METHOD FOR SEPARATING HIGH-BOILING CARBOXYLIC ACID VINYL ESTER/CARBOXYLIC ACID MIXTURES

Abstract

The invention relates to a method for separating a mixture containing at least one carboxylic acid vinyl ester of general formula RC(O)OCHCH.sub.2 and at least one carboxylic acid of general formula RCOOH, wherein R in either case can be an aliphatic group having 12 to 22 C atoms or a cycloaliphatic group having 12 to 22 C atoms, or an aromatic group having 12 to 22 C atoms, and R can be identical or different, characterized in that the carboxylic acid is converted to its anhydride RC(O)OC(O)R and the carboxylic acid vinyl ester is subsequently separated.

Claims

1. A process for separating a mixture comprising at least one vinyl carboxylate ester of general formula RC(O)OCHCH.sub.2 and at least one carboxylic acid of general formula RCOOH, wherein in each case R may be an aliphatic radical having 12 to 22 carbon atoms or a cycloaliphatic radical having 12 to 22 carbon atoms or an aromatic radical having 12 to 22 carbon atoms and R may be identical or different, said process comprising the steps of converting the carboxylic acid into its anhydride RC(O)OC(O)R and subsequently removing the vinyl carboxylate ester.

2. The process as claimed in claim 1, wherein the conversion of the carboxylic acid RCOOH into the corresponding anhydride RC(O)OC(O)R is effected by reaction with an anhydride of general formula R.sup.*C(O)OC(O)R.sup.*, wherein R.sup.* is identical or different and represents an aliphatic radical having 1 to 10 carbon atoms or a cycloaliphatic radical having up to 10 carbon atoms or an aromatic radical having up to 10 carbon atoms.

3. The process as claimed in claim 2, wherein 0.1 to 5 molar equivalents of the anhydride R.sup.*C(O)OC(O)R.sup.* relative to the carboxylic acid RCOOH are employed and the reaction is effected at temperatures of 0 C. to 150 C., at a pressure of 0.001 to 10 bar abs., and with a reaction time of up to 5 hours.

4. The process as claimed in claim 2, wherein the anhydride of general formula R.sup.*C(O)OC(O)R.sup.*employed is an anhydride selected from the group consisting of anhydrides of acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, 2-methylbutyric acid, 3-methylbutyric acid, pivalic acid, caproic acid, cyclohexanecarboxylic acid, n-heptanoic acid, 2-methylhexanoic acid, 2-ethylhexanoic acid, n-octanoic acid, n-nonanoic acid, isononanoic acid, neononanoic acid, n-decanoic acid, and neodecanoic acid.

5. The process as claimed in claim 1, wherein the conversion of the carboxylic acid RCOOH into the corresponding anhydride RC(O)OC(O)R is effected by transition-metal-catalyzed reactive distillation with a vinyl carboxylate ester of general formula RC(O)OCHCH.sub.2, wherein R may be an aliphatic radical having 1 to 10 carbon atoms or a cycloaliphatic radical having up to 10 carbon atoms or an aromatic radical having up to 10 carbon atoms.

6. The process as claimed in claim 5, wherein the reactive distillation is performed in the presence of Ru compounds or Pd compounds as catalyst, with a molar ratio of vinyl carboxylate ester RC(O)OCHCH.sub.2 to carboxylic acid RCOOH of 1:1 to 40:1 and at a temperature of 100 C. to 180 C.

7. The process as claimed in claim 5, wherein the vinyl carboxylate ester RC(O)OCHCH.sub.2employed is a vinyl carboxylate ester having an alkyl radical having 1 to 6 carbon atoms as radical R.

8. The process as claimed in claims 1, wherein the vinyl carboxylate ester is removed by distillation.

9. The process as claimed in claims 1, wherein the conversion of the carboxylic acid into its anhydride is preceded by a transvinylation of a carboxylic acid of general formula RCOOH with a vinyl carboxylate ester of general formula RC(O)OCHCH.sub.2.

10. The process as claimed in claim 9, wherein the transvinylation comprises a transvinylation of vinyl acetate with stearic acid and/or palmitic acid which is catalyzed with a ruthenium or palladium catalyst.

11. The process as claimed in claim 7, wherein the vinyl carboxylate ester is vinyl acetate.

Description

EXAMPLES

[0033] The examples which follow serve to more particularly elucidate the invention.

[0034] The reported compositions of the reaction mixtures were determined by means of quantitative NMR spectroscopy.

Example 1

[0035] Separation of a vinyl stearate/stearic acid mixture by addition of acetic anhydride

[0036] A mixture of 35 g (113 mmol) of vinyl stearate (ABCR #AB123736) and 15 g (53 mmol) of stearic acid (Merck # 800673) was admixed with 8.1 g (79 mmol) of acetic anhydride (Aldrich # 110043) and stirred for 1 hour at 80 C. before excess acetic anhydride and the acetic acid formed were removed on a rotary evaporator. The mixture obtained thereafter was composed of 96.2 wt % vinyl stearate, 3.2 wt % stearic anhydride and 0.6 wt % stearic acid. Vacuum distillation at 100 C.-120 C. (0.02 mbar abs.) afforded the vinyl stearate in 99% purity.

[0037] The example shows that addition of acetic anhydride converts the stearic acid into stearic anhydride and that vinyl stearate can be obtained in high purity via a subsequent vacuum distillation.

Example 2

[0038] Separation of a vinyl stearate/stearic acid mixture from a transvinylation reaction by addition of acetic anhydride (in the absence of catalyst)

[0039] In a 100 ml Berghoff autoclave 20.0 g (70 mmol) of stearic acid (Merck # 800673), 48.4 g (562 mmol) of vinyl acetate (Wacker Chemie AG), 0.068 g (0.3 mmol) of phenothiazine and 0.086 g (0.3 mmol) of [Ru.sub.3O(OAc).sub.6(H.sub.2O).sub.3]OAc (in the form of an acetic acid solution comprising 4.5 wt % Ru from Umicore) were heated to 140 C. for 4 hours at not more than 10.0 bar abs. Once cooled, acetic acid and vinyl acetate were removed on a rotary evaporator. Vinyl stearate and stearic acid were then distilled off at 154 C.-173 C. (1 mbar abs.).

[0040] The obtained 18.5 g of a mixture of 94 wt % (17.4 g, 56 mmol) vinyl stearate and 6 wt % (1.1 g, 4 mmol) stearic acid were admixed with 0.59 g (6 mmol) of acetic anhydride (Aldrich # 110043) and stirred for 1 hour at 80 C. before excess acetic anhydride and the acetic acid formed were removed on a rotary evaporator. Renewed vacuum distillation at 173 C. (1 mbar abs.) afforded the vinyl stearate in 99.8% purity.

Example 3

[0041] Separation of a vinyl stearate/stearic acid mixture from a transvinylation reaction by addition of acetic anhydride (in the presence of catalyst)

[0042] In a 100 ml Berghoff autoclave 20.0 g (70 mmol) of stearic acid (Merck # 800673), 48.4 g (562 mmol) of vinyl acetate (Wacker Chemie AG), 0.068 g (0.3 mmol) of phenothiazine and 0.086 g (0.3 mmol) of [Ru.sub.3O(OAc).sub.6(H.sub.2O).sub.3]OAc (in the form of an acetic acid solution comprising 4.5 wt % Ru from Umicore) were heated to 140 C. for 4 hours at not more than 10.0 bar abs. Once cooled, acetic acid and vinyl acetate were removed on a rotary evaporator.

[0043] The reaction mixture which comprised 19.2 g (62 mmol) of vinyl stearate and 1.56 g (5.5 mmol) of stearic acid was then admixed with 1.12 g (11 mmol) of acetic anhydride (Aldrich # 110043) and stirred for 1 hour at 80 C. before excess acetic anhydride and the acetic acid formed were removed on a rotary evaporator. Vacuum distillation at 105 C.-130 C. (0.07 mbar abs.) afforded the vinyl stearate in 99% purity.

Example 4

[0044] Separation of a vinyl palmitate/palmitic acid mixture from a transvinylation reaction by reactive distillation with vinyl acetate

[0045] 220 g/h of a mixture of palmitic acid (Carl Roth #5907.2) and catalyst (active Ru catalyst solution based on RuCl.sub.3, as disclosed in DE 102014206915, 1000 ppm Ru relative to palmitic acid) and 27.7 l/min of gaseous vinyl acetate were introduced into a 2 l glass reactor equipped with a dip tube. Vinyl acetate and the acetic acid formed were discharged in gaseous form and condensed outside the reactor. The reaction was performed with a constant reactor fill volume of 1750 ml, an average residence time of 6.7 hours and at an internal reactor temperature of 140 C. A mixture composed of 76 wt % vinyl palmitate, 20 wt % palmitic anhydride and 4 wt % palmitic acid was obtained. Removal of the vinyl palmitate was effected via a vacuum distillation at 150 C. (1 mbar abs.).

Example 5

[0046] Separation of a vinyl stearate/stearic acid mixture from a transvinylation reaction by reactive distillation with vinyl acetate

[0047] 225 g/h of a mixture of stearic acid (Carl Roth #9459.2) and catalyst (active Ru catalyst solution based on RuCl.sub.3, as disclosed in DE 102014206915, 1000 ppm Ru relative to stearic acid) and 25.5 l/min of gaseous vinyl acetate were introduced into a 2 l glass reactor equipped with a dip tube. Vinyl acetate and the acetic acid formed were discharged in gaseous form and condensed outside the reactor. The reaction was performed with a constant reactor fill volume of 1750 ml, an average residence time of 6.5 hours and at an internal reactor temperature of 140 C. A mixture composed of 79 wt % vinyl stearate, 18 wt % stearic anhydride and 3 wt % stearic acid was obtained. Removal of the vinyl stearate was effected via a vacuum distillation at 175 C. (1 mbar abs.).