Hydrolysis of an ester compound

Abstract

The present invention concerns a process to carry out an ester hydrolysis wherein the ester compound (c) is made from at least an alcohol (a) and a carboxylic acid (b), and wherein said alcohol (a) and said carboxylic acid (b) are forming a biphasic liquid system when mixed together; comprising at least a step of producing an ester compound (c)/water emulsion by using as stabilizing species amphiphilic solid particles of nanometric dimension and optionally a catalyst X.

Claims

1. A process for carrying out an ester hydrolysis of an ester compound (c) made from at least an alcohol (a) and a carboxylic acid (b), and wherein said alcohol (a) and said carboxylic acid (b) form a biphasic liquid system when mixed together; the process comprising: a) Producing an ester compound (c)/water emulsion by using amphiphilic solid particles of nanometric dimension as stabilizing species and optionally a catalyst X; b) hydrolyzing the ester compound (c), by setting the temperature, and c) Isolating the resulting compounds.

2. The process according to claim 1, wherein the immiscibility of alcohol (a) and carboxylic acid (b) is defined according to protocol P, protocol P blending alcohol (a) and carboxylic acid (b) together, setting a temperature T, which is 5 C. above the highest of the melting points of alcohol (a) or carboxylic acid (b), under atmospheric pressure, stirring the blend for 5 mins, and settling for 30 mins.

3. The process according to claim 1, wherein alcohol (a) is a hydrophilic alcohol of formula (I) as follows:
R.sup.1(OH)p(I) wherein R.sup.1 represents the skeleton moiety of the alcohol, p is an integer ranging from 1 to 20.

4. The process according to claim 3, wherein R.sup.1 represents the skeleton moiety of a glycerol and p is 3.

5. The process according to anyone of claim 1, wherein alcohol (a) is selected from the group consisting of: ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,4-butylene glycol, 1,6-hexylene glycol, 1,8-octylene glycol, 1,10-decylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, glycerol, diglycerol, pentaerythritol and sorbitol.

6. The process according to claim 1, wherein alcohol (a) is a hydrophobic alcohol of formula (II) as follows:
R.sup.2(OH)(II) wherein R.sup.2 represents an alkyl, aryl, alkenyl or alkoxy radical comprising 6 to 36 carbon atoms.

7. The process according to claim 6, wherein alcohol (a) is selected from the group consisting of: 2-ethylhexyl alcohol, octyl alcohol, decyl alcohol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, isostearyl alcohol, oleyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol monopropyl ether, polyethylene glycol monobutyl ether, polypropylene glycol monomethyl ether, polypropylene glycol monoethyl ether, polypropylene glycol monopropyl ether and polypropylene glycol monobutyl ether.

8. The process according to anyone of claim 1, wherein carboxylic acid (b) is a compound of formula (III) as follows:
R.sup.3COOH(III) wherein R.sup.3 represents the skeleton moiety of the carboxylic acid.

9. The process according to claim 8, wherein R.sup.3 is an alkyl radical comprising from 1 to 30 carbon atoms.

10. The process according to anyone of claim 1, wherein carboxylic acid (b) is selected from the group consisting of: myristoleic acid, palmitoleic acid, sapienic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linoelaidic acid, -linolenic acid, arachidonic acid, eicosapentaenoic acid, erucic acid, docosahexaenoic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, ricinolic acid, tallow acid, coco acid, benzoic acid, substituted benzoic acid, citric acid, malic acid, and oxalic acid.

11. The process according to claim 1, wherein ester compound (c) is a compound of formula (IV) and/or formula (V) as follows:
(R.sup.3COO)pR(IV)
R.sup.3COOR.sup.2(V) Wherein R.sup.1 represents the skeleton moiety of the alcohol, p is an integer ranging from 1 to 20, R.sup.2 represents an alkyl, aryl, alkenyl or alkoxy radical comprising 6 to 36 carbon atoms, and R.sup.3 represents the skeleton moiety of the carboxylic acid.

12. The process according to anyone of claim 1, wherein the ester compound (c) is selected from the group consisting of: monoglyceride, diglyceride and triglyceride.

13. The process according to claim 1, wherein ester compound (c) is selected from the group consisting of: monolaurylglyceryl ester, monomyristylglyceryl ester, dilaurylglyceryl ester, triformin, triacetin, triheptanoin, trimyristin, tripalmitin, trilinolein, triolein, trilaurin, and tricaprin.

14. The process according to claim 1, wherein the catalyst X is selected from the group consisting of: Brnsted acids, vitriolic acids, nitric acids, muriatic acids, sulfonic acids, phosphoric acids, carboxylic acids and Lewis acid.

15. The process according to anyone of claim 1, wherein the catalyst X is a sulfonic acid catalyst selected from the group consisting of: perhalogenated sulfonic acids; benzyl derivatives sulfonic acids; alkyl sulfonic acids; cycloalkyl sulfonic acid; and alkoxyglyceryl sulfonic acids.

16. The process according to claim 1, wherein the amphiphilic solid particles of nanometric dimension provide a catalytic function permitting the carrying out of the ester hydrolysis of the ester compound (c).

17. The process according to claim 16, wherein the amphiphilic solid particles of nanometric dimension comprise SO.sub.3H groups directly grafted or supported on said particles.

18. The process according to claim 1, wherein the weight ratio of ester compound (c) to water at the start of the reaction is between 0.05:1 and 1:0.05.

19. The process according to claim 1, wherein the reaction temperature used in step b) is between 50 C. and 250 C.

Description

EXPERIMENTAL PART

Example 1

Propyl and Sulfonic Acid-Grafted Silica Nanoparticles

(1) 1.1 Grafting of Propyl and Mercapto Functions Aerosil 200 (0.5 g) from Evonik Degussa was placed in a round flask, and then cyclohexane (50 mL) was added. The mixture was stirred until homogenous distribution of Aerosil 200. Then, different amount of silanes [20%: 0.4 mL of (OMe).sub.3Si(CH.sub.2).sub.3SH and 1.5 mL of (OMe).sub.3Si(CH.sub.2).sub.3] were added and stirred in flask, respectively. Then, 4-toluene sulfonic acid (0.0033 g) was added. The flask was placed on a pre-heated hotplate at 120 C. and the mixture was stirred for 4 hours. After cooling down to room temperature, the mixture was filtrated or centrifuged and washed by cyclohexane and ethanol for several times in order to remove 4-toluene sulfonic acid and unreacted silanes. The obtained samples were heated at 100 C. overnight.

(2) 1.2 H.sub.2O.sub.2 Oxidation

(3) The above samples were placed in a round flask. H.sub.2O.sub.2 (30 wt %, m(H.sub.2O.sub.2): m(sample)=60:1) was added into flask and the mixtures were stirred at 40 C. for 24 h. After filtration and washing by Ethanol at 95%, the samples were dried at 40 C. under vacuum for 4 h.

(4) 1.3 Acidification

(5) Samples and H.sub.2SO.sub.4 solution (0.8 M, m (H.sub.2SO.sub.4): m(sample)=60:1) were added in a flask. The mixtures were stirred at room temperature for 2 h. After filtration and washing by ethanol (95%) until suspension pH equal to 7, the obtained solids were dried at 100 C.

Example 2

Co-Precipitated Silica Nanoparticles Functionalized by Octadecyl and Sulfonic Acid Groups

(6) A solution of ammonium hydroxide (NH.sub.3H.sub.2O) (16.2 ml, 25-28%) in absolute ethanol (200 ml) and bi-distilled water (28 ml) was firstly prepared in 40 C. for 10 minutes. A solution of TEOS (9.3 g) in ethanol (9.3 g) was added dropwise with vigorous stirring in the first solution. After about 5 minutes of pre-hydrolysis of TEOS, octadecyl silane ((OMe).sub.3Si(CH.sub.2).sub.17CH.sub.3) and SH-siliane were added in succession with a delay of 5 minutes. The TEOS/organosilanes molar ratio is 80/20, with C.sub.18 silane/SH silane molar ratio of 4. After 30 minutes, the white precipitation was separated by centrifugation at 8,000 rpm for 15 minutes. The obtained solids were washed with and centrifuged several times until that the suspended solution was neutral. The oxidation of SH to SO.sub.3H in samples was oxidized by H.sub.2O.sub.2 in the same condition as the above method. Finally, samples were treated by acid wash same as above described.

Example 3

Esterolysis of Monolaurylglyceryl Ester by Several Catalysts

(7) Reaction:

(8) ##STR00002##

(9) Silica nanoparticles bearing alkyls and alkyl sulfonic aid have been used to catalyse the hydrolysis reaction of monolaurylglyceryl ester. Conversions and reaction conditions were listed in Table 1.

(10) TABLE-US-00001 TABLE 1 Ester/ Catalyst Catalyst H.sub.2O (weight (molar (wei- Temp/ Con- Catalyst %) %) ght) Time version TON TFA 1.1% 2% 2:1 70 C./5 h 36.1% 17 SA 0.73% 2% 2:1 100 C./5 h 37.1% 18 PTSA 1% 16.9% 1:3 95 C./11 h 52.9% 32 SiO.sub.2 20/80 2% 0.0116% 1:3 95 C./11 h 6% 496 SO.sub.3H/C.sub.3 10% 0.0519% 1:3 95 C./11 h 48.7% 886 SiO.sub.2 20/80 4% 0.0151% 1:3 95 C./11 h 22.5% 1403 SO.sub.3H/C18 SiO.sub.2 20/80 2% 0% 1:3 95 C./11 h 0.6% NA SH/C.sub.3 particles PTSA + 1%, 2% 16.9% 1:3 95 C./11 h 57.1% 32 SiO.sub.2 20/80 SH/C.sub.3 NH.sub.4Cl + 1%, 2% 0% 1:3 95 C./11 h 2.3% NA SiO.sub.2 20/80 SH/C.sub.3

(11) TFA is CF.sub.3SO.sub.3H. SA is H.sub.2SO.sub.4. PTSA is CH.sub.3C.sub.6H.sub.4SO.sub.3H

(12) Catalyst (weight %) corresponds to the weight amount of catalyst to the weight amount of ester. Catalyst (molar %) corresponds to the molar amount of catalyst acid sites to the molar amount of ester. The ester/H.sub.2O ratio corresponds to the weight amount of ester to the weight amount of water. TON is the turn over number corresponding to the ratio between the molar amount of monolaurin ester by molar amount of acid functions.

(13) It appears then that the catalytic activity of grafted silica particles is 100 to 1000 times better than PTSA, CF.sub.3SO.sub.3H or H.sub.2SO.sub.4 based on conversion of MGLE per molar acid. The maximum conversion of MGLE by 10% particles added can reach 48% at 10 hours.

(14) When 2% SiO.sub.2 20/80 SH/C.sub.3 are added as catalyst in the reaction system, the wettability of these particles are almost same with SiO.sub.2 20/80 SO.sub.3H/C.sub.3; but the conversion of MLGE is only 0.6%. This means that particles without catalytic functional group can't help the esterolysis.

(15) When 1% PTSA with 2% SiO.sub.2 20/80 SH/C.sub.3, are used as catalysts, the conversion increased+8% compared with 1% obtained with PTSA itself. This result reveals that particles have helped to increase the interface between the two phases and that it leads to a higher conversion of the reaction.

(16) The last reaction was done with 1% NH.sub.4Cl and 2% SiO.sub.2 20/80 SH/C.sub.3 as catalyst. The pH value of 1% NH.sub.4Cl is much lower than 1% acid like PTSA, CF.sub.3SO.sub.3H, or H.sub.2SO.sub.4. Generally, the esterolysis reaction won't happen under such conditions; but silica nanoparticles of the present invention helped it to get conversion at 2.3%.

(17) NMR spectrum of MLGE:

(18) .sup.1H NMR (300 MHz, DMSO-d.sub.6): .sub.H=4.89 (d, J=5.1 Hz, 1H), 4.64 (t, J=5.7 Hz, 1H), 4.02 (2dd, J=14.8, 4.2 Hz, 1H), 3.88 (2dd, J=14.8, 6.6 Hz, 1H), 3.65-3.59 (m, 1H), 3.68-3.31 (m, 3H), 2.28 (t, J=7.5 Hz, 21H), 1.53-1.49 (m, 2H), 1.24 (br s, 16H), 0.85 (t, J=6.3 Hz, 3H) ppm

(19) NMR spectrum of lauric acid

(20) .sup.1H NMR (300 MHz, DMSO-d.sub.6): .sub.H=11.97 (S, 1H), 2.17 (t, J=7.8 Hz, 2H), 1.50-1.45 (m, 2H), 1.24 (br s, 16H), 0.85 (t, J=6.9 Hz, 3H) ppm

(21) NMR Spectrum of Glycerol

(22) .sup.1H NMR (300 MHz, DMSO-d.sub.6): .sub.H=4.53 (d, J=4.8 Hz, 1H), 4.34 (t, J=5.4 Hz, 2H), 3.43-3.24 (m, 5H) ppm

(23) It appears then that NMR is a good method for the quantification of lauric acid content in the mixture. There is no overlap at 2.17-2.28 ppm (the second CH.sub.2 from CO) among lauric acid, monlaurylglyceryl ester and glycerol. So the NMR quantitative method was developed based on this fact. The linearity R.sup.2 is 0.999.

Example 4

Phenyl Sulfonic Acid-Grafted Silica Amphiphilic Nanoparticles

(24) I.1. Preparation of MCM41

(25) A solution of sodium silicate was first prepared: 32 g of NaOH were stirred with 187 ml of Ludox. This mixture is stirred 24 h at 40 C.

(26) In a first erlen, 345 mL of this sodium silicate solution were stirred 1 hour at 60 C. In a second erlen, 13.83 g of CTATos (cetyltrimethyl amine tosylate) are stirred with 500 mL of water during 1 hour at 60 C. Then the first erlen is slowly added to the second erlen. This new mixture is stirred at 60 C. until we obtained an homogenous solution by around 1 hour. This new solution is divided in equal part in the autoclaves and put into the microwave. The ramp from room temperature to 180 C. is 15 min, the step at 180 C. is 9 min. Then the mixture is filtrated under vacuum and wash with ethanol (three times 50 mL) and acetone (one time 50 mL). Then the powder is dry overnight in oven at 80 C. and we obtain 22.61 g of white powder. TGA, BET and XRD were done.

(27) I.2. Surfactant Extraction

(28) 22 g of MCM41 previously obtained were dispersed into 350 mL of ethanol, 2 equivalent of hydrochloric acid are added. This mixture is stirred 1 hour at 60 C., then filtrated under vacuum and wash with ethanol (three times 50 mL) and acetone (one time 50 mL). This operation was repeated twice. Then the powder is dry overnight in oven at 80 C. TGA, BET and XRD were done.

(29) If there is still some surfactant, the rest is removed by a soft calcination under nitrogen: 5 C. per minute until 500 C., then keep this temperature during 2 hours. Then the powder is washed with ethanol (three times 50 mL) and acetone (one time 50 mL). Then the powder is dry overnight in oven at 80 C. TGA, BET and XRD were done.

(30) I.3. Grafting of Trimethoxyphenylsilane on MCM41

(31) 5.2 g of MCM41 were first activated at 130 C. during 1 hour. After cooling down to room temperature, 150 mL of cyclohexane are added. This mixture is stirred until we get an homogeneous dispersion. Then the trimethoxyphenylsilane (1 eq-7.28 mmol-1.36 mL) is added. The mixture is stirred at reflux at 80 C. during 5 hours. Then the mixture is filtrated under vacuum and wash with ethanol (three times 50 mL) and acetone (one time 50 mL). Then the powder is dry overnight in oven at 80 C. and we obtain 22.61 g of white powder. TGA, BET and XRD were done.

(32) I.4. Sulfonation of the Trimethoxyphenylsilane-MCM41

(33) The silica is introduced to a glass column between 2 filters. At the bottom of the column a round flask with 50 mL of sulfuric fuming acid (35%) was fixed. The sulfuric fuming acid flows throw the silica in order to sulfonate it. Some argon bubbled in the sulfuric fuming acid in order to help him to go up to the column. At the top of the column after the filter the sulfuric fuming acid go to a trap in order to avoid sulfuric acid vapor go out. In the trap helianthine color indicator was put in order to know when the water in the trap becomes acid (which means the reaction is over). Then the powder is washed with Ethanol (three times 50 mL) and acetone (one time 50 mL). Then the powder is dry overnight in oven at 80 C. TGA, BET and XRD were done.

(34) I.5. Amphiphilic Nature of Nanoparticles

(35) 1% by weight of nanoparticles previously obtained are mixed with 50% vol of ester and 50% vol of water at 70 C. The resulting blend is stirred for 5 minutes at 13000 rpm. After a storage of 24 hours, the medium is observed with a microscope. Observation of an emulsion with droplets of ester/water or water/ester is an indication that nanoparticles provide an amphiphilic property.

Example 5

Esterolysis of Monolaurylglyceryl Ester by Several Catalysts

(36) Reaction:

(37) ##STR00003##

(38) Silica nanoparticles bearing alkyls and alkyl sulfonic acid have been used to catalyse the hydrolysis reaction of monolaurylglyceryl ester. Conversions and reaction conditions were listed in Table 2.

(39) TABLE-US-00002 TABLE 2 Catalyst Catalyst Ester/ (weight (molar H.sub.2O Temp/ Con- Catalyst %) %) (weight) Time version TON MCM41- 0.2% 0.0013 eq 1:3 95 C./24 h 31.91 237.87 Phenyl- SO.sub.3H MCM41- 10% 0.058 eq 1:3 95 C./24 h 47.09 8.17 Phenyl- SO.sub.3H PTSA 1% 0.017 eq 1:3 95 C./24 h 53.7 31.29 PTSA 10% 0.14 eq 1:3 95 C./24 h 81.41 5.8

(40) Catalyst (weight %) corresponds to the weight amount of catalyst to the weight amount of ester. Catalyst (molar %) corresponds to the molar amount of catalyst acid sites to the molar amount of ester. The ester/H.sub.2O ratio corresponds to the weight amount of ester to the weight amount of water. TON is the turn over number corresponding to the ratio between the molar amount of monolaurin ester by molar amount of acid functions.

(41) It appears then that the TON is higher with silica particles of the present invention. The silica particles increased the contact of monolaurylglyceryl ester and water. Then the catalytic sites on silica surface may help the catalytic hydrolysis also.

Example 6

Esterolysis of trilaurylglyceryl ester by several catalysts

(42) Reaction:

(43) ##STR00004##

(44) Silica nanoparticles bearing alkyls and alkyl sulfonic aid have been used with TFA to catalyse the hydrolysis reaction of trilaurylglyceryl ester. Conversions and reaction conditions were listed in Table 3.

(45) TABLE-US-00003 TABLE 3 Catalyst Catalyst Ester/ (weight (molar H.sub.2O Temp/ Con- Catalyst %) %) (weight) Time version TON TFA 2.3% 0.1 eq 1:3 95 C./8 h 26.1% 2.6 TFA 23.3% 1 eq 1:3 95 C./8 h 68.2% 0.68 TFA 69.8% 3 eq 1:3 95 C./8 h 93.2% 0.31 H.sub.2SO.sub.4 23.0% 3 eq 1:3 95 C./8 h 72.4% 0.24 H.sub.2SO.sub.4 7.7% 1 eq 1:3 95 C./8 h 32.9% 0.33 TFA + SiO.sub.2 23.3%, 1 eq, 1:3 95 C./8 h 76.8% 0.77 20/80 4% 0.004 eq SO.sub.3H/C.sub.3 TFA + SiO.sub.2 23.3%, 1 eq, 1:3 95 C./8 h 87.9% 0.88 20/80 4% 0.004 eq SO.sub.3H/C.sub.8 TFA + SiO.sub.2 23.3%, 1 eq, 1:3 95 C./8 h 78.2% 0.78 20/80 4% 0.004 eq SO.sub.3H/C.sub.18

(46) Catalyst (weight %) corresponds to the weight amount of catalyst to the weight amount of ester. Catalyst (molar %) corresponds to the molar amount of catalyst acid sites to the molar amount of ester. The ester/H.sub.2O ratio corresponds to the weight amount of ester to the weight amount of water. TON is the turn over number corresponding to the ratio between the molar amount of trilaurin ester by molar amount of acid functions.

(47) It appears then that the catalytic activity can be increased with silica particles of the present invention, notably by improving the contact of trilaurylglyceryl ester and water and the presence of catalytic sites on silica surface.