Transesterification process

Details Transesterification process Transesterification process

2002-03-06

2003-02-04

Lambkin, Deborah C. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

Reexamination Certificate

active

06515138

ABSTRACT:

This invention relates to a process to prepare monomers, more specifically this invention relates to a transesterification process to prepare (meth)acrylate monomers.
It is known, for example in EP-A-0,902,017, that (meth)acrylates of Formula I, such as N-(2- methacryloyloxyethyl) ethylene urea (MEEU), and the alcohol of Formula IV, such as methanol, may be produced by the transesterification of an alkyl (meth)acrylate of Formula II, such as methyl methacrylate (MA) with a hydroxyl alkyl imidazolidin-2-one of Formula III, such as hydroxyethyl ethylene urea (HEEU), using a transesterification catalyst and in the presence of a polymerization inhibitor.
where R=H or CH
3
;
where R″=C
1
-C
8
straight or branched alkylene;
where R=H or CH
3
; and
where R′=C
1
-C
8
straight or branched alkyl;
where R″=C
1
-C
8
straight or branched alkylene;
R′—OH  FORMULA IV
where R′=C
1
-C
8
straight or branched alkyl.
Conventionally, the transesterification catalyst is added to the well-mixed reaction mixture containing the alkyl (meth)acrylate of Formula II and the hydroxyl alkyl imidazolidin-2-one of Formula III. We have unexpectedly discovered that level of conversion of the hydroxyl alkyl imidazolidin-2-one of Formula III to the (meth)acrylate of Formula I may be increased for the above-described transesterification process by ensuring that the transesterification catalyst has ample opportunity to be in contact with the hydroxyl alkyl imidazolidin-2-one of Formula III by introducing the transesterification catalyst to the hydroxyl alkyl imidazolidin-2-one of Formula III while the reaction mixture is unagitated.
Statement of the Invention
We have discovered an improved process for forming the (meth)acrylate monomer of Formula I:
where R=H or CH
3
;
where R″=C
1
-C
8
straight or branched alkylene; comprising the sequential steps of:
(1) forming a reaction mixture, comprising:
(a) hydroxyl alkyl imidazolidin-2-one of Formula III:
 where R″=C
1
-C
8
straight or branched alkylene;
(b) 10 to 10,000 ppm, based on weight of said hydroxyl alkyl imidazolidin-2-one of Formula III, of at least one polymerization inhibitor selected from the group consisting of diethylhydroxylamine, p-methoxy phenol, hydroquinone, phenothiazine, 4-hydroxy-2,2,6,6-tetramethyl piperidnyl free radical, 4-methacryloyloxy-2,6,6-tetramethyl piperidinyl free radical, and 4-hydroxy-2,6,6-tetramethyl N-hydroxy piperidine;
(2) adding to said reaction mixture 0.1 to 10 mole % of a transesterification catalyst selected from the group consisting of dibutyl tin oxide, reaction products of dibutyl tin oxide with components in the transesterification of various alcohols with alkyl (meth)acrylates; dibutyl tin dimethoxide, reaction products of dibutyl tin dimethoxide with components in the transesterification of various alcohols with alkyl (meth)acrylates; methanolic magnesium methylate; lithium; lithium carbonate; anhydrous alkali metal hydroxide; hydrates of alkali metal hydroxide; and mixtures thereof;
wherein said reaction mixture is unagitated when said catalyst is added;
(3) adding to said reaction mixture at least one alkyl (meth)acrylate of Formula II:
where R=H or CH
3
; and
where R′=C
1
-C
8
straight or branched alkyl; under conditions to effect the transesterification of said alkyl (meth)acrylate of Formula II and said hydroxyl alkyl imidazolidin-2-one of Formula III to form a (meth)acrylate of Formula I:
where R=H or CH
3
;
where R″=C
1
-C
8
straight or branched alkylene; and the alcohol of Formula IV:
R′—OH  FORMULA IV
where R′=C
1
-C
8
straight or branched alkyl; and
wherein the mole ratio of said hydroxyl alkyl imidazolidin-2-one of Formula III to total said alkyl (meth)acrylate is from 1:1 to 1:20.
The reaction mixture may further comprise an alkyl (meth)acrylate of Formula II:
where R=H or CH
3
; and
where R′=C
1
-C
8
straight or branched alkyl.
The process may further comprise the step of azeotropically removing a mixture of said alkyl (meth)acrylate of Formula II and said alcohol of Formula IV.
The process may further comprise the step of adding water to enable recycling of said transesterification catalyst, if said catalyst has low water solubility.
The process may further comprise the step of recycling the alkyl (meth)acrylate of Formula II.
The process may further comprise the step of distilling the (meth)acrylate of Formula I.
It is not necessary to separate the catalyst or catalyst by-products from the reaction mixture. In addition, it is not necessary to separate the catalyst or catalyst by-products from the reaction mixture, under process conditions where:
(a) excess alkyl (meth)acrylate is used and diluted with water; or
(b) the reaction mixture is treated with water to effect an exchange of the excess alkyl (meth)acrylate with water to produce a mixture of (meth)acrylate of Formula I in water.
There are a number of different ways that the transesterification catalyst may be exposed to increased contact with the hydroxyl alkylene imidazolidin-2-one of Formula III relative to conventional processes. This includes introducing the transesterification catalyst to the hydroxyl alkylene imidazolidin-2-one of Formula III while the reaction mixture is unagitated and wherein the reaction mixture includes:
(a) the hydroxyl alkylene imidazolidin-2-one of Formula III neat (i.e., molten and not provided in solvent, including monomers such as alkyl (meth)acrylate of Formula II); or
(b) the hydroxyl alkylene imidazolidin-2-one of Formula III combined with the alkyl (meth)acrylate of Formula II.
The process of this invention is capable of producing (meth)acrylate monomers of the general formula:
where R H or CH
3
; and
where R′=C
1
-C
8
straight or branched alkylene. Such (meth)acrylate monomers include N-(2-methacryloyloxyethyl) ethylene urea (MEEU). Such monomers are useful as polymerized units in polymers and provide enhanced properties to such polymers, including adhesion.
One of the reactants that participates in the transesterification reaction is an hydroxyl alkyl imidazolidin-2-one of Formula III:
where R′=C
1
-C
8
straight or branched alkylene; Suitable hydroxyl alkylene imidazolidin-2-one of Formula III include hydroxyethyl ethylene urea (HEEU).
The other reactants that participates in the transesterification reaction is an alkyl (meth)acrylate of Formula II:
where R=H or CH
3
; and
where R′=C
1
-C
8
straight or branched alkyl;
Preferred alkyl (meth)acrylates include methyl methacrylate, butyl acrylate and ethyl acrylate. Methyl methacrylate is most preferred.
The mole ratio of hydroxyl alkyl imidazolidin-2-one of Formula III to alkyl (meth)acrylate of Formula II is typically from 1:1 to 1:20, preferably from 1:1 to 1:15, and more preferably from 1:1.2 to 1:10.
The reaction mixture also includes at least one polymerization inhibitor. Suitable polymerization inhibitors include diethylhydroxylamine, p-methoxy phenol, hydroquinone, phenothiazine, 4-hydroxy-2,2,6,6-tetramethyl piperidinyl free radical (4-hydroxy-TEMPO), 4-methacryloyloxy-2,6,6-tetramethyl piperidinyl free radical, and 4-hydroxy-2,6,6-tetramethyl N-hydroxy piperidine and mixtures thereof
The amount of inhibitor added to the reaction vessel is typically from 10 to 10,000 parts per million, based on the weight of the hydroxyl alkyl imidazolidin-2-one of Formula III, preferably from 100 to 5,000 ppm, and most preferably 200 to 3,000 ppm.
Suitable transesterification catalysts include dibutyl tin oxide, reaction products of dibutyl tin oxide with components in the transesterification of various alcohols with methyl meth(acrylate) or alkyl (meth)acrylates; dibutyl tin dimethoxide, reaction products of dibutyl tin dimethoxide with components in the transesterification of various alcohols with methyl (meth)acrylate or alkyl (meth)acrylates, methanolic magnesium methylate, lithium, lithium c

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