Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-10-31
2003-05-27
Rotman, Alan L. (Department: 1625)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C549S540000
Reexamination Certificate
active
06570028
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for the preparation of glycidylesters of branched carboxylic acids.
BACKGROUND OF THE INVENTION
More in particular the present invention relates to a multistep process for the preparation of glycidylesters of &agr;,&agr;′-branched dicarboxylic acids.
Glycidylesters of &agr;-branched carboxylic acids are useful for the preparation of epoxy resins, acrylic polyester resins and alkyd resins, either directly or via intermediate products such as adducts with (meth)acrylic acid amines, polyols and polyacids, or as reactive diluents for the preparation of thermoset acrylic, epoxy, polyester and/or urethane paints and coatings.
Glycidylesters of mono, &agr;-branched carboxylic acids and their method of preparation are disclosed in U.S. Pat. No. 3,075,999, 3,178,454, 3,275,583 and 3,397,176.
In particular diglycidylesters of &agr;,&agr;-branched aliphatic dicarboxylic acids and diglycidyl esters of &agr;,&agr;,&agr;′,&agr;′-branched aliphatic dicarboxylic acids are known from NL-286209A, DT-OL 1942836A, U.S. 3,629,295A, GB-1,360,811B, GB-1,360,812B, GB-1,360,813B, EP-0518408B1 and from WO98/52932.
In the majority of said publications, said glycidyl-esters are made by reacting an alkali salt of the carboxylic acid with a halo-substituted monoepoxide such as an epihalohydrin, e.g., epichlorohydrin (1-20 molar excess). The mixture is heated (50-150° C.) in the presence of a catalyst forming glycidylester plus alkali salt and water. The water and excess epihalohydrin are removed by azeotropic distillation, and the salt by-product, e.g., NaCl, is removed by filtration and/or washing. The glycidylesters can also be made by reacting the carboxylic acid directly with epichlorohydrin under similar process conditions. The chlorohydrin ester intermediate formed during this reaction is subsequently treated with an alkaline material, e.g., sodium or potassium hydroxide, which yields the desired glycidylester. By-product salt is removed by washing and/or filtration, and water is removed by drying.
However, said conventional processes have appeared to provide glydicylesters which showed unattractive halogen contents, making them not applicable for highly sophisticated coating applications on metal substrates, for which high corrosion resistances are required.
On the other hand the economics of modern coating industries, in which an important proportion of the total output of said glycidylesters is used as starting material, required lower prices per unity active product (i.e. higher EGC values) and related therewith lower manufacturing costs of said glycidylester starting materials.
In the more recent publication WO98/52932 diglycidylesters of a specific group of 3,4,5,6-alkyl-substituted cyclohexane-1,2-dicarboxylic acid were prepared by means of a Diels-Alder reaction of maleic anhydride and specific dienes, such as allo-ocimene.
However again, the products of such a preparation were characterized by relative low EGC values (as compared to the theoretical yield) and a relatively bad efficiency.
It will be appreciated that for particular application of said glydicylesters in clear coatings, there has been developed a growing need for colourless and colour stable products.
It is generally known that mono- and diglycidylesters are thermally and chemically reactive molecules, which cannot be easily recovered from initially prepared, coloured crude glycidylesters.
It has been found that standard atmospheric distillation techniques usually increase the amount of by-products as well as the degree of colour of the esters. It is known that this increase in colour is caused by the reaction at elevated temperatures, as encountered during distillation, of the glycidyl functionality present in the desired product with functionalities present in the by-products, thereby forming additional by-products, which are not separable from the glycidylester and which are extremely sensitive to discoloration upon heating.
It will be appreciated that there is still a need for an improved manufacturing process for glycidylesters of &agr;,&agr;′-branched dicarboxylic acids, and in particular of &agr;,&agr;,&agr;′,&agr;′-branched aliphatic dicarboxylic acids, which may lead to diglycidylesters of the performance of the product aimed at, and at a lower cost price.
An object of the present invention therefor is to provide a process for the manufacture of glycidylesters of &agr;,&agr;′-branched dicarboxylic acids, with significantly lower halogen content (i.e. total halogen content and hydrolyzable halogen content), heat stability and colour stability and/or higher purity, which must be reached at a reduced cost price per product unit.
As a result of extensive research and experimentation, such a process has been surprisingly found now.
SUMMARY OF THE INVENTION
Accordingly, the invention relates to a process for the manufacture of diglycidylesters of &agr;,&agr;′-branched dicarboxylic acids, comprising
(a) the reaction of the &agr;,&agr;′-branched dicarboxylic acid with a halo substituted monoepoxide such as an epihalohydrin (e.g. epichlorohydrin) in a 1.1-20 acid equivalent ratio relative to the &agr;,&agr;′-branched aliphatic dicarboxylic acid and preferably in acid equivalent ratio of 3-20, optionally in the presence of water and water-miscible solvent and preferably an aqueous alkanol as solvent, and in the presence of a catalyst in an amount of at most 45 mol % of the acid equivalent amount of the &agr;,&agr;′-branched aliphatic dicarboxylic acid, and preferably at most 20% and more preferably of at most 10%, at a temperature in the range of from 30 to 110 (and preferably from 65 to 95° C.), during a period in the range of from 0.5 to 2.5 hr,
(b) addition of alkali metal hydroxide or alkali metal alkanolate up to an acid equivalent ratio as to the &agr;,&agr;′-branched aliphatic dicarboxylic acid in the range of from 0.9:1 to 1.2:1 and preferably from 0.95:1 to 1.10:1 and reaction at a temperature of from 0 to 80° C. (and preferably from 20 to 70° C.),
(c) distillation of the obtained reaction mixture to remove the excess halo substituted monoepoxide and the solvent and water formed, and
(d) removal of alkali metal halide salt, preferably by washing the obtained diglycidylester with water mixed with an inert organic solvent, after optionally treating the residual product with a concentrated aqueous alkali metal hydroxide solution, in order to complete the dehydrohalogenation (and preferably a dehydrochlorination).
It will be appreciated that the diglycidylester obtained after step (d), can be dried in addition e.g. by distillation or treating with water absorbers.
DETAILED DESCRIPTION OF THE INVENTION
The process according to the present invention can be carried out either as batch process or as a continuous process. The process preferably uses &agr;,&agr;,&agr;′,&agr;′-branched aliphatic dicarboxylic acids, containing from 8 to 24 carbon atoms.
Of particular interest are diglycidylesters of &agr;,&agr;′-branched aliphatic carboxylic acids represented by the formula:
wherein R
1
, R
2
, R
3
, R
4
, R
5
, R
7
, R
8
, R
9
, R
11
, R
12
, R
13
and R
14
may be the same or different and each may represent hydrogen or a lower alkyl group containing from 1-4 carbon atoms and preferably 1 or 2 carbon atoms, wherein R
6
and R
10
may be the same or different and each may represent an alkyl group containing from 1 to 10 carbon atoms and preferably from 1 to 4 or a cycloaliphatic ring having 5 or 6 carbon atoms, optionally substituted with one or more lower alkyls, and wherein the total carbon atoms in the diacid part of the diglycidyl esters of formula 1 are in the range of from 8 to 24 carbon atoms, and preferably from 10 to 14 carbon atoms, and wherein n is an integer in the range of from 0 to 8, and preferably from 2 to 6.
Preferred diglycidylester of dicarboxylic acids of formula I are those wherein R
5
, R
6
, R
9
and R
10
are methyl and/or ethyl groups, wherein R
7
an
Heymans Denis Marie Charles
Smits Jozef Jacobus Titus
Stichter Hendrik
Van Noort Leo Wim
Covington Raymond
Jones Lisa Kimes
Resolution Performance Products LLC
Rotman Alan L.
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