DE2455327A1 - PROCESS FOR PRODUCING POLYGLYCERIN - Google Patents

Description

Our Kr. 19 557 · .. Ec / tk

The Procter & Gamble Company Cincinnati, Ohio, V.St.A.

Process for the production of polyglycerine

The invention relates to a process for the production of polyglycerol, in which glycerol is used under certain temperature and pressure conditions in the presence of a catalytic! Amount of an auxiliary system capable of accelerating the polymerization, treated. The auxiliary system contains sulfuric acid and a glycerol ester of a lower aliphatic acid. When about 25 to about 75 % of the glycerin is polymerized, the. Glycerol polymerization is terminated by inactivating the auxiliary system. This can be achieved by neutralizing the auxiliaries with an essentially stoichiometric amount of a neutralizing agent. Unreacted glycerin and cyclic diglycerin are then removed by distillation. The polyglycerine produced in this way

B09824 / 0325

Mixture contains a high percentage of linear di- and triglycerols and a low percentage of polyglycerols, which contain 1 or more glycerol units. The polyglycerol mixture can be esterified in a known manner with a fatty acid, fatty acid polyglycerol esters whose polyglycerol distribution is essentially the same as that in the polyglycerol before the esterification. These esters are particularly suitable for use as emulsifiers in the food field.

Polyglycerols and the corresponding esters of these polyglycerols and higher fatty acids are known additives for food, especially emulsifiers, and have also been used in various food applications. Example - Sometimes fatty acid polyglycerol esters were used as anti-splash ** agent used in cooking and salad oils, as can be seen from US Pat. Nos. 3,415,658 and 3,415,659. The US PS 3,528,832 describes a liquid shortening which is used as Emulsifier contains a fatty acid polyglycerol ester.

It is known that fatty acid polyglycerol esters are produced can be by polymerizing glycerol in the presence of an alkaline or acidic condensation catalyst and the polyglycerols thus obtained are esterified with fatty acids in the presence of an esterification catalyst. The catalytic polymerization of glycerol to polyglycerol is described, for example, in US Pat. No. 2,487,208. The polymerization is carried out under normal pressure at an elevated temperature, e.g. 200 to 280 ° C, wherein Alkali metal and alkaline earth metal compounds can be used as condensation catalysts. The CA-PS 834 214 describes the preparation of monoesters of

609824 / 092S

Polyglycerine and fatty acids, the alkaline condensation catalyst, which is used is not only deactivated before the esterification, but practically completely is removed from the condensate! To this end The condensation mixture is brought into contact with both anionic and cationic exchange resins. ·

US Pat. No. 2,182,397 describes a method of manufacture of ether derivatives of polyhydric alcohols including those derivatives that are esterified fatty acids groups included. The polyhydric alcohol such as glycerin is partially mixed with a carboxylic acid of 2 or more Esterified carbon atoms. The Veratherung (polymerization) is in the presence of a water-binding agent and a Esterification catalyst, such as sulfur acids and certain aromatic sulfonic acids. It is also stated that the acidic catalyst neutralizes can be.

While the previous procedures are confusing and versatile, polyglycerin mixtures have not been considered with a special distribution of highly functional emulsifier precursors through the polymerization of glycerine ■ in the presence of auxiliaries capable of controlling the polymerization. It was described that the neutralization of an alkaline carbon dioxide catalyst is insufficient, since traces of the alkaline material presumably escape neutralization and are therefore still present during the subsequent esterification. This causes the polymerization to continue favored from glycerin and lower polyglycerols to higher polyglycerols. It was observed

50 9 82 A / 09 2 5 bad

that acidic by-products are formed during the polymerization of glycerol in the presence of an alkaline catalyst will. During the condensation, these by-products react with the alkaline catalyst to form organic salts which cannot be easily deactivated or removed and which act as condensation and uresterification catalysts.

The present invention is based on the object of providing a process for the production of polyglycerols, which can be used advantageously for the production of highly functional fatty acid polyglycerine esters, the polyglycerols obtained have a high percentage of lower polyglycerols and a low percentage of polyglycerols with 7 or more glycerol units.

The invention is based in part on the fact that special polyglycerol mixtures which, after simple esterification, are highly functional Emulsifiers can be prepared by applying certain polymerization conditions applies, which are explained in more detail below. This method consists in that one glycerin under reduced Pressure in the presence of a catalytic! Amount of auxiliaries capable of glycerol polymerization favor, heated until a given proportion of glycerin has polymerized. The condensation is then ended, by inactivating the catalyst by adding a substantially stoichiometric amount of a suitable neutralizing agent. Unreacted glycerine and eyelish Diglycerin is then removed by distillation. The polyglycerin produced in this way can with a

509824/0925 BAD

Fatty acid esterified "to a fatty acid polyglycerol ester to obtain which can advantageously be used as an emulsifier in the food field.

The invention relates to a method for producing Polyglycerin, in which one (1) glycerin under certain conditions in the presence of an auxiliary system that capable of promoting polymerization, heated,; (2) the aids by adding an essentially deactivated stoichiometric amount of a suitable neutralizing agent and (3) unreacted glycerol distilled off. Each of these essential stages is explained in more detail below.

In the first stage, glycerol is heated to a temperature of about 110 to about 180 ° C., preferably about 120 to about I ² IS ⁰ C, under a pressure below about 400 mm, preferably from about 1 to about 20 mm Hg absolute . _% The condensation of the glycerol is in the presence of an auxiliary system of about 0.03 to about 3 percent by weight / preferably about 0.08 to about 0.3 percent by weight of sulfuric acid and about 0.1 to about 10 percent by weight. preferably about 0.5 to about 5 percent by weight of a glyceride of the formula:

carried out in which R. is the methyl or ethyl group and η is an integer from 1 to 3. The polymerization is carried out until about 25 to about 75 %, preferably about 35 to about 60 % of the glycerol has polymerized.

509824/0925

The condensation temperature (polymerization temperature) is in the range from about 110 to about 180 ° C. By heating the reaction mixture to a temperature below about 110 ° C., a certain degree of glycerol polymerization is often achieved; however, the reaction speed is insufficient for practical use. When the condensation is performed at a temperature above about 180 ⁰ C, polyglycerols can be formed with undesirable color and odor properties.

The condensation occurs under a pressure below about 400 mm, preferably in the range from about 1 to about 20 mm Hg absolut carried out. A glycerine polymerisation at a higher pressure would easily be too slow.

The auxiliary system contains sulfuric acid and one Glycerol ester of a lower carboxylic acid. This glycerine ester is the esterification product of glycerine with acetic acid or propionic acid. Mixed esters can also be used can be used. Particularly preferred for use in accordance with of the present invention are glycerol mono-, di- and triacetate. The glyceride can also be made in situ from its Precursors, i.e. acetic anhydride or. Propionic anhydride and glycerin.

The glycerol condensation is catalyzed by the addition of sulfuric acid and a special glycerol ester in the amounts indicated above. The minimum amounts of sulfuric acid (0.0350 and glyceride (0.1 %) are necessary so that the advantages of the process according to the invention are noticeable. The use of more than 3 % sulfuric acid can lead to, especially towards the end of the condensation,

509824/0925

that organic matter is charred and undesirable by-products are formed. The use of more than 10 % of the glyceride can result in the formation of polyglycerol esters of low molecular weight carboxylic acids as a result of transesterification. These latter compounds can adversely affect the emulsifying properties of the fatty acid polyglycerol esters.

The glycerol condensation is terminated when about 25 to about 75 percent by weight, preferably about 35 to about 60 percent by weight, of the glycerol has polymerized. The end point of the condensation is determined by reading the refractometer index (Butyro scale at 6.0 ° C) according to the method in "Official Methods of Analysis of the Association of Official Agricultural Chemists", 9; Edition, 1960, published by the Association of Official Agricultural Chemists, Washington, DC, page 359. Apparently, the initial rate of diglycerol formation in glycerol polymerization is higher than that of the formation of the longer-chain polymers. The diglycerol content reaches its maximum concentration when about 50 % of the glycerol has polymerized. From this point on, the rate at which diglycerol is formed becomes slower than the rate at which diglycerol is further polymerized. Therefore, the concentration of diglycerol then falls. A high degree of completeness of the polymerization is therefore proportional to a wide distribution of polymer types. This in turn is useful because the concentration of the lower polyglycerol can be varied to some extent by terminating the condensation at a more or less advanced degree of glycerol condensation within the claimed range.

6098Z470926 bad original

During the condensation, a gas is usually preferably nitrogen, atomization and / or mechanical stirring are used.

The terms "polyglycerine" and "polyglycerine mixture" used here are interchangeable and refer to a mixture of compounds which consists of a mixture of glycerine, diglycerine and homologous polyglycerine molecules. The terms "polymerization" and "condensation" (of glycerine) used herein are also interchangeable and refer to the reaction that results in the etherification of 2 or more molecules of glycerine to form water. The terms " ^{auxiliary, c} ; medium ⁿ > " auxiliary system "and" catalyst "are also used interchangeably and are intended to puncture the combination of sulfuric acid and the glycerol derivative for the purpose of modifying or increasing the rate of glycerol polymerization in a catalytic manner, ie without during / to undergo a major chemical change during condensation.

When the desired degree of glycerol condensation is reached, the polymerization is terminated by adding the catalyst, i.e., essentially the sulfuric acid, with an essentially stoichiometric amount of a suitable one Neutralizing agent neutralized. All known agents can be used as neutralizing agents represent suitable agents for the neutralization of sulfuric acid. Examples of suitable neutralizing agents are alkali metal and alkaline earth metal hydroxides, carbonates and bicarbonates, such as sodium hydroxide, potassium hydroxide, Lithium hydroxide, barium hydroxide, calcium hydroxide, sodium

S09824 / 0925

-Q-

carbonate, sodium bicarbonate, potassium bicarbonate, calcium oxide and the like. Other neutralizing agents can also be used. It may be desirable to cool the reaction mixture during the neutralization, especially if the amount of sulfuric acid present is more than about 1. % . This eliminates the risk of overheating due to excessive heat of neutralization, which could destroy the reaction mixture (especially with regard to color and odor).

After the catalyst has been inactivated (neutralized), the unreacted glycerol and most of the cyclic diglycerol are distilled off by (fractional) distillation. This is usually at a temperature in the range of door about 150 to about: absolutely performed 3Ö0 ° C and a pressure below about ¹ mm IOO, preferably in the range of about 1 to about 20 mm Hg. These distillation conditions represent a practical optimization for the purpose of removing the undesired glycerol without adversely affecting the overall quality, in particular the color and smell, and the emulsifying properties, e.g. of the fatty acid polyglycerol esters produced from the polyglycerol produced according to the invention.

The polyglycerol distribution of the corresponding fatty acid polyglycerol esters is critical for achieving superior emulsifying properties in food applications. Known polyglycerol esters which contain less than 25 % di- and triglycerol esters are unsatisfactory from the standpoint of creating useful emulsifying groups for shortening. .Similar are polyglycerol esters that have high proportions, for example more than 15 %

50 9824/0925

Mono- and diglycerides (mono- and diesters of glycerine) or long-chain polyglycerine esters (with more than 7 glycerine units) for the manufacture of products with superior properties for applications not suitable for the food area. The presence of mono- and diglycerides is detrimental to performance of polyglycerol esters in most food applications. While the harmful effect of the ß-directed diglycerides occurs immediately, the effect of the monoglycerides occurs more slowly and becomes apparent gradually with aging. Mono- and diglycerides can be found in polyglycerol esters as a result of impurities to be available. The completeness of the polymerization of glycerine to polyglycerine thus affects the amount of Glycerine, which is present in the polyglycerine and for the formation of mono- and diglycerides in a subsequent one Esterification is available. As already stated, glycerol leads to a complete conversion in polyglycerine for the formation of high proportions of long-chain Polyglycerols such as hexa-, hepta- and octaglycerols. However, these long chain polyglycerols yield Monoesters that are neither fat-soluble nor functional emulsifiers. In terms of the unsatisfactory Emulsifying properties of polyglycerol esters containing mono- and diglycerides have become so-called "average" Hexapolyglycerols and higher polyglycerols preferred for food applications, as they contain only small amounts of mono- and diglycerides. After the unreacted glycerine and (partially) the cyclic diglycerol has been removed, the remaining polyglycer! ..-! mixture contains a high proportion of lower polyglycerols (di- and tripolyglycerols)

509 824/0925

BATH ORIGINAL

and a low proportion of polyglycerols with 7 or more glycerine units. The polyglycerin can then be esterified with a fatty acid or a mixture of fatty acids to make emulsifiers for foods obtain. These emulsifiers are made from fatty acid epolyglycerol esters For example, baking fats can be added, which are used in cake mixes, edible cream fillings, glazes and other bakery products.

It canoe erv be ünscht ^T, the poly · above tailor glycerol mixture further to scale. The term "tailor" is intended to mean that the length of the polyglycerol chain which is used to produce the corresponding emulsifying ester can be varied for special (tailor-made) application forms. For example, the above poly-glycerol mixture can be distilled at temperatures from about 235 to about 255 ° C. and 5 mm Hg absolute in order to fractionate the linear diglycerol together with a small amount of glycerol. The latter is then removed in a separate distillation stage.

The polyglycerol mixtures produced according to the invention can be esterified or transesterified with fatty acids to produce very effective polyglycerol ester emollients. When the polyglycerin after esterification as a food emulsifier To be used, it is desirable that the polyglycerol ester be substantially odorless and also has a mild taste. For this purpose, the polyglycerol ester is preferably freed from odors. If the odor removal is only carried out with the polyglycerol ester alone or in combination with a shortening, changes in the composition can occur occur that often lead to a loss of "the

5 0.9 8 2 4/0925 BAD

Effectiveness. These changes can can be appropriately avoided by one. the Removal of odors in the presence of an excess of polyglycerin, preferably immediately after the completion of the Esterification. Getting rid of odors will preferably carried out at the same temperature as the esterification.

The following examples illustrate the invention. example 1

A stainless steel reaction vessel equipped with an atomizer ring for nitrogen and a mechanical stirrer was charged with 211.4 kg of glycerin, 5.42 kg of technical grade glycerin monoacetate and 239 g of sulfuric acid. The glycerol polymerization was carried out at 132 ° C. and 5 mm Hg absolute. The polymerization was terminated by adding 180 g of sodium hydroxide when the refractive index had reached 72 # (at 60 ° C. on the butyro scale). At this stage 5 ^, 8 % of the glycerine had polymerized. The composition of the reaction mixture and the refraction index had developed as shown in the following table:

5 0 9 8 2 4/0925 _{mQ mmmL}

Oi CD CD CO KJ

Refractive index

(Butyro scale: 60 ° C)

66.6

7O

, 1 71.0 72.7

Glycerin

linear diglycerin cyclic diglycerin linear triglycerin cyclic triglycerin linear tetraglycerine linear pentaglycerine hexaglycerine

58.9 52.4

24.4 27.7

1.7 1.7

8.8

1.2
3.2
1.2
0.6

10.4
1.2

1.6
1.0

48.2

28.7

1.8

11.0

1.4

5.6

2.1

45.2

29.1

2.5

12.0

The glycerol and- represents. Cyclic diglycerol therein were completely distilled off at temperatures of 1 ^J f9 to 20'J ⁰ C and 5 mm Hg. The distillation was monitored by checking the refractive index. When the refractive index reached 87.5, the distillation was complete. Dar; Polyglycerin produced in this way had the following composition:

Part of the composition of the

Polyglycerin in Ge

Glycerin 2.3

linear diglycerin · ■ 55.2

cyclic diglycerin. 0.5

linear triglycerol 22.1

cyclic triglycerol 1, ^ 1

linear tetraglycerin. 9 * 2

cyclic tetraglycerol 1,2

linear pentaglycerol 5.2

Hexaglycerin 1.8

Heptaglycerin 0.6

Glycerine with more than 7 glycerine units; organic and inorganic salts, by-products
of polymerisation, moisture — rest to 100—

36.3 kg of the above polyglycerol mixture were mixed with 2 * 1.9 kg of stearic acid (with a Degree of purity for food) esterified. The fatty acid polyglycerol ester obtained had excellent emulsifying properties. properties when used in cakes and liquid shortening xvurde.

509824/0925

SÄO ORIGINAL

Example 2

The polyglycerol obtained according to the procedure of Example 1 was further cut to size. 7 ^, B kg of this polyglycerol was placed in a stainless steel reaction vessel equipped with a nitrogen atomizer ring, steam and electrical heaters, mechanical stirrer, condensers, receptacles and vacuum vents. ^{The polyglycerin was gradually heated from 2 ^ 3 to 269 °} C. under a pressure of 5 mm Hg absolute, the linear diglycerin and the remaining glycerin being distilled off. The distillation was stopped when 37.6 kg was collected. In order to remove the small amount of glycerin from the distillate, the latter was again placed in the stainless steel reaction vessel and held at about 227 ° C. under a pressure of 5 mm Hg absolute for about 1 hour. The linear diglycerin that remained had the following composition:

Part of the composition of the

Polyglycerine in weight $

Glycerin traces ·.

linear diglycerol 85.1

cyclic diglycerol 0.2

linear triglycerin. 6.6

cyclic triglycerin. 2.3

linear ;? Tetraglycerin 4.5

cyclic tetraglycerol 0.1

linear pentaglycerin 0.6

Glycerine with more than 7 glycerine

units; organic and inorganic.

Ganic salts, by-products of

Polymerization, moisture. —Rest to 100—

509824/0925

15> 9 kg of this polyglycerol were, in a reaction?; - ·
A stainless steel vessel equipped with a mechanical stirrer, an electric heater and a nitrogen atomizer.
Then 10.55 kg of stearic acid (degree of purity for
Food) added, whereupon the reaction mixture
was heated to a temperature of about 238 ° C. with stirring. The esterification was carried out under a pressure of about 279 nm Hg. When the free fatty acid content fell below 2 % , the esterification product was deodorized for about 1 hour with stirring and nitrogen atomization and an absolute pressure of 6 mm Hg. The reaction product contained 0.1 % free fatty acid and was a fatty acid polyglycerol ester which was useful as an emulsifier for a wide range of food applications such as cake baking, pie dough, salad dressings and frying. 35 % of the hydroxyl groups of the polyglycerin were
implemented.

09824/0925

BATH ORIGINAL

Claims (1)

⁽ 1. A process for the preparation of polyglycerol, characterized in that (a) glycerol under a pressure of below about 400 mm Hg absolute in the presence of about 0.03 to about 3 percent by weight of sulfuric acid and from about 0.1 to about 10 weight percent of a glyceride of the formula (R ₁ COO) _n where R. is a methyl or ethyl group and η is an integer from 1 to 3, "heated to a temperature in the range from about 110 to about 180 ° C, until about 25 to about 75 % of the glycerol is polymerized, ( b) the sulfuric acid is inactivated by adding an essentially stoichiometric amount of a neutralizing agent and (c) the unreacted glycerol is removed by distillation. 2. The method according to claim 1, characterized in that the sulfuric acid in an amount of about 0.08 up to about 0.3 percent by weight and the glyceride is used in an amount of about 0.5 to about 5 percent by weight, 3. The method according to claim 2, characterized in that. the polymerization is terminated when about 35 to about 60 % of the glycerol has polymerized. - 4. The method according to claim 3, characterized in that that the glycerine under a pressure of about 1 to 5 09824/0925 2Λ55327 - 13 - about 20 mm Hg absolute to a temperature in the range heated from about 120 to about 1'ί5 ° C. 5. Process according to claim H ₃ , characterized in that an alkali metal or alkaline earth metal hydroxide, carbonate or bicarbonate is used as the neutralizing agent. 6. The method according to claim 5, characterized in that the glyceride is glycerol mono-, di- or triacetate used. 7. The method according to claim 1 to 6, characterized in that (a) glycerol under an absolute pressure of about 1 to about 20 mm Hg in the presence of about 0.08 to about 0.3 percent by weight of sulfuric acid and of about 0.5 heated to about 5 percent by weight of glycerol triacetate -dioder to a temperature in the range of about 120 to about 145 ⁰ C, are polymerized to about 35 to about 60% of glycerine, (b), the sulfuric acid by addition of a substantially stoichiometric amount a neutralizing agent is inactivated and (c) the unreacted glycerine is removed by distillation " For: The Procter ft Gamble Company Cincinnati, Ohio, V.St.A. Dr .H. J.Wolf f. Lawyer 60 9 8 24/0925