DE1135445B - Process for the preparation of complex esters which can be used as lubricating oils or lubricating oil components - Google Patents

Description

GERMAN

PATENT OFFICE

EXPLAINING EDITORIAL 1135445

St 8392 IVb / 12 ο

REGISTRATION DAY 2 JULY 1954

NOTICE
THE REGISTRATION
AND ISSUE OF THE
EDITORIAL: AUGUST 30, 1962

It is known what are known as complex esters of the general formula

R'OOC-R "-COO-R-OOC-R" -COOR '

in which R is the hydrocarbon radical of a glycol, R 'the hydrocarbon radical of a monovalent aliphatic Alcohol and R "denotes the hydrocarbon radical of an aliphatic dicarboxylic acid, by esterification of 2Mol of a dicarboxylic acid HOOC-R "—COOH with 2Mol of an aliphatic monohydric alcohol ROH and 1 mol of a glycol HO — R — OH in one or more process stages produce, with preferably sebacic acid and / or adipic acid as dicarboxylic acids, as a monohydric alcohol, preferably a branched, saturated alcohol, e.g. B. 2-ethylhexanol, and a polyethylene glycol, for example, can be used as the glycol.

In particular, it is also known to initially use 1 mol of glycol in the preparation of such complex esters 2 moles of dicarboxylic acid to convert to a half ester and this half ester, which is at both ends of his Molecule has free carboxyl groups, then in a second process stage with the monovalent Completely esterify alcohol.

Other known ways of preparing such complex esters are that you all Reacts reaction agents at the same time in the stoichiometrically required proportions, or that one first equimolecular amounts of the monohydric alcohol ROH and the dicarboxylic acid HOOC-R "—COOH converts to the alcohol half-ester R'OOC — R" —COOH and then esterified 2 moles of this half-ester with 1 mole of the glycol HO — R — OH.

The esterification is usually under reflux at temperatures of 120 to 160 ° C and below Method of manufacture

of as lubricating oils or lubricating oil ingredients

usable complex esters

Applicant:

Esso Research and Engineering Company,
Elizabeth, NJ (V. St. A.)

Representative: E. Maemecke, Berlin-Lichterfelde West, and Dr. W. Kühl, Hamburg 36, Esplanade 36 a,
Patent attorneys

Claimed priority:
Great Britain July 2, 1953

Use of an esterification catalyst such as sulfuric acid or an alkali bisulfate is preferred Sodium bisulfate, or an aryl sulfonic acid, and also a water entrainer, such as one with water an azeotropic mixture of light carbon

Hydrogen fraction.

The preferred method of production using the glycol half-ester can be represented as follows:

, OH COOH

+ 2 R "^
OH ^X COOH

HOOC-R "-COO-R-OOC-R" -COOH

HOOC-R "-COOR-OOCR" -COOH + 2 ROH >

> R'OOC — R "—COO- R — OOC — R" —COOR '

The following substances are preferably used as starting materials: as dicarboxylic acid, adipic or sebacic acid or mixtures thereof, as monohydric alcohols, branched-chain saturated C ₈ . ₉ alcohols, e.g. B. Oxo-

209 6Ϊ8 / 422

alcohols or mixtures in which such alcohols predominate, and as glycols polyethylene glycols to to hexaethylene glycol or poryethylene glycol fractions, the average molecular weight of which is not significant is higher than that of hexaethylene glycol. The preferred formation of the glycol half ester in the first stage of the process is achieved by appropriately dimensioning the molar ratio of dicarboxylic acid guaranteed to glycol in the implementation.

reaction product to be used as a lubricating oil or a lubricating oil component as a bottom residue remains behind.

Liquid complex esters of the type described above

In addition, the esterification is known per se Way done. The mentioned total reaction time of the first process stage of the glycol esterification can be determined by a blind test 5 in which the reaction vessel is already closed Beginning with the entire amount of dicarboxylic acid and glycol is charged.

It is believed that the beneficial effect of this procedure is due to the fact that In the case of the esterification according to the known process, this results in the formation of higher molecular weight, for locking the result is a mixture of different esters, polyesters with a tendency towards thickness, for example from polyches contains higher linear polyester. This reactalkylene glycol and dicarboxylic acid are strongly suppressed tion mixture is then usually made by vacuum.

distillation of the more volatile, not re-Preferably one extends the glycol additive over the

set reactants freed, with the 15 total period of glycol esterification from (that is

usually the stage in which the glycol half-ester is formed). It is also essential that Stir the reaction mixture vigorously during the entire supply of glycol. In general it is desirable today, in view of their excellent 20 in the second stage of the esterification, an excess Lubricity and resilience primarily than add to monohydric alcohol, usually Lubricating oils or components of lubricating oils are 20%>. So if the esterification of the glycol with the turns. The viscosity-temperature behavior of the dicarboxylic acid (with the formation of the glycol half ester) The most complex is better than that of the mineral - a total of 10 hours is the length of time lubricating oils. But now it comes to the lubrication 25 of the addition of the glycol to the reaction mixture of aircraft turbines very particularly on the low according to the invention at least 2 hours.

In the process according to the invention, the preferred formation of the low by-product is in the first stage Glycol half ester in comparison with the previously known method is still favored by the fact that due to the slow addition of the glycol and the mixing of the reactants by strong Stirring is ensured that at all points of the reaction mixture a stoichiometric

The reason for this peculiar, at low 35 shear excess of carboxyl groups at the dicarbon temperatures The effect that occurs is not yet evident via the hydroxyl groups of the glycol clarified. After all, it takes place at low temperatures.

temperatures, for example at about - 40 ⁰ C, in the course of the first stage, in which the glycol of the dicarbon

the time a thickening of the complex ester or the acid is added dropwise, one must first containing mixture. This thickening is visible because the acid is solid and local reversible, d. i.e., the mixture increases when heated, and overheating must be avoided. Preferably again the same viscosity as it was before the use of a water entrainer, its had cooling. In addition, however, the boiling point rises above the melting point of the acid, the time with further cooling, the originally in such excess that the glycol has a fairly low viscosity at low temperature. 45 slurry of acid is added. The application dies is of course for the lubrication of aircraft dung from water entrainers during esterification turbines of considerable disadvantage. is known per se; however, it was found

The purpose of the invention is now to develop that the use of excess amounts of a solein Process for the production of complex water entrainers also for improvement esters that have this tendency at low temperatures to 50% of the low-temperature properties of the complex ester thick, to a considerably reduced extent. contributes.

The Process According to the Invention for Production The value of the process according to the invention goes

of complex esters from glycols, dicarboxylic acids from the following example, in which and monohydric alcohols is based on the knowledge that the two-stage production of a complex ester from a polyethylene glycol with a medium molar low temperature behavior leads to reaction products if one has a molecular weight of about 200, sebacic acid and 2-ethyl ensures that in the first stage of the above formula-based reaction, the local concentration of glycol in the reaction vessel is kept low. This is achieved by in 60
the glycol esterification stage slowly add the glycol to the reaction mixture with vigorous stirring in the course of at least Vs that for esterification of the dicarboxylic acid with the glycol to form the half-ester of the formula

HOOC-R "-COO-R-OOC-R" -COOH

normally required reaction time begins under otherwise identical conditions.

temperature behavior of the lubricating oil. In this regard, the lubricating oil is all the more valuable, one the lower the tendency to thicken at low temperatures-es having.

The complex esters described above, known per se, prepared by the processes customary up to now now have the disadvantage of becoming thick slightly after prolonged exposure to low temperatures.

hexanol in a molar ratio of 1: 2 at : 2 is described. ; St 98.9 ° C Viscosity, < at -40 ° C 60 after 10.7 at 17 hours -4O ⁰ C at -40 ° C 30 500 65 Most complex A ... 10.7 24150 Most complex in which usual way fixed posed 25 900

Preparation of the complex ester A
according to the invention

Components of the reaction mixture:

Mineral spirits,
Beginning of boiling between
100 and 120 ° C,
End of boiling between
155 and 165 ° C ... 386.41

Sebacic acid 355.6 kg = 1.76 kg per mole

Polyethylene glycol .. 160 kg = 0.88 kg per mole

Sodium bisulfate at 2.177 kg

2-ethylhexanol .... 281.2 kg = 2.19 kg per mole

First stage of the procedure

The mineral spirits, the sebacic acid and the sodium bisulfate are er ao in a reaction vessel heats. After 5 hours and 50 minutes a temperature of 124 ° C has been reached and the Addition of polyethylene glycol started. The polyethylene glycol is added at one rate of about 21.77 kg per hour and therefore takes 7 hours and 20 minutes. Then the Reactant heated to 130 ° C. for a further 14 hours. The resulting water of reaction is removed as an azeotrope with the mineral spirits throughout the esterification.

sebacic acid is used in excess in the preparation according to the above example.

Second stage of the procedure

relationship Kinematic viscosity, cSt at
-40 ° C at -40 ^; C. 5 of polyglycol too after
17 hours at
98.9 ° C at -40 ° C Sebacic acid 4916 1: 4 7890 5081 IO 1: 3 5.42 7920 In the usual way 6.43 provided mixture of complex esters 12800 and diester 62200 7.5

30th

2-Ethylhexanol is then added to the reaction product formed, and the mixture itself converted to the complex ester A in a known manner.

The total duration of the glycol esterification in the first process stage is therefore 21 hours and 20 minutes, whereby according to the invention the glycol is added over the course of 7 hours and 20 minutes will.

The conversion of the glycol in the first process stage can be carried out with an excess of sebacic acid be performed. In this way, a reaction mixture is obtained which, after the end of the first process stage contains free sebacic acid, which then in the second process stage or the other Process stages can be esterified with the monohydric alcohol. This is how you get mixtures of complex esters and diesters which contain relatively large amounts of diesters. Because this diester are relatively fluid, the products obtained in this way have lower viscosities than the normal complex esters.

The diester component can be used to obtain mixtures of the viscosity range of normal complex esters partially or completely strip off and on by vacuum and / or steam distillation this way increase the viscosity of the oil. The complex ester can also, for example, by adsorption separated from the diester e.g. B. by chromatographic adsorption on silica gel. The diester can be eluted with aromatic solvents such as benzene, with the complex ester remains on the adsorbent. The complex ester can then from the adsorbent through a stronger polar solvent such as acetone can be eluted. The table below shows the results when

Claims (2)

PATENT CLAIMS: 1. Process for suppressing the formation of higher molecular weight polyester-like by-products in the known production of lubricating oils or lubricating oil components usable complex esters of the general formula RO O C — R "—C O O — R — O O C — R" —C O O R ' or mixtures of complex esters of the above composition with diesters of the general formula R'OOC — R "—COOR ' where R is the hydrocarbon radical of a glycol, in particular a polyethylene glycol with at most 6 ethylene groups, R 'the hydrocarbon radical of a monohydric aliphatic alcohol, in particular a branched-chain alcohol with 8 to 9 carbon atoms in the molecule, and R " the hydrocarbon radical of an aliphatic dicarboxylic acid, especially sebacic acid and / or adipic acid, means by reaction of at least 2 moles of dicarboxylic acid HOOC - R "- COOH with 1 mol of glycol HO - R - OH to form a half ester of the general formula HOOC-R "-COOR-OOC-R" -COOH or to a mixture of half-ester and free dicarboxylic acid HOOC - R "- COOH and subsequent complete esterification of this half-ester or the mixture of half-ester and dicarboxylic acid with a monohydric aliphatic alcohol ROH, both process stages at temperatures of about 120 to 160 ° C in The presence of known esterification catalysts and water entrainers are carried out, characterized in that in the first process stage the glycol is slowly added to the reaction mixture with vigorous stirring in the course of at least V ₆ of the esterification of the dicarboxylic acid with the glycol to give the half-ester of the formula HOO C-R "-CO O-R-O O C-R" -CO O H normally required reaction time added under otherwise identical conditions. 2. The method according to claim 1, characterized in that in the glycol esterification 7 8 grade one to form a slurry. Documents considered: German patent application St 3675 IV b / 12 ο (surplus of a water entrainer added, made known on November 13, 1952); whose boiling point is higher than the melting point of British Patent Nos. 659 103, 662 650, Dicarboxylic acid. 5 664 992, 666 697, 668 663. © 209 634/422 8.62