KR101810646B1 - A manufacturing method of linear polyglycerol - Google Patents

Abstract

The present invention relates to a process for producing a straight chain polyglycerol, which comprises reacting glycerol with a main catalyst and a cocatalyst to produce a linear polyglycerol, whereby the reaction can be carried out in an environmentally friendly manner without using a solvent . Also, it is possible to produce linear polyglycerols, especially diglycerol and triglycerol, with high yield and high selectivity by suppressing the side reaction using a promoter capable of controlling the high activity of the main catalyst.

Description

[0001] The present invention relates to a method for producing linear polyglycerol,

The present invention relates to a process for producing a linear polyglycerol with high yield and high selectivity, which can be carried out in an environmentally friendly manner without using a solvent.

In the 21st century, problems such as environmental pollution, global warming, depletion of fossil fuels are intensifying, and much attention has been focused on research to solve them. Biodiesel, which has been recently actively researched and produced as a substitute for fossil fuels such as petroleum, coal and natural gas, which has a limited volume, is mainly used in the transesterification reaction of triglyceride and methanol contained in vegetable oil And glycerol is produced as a by-product ( Angew . Chem . Int . Ed. 2007, 46, 4434).

As the amount of the biodiesel used increases gradually, the production amount of glycerol, which is a by-product of the biodiesel production process, also increases proportionally. As a result, the overproduction of glycerol is growing to such an extent that the amount of glycerol produced is much larger than the amount consumed, which means that the glycerol should be treated as waste. Therefore, studies on high-value-added derivatives based on the above-produced glycerol have been actively conducted.

Among the derivatives of glycerol, polyglycerol is used in various fields. Of these straight-chain polyglycerols, diglycerol (DG) and triglycerol (TG) are esterified with fatty acid and transesterified with fatty acid ester It is used as raw material and used to make alkyd resin. In addition, it is used in various fields such as a fabric softener, a wetting agent, a thickener, a defoaming agent, a dispersing agent, and a lubricant as well as a high-grade emulsifier for controlling the balance between lipophilicity and hydrophilicity in the pharmaceutical, cosmetic and food industries.

The method for producing the straight-chain polyglycerol may include a method in which glycerol is distilled and recovered from the remaining residue, a method in which glycerol is dehydrated and condensed, a method in which glycerol and epichlorohydrin are polymerized and hydrolyzed and desalted, A method of adding glycidol to glycerin using an alkali catalyst such as sodium hydroxide or amine or an acidic catalyst such as acetic acid. However, these methods have a problem in that the selectivity of the reaction is so low that a cyclic compound having a low molecular weight or a linear polyglycerol having a high molecular weight is produced and the physical properties of the product are deteriorated and the production cost is increased due to the use of an expensive raw material .

A method for producing diglycerol (DG) or triglycerol (TG) will be described in detail. European Patent Publication No. 033984 discloses a method for producing diglycerol by reacting glycerol with glycidol (or epichlorohydrin) Lt; / RTI > However, the reaction proposed in the patent has low selectivity to the product, and when epichlorohydrin is used, there is a problem that a large amount of chlorine ions contained in the product after the reaction must be removed. Further, when glycidol is used, there is an advantage that chlorine ion is not contained in the product, but there is a problem that economical efficiency is relatively low due to high price of glycidol, which is a reactant.

In order to solve such problems, U.S. Patent No. 3,637,774 discloses a method of producing glycerol into a linear glycerol polymer by using an alkali catalyst such as caustic soda. Specifically, a method is disclosed in which a glycerol polymer is prepared using an alkali catalyst in an anhydrous solvent at 100 占 폚 or higher, diluted with water, and then decolorized by adding a decolorizer at 100 占 폚 or lower. However, the above-mentioned technology has a problem that the content of the cyclic glycerol polymer in the product is high, which makes it difficult to separate and purify the linear glycerol polymer, increase the production cost, and decrease the yield of the linear glycerol polymer.

Japanese Patent Publication No. 5-001291 discloses a method in which phosphoric acid is added as a catalyst to glycerol or a glycerol polymer and an addition reaction of glycidol is carried out at a temperature of 115 to 125 ° C. In JP-A 7-216082 Discloses a method of polycondensation of glycerol while boiling the reaction mixture at a temperature of 200 to 270 DEG C in the presence of an alkali catalyst. Japanese Patent Laid-Open Publication No. 2002-030144 discloses a method of producing glycerol In addition, a method of sequentially adding a phosphoric acid-based acid catalyst and glycidol to glycerol is disclosed in International Patent Publication No. WO2004 / 048304. These techniques require expensive glycidol as in the conventional methods described above, or have a problem in that it is difficult to separate and purify the linear glycerol polymer because the content of the cyclic glycerol polymer is high.

U.S. Patent No. 6,620,904 discloses that glycerol is reacted for 15 hours at 230 ° C and 150 mmHg using 0.1 wt% of calcium hydroxide (Ca (OH) ₂ ) as a catalyst to obtain 43 wt% of glycerol balance, 33 wt% Diglycerol, 14 wt% of triglycerol, 7 wt% of tetraglycerol or higher linear polyglycerol and 2.3 wt% of cyclic polyglycerol were obtained. The above-mentioned technique can reduce the discoloration and odor of the product by lowering the reaction temperature as compared with the conventional method by promoting the reaction by removing water which is a reaction by-product through the decompression, and at the same time, the reaction time can be shortened. However, there is a problem in that byproducts such as cyclic polyglycerol are increased due to high reactivity of the catalyst remaining in the product during distillation of the product at 200 DEG C and 4 mmHg to remove glycerol as a reactant.

Therefore, unlike the conventional method, there is a demand for a method capable of producing diglycerol and triglycerol with high yield and selectivity without using an expensive raw material such as epichlorohydrin or glycidol and a strong basic catalyst .

United States Patent No. 3,637,774 Japanese Patent Publication No. 5-001291 Japanese Patent Publication No. 7-216082 Japanese Patent Laid-Open No. 2002-030144 U.S. Patent No. 6,620,904

Angew. Chem. Int. Ed. 2007, 46, 4434

An object of the present invention is to provide a process for producing a linear polyglycerol with high yield and high selectivity, which can be carried out in an environmentally friendly manner without using a solvent.

In order to accomplish the above object, the present invention provides a method for producing straight chain polyglycerol, which comprises reacting glycerol in the presence of a main catalyst which is an acetate salt containing an alkali metal cation and an acetate anion to produce linear polyglycerol .

The basicity (pK _b ) of the main catalyst may be 9 to 10.

During the reaction, a cocatalyst which is an inorganic salt including alkali metal cations and inorganic anions can be added.

The linear polyglycerol may be diglycerol, triglycerol and glycerol mixed therewith.

Alkali metal cations contained in the main catalyst and co-catalyst is lithium (Li ⁺⁾ cation, a sodium (Na ⁺⁾ cation, potassium (K ⁺⁾ cation, a rubidium (Rb ⁺⁾ cation, and cesium (Cs ⁺⁾ group consisting of a cationic ≪ / RTI >

Inorganic anions contained in the co-catalyst is a hydrogen phosphite ^{_{(HP (H) O 3 -}} ), hydrogen phosphate (HPO ₄ ^2-), hydrogen phosphate (H ₂ PO ₄ ^-), sulfites (HSO ₃ ^-) and And hydrogen sulfate (HSO ₄ ^- ).

The main catalyst may be added in an amount of 0.1 to 0.9 mole based on 1 mole of glycerol.

The cocatalyst may be added in an amount of 0.1 to 5 mol based on 1 mol of the main catalyst.

The glycerol may be subjected to an etherification reaction at 200 to 290 ° C for 1 to 6 hours under a mixed catalyst of a main catalyst or a main catalyst and a cocatalyst.

The method for producing the straight chain polyglycerol of the present invention is an environmentally friendly method without using a solvent. By using a main catalyst showing high activity and a cocatalyst for controlling the activity of the main catalyst, diglycerol and tri The yield and selectivity of glycerol can be increased. Further, polyglycerol having a tetra or higher molecular weight is poor in physical properties and is difficult to be industrially used. Therefore, it is better that the amount of polyglycerol produced is smaller, and the production amount of polyglycerol higher than tetra can be remarkably reduced by the production method of the present invention. As the by-product, tetra or higher polyglycerol production amount is remarkably reduced, the selectivity to diglycerol and triglycerol is excellent and a high yield is obtained.

Further, since the present invention does not use expensive reaction materials such as epichlorohydrin and glycidol, it is possible to lower the production cost, and it is not necessary to neutralize hydrogen chloride, which is a byproduct having strong acidity and strong corrosivity after reaction, Can be simplified, and the stability of the process can be improved.

The present invention relates to a process for producing a linear polyglycerol with high yield and high selectivity, which can be carried out in an environmentally friendly manner without using a solvent.

Examples of the straight-chain polyglycerol include diglycerol, triglycerol, and glycerol mixed therein, which can be applied to various industrial fields. The glycerol used in the reaction of the present invention is a by-product generated in the production process of biodiesel.

Hereinafter, the present invention will be described in detail.

The method for producing the straight chain polyglycerol of the present invention includes a step of reacting glycerol with a main catalyst or a mixed catalyst of a main catalyst and a cocatalyst to produce linear polyglycerol. For example, the etherification reaction of glycerol may be performed by using the main catalyst having a relatively low basicity as compared with the conventional catalyst and the promoter, which is a proton donor, to selectively produce diglycerol and triglycerol, The generation can be remarkably reduced.

The main catalyst is a weak base material having a basicity (pK _b ) of 9 to 10, specifically, an acetate salt mixed with an alkali metal cation and an acetate anion. When the strong base material (pK _b < 1) is used as the main catalyst, the yield of diglycerol and triglycerol is low, and the yield is not improved even when the co-catalyst is added.

The alkali metal cations include lithium (Li ⁺⁾ cation, a sodium (Na ⁺⁾ cation, potassium (K ⁺⁾ cation, a rubidium (Rb ⁺⁾ cation, and cesium at least one selected from the group consisting of (Cs ⁺⁾ cation . When other cations such as alkaline earth metal or transition metal other than the alkali metal cation are used as the cation, the etherification reaction to glycerol may not be performed smoothly, and a large amount of by-products such as tetraglycerol may be produced even if the reaction is performed .

When other anions such as a chloride anion, a bromide anion, an iodide anion, a nitrate anion, a chelate anion, an ethanesulfonate anion and a methanesulfonate anion are used in place of the acetate anion, the etherification reaction is not carried out at all or smoothly May not be performed.

The main catalyst is used in an amount of 0.1 to 0.9 mol, preferably 0.2 to 0.6 mol based on 1 mol of glycerol. If the content of the main catalyst is less than the lower limit, the etherification reaction may not be performed. If the content of the main catalyst is higher than the upper limit, a large amount of by-products such as tetraglycerol may be produced.

The cocatalyst is a substance used to control the reactivity of the main catalyst, and is an inorganic salt in which alkali metal cations and inorganic anions are mixed.

The alkali metal cations include lithium (Li ⁺⁾ cation, a sodium (Na ⁺⁾ cation, potassium (K ⁺⁾ cation, a rubidium (Rb ⁺⁾ cation, and cesium at least one selected from the group consisting of (Cs ⁺⁾ cation . When other cations such as an alkaline earth metal or a transition metal other than the alkali metal cation are used as the cation, the reactivity of the main catalyst can not be controlled and a large amount of by-products can be produced.

Examples of the inorganic anion include hydrogen phosphite (HP (H) O ₃ ^- ), hydrogen phosphate (HPO ₄ ^{2 -} ), dihydrogen phosphate (H ₂ PO ₄ ^- ), sulfite (HSO ₃ ^- (HSO ₄ ^- ). Other anions such as chloride anion, bromide anion, iodide anion, nitrate anion, BF ₄ ^- , PF ₆ ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , AcO ^- , TfO ^- (trifluoromethanesulfonate) When used, the product does not weaken the bond between the alkali metal cations, resulting in a much over-produced by-product compared to diglycerol and triglycerol.

The promoter is used in an amount of 0.1 to 5 mol, preferably 0.2 to 1.5 mol, per mol of the main catalyst. If the content of the cocatalyst is less than the lower limit, a large amount of by-products can be produced, and if the content exceeds the upper limit, the etherification reaction of glycerol can be prevented.

The etherification reaction carried out in the production of the linear polyglycerol according to the present invention is conducted under normal pressure at 200 to 290 ° C for 1 to 6 hours. Specifically, when the reaction temperature is 260 ° C, the reaction is carried out for 6 hours, and when the reaction temperature is 280 ° C, the reaction is carried out for 2 hours.

When the reaction temperature and the reaction time are less than the lower limit value, the etherification reaction may not be performed, and when the upper limit value is exceeded, a large amount of by-products may be produced.

The etherification reaction of the present invention can be carried out by a synthesis process commonly used in the art, for example, a batch process using a reactor equipped with a stirrer and a continuous process using a bubble column.

The method for producing the straight chain polyglycerol of the present invention is characterized in that glycerol is reacted with a main catalyst or a mixed catalyst of a main catalyst and a cocatalyst according to the following Reaction Scheme 1 to form diglycerol, ], It is reacted with glycerol under the mixed catalyst of the main catalyst or the main catalyst and the cocatalyst to form triglycerol.

[Reaction Scheme 1]

[Reaction Scheme 2]

Specifically, the method of producing straight chain polyglycerols (diglycerol and triglycerol) of the present invention is such that the hydroxyl group of the first glycerol interacts strongly with the cation of the alkali metal of the main catalyst, and the hydroxyl group of the second glycerol reacts with the cation The first glycerol combined with the glycerol is readily attacked and the etherification reaction proceeds to produce diglycerol, and water is produced as a by-product of the reaction. In addition, the reaction product, diglycerol, is strongly bound to the alkali metal and reacts with the third glycerol to form triglycerol.

During the reaction, glycerol may be continuously added to the reaction products (diglycerol and triglycerol) to promote the production of by-products having a higher molecular weight than tetraglycerol. The production of the large molecular weight by- (Diglycerol and triglycerol) and the alkali metal cations to inhibit the reaction of the reaction products (diglycerol and triglycerol) with glycerol. As a result, the selectivity between diglycerol and triglycerol is improved.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Comparative Example  1-8. Main catalyst (Sodium or potassium Hydroxide ) _ Co-catalyst  skip

Glycerol (30 g, 0.33 mol), sodium hydroxide (0.064 g, 0.0016 mol) or potassium hydroxide (0.090 g, 0.0016 mol) were placed in a 100 mL 2-neck flask and equipped with a Dean- And then reacted under reflux at atmospheric pressure.

The basicity of sodium hydroxy main catalyst (pK _b) is 0.2, and the basicity (pK _b) of the primary hydroxy group of potassium catalyst is 0.5.

Comparative Example  9-16. Main catalyst (Sodium or potassium Hydroxide ) + Cocatalyst (sodium or potassium Hydrogen sulfate )

Sodium or potassium hydrogen sulfate (0.064 g, 0.0016 mol) or potassium hydroxide (0.090 g, 0.0016 mol) was added to a 100 mL 2-neck flask and the cocatalyst sodium or potassium hydrogen sulfate After the addition, the Dean-Stark apparatus and the condenser were mounted and reacted under reflux at normal pressure.

Sodium hydrogen sulfate, the pH of the co-catalyst (pK _a) is 1.99, and the potassium hydrogen sulfate (pK _a) the pH of the co-catalyst is 2.0.

Test Example  One.

After the reaction is completed, the conversion of glycerol, yield and selectivity of the reaction product are calculated according to the following formula using liquid chromatography (HPLC).

[Equation 1]

&Quot; (2) &quot;

&Quot; (3) &quot;

&Quot; (4) &quot;

&Quot; (5) &quot;

&Quot; (6) &quot;

&Quot; (7) &quot;

Table 1 below shows conversion ratios of diglycerol (DG) and triglycerol (TG) produced according to the method of Comparative Example 1-8, yield and selectivity of reaction products.

Comparative Example
catalyst
Temperature
(° C)
Time (h)
Glycerol
Conversion Rate
DG Yield
(Selectivity)
TG yield
(Selectivity)
DG + TG
yield
(Selectivity)
Tetraglycerol
Abnormal yield
(Selectivity)
One Sodium hydroxide
220
6
12.3
7.6
(61.8)
- (-)
7.6
(61.8)
4.7
(38.2)
2 Sodium hydroxide
240
6
52.1
19.6
(37.6)
11.0
(21.1)
30.6
(58.7)
21.5
(41.3)
3 Sodium hydroxide
260
6
77.3
18.9
(24.5)
15.1
(19.5)
34.0
(44.0)
43.3
(56.0)
4 Sodium hydroxide
280
2
82.1
28.2
(34.3)
17.1
(20.8)
45.3
(55.1)
36.8
(44.9)
5 Povidic hydroxide
220
6
16.2
7.8
(48.1)
1.7
(10.5)
9.5
(58.6)
6.7
(41.4)
6 Povidic hydroxide
240
6
57.6
22.4
(38.9)
10.7
(18.6)
33.1
(57.5)
24.5
(42.5)
7 Povidic hydroxide
260
6
81.9
15.5
(18.9)
11.9
(14.5)
27.4
(33.4)
54.5
(66.6)
8 Povidic hydroxide
280
2
89.7
24.3
(27.1)
16.2
(18.1)
40.5
(45.2)
49.2
(54.8)

As shown in Table 1, according to Comparative Examples 1 to 8 using a strong base as a main catalyst, the selectivity of diglycerol and triglycerol was excellent at a low temperature, but the yield was low. At high temperatures, a high molecular weight glycerol The yield and selectivity were confirmed to be high.

Table 2 below shows conversion ratios of diglycerol (DG) and triglycerol (TG) produced according to the method of Comparative Examples 9-16, yield and selectivity of reaction products.

Comparative Example
catalyst
Catalyst moles per mole of main catalyst
Temperature (℃)
Time (h)
Glycerol
Conversion Rate
DG Yield
(Selectivity)
TG yield
(Selectivity)
DG + TG
yield
(Selectivity)
Tetraglycerol
Abnormal yield
(Selectivity)
9 Sodium hydroxide
NaHSO ₄ 0.5
260
6
62.1
19.7 (31.7)
11.2 (18.0)
30.9 (49.7)
31.2 (50.3)
10 Sodium hydroxide
NaHSO ₄
One
260
6
44.3
15.4 (34.8)
11.8 (26.6)
27.2 (61.4)
17.1 (38.6)
11 Sodium hydroxide
NaHSO ₄ 0.5
280
2
57.2
16.9 (29.5)
6.9 (12.1)
23.8 (41.6)
33.4 (58.4)
12 Sodium hydroxide
NaHSO ₄
One
280
2
39.4
19.6 (49.7)
8.0 (20.3)
27.6 (70.0)
11.8 (30.0)
13 Potassium hydroxide
KHSO ₄ 0.5
260
6
66.3
16.3 (24.6)
11.7 (17.6)
28.0 (42.2)
38.3 (57.8)
14 Potassium hydroxide
KHSO ₄
One
260
6
51.5
19.7 (38.3)
8.1 (15.7)
27.8 (54.0)
23.7 (46.0)
15 Potassium hydroxide
KHSO ₄ 0.5
280
2
64.4
20.1 (31.2)
9.1 (14.1)
29.2 (45.3)
35.2 (54.7)
16 Potassium hydroxide
KHSO ₄
One
280
2
44.8
15.2 (33.9)
8.1 (18.1)
23.3 (52.0)
21.5 (48.0)

As shown in Table 2 above, according to Comparative Examples 9 to 16, the conversion of glycerol and the yield and selectivity of high molecular weight glycerol having a tetra or higher content, which are byproducts, are decreased with the addition of the promoter but the yield and selectivity of diglycerol and triglycerol And that there was no significant effect on From these results, it can be seen that the effect of cocatalyst on the strong base catalyst is insignificant.

Example  1-11. Main catalyst (Sodium acetate) _ Co-catalyst  skip

Glycerol (30 g, 0.33 mol) and sodium acetate (0.13 g, 0.0016 mol) were placed in a 100 mL 2-neck flask and reacted with a Dean-Stark apparatus and a condenser at atmospheric pressure.

The basicity (pK _b ) of the sodium acetate main catalyst is 9.25.

Example  12-19. Main catalyst (Sodium acetate) + cocatalyst ( Sodium hydrogen sulfate )

Add gaseous hydrogen sulphate (0.1 g, 0.0016 mol) and glycerol (30 g, 0.33 mol) into a 100 mL 2-neck flask and add the dean-stark apparatus and condenser. Lt; / RTI &gt;

The sodium hydrogen sulphate promoter has an acidity (pK _a ) of 1.99.

Test Example  2.

After completion of the reaction, conversion of glycerol, yield and selectivity of reaction products are calculated according to the above equation using liquid chromatography (HPLC).

Table 3 below shows conversion ratios of diglycerol (DG) and triglycerol (TG) produced according to the method of Example 1-11, yield and selectivity of reaction products.

Example
Temperature
(° C)
time
(h)
Glycerol
Conversion Rate
DG Yield
(Selectivity)
TG yield
(Selectivity)
DG + TG
yield
(Selectivity)
Tetraglycerol
Abnormal yield
(Selectivity)
One
220
6
7.0
6.6
(94.3)
- (-)
6.6
(94.3)
0.4
(5.7)
2
240
One
11.3
9.8
(86.7)
- (-)
9.8
(86.7)
1.5
(13.3)
3
240
2
17.3
13.7
(79.2)
- (-)
13.7
(79.2)
3.1
(20.8)
4
240
4
28.2
18.0
(63.8)
3.4
(12.1)
21.4
(75.9)
6.8
(24.1)
5
240
6
49.8
21.3
(42.8)
11.8
(23.7)
33.1
(66.5)
16.7
(33.5)
6
260
One
21.6
17.2
(79.6)
2.2
(10.2)
19.4
(89.8)
2.2
(10.2)
7
260
2
41.9
27.5
(65.6)
9.9
(23.6)
37.4
(89.2)
4.5
(10.8)
8
260
4
59.3
35.5
(59.9)
14.6
(24.6)
50.1
(84.5)
9.2
(15.5)
9
260
6
72.8
28.2
(38.7)
23.2
(31.9)
51.4
(70.6)
21.4
(29.4)
10
280
One
58.8
35.0
(59.4)
16.2
(27.6)
41.2
(87.0)
7.6
(23.0)
11
280
2
77.0
31.9
(41.5)
21.7
(28.1)
53.6
(69.6)
23.4
(30.4)

As shown in Table 3, Examples 1 to 11 of the present invention show that the yield and selectivity of diglycerol and triglycerol are excellent, and the yield and selectivity of the by-product tetra or higher-molecular-weight glycerol are low. Particularly, according to the conditions of Example 6, Example 7 and Example 10, it was confirmed that the yield and selectivity of diglycerol and triglycerol were even better.

In Examples 1 to 11 of the present invention, diglycerol and triglycerol were obtained in an excellent yield and selectivity, and yield and selectivity of by-products were lower than those of Comparative Examples 1 to 8 using a strong base catalyst.

Table 4 below shows conversion ratios of diglycerol (DG) and triglycerol (TG) produced according to the method of Examples 12-19, yield and selectivity of reaction products.

Example
NaHSO ₄ (moles relative to 1 mol of the main catalyst)
Temperature
(° C)
time
(h)
Glycerol
Conversion Rate
DG Yield
(Selectivity)
TG yield
(Selectivity)
DG + TG
yield
(Selectivity)
Tetraglycerol
Abnormal yield
(Selectivity)
12
0.5
260
6
65
34.9 (53.7)
19.8 (30.5)
54.7 (84.2)
10.3 (15.8)
13
0.25
280
2
89.7
18.4 (20.5)
19.9 (22.2)
38.3 (42.7)
51.4 (57.3)
14
0.3
280
2
88.5
21.5 (24.3)
18.8 (21.2)
40.3 (45.5)
48.2 (54.5)
15
0.4
280
2
77.9
21.5 (27.6)
17.6 (22.6)
39.1 (50.2)
38.8 (49.8)
16
0.5
280
2
72.5
38.2 (52.7)
24.1 (33.2)
62.3 (85.9)
10.2 (14.1)
17
One
280
2
54.5
34.8 (63.8)
14.3 (26.2)
49.1 (90.1)
5.4 (9.9)
18
0.5
280
2.5
74.6
34.2 (45.8)
21.8 (29.2)
56.0 (75.0)
18.6 (25.0)
19
0.5
280
3
77.7
29.8 (38.4)
22.3 (28.7)
52.1 (67.1)
25.6 (32.9)

As shown in Table 4, Examples 12 to 19 of the present invention show superior yields and selectivities of diglycerol and triglycerol as compared with Examples 1 to 11 in which no promoter is used, It was confirmed that the yield and selectivity of the molecular weight glycerol were low. Particularly, it was confirmed that the yield and selectivity of diglycerol and triglycerol were more excellent according to the conditions of Example 28, Example 32, and Example 33.

Further, Examples 12 to 19 of the present invention were found to have superior yield and selectivity of diglycerol and triglycerol and lower yield and selectivity of by-products, as compared with Comparative Examples 9 to 16.

Example  20-29. Main catalyst (Potassium acetate) _ Co-catalyst  skip

Glycerol (30 g, 0.33 mol) and potassium acetate (0.16 g, 0.0016 mol) were placed in a 100 mL 2-neck flask and reacted with a Dean-Stark apparatus and condenser under reflux at normal pressure.

The basicity (pK _b ) of the potassium acetate main catalyst is 9.24.

Example  30-37. Main catalyst (Potassium acetate) + cocatalyst ( Potassium hydrogen sulfate )

To the 100 mL 2-neck flask, glycerol (30 g, 0.33 mol) and potassium acetate (0.16 g, 0.0016 mol) were added and the catalyst, potassium hydrogen sulfate, was added. The mixture was loaded with a Dean- Lt; / RTI &gt;

The potassium hydrogen sulphate promoter has an acidity (pK _a ) of 2.0.

Test Example  3.

After completion of the reaction, the conversion of glycerol, yield and selectivity of the reaction product are calculated according to the above equation using liquid chromatography (HPLC).

Table 5 below is a table showing the conversion of diglycerol (DG) and triglycerol (TG) produced according to the method of Examples 20-29, the yield and selectivity of reaction products.

Example
Temperature
(° C)
time
(h)
Glycerol
Conversion Rate
DG Yield
(Selectivity)
TG yield
(Selectivity)
DG + TG
yield
(Selectivity)
Tetraglycerol
Abnormal yield
(Selectivity)
20
240
One
14.5
13.0
(89.7)
- (-)
13.0
(89.7)
1.5
(10.3)
21
240
2
25.3
20.6
(81.4)
- (-)
20.6
(81.4)
4.7
(18.6)
22
240
4
43.1
23.3
(54.1)
6.4
(14.8)
29.7
(68.9)
13.4
(31.1)
23
240
6
66.2
23.9
(36.1)
17.2
(26.0)
41.1
(62.1)
25.1
(37.9)
24
260
One
31.0
24.0
(77.4)
4.0
(12.9)
28.0
(90.3)
3.0
(9.7)
25
260
2
45.8
32.5
(71.0)
7.4
(16.1)
39.9
(87.1)
5.9
(12.9)
26
260
4
78.0
31.2
(40.0)
21.1
(27.1)
52.3
(67.1)
25.7
(32.9)
27
260
6
82.6
27.1
(32.8)
20.7
(25.1)
47.8
(57.9)
34.8
(42.1)
28
280
One
75.0
33.6
(44.8)
22.7
(30.3)
56.3
(75.1)
18.6
(24.9)
29
280
2
88.5
21.5
(24.3)
19.2
(21.7)
40.7
(46.0)
47.8
(54.0)

As shown in Table 5, it was confirmed that the yield and selectivity of diglycerol and triglycerol were excellent and the yield and selectivity of high molecular weight glycerol higher than tetra, which is a by-product, were low according to Examples 20 to 29 of the present invention. Particularly, according to the conditions of Example 24 and Example 25, it was confirmed that the yield and selectivity of diglycerol and triglycerol were even better.

In addition, Examples 20 to 29 of the present invention were found to have superior yield and selectivity of diglycerol and triglycerol and lower yield and selectivity of by-products, as compared with Comparative Examples 1 to 8 using a strong base catalyst.

Table 6 below is a table showing the conversion of diglycerol (DG) and triglycerol (TG) produced according to the method of Examples 30-37, the yield and selectivity of reaction products.

Example
KHSO ₄ (mole per one mole of the main catalyst)
Temperature
(° C)
time
(h)
Glycerol
Conversion Rate
DG Yield
(Selectivity)
TG yield
(Selectivity)
DG + TG
yield
(Selectivity)
Tetraglycerol
Abnormal yield
(Selectivity)
30
0.5
260
6
39.6
30.4 (76.7)
8.7 (21.9)
39.1 (98.6)
0.5 (1.4)
31
0.25
280
2
90.3
20.4 (22.6)
20.9 (23.1)
41.3 (45.7)
49.0 (54.3)
32
0.3
280
2
84.7
26.1 (30.8)
21.5 (25.4)
47.6 (56.2)
37.1 (43.8)
33
0.4
280
2
76.4
33.2 (43.5)
21.4 (28.0)
54.6 (71.5)
21.8 (28.6)
34
0.5
280
2
73.2
36.2 (49.5)
26.7 (36.5)
62.9 (86.0)
10.3 (14.0)
35
One
280
2
48.2
29.4 (61.0)
11.9 (24.7)
41.3 (85.7)
6.9 (14.3)
36
0.5
280
2.5
67.5
32.6 (48.3)
20.0 (29.6)
52.6 (77.9)
14.9 (22.1)
37
0.5
280
3
82.4
29.1 (35.4)
22.5 (27.4)
41.6 (62.8)
30.7 (37.2)

As shown in Table 6 above, Examples 30 to 37 of the present invention show superior yields and selectivities of diglycerol and triglycerol as compared with Examples 20 to 29 in which no promoter is used, It was confirmed that the yield and selectivity of the molecular weight glycerol were low. Particularly, according to the conditions of Example 30, Example 34, and Example 35, it was confirmed that the yield and selectivity of diglycerol and triglycerol were even better.

In Examples 30 to 37 of the present invention, the yield and selectivity of diglycerol and triglycerol were superior to those of Comparative Examples 9 to 16, and the yield and selectivity of by-products were low.

That is, the present invention using a weak base material as the main catalyst is superior in the yield and selectivity of diglycerol and triglycerol as compared with the case where a strong base is used as the main catalyst, and the yield and selectivity of the by-product tetra or higher molecular weight glycerol are low.

Claims (9)

Reacting glycerol with a primary catalyst which is an acetate salt containing an alkali metal cation and an acetate anion and a cocatalyst which is an inorganic salt containing an alkali metal cation and an inorganic anion to produce a linear polyglycerol,
0.1 to 5 moles of the cocatalyst is used per mole of the main catalyst,
Wherein the alkali metal cations of the main catalyst and the alkali metal cations of the cocatalyst are the same metal cations. 2. The method according to claim 1, wherein the basicity (pK _b ) of the main catalyst is from 9 to 10. delete The method according to claim 1, wherein the linear polyglycerol is diglycerol, triglycerol, or glycerol mixed therewith. The method of claim 1 or claim 2, wherein the alkali metal cation is a lithium (Li ⁺⁾ cation, a sodium (Na ⁺⁾ cation, potassium (K ⁺⁾ cation, a rubidium (Rb ⁺⁾ cation, and cesium (Cs ⁺⁾ cation Wherein the polyglycerol is at least one selected from the group consisting of polyglycerol and polyglycerol. The method according to claim 1, wherein the inorganic anion contained in the cocatalyst is selected from the group consisting of hydrogen phosphite (HP (H) O ₃ ^- ), hydrogen phosphate (HPO ₄ ^2- ), dihydrogen phosphate (H ₂ PO ₄ ^- (HSO ₃ ^- ) and hydrogen sulfate (HSO ₄ ^- ). The method according to claim 1, wherein the main catalyst is added in an amount of 0.1 to 0.9 mole based on 1 mole of glycerol. delete The method according to claim 1, wherein the glycerol is subjected to an etherification reaction at 200 to 290 ° C for 1 to 6 hours.