WO2001030881A1

WO2001030881A1 - Process for glycidation of carboxylic acids

Info

Publication number: WO2001030881A1
Application number: PCT/EP2000/010628
Authority: WO
Inventors: Leo Wim Van Noort; Jozef Jacobus Titus Smits; Hendrik Stichter
Original assignee: Shell Internationale Research Maatschappij B.V.
Priority date: 1999-10-27
Filing date: 2000-10-26
Publication date: 2001-05-03
Also published as: AU7923800A

Abstract

Process for the glycidation of carboxylic acids with a halosubstituted monoepoxide in the presence of a base, at a temperature in the range of from 0 to 110 °C, followed by an dehydrogenation step, characterized on that the base is formed by a alkali metal or alkaline earth metal carbonate and/or carbonate hydrogen and in the presence of an aprotonic dipolar organic solvent, having a static relative dielectrical constant of greater than 15 at 25 °C and a permanent dipole moment of equal to or greater than 2.5 D, during at least the dehydrohalogenation step.

Description

PROCESS FOR GLYCIDATION OF CARBOXYLIC ACIDS

The present invention relates to a process for the glycidation of carboxylic acids . More in particular the present invention relates to the glycidation of carboxyl groups in starting molecules, which have no sterical hindrance at all or only in a small degree.

Industrial glycidation processes i.e. the conversion of a ca'rboxylic acid with epihalohydrin and more in particular epichlorohydrin into a glycidylester group, were usually carried out up to now, using an aqueous solution of caustic and more in particular sodium hydroxide .

However, the initially prepared glycidylesters have been found to be susceptible to hydrolysis and could not be produced in desired good yields of products with low hydrolyzable halogen and in particular chlorine contents, as far as the initially formed glycidylesters are not sterically hindered, as can be derived from EP-0447360 and 098/42768. Examples of such sterically hindered glycidylesters are CARDURA E5 or ElO esters (CARDURA is a trademark), which have been derived from α, α-branched carboxylic acids, containing from 5 to 30 carbon atoms, available under the tradename VERSATIC 10 acids, by glycidation with aqueous caustic.

It will be appreciated that there is a growing pressure to reduce said hydrolyzable chlorine content in glycidylesters, while maintaining a high epoxy yield, due to a number of applications of these esters in sophisticated end-products derived from metals, wherein corrosion even after a long time has to be eliminated such as in electronic applications . (e . g . printed circuit boards or encapsulated chips or semiconductors) . Therefore it is an object of the present invention to provide an improved manufacturing process for glycidylesters of carboxylic acids and more in particular non α-branched carboxylic acids, which do not show steric hindrance at all or only in a small degree. Another object of the present invention is to provide improved glycidylesters of carboxylic acids, showing an acceptable low hydrolyzable chlorine content, i.e. below 10.000 ppm and preferably below 5000 ppm and more preferably below 3000 ppm, in combination with a relatively high epoxy yield i.e. above 90% of the theoretical value. E.g. Suitable EGC values will be in the range of from 3600 to 4100.

As a result of extensive research and experimentation, the process and products aimed at have been surprisingly found.

Accordingly the invention relates to a process for the glycidation of carboxylic acids with a halosubstituted monoepoxide such as epihalohydrin in the presence of a base, at a temperature in the range of from 0 to 110 °C, followed by a dehydrohalogenation step, characterized in that the base is formed by alkali metal or alkaline earth metal carbonate and/or carbonate hydrogen, and in the presence of an aprotonic dipolar organic solvent having a static relative dielectrical constant of greater than 15 (at 25 °C) , and a permanent dipole moment of equal to or more than 2.5 D, during at least the dehydrohalogenation step. The dielectrical constant being preferably in the range of from 15 to 65, more preferably in the range of from 15 to 50 and the permanent dipole moment preferably being in the range from 2.7 to 5.

With the term "dehydrohalogenation step" is meant the final conversion of the initially formed halohydrin ester and preferably chlorohydrin ester into a finally desired glycidylester .

It will be appreciated that either the carbonate or carbonate hydrogen or the polar organic solvent or both may optionally be present before the dehydrohalogenation step, but must be present both during said step.

It will be appreciated that if the hereinbefore specified process is carried out without any alkali metal or alkaline earth metal carbonate or carbonate hydrogen before the dehydrogenation step, another conventional base such as sodium hydroxide or potassium hydroxide and the like and preferably sodium hydroxide must be present in a catalytic amount during the first reaction step wherein epihalohydrin is reacted with the starting acid to form the halohydrin ester.

According to a preferred embodiment of the process of the invention the carbonate base as well as the cosolvent are present before the dehydrohalogenation step and more preferably from the start of the reaction. According to a more preferred embodiment of the process of the invention, a small amount of water has been added to the aprotonic dipolar organic solvent. Said amount of water is at least 3 wt% relative to the weight of water and polar organic solvent and preferably in the range of from 3 to 7 wt% and more preferably in the range of from 4 to 6 wt% .

As base carbonate salt reagent can be used e.g. magnesium carbonate, calcium carbonate, barium carbonate, potassium carbonate, sodium carbonate, lithium carbonate, potassium carbonate hydrogen, sodium carbonate hydrogen, lithium carbonate hydrogen or hydrates thereof, of which potassium carbonate is the most preferred.

Suitable aprotonic dipolar organic solvents are selected from the group comprising acetonitrile, acetone, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, 4-methyl-l, 3-dioxol-2-one, tetramethylene sulfone, l-methyl-2-pyrrolidone nitrobenzene, hexamethyl phosphoric acid triamide and the like, or mixtures thereof, of which acetonitrile, dimethylsulfoxide, dimethylformamide are preferred and of which acetonitrile is the most preferred.

As indicated earlier, in particular carboxylic acids or hydroxyl containing compounds showing no sterically hindrance or only a small amount can be converted by the present process into products having low hydrolyzable halogen content .

Suitable starting acids can be selected from primary or secondary mono- and/or di-acids such as acrylic acid, methacrylic acid optionally α-substituted with an alkyl group of 1 to 4 C atoms, 1, 4-cyclohexane dicarboxylic acid, 1, 2-cyclohexane dicarboxylic acid, suberic acid, pimelic acid, azelaic acid, adipic acid, lauric acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, butyric acid, isovaleric acid, myristic acid, n-heptylic acid, pelargonic acid, glycolic acid, lactic acid, hydrocarboxylic acids derived from sugars such as gluconic acid, valeric acid, caproic acid, caprylic acid, arachidic acid, behenic acid, lignoceric acid, cerotiolactic acid, methoxy acetic acid, glyoxylic acid, vinyl acetic acid, phenyl acetic acid or carboxyl functional polyester oligomers derived from dicarboxylic acids and dialcohols, having terminal primary or secondary carboxyl groups.

The process of the present invention is preferably carried out with epichlorohydrin in a 2-20 molar excess, relative to the carboxyl group amount.

The carbonate or carbonate hydrogen to be applied can be used in a molar ratio of from 1:1 to 8:1 relative to the molar amount of the carboxylic acid groups, preferable in a molar ratio of from 1:1 to 3:1 and more preferably in a molar ratio of from 1:1 to 2:1. Preferred temperatures for the process of the present invention are in the range of from 20 to 90 °C.

The molar ratio between the dipolar solvent and the carboxylic acid starting material is in the range of from 4:1 to 6:1 while the molar ratio between epichlorohydrin and carboxylic acid is in the range from 6:1 to 9:1. It will be appreciated that during and after the reaction with epihalohydrin and preferably with epichlorohydrin, the reaction mixture is distilled to remove the excess epihalohydrin and the cosolvent and water and that finally the alkali metal or alkaline earth metal halide salts are removed by washing the initially formed glycidylester with water. According to a preferred embodiment of the present process, glycidylesters are prepared from carboxyl functional polyester resins or oligomers, derived from at least one dicarboxylic acid and at least one dialcohol and, bearing at least two terminal non-tertiary carboxyl groups, such as disclosed in EP-0447360A1, EP-0634434A2, EP-0720997A2, and W098/42768.

It will be appreciated that the present invention also relates to the glycidylesters, obtained by the hereinbefore specified process and characterised by a significant lower hydrolyzable halogen content and in particular chlorine content, in combination with a relatively high epoxy content (above 90% of the theoretical value) , as compared to corresponding glycidylesters prepared according to prior art processes. Accordingly the invention relates to glycidylesters, showing a hydrolyzable halogen and more in particular chlorine content below 5000 ppm and preferably below 3000 ppm and in particular as low as 1000 ppm in combination with an epoxy content of at least 90% of the theoretical value. It will be appreciated that another aspect of the present invention is formed by coating compositions, the binder of which is derived from the glycidylesters of the present invention and more preferably the polyglycidylesters derived from carboxyl functional polyester resins or oligomers .

A further aspect of the present invention is formed by these coatings, applied on a substrate and in particular a metal substrate in uncured or cured form. It is true, that from US patent 4,722,983 a process was known for the preparation of glycidylethers, by reacting a compound containing at least one phenolic group with at least the equivalent amount, based on the phenolic groups of a halohydrin in a substantially anhydrous, aprotonic solvent, in the presence of a solid, substantially anhydrous basic compound.

However it will be appreciated by persons skilled in the art, that the process of the present invention for the preparation of glycidylesters having low hydrolyzable halogen content, and in particular chlorine content, in combination with a relatively high epoxy yield (>90% of the theoretical value) , could not be derived from said patent .

The invention is illustrated by the following examples, however without restricting its scope to these specific embodiments.

In these examples, the hydrolizable chlorine content (without correction for the possible presence of inorganic chlorine) was determined by the following method:

A weighted amount of test sample was dissolved in 15 ml toulene and 50 ml methyl ethyl ketone and, if the sample was a solid resin, in 50 ml tetrahydrofuran (THF) . Subsequently, 50 ml of a solution of KOH in methanol (0.1 mol/L) was added, and the mixture was refluxed for 30 minutes. After addition of 1 ml acetic acid, the chlorine content in the sample was determined by potentiometric titratin with standard silver nitrate solution and the hydrolyzable chlorine content of the sample is calculated from the data obtained. Example 1

To a 500 ml glass reactor are subsequently added 84.4 g of an adduct of one mole of 1, 4-dicarboxyl cyclohexane and 2 moles of hydroxypivalic acid, (AV = 5405 mmol/kg) , 82 g of acetonitrile, 334,4 g of epichlorohydrin and 4.3 g of water under stirring.

At a temperature of 28 °C the dosing of K2CO3 -_j__s started and the complete amount is added within 5 minutes causing a temperature rise up to 32 °C. After additional stirring during one hour, the temperature has decreased to 28 °C and the exteranl heating is started. After 1.25 hours the inner temperature is 46.8 °C and 0.31 g of benzyltriethylammonium chloride (BETEC) is added. The temperature is increased until 78 °C. After four hours stirring, the reaction mixture is cooled and the reaction mixture is filtrated. The organic liquid is stripped to 135 °C and 7 mbar.

A yellow liquid is separated, having an EGC of 3346 mmol/kg (theoretical EGC = 4150 mmol/kg) and showing hydrolyzable chlorine content of 2100 ppm.

Example 2

A well stirred 250 ml glass reactor equipped with a reflux condensor was charged with 50 grams of the crude adduct of one mole 1, 4-dicarboxyl cyclohexane and two moles hydroxypivalec acid, and 100 ml acetonitrile. The hydrolysable chlorine content of this resin is 12000 ppm.

The mixture was stirred until the epoxy resin was fully dissolved and then the mixture was brought to reflux (approximately 86 °C) . Then the required amount (1 to 8 moles per mol hydrolysable chlorine) of potassium carbonate (K2CO3) was added at once. The mixture was stirred for 1 to 4 hours and the mixture was kept at reflux temperature. Then, 50 ml MIBK was added, the mixture was cooled to 30 °C and washed several times with 25 ml H2O until the pH of the washwater was neutral. The organic was concentrated in vacuo to yield the final epoxy resin. Example 3

The proceedings of example 2 were repeated except that other solvents, reaction times and starting materials were used. The following Table shows the starting materials and the relevant reaction conditions, but also the characteristics of the obtained glycidylesters. The crude epoxypolyester I was derived from the adduct of one mole hydrogenated diphenylolpropane and two moles 3-methyl hexahydrophtalic anhydride. The crude epoxypolyester II was derived from hexahydrophtalic anhydride. The crude epoxypolyester III was derived from 3-methyl hexahydrophtalic anhydride. The crude epoxypolyester IV was derived from the adduct of one mole 1, 4-dicarboxyl cyclohexane and two moles hydroxypivalic acid.

TABLE

^rK/Cl molar ration potassium carbonate/hydrolysable chlorine

Claims

C L A I M S

1. Process for the glycidation of carboxylic acids with a halosubstituted monoepoxide in the presence of a base, at a temperature in the range of 0 °C ot 110 °C, followed by a dehydrohalogenation step, characterized in that the base is formed by alkali metal or alkaline earth metal carbonate and/or carbonate hydrogen and in the presence of an aprotonic dipolar organic solvent, having a static relative dielectrical constant of greater than 15 (at 25 °C) and a permanent dipole moment of equal to or greater than 2.5 D, during at least the dehydrohalogenation step.

2. Process according to claim 1, characterized in that the aprotonic dipolar solvent has a static relative dielectrical constant in the range of from 15 to 65.

3. Process according to claim 1, characterized in that the aprotonic dipolar solvent has a permanent dipole moment in the range from 2.7 to 5.

4. Process according to claims 1-3, characterized in that a small amount of water is present in the aprotonic dipolar organic solvent.

5. Process according to claim 4, wherein the amount of water is in the range of from 3 to 7 wt% relative to the weight of water and organic solvent.

6. Process according to claim 5, wherein the amount of water is in the range of from 3 to 6 wt% .

7. Process according to claims 1-6, characterized in that the aprotonic dipolar organic solvents are selected from acetonitrile, N,N-dimethylformamide, acetone, N,N- dimethylacetamide, dimethylsulfoxide, 4-methyl-l, 3-dioxol 2-one, tetramethylene sulfone, 2-methyl-2-pyrrolidone, nitrobenzene, hexamethylphosphoric acid nitrobenzene, hexamethylphosphoric acid triamide, or mixtures thereof.

8. Process according to claim 7, characterized in that acetonitrile, dimethylsulfoxide or N, N-dimethylformamide or mixtures thereof, is used.

9. Process according to claim 8, characterised in that acetonitrile is used as dipolar organic solvent.

10. Glycidyl esters of non-α-branched carboxylic acids, not showing any steric hindrance at all or only in small degree, having a hydrolyzable chlorine content below

5000 ppm and preferably below 3000 ppm, in combination with a relatively high epoxy content (>90% of the theoretical value) , and obtainable according to the process of claims 1-9.