azeotropic fraction comprising:
- alkyl acrylate,
- R1OH,
- acetaldehyde, and
- CH3CH(OR1)2;
- (iii) distilling the azeotropic fraction to yield:
- an acetaldehyde-rich fraction and
- a low-acetaldehyde fraction;
- (iv) reacting R1OH in the low-acetaldehyde fraction with acrylic acid to yield alkyl acrylate;
- and
- (v) recycling the alkyl acrylate product of step (iv) to the reaction of step (i).
Dependencies are inferred from the claim text.