Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acid esters
Patent
1998-07-20
2000-03-21
Keys, Rosalynd
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acid esters
560221, 560225, C07C 6703
Patent
active
060404736
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for the production of alkoxy polyglycol (meth)acrylates by basically catalyzed re-esterification, where a mixture of lithium chloride and calcium hydroxide or calcium hydroxide alone is used as the catalysts.
STATE OF THE ART
Esters of (meth)acrylic acid with polyethylene glycol, or the mono-ether derivatives of the same, are of quite some technical interest as monomers with a dispersant effect. It is all the more important to have as advantageous as possible a production method available.
Re-esterification of (meth)acrylic acid alkyl esters from lower alkanols. particularly of the methyl and ethyl esters with higher or with substituted alcohols. under catalysts with various catalysts, represents a relatively elegant method for the production of higher or more complex esters of (meth)acrylic acid.
Among the (meth)acrylic acid esters which are of interest because of their many different possibilities of use are those with alkoxy polyglycols.
While the re-esterification reaction of the stated, low (meth)acrylic acid esters with alkoxy polyglycols, for example under catalysts with the ortho-titanic acid esters which are used in the relevant literature (see GB 960 005; 962 928; DE-A 4 121 811) proceeds somewhat satisfactorily, processing of the re-esterification batches is extraordinarily difficult. While one obtains a product in good yield and with little inherent color under catalysts with tetraisopropyl titanate, for example, when the titanate is transformed into insoluble, hydratized titanium dioxide by adding water, which is unavoidable, a hydrolysis product is obtained which is extremely difficult to filter. The filtration process takes too much time to conduct the process on a production scale, so that processing can take days.
As an alternative to titanium catalysts, a possibility is catalysts by alkali alkoxides (CH-PS 239 750), for example, or with a certain lithium compound, particularly lithium hydroxide, preferably in combination with a catalyst that contains calcium oxide (see U.S. Pat. No. 4,672,105; U.S. Pat. No. 4,745,213; DE-A 2 744 641; GB-C 1 094 998).
TASK AND SOLUTION
In view of experience with the commonly used catalysts based on titanium, as explained above, there was a special need to have an effective and cost-effective re-esterification process available for the production of (meth)acrylic acid esters from polyethylene glycols, possibly mono-ethered.
However, corresponding experiments with the catalyst lithium hydroxide, or with the catalyst systems of lithium hydroxide and calcium hydroxide or lithium chloride and calcium oxide, which were very successfully used as alternatives to titanium catalysts, were disappointing. If, for example, methyl methacrylate is reacted with methoxypolyethylene glycol, under catalysts with the re-esterification catalysts mentioned, under the conditions which have otherwise proven themselves for other alcohols as edducts, products with a yellow to red-brown color are obtained, and they cannot be sold in this form.
(For the catalyst system of lithium hydroxide/calcium oxide, for example, the best yields were reported for reactions with polyols, in U.S. Pat. No. 4.672,105.) Therefore this type of re-esterification catalysts also appeared to be unsuitable for accomplishing the present task.
It was now found that the present task, that of making available a re-esterification process for the production of (meth)acrylic acid esters from polyethylene glycols and polypropylene glycols or their mono-ethers, which is satisfactory in every regard, can be accomplished according to the invention by using a catalyst system which consists of lithium chloride and calcium hydroxide or calcium hydroxide alone. The reaction products of these processes are characterized, among other things, in that if any discoloration does occur, it is practically insignificant. The good filterability of the batches should also be emphasized.
The present invention particularly relates to a re-esterification process f
REFERENCES:
patent: 4672105 (1987-06-01), Schlosser et al.
patent: 4745213 (1988-05-01), Schlosser et al.
patent: 5362904 (1994-11-01), Kearns
Knebel Joachim
Spalt Werner
Keys Rosalynd
Roehm GmbH
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