GB2212493A - Production of di- or tri- esters - Google Patents
Production of di- or tri- esters Download PDFInfo
- Publication number
- GB2212493A GB2212493A GB8823512A GB8823512A GB2212493A GB 2212493 A GB2212493 A GB 2212493A GB 8823512 A GB8823512 A GB 8823512A GB 8823512 A GB8823512 A GB 8823512A GB 2212493 A GB2212493 A GB 2212493A
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- United Kingdom
- Prior art keywords
- entrainer
- ester
- esterification
- tri
- reaction
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C69/00—Esters of carboxylic acids; Esters of carbonic or haloformic acids
- C07C69/02—Esters of acyclic saturated monocarboxylic acids having the carboxyl group bound to an acyclic carbon atom or to hydrogen
- C07C69/12—Acetic acid esters
- C07C69/16—Acetic acid esters of dihydroxylic compounds
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
A process for producing substantially pure di-or triester of a glycol or a triol respectively by esterifying said glycol or triol with a monocarboxylic acid followed by distillation in which an entrainer is added to the esterification reaction mixture or to a crude di- or tri- ester product immediately prior to distillation. The entrainer being a monoester of a monohydric alcohol and the same monocarboxylic acid as is used in producing di- or tri- ester.
Description
ESTERIFICATION PROCESS
The present invention relates to a process for producing substantially pure di- and triesters by using an entrainer during the esterification reaction or during the purification of the crude ester product.
Esters are conventionally produced by reacting a hydroxy compound with a carboxyl compound with or without an esterification catalyst. The product of such a reaction is inevitably contaminated with the unreacted carboxylic acid, the unreacted alcohol, some water resulting from the reaction of the hydroxyl and carboxyl compounds to form the ester linkage and, in the case where the ester product is a diester or triester, some of the monoester.
The desired ester product is usually separated from the contaminants by distillation and generally by azeotropic distillation because such mixtures generally tend to form azeotropes. In order to avoid the formation of azeotropes and to facilitate purification, entrainers are generally used either in the esterification reaction mixture or, after an initial crude separation, added to the crude ester prior to purification thereof by azeotropic distillation.
Conventional entrainers used for such reactions include cyclohexane, benzene and toluene. However, if these entrainers are used, especially in the initial esterification reaction mixture, they have one or more of the following disadvantages: (i) longer esterification reaction times, (ii) greater loss of the reactant carboxylic acid with waters of
esterification, and (iii) risk of toxicity/environmental hazards.
It has now been found that by a suitable choice of entrainers, the above disadvantages may be substantially mitigated.
Accordingly, the present invention relates to a process for producing substantially pure di- or triesters derivable by reacting under esterification conditions a glycol or a triol respectively with a monocarboxylic acid followed by distillation whereby an entrainer is added either to the esterification reaction mixture or to the crude di- or triester products immediately prior to distillation, characterised in that the entrainer is a monoester of a monohydric alcohol and the same monocarboxylic acid as is used in producing the di- or triester.
Thus, for example, the di- or triester may be derived from a glycol or a triol containing from 2-4 carbon atoms. Specific examples of such compounds include ethylene glycol and glycerol.
Similarly, the monocarboxylic acid used to derive the di- or triester may be a C1-C4 monocarboxylic acid, e.g. formic, acetic, propionic, butyric or isobutyric acid.
The monoester entrainer used either during the esterification reaction itself and/or during the purification of the crude diester or triester product by distillation has the same monocarboxylate moiety as that present in the ester being purified. Thus, for example, a monoester of a C1-C4 monohydric alcohol and one of the
C1-C4 monocarboxylic acids used to produce the desired di- or triester can be used as the entrainer. For example, if the diester being produced and purified is ethylene glycol diformate or ethylene glycol diacetate, the entrainers that can be used are e.g. isobutyl formate and n-propyl acetate respectively.
The amount of entrainer used will depend not only upon the nature of the desired ester and the nature of the corresponding monoester entrainer but also upon the esterification and/or distillation conditions used and the nature of the impurities to be removed.
The distillation of the crude ester can be carried out at atmospheric or reduced pressure to form a substantially pure di- or triester.
The entrainers used in the present invention have the following advantages over conventional hydrocarbon entrainers: (i) shorter esterification times, (ii) lower losses of monocarboxylic acid reactant in the waters of
esterification, and (iii) lower toxicity/environmental hazards.
The present invention is further illustrated with reference to the following Examples and Comparative Tests.
Example 1 - Preparation of Ethylene Glycol Diacetate
Ethylene glycol (403g) was reacted with glacial acetic acid (936g) in the presence of n-propyl acetate as entrainer and p-toluene sulphonic acid (60%, 1.8g) as catalyst in a 2 litre, r.b.
3-neck (parallel) flask provided with a glass column (250 mm x 15 mm) packed with glass rings, a condenser-decanter, a still head, a sampling device, a variac temperature controller and a thermometer for head temperature in (270 mm deep) thermometer pocket. Initially 150g of the entrainer was added, but further aliquots of the entrainer were added during the reaction so that by the end of the reaction, which lasted 6 hours, a total of 250g of entrainer had been added. During this period the flask temperature was maintained from 110 - 140"C and the head temperature from 83 - 98"C. An additional 100g of glacial acetic acid was also added to compensate for any losses of acid with water of esterification.The esterification was considered to be complete when the ratio of ethylene glycol diacetate (EGDA) to ethylene glycol monoacetate (EGMA) in the contents of the flask reached an acceptable level, ie.
less than 2% by weight. This was achieved after 6 hours of reaction.
The initial acidity of the water of esterification was 0.15% which reached a steady state of 1.2% after 2 hours into the reaction and remained at that value at the end of the 6 hour reaction period. The esterification products were then distilled as follows: low boiling fractions were removed at a reflux ratio of 5:2 before collecting the main fraction without any direct reflux (i.e.
controller set to total distillate take off, but with natural condensation on glass column walls forming a minimal reflux).
Distillation took 5 hours and the following fractions were collected:
EXAMPLE 1 - TABLE 1
Fraction Fraction Fraction Main Fraction I II III Flask Temperature C 127 - 132 132 - 135 135 - 139 139 Head Temperature C 80 - 90 80 - 114 114 - 134 134 - 138 Pressure mm Hg 452 - 277 177 147 - 142 147 - 137 Analysis of each of the fractions produced as above by distillation gave the following compositions: :
EXAMPLE 1 (CONT.) - TABLE 2
Fraction I Fraction II Fraction III Main Fraction Weight in grams 125 100 40 895 Acidity as acetic 2.6 8.5 - acid (%w/w) Entrainer (nPA)(%w/w) 97.1 90.7 - EGMA (%w/w) - - 0.2 0.6 EGDA (%w/w) - 0.8 99.8 99.4 Analysis of residue (15g) remaining in the flask gave the following compositions::- Zw/w EGMA 1.5
EGDA 54.8
Di-EGDA 19.8
Tri-EGDA 18.8
In a Comparative Test 1 (not according to the invention) the above process was repeated using benzene instead of n-propyl acetate as entrainer. Initially, 150g of benzene was added but the reaction lasted 10 hours to achieve the same EGDA/EGMA ratio ie. less than 2%w/w of EGMA in the contents of the flask and the total amount of benzene entrainer added was 260g instead of 250g for n-propyl acetate.
In this case, the flask temperature was maintained from 97 118"C whereas the head temperature was from 70 - 80"C during the 10 hour reaction. The initial acidity of the water of esterification was 6.4%w/w which increased to 10.2Xw/w after 6 hours and to an overall value of 11Xw/w at the end of the reaction.
These results show that using the entrainers according to the present invention, the reaction proceeds more rapidly and that there is less loss of reactant acid along with water of esterification.
Example 2 - Preparation of Ethylene Glycol Diformate
This reaction was carried out by reacting ethylene glycol (1346g) with formic acid (85%, 2628g) in the presence of isobutyl formate (800g) and para-toluene sulphonic acid (60%, 14g). The reactants were charged into a 5 litre flange neck r.b. flask provided with multineck lid, glass column, (300 mm x 25 mm) packed with 6 mm glass balls, condenser-decanter tactical controller, stirrer and isomantle.
The reaction mixture was heated under reflux at atmospheric pressure with stirring. The distillate from the reaction was diverted to a Dean and Stark head to remove water of esterification. Esterification was considered to be complete after 22 hours.
During the reaction, the flask temperature was 104 - 1320C and the head temperature was 84 - 98"C. The acidity of the water of esterification was 9.8 - 10%.
The crude product from the reaction was neutralised with soda ash (20g) and then distilled to collect three fractions as shown in the following table.
EXAMPLE 2 - TABLE 3
Fraction I Fraction II Fraction III Flask Temperature ec 128 128 - 130 130 Head Temperature C 88 88 - 123 123 - 128 Pressure mm Hg 220 200 200 GC analysis of the fractions revealed the following composition (%w/w).
EXAMPLE 2 (CONT) - TABLE 4
Fraction I Fraction II Fraction III Residue Weight of fraction (g) 840 450 1900 30 Isobutyl Formate(%w/w) 90.3 0.1 0.1 EGMF (%w/w) 7.6 35.7 6.4 - EGDF (%w/w) 0.7 64.0 93.5 99.5 EGMF - Ethylene glycol monoformate
EGDF - Ethylene glycol diformate
In a Comparitive Test 2 (not according to the.invention), the above procedure was repeated, except that: (a) cyclohexane (250g) was used as entrainer, (b) ethylene glycol (1364g) was used, (c) formic acid (2500g) was used, and (d) p-toluene sulphonic acid (60%, 19.3g) was used.
These reactants were charged into a 5 litre 3 neck r.b. flask provided with an Oldershaw column, still head, condenser, stirrer, tactical controller, isomantle and a Dean and Stark condenser.
In this case, the reaction took 44 hours to be completed. The flask temperature was 83 - 90"C, the head temperature was 76 - 78"C and the acidity of water of esterification was 50 - 51%. To compensate for the excessive loss of acid in this manner, an additional 476g of formic acid had to be added during the reaction.
The crude product was neutralised as previously with soda ash and then distilled to recover four fractions as follows:
COMPARATIVE TEST 2 - TABLE 5
Fraction I Fraction II Fraction III Fraction IV Flask Temperature C 141 144 141 139 Head Temperature C 138 140 139 135 Pressure mm Hg 276 256 207 167 A residue (30g) was left behind in the flask.GC analysis of the reactions revealed these to have the following composition (%w/w):
COMPARATIVE TEST 2 (CONT) - TABLE 6
Fraction Fraction Fraction Fraction Residue I II III IV Weight of fractions (g) 530 200 800 800 30 Cyclohexane (%w/w) 99.5 92.0 - - - EGMF (%w/w) ~ 1.0 18.5 21.5 25.4 EGDF (%w/w) 0.2 5.9 80.6 78.1 74.0 Example 3 - Preparation of Ethylene Glycol Diacetate
Ethylene glycol (372g) was reacted with 15Z excess glacial acetic acid (828g) in the presence of n-propyl acetate as entrainer and Eltesol (60% p-toluene sulphonic acid, 1.9g) as catalyst in a 2 litre, r.b. parallel 3-neck flask provided with a glass column (250 mm x 15 mm) packed with glass rings, a condenser-decanter, a still head, a sampling device, a variac temperature controller and a thermometer for head temperature in (270 mm deep) thermometer pocket. Initially 250g of the entrainer n-propyl acetate was added, but a further lOg of the entrainer was added to compensate for any losses during the reaction so that by the end of the reaction, which lasted 5 hours, a total of 260g of entrainer had been added.During this period the flask temperature was maintained from 109 - 1400C and the head temperature from 82 - 98"C. The esterification was considered to be complete when the ratio of ethylene glycol diacetate (EGDA) to ethylene glycol monoacetate (EGMA) in the contents of the flask reached an acceptable level ie.
less than 3Xw/w. The reaction time was 5 hours for an esterification to EGDA of 97.4% w/w.
The esterification products were then distilled as shown in
Table 10 below:
In a comparative Test 3 (not according to the invention)
Example 3 was repeated using benzene as entrainer instead of n-propyl acetate (n-pA). The amount of entrainer (over and above the initial 250g) added during the reaction was 20g. The reaction took 9.5 hours to achieve an esterification to EGDA of 97.4% w/w.
The reaction conditions and results are tabulated below in
Tables 7 - 13.
EXAMPLE 3 WITH N-PROPYL ACETATE - TABLE 7
Time Flask Head Esterification Z Acidity Remarks Hours Temp Temp Water collected as Acetic "C C gm in water 10:15 19 Full heat on Variac @ 220V, Stirrer @ 2.5 10:45 109 82 - - Variac @ 170V 11:45 113 83 91.0 1.6 12:45 126 86 76.0 1.8 10g nPA added 13:45 135 91 37.5 1.9 14:45 139 95 14.0 3.2 15:45 139 95 8.0 3.7 COMPARATIVE TEST 3 WITH BENZENE - TABLE 8
Time Flask Head Esterification Z Acidity Remarks Hours Temp Temp Water collected as Acetic C C gm in water 10:15 19 Full heat on Variac @ 220V Stirrer @ 2.5 10:45 96 72 - - Variac @ 170V 11:45 95 71 57 10.7 12:45 98 70 49 8.45 lOg Benzene added 13:45 103 70 50 10.1 14:45 109 75 45 16.0 15:45 115 77 27 24.0 10g Benzene added 16:45 117 78 14 26.4 Shut down overnight 08.30 20 Full heat on Variac @ 220V Stirrer @ 2.5 09:00 116 73 - - Variac @ 170V 10:00 118 79 10 27.6 12:30 118 80 7 30.0 TABLE 9
Preparation Total Total Total loss of GC Analysis at the end of Esterification Esterification Esterification Acid with % wt/wt Time, hours Water Esterification Collected gm Water gm EGDA * EGMA * ACETIC ENTRAINER ACID Example 3 5 226 4.3 97.4 2.6 11.8 18.4 Comparative 9.5 260 37.5 97.4 2.6 7.1 27.0 Test 3 * REPRESENTS EGDA:EGMA ratio EXAMPLE 3 - TABLE 10
Fraction Flask Head Vacuum Reflux Time Variac Mass of Temp C Temp C mbar Ratio Taken Setting Fraction min V gm Recovery 102-109 96-120 ATM 1:1 45 of 102-109 96-120 nPA + excess acid I 109-140 120-134 600 5:1 55 210 25 II 139-140 133-134 171 5::1 25 220 20 Main 140-139 133 170-140 Total 60 220 806 Take Off Residue | - | - | - | - | - | - | 24 COMPARATIVE TEST 3 - TABLE 11
Fraction Flask Head Vacuum Reflux Time Variac Mass of Temp C Temp C mbar Ratio Taken Setting Fraction min V gm Recovery 85-139 72-100 ATM 1:1 60* 160-220 318 of Benzene + excess Acid I 139-140 100-120 151-171 5::1 50 220-210 28 II 140-145 - 171 5:1 20 220 30 Main 145-144 130 171-170 Total 50 220 782 Take Off Residue | - | - | - | - | - | - | 20 * foaming in the flask
TABLE 12
EXAMPLE 3 - ANALYSIS OF EARLY FRACTIONS
Fraction % Acidity GC Analysis Z wt/wt as Acetic nPA EGDA EGMA EDIGA DEGDA nPa + Acid 52.0 47.4 0.14 - - I 93.3 0.96 4.75 - - II 5.2 0.04 92.5 0.18 0.27 Residue Neut - 78.3 0.31 12.52 7.4 DEDGA - Diethyleneglycol diacetate
TABLE 13
COMPARATIVE TEST 3 ANALYSIS OF EARLY FRACTIONS
Fraction X Acidity GC Analysis Z wt/wt as Acetic Benzene EGDA EGMA EDIGA DEGDA Benzene + 28.4 72.4 0.12 - | - | - Acid I 16.9 0.07 80.9 1.43 0.1 II 0.15 - 98.6 0.83 0.48 Residue Neut - 76.47 0.72 12.85 | 8.88 EDIGA - Ethyldiglycol acetate
ANALYSIS OF MAIN FRACTIONS - TABLE 14
Test Product Example 3 Compatative Specification Test 3 Colour, Hazens 10 max 5 5 Z Acidity, as Acetic 0.05 max 0.012 0.015 X Water Content 0.20 max 0.02 0.02 Sp. Gravity at 20 C 1.100 - 1.110 1.104 1.104 X wt/wt GC Analysis EGMA 2.0 max 0.65 1.29 EGDA 97.0 min 97.6 96.4 DEGDA 1.0 max - X Ester content, by 98.0 min 98.4 98.6 Sap No.
IBP 188.4 IBP 189.2 Distillation Range 95% between 98% 98% 182 - 195 C EP 200.0 EP 201 % Yield - 92 89 The results in Tables 7 - 13 show the following advantages of n-propyl acetate as an entrainer over benzene: 1. The reaction (esterification) time was almost half with
n-propyl acetate, ie. 5 hours compared to 9.5 hours with
benzene, a considerable time saving. The formation of ester
with the use of n-propyl acetate was 99.3% after 4 hours.
Where as with the use of benzene was 92.4Z. It took one more
hour and 5.5 more hours respectively to completion.
2. With benzene the rapid rise in the acidity of esterification
water shows larger losses of acetic acid from the reaction
mixture, which may affect the reaction rate.
The percentage loss of acetic acid with evolved esterification
water in the Example 3 (ie with n-propyl acetate) was 0.52,
whereas in Comparative Test 3 (ie with benzene) it was 4.53, a
factor of 9 times greater in the latter case.
3. The higher losses of acetic acid with esterification water
when using benzene means high loss of neutralising and
disposing waste waters and a loss of unrecoverable raw
material.
4. The distilled product, made by using n-propyl acetate has low
monoester content and high diester content. But, there was no
odour of entrainer in either of final products.
5. The most significant advantage of using n-propyl acetate is
reduced occupational hygiene and environmental hazard. Benzene
is slightly soluble (about 1000 ppm) in water and is a
contaminant in esterification water which finally goes to
effluent after neutralisation.
On the health aspects, benzene has very low TLV value, very low
flashpoint of -ll.00C compared to the flashpoint of 14"C of
n-propylacetate. Benzene is also a skin irritant (may cause
blistering on prolonged contact).
The above results again confirm that using ester entrainers according to the present invention results in a shorter reaction time, a lower amount of the undesirable monoester formation and reduced loss of reactant acid with water of esterification.
Claims (6)
1. A process for producing substantially pure di- or tri-esters
derivable by reacting under esterification conditions a glycol
or a triol respectively with a monocarboxylic acid followed by
distillation whereby an entrainer is added to the
esterification reaction mixture or to the crude di- or
tri-ester products immediately prior to distillation,
characterised in that the entrainer is a monoester of a
monohydric alcohol and the same monocarboxylic acid as is used
in producing the di-or tri-ester.
2. A process according to claim 1 wherein the di- or tri-ester is
derived from a glycol or a triol containing 2-4 carbon atoms
3. A process according to claim 1 or 2 wherein the glycol or triol
is ethylene glycol or glycerol respectively.
4. A process according to any one of the preceeding claims wherein
the monocarboxylic acid used to derive the di- or tri-ester is
a C1-C4 monocarboxylic acid.
5. A process according to any one of the preceding claims wherein
the mono-carboxylic acid is selected from formic, acetic,
proponic and the butyric acids.
6. A process according to any one of the preceding claims wherein
the di-ester purified is ethylene glycol diformate or ethylene
glycol diacetate using respectively a formate or an acetate
ester of a monohydric alcohol as entrainer.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB878726973A GB8726973D0 (en) | 1987-11-18 | 1987-11-18 | Esterification process |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8823512D0 GB8823512D0 (en) | 1988-11-16 |
| GB2212493A true GB2212493A (en) | 1989-07-26 |
Family
ID=10627142
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB878726973A Pending GB8726973D0 (en) | 1987-11-18 | 1987-11-18 | Esterification process |
| GB8823512A Withdrawn GB2212493A (en) | 1987-11-18 | 1988-10-06 | Production of di- or tri- esters |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB878726973A Pending GB8726973D0 (en) | 1987-11-18 | 1987-11-18 | Esterification process |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8726973D0 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011001249A1 (en) * | 2009-07-01 | 2011-01-06 | Rhodia Poliamida E Especialidades Ltda | Process to obtain a mixture of lower carboxylic mono, di and triesters from raw glycerin |
| CN103880659A (en) * | 2014-04-08 | 2014-06-25 | 江苏斯威森生物医药工程研究中心有限公司 | Synthetic process of glycol diformate |
| CN107814716A (en) * | 2017-10-16 | 2018-03-20 | 上海邦高化学有限公司 | A kind of industrial method for producing ethylene glycol diformate |
-
1987
- 1987-11-18 GB GB878726973A patent/GB8726973D0/en active Pending
-
1988
- 1988-10-06 GB GB8823512A patent/GB2212493A/en not_active Withdrawn
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2011001249A1 (en) * | 2009-07-01 | 2011-01-06 | Rhodia Poliamida E Especialidades Ltda | Process to obtain a mixture of lower carboxylic mono, di and triesters from raw glycerin |
| EP2272818A1 (en) * | 2009-07-01 | 2011-01-12 | Rhodia Poliamida E Especialidades Ltda | Process to obtain a mixture of lower carboxylic mono, di and triesters from raw glycerin |
| CN102471216A (en) * | 2009-07-01 | 2012-05-23 | 罗狄亚聚酰胺特殊品有限公司 | Process to obtain a mixture of lower carboxylic mono, di and triesters from raw glycerin |
| US8754253B2 (en) | 2009-07-01 | 2014-06-17 | Rhodia Poliamida E Especialidades Ltda | Process to obtain a mixture of lower carboxylic mono, di and triesters from raw glycerin |
| CN102471216B (en) * | 2009-07-01 | 2014-11-12 | 罗狄亚聚酰胺特殊品有限公司 | Process to obtain a mixture of lower carboxylic mono, di and triesters from raw glycerin |
| CN103880659A (en) * | 2014-04-08 | 2014-06-25 | 江苏斯威森生物医药工程研究中心有限公司 | Synthetic process of glycol diformate |
| CN103880659B (en) * | 2014-04-08 | 2016-03-02 | 江苏斯威森生物医药工程研究中心有限公司 | A kind of synthesis technique about glycol diformate |
| CN107814716A (en) * | 2017-10-16 | 2018-03-20 | 上海邦高化学有限公司 | A kind of industrial method for producing ethylene glycol diformate |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8823512D0 (en) | 1988-11-16 |
| GB8726973D0 (en) | 1987-12-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |