DE1124935B - Process for the production of mixtures of mixed esters with dicarboxylic acid esters, which are used as lubricants - Google Patents

Description

GERMAN

PATENT OFFICE

E10654 IVb / 12 ο

ANNKLDETAGt 30. A P R I L 1955

NOTICE THE REGISTRATION ANDOUTPUTE EDITORIAL:

MARCH 8, 1962

The invention relates to a method for producing mixtures of mixed esters which are used as lubricants with dicarboxylic acid esters of high viscosity index and very low pour point.

According to the invention there is a reaction between a dialkyl dicarboxylate, a glycol and a dicarboxylic acid instead.

Mixed esters used as synthetic lubricating oils, which are formed by the conversion of glycols, dicarboxylic acids, Monocarboxylic acids and monoalcohols are produced are known.

The use of dialkyl dicarboxylates as lubricants for various purposes is also possible known; these diesters can in a known manner with complex esters of the type mentioned to form products which are more effective as lubricants than their individual components.

The inventive method for the preparation of mixtures of mixed esters of the general formula

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

with dicarboxylic acid esters of the general formula
R-OOC-R '-COO -R

in which R is an alkyl radical having 6 to 10 carbon atoms, R 'is an alkylene radical having 6 to 8 carbon atoms and R "represents an alkylene radical containing an oxygen atom in an ether bond, consists in that about 2 moles of a dialkyl ester of a dicarboxylic acid with about 1 mole of a glycol and about 1 mole a free dicarboxylic acid in the presence of a process for the preparation

of mixtures of mixed esters with dicarboxylic acid esters serving as lubricants

Applicant:

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

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

Patent attorneys

Claimed priority:
V. St. v. America, December 15, 1954 (No. 475 562)

esterification catalyst at a temperature of about 225 to 270 ⁰ C within about 3 to 6 hours under normal or negative pressure.

The exact course of the reaction is not entirely clear; schematically it takes place according to the following general Equation:

COOR

COOH

COOR OH COOH
R - OOC - R '--COO - R "- OOC - R' - COO - R + R - OOC - R '- COO - R + 2H ₂ O

The following alcohols are particularly suitable as components of the dicarboxylic acid esters to be converted: n-hexanol, 2-ethylbutanol, n-octanol, 2-ethylhexanol, Cetyl alcohol.

The so-called oxo alcohols, which are produced by reacting olefins with carbon monoxide, are also suitable and hydrogen are produced in the presence of a cobalt catalyst and which are usually are branched.

Examples of dicarboxylic acids which are suitable for the process according to the invention are: Adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid.

Suitable glycols are ζ. B. ethylene glycol and its homologues with up to 18 carbon atoms, such as ethylene glycol, propylene glycol, butylene glycols, pinacol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol; also diethylene glycol, triethylene glycol, polyethylene glycols of the composition
HOCH ₂ -CH ₂ O (CH ₂ CH ₂ O) ^ H

(n = 1 to 26). Polypropylene glycols of the general formula
HO ■ CH (R ¹ ) -CH (R ^a ) O- [CH (R ¹ ) -CH (R ^s ) O] _{) I} -H (R ¹ or R ² = methyl, the other radical = hydrogen; «= 1 to 20).

209 518/447

Preferred glycols to be used have the general formula

HO (C "H ₂ " O) _y H 10% sodium carbonate solution and 900 ecm isopropanol, then washed with a mixture of 900 ecm water and 700 ecm heptane and finally with a mixture of 720 ecm water and 540 ecm isopropanol. Water and solvent were ^{driven off at 170 °} C. and about 5 mm. The reaction product was then filtered and gave 1806 g of ester mixture as the end product. Composition and properties of the final product are in the first

(h and y = 1 to 6).

The reaction is carried out in the presence of an acidic or basic catalyst, such as sodium bisulfate, sulfuric acid, Toluenesulfonic acid, calcium oxide, lithium oxide, an alkali alcoholate, a carboxylic acid salt,

such as calcium sebacate, zinc stearate. The io column of the table compiled.
Catalyst can also be used during the reaction by b) For comparison purposes, a was used as a lubricant

Reaction of sodium with an alcohol or a serving mixed ester can be formed according to one of the usual acidic acids. It is made in a lot of esterification processes. For this purpose, 0.001 to 1 percent by weight, calculated on the theoretical 3-liter flask equipped with a stirrer, thermometer, physical weight of the mixed ester to be produced, a water seal and a cooler, were used with the following. If necessary, smaller amounts of substances can be added:
an antioxidant, e.g. B. Phenothiazine in
Amounts from about 0.01 to about 2.0 percent by weight,
based on the calculated weight of the complex ester to be produced. 20th

When a dicarboxylic acid ester is reacted with a glycol, the alcohol component becomes the more volatile of the diester in exchange for the less volatile Glycol set free. For example, di-2-ethylhexyl sebacate is reacted with polyethylene glycol with the development of 2-ethylhexanol.

According to the invention, the more volatile alcohol component of the diester now reacts with a dicarboxylic acid

subject to the formation of a corresponding mixture of 30 tests:
Diesters with a mixed ester that has an excellent ASTM viscosity rating at 98.9, 37.8, -17.8

Shows low temperature behavior. This simple synthesis runs particularly economically, and mixtures of any viscosity can be created by simply changing them are produced on proportions of the reactants.

example

2-ethylhexanol 6.48 mol = 843 g

Sebacic acid. 4.64 moles = 937 g

Tetraethylene glycol 1.82 mol = 364 g

Phenothiazine 9.1 g

Heptane 63 g

NaHSO ₄ as a catalyst (0.4%) 5.6 g

The mixture was implemented according to the instructions given under a). Composition and properties of the end product are listed in the second column of the table.

The ester mixtures of a) and b) were as follows

a) The following substances were in a 3-1 flask and -4O ⁰ C. In addition, the viscosity index, the ASTM flash point, fire point and pour point were determined. The lead corrosion test is carried out as follows: 500 g of test oil were placed in a beaker. A stainless steel stirrer with a weighed lead strip attached was immersed in the oil. A copper strip of comparable size was also placed in the oil. The sample was under

introduced, which heated with a stirrer, thermometer, cooler 40 bubbling air to 163 ° C. After one hour

and a catcher for water was provided

Sebacic acid di-2-ethylhexyl ester 3 mol = 1278 g

Polyethylene glycol (6% excess) 1.59 mol = 302 g

Sebacic acid 1.5 moles = 303 g

Phenothiazine (pure) (0.5% on calculated 1829 g mixture of mixed ester and diester) 9.1 g

Heptane 60 g

NaHSO ₄ as a catalyst (0.4% based on the calculated 1829 g mixture of mixed ester and diester) 7.3 g ^

The mixture was heated to 225 ° C. for 3 hours at atmospheric pressure with stirring; During this time, 58 ecm of water was collected in the template. The pressure was then reduced to 10 mm, the temperature increased to about 230-235 ° C. and the mixture was heated for a further 3 hours. During this period of time, 81 ecm (60 g) of heptane was transferred. The crude ester mixture obtained had a neutralization number of 2.0 and a hydroxyl number of 2.7; this indicates a practically complete implementation; the neutralization number is due in part to the acidity of the catalyst, which was not filtered off. The mixture was diluted with 200 ecm of heptane, the lead strip was removed with a mixture of 900 ecm, cleaned and the weight loss determined. The samples were also tested in the SAE testing machine to determine the load capacity. Every 10 seconds the load was increased by a weight of 22.7 kg until the bearings running in the test oil rubbed. The reported values indicate the total load capacity before starting the grinding.
The results are compiled in the table:

Viscosity, cSt at

98.9 ° C

37.8 ° C

-17.8 ° C

-4O ⁰ C

Viscosity index

Pour point ( ⁰ C)

Flash point ( ⁰ C)

Focus ( ⁰ C)

1 hour SOD lead corrosion (mg weight loss)

Example a)

8.11 39.13 1034 12470 156

<-59.4 260 287.8

23

Example b)

8.16 39.68 1048 12740 155

<-59.4 240.6 282.2

166

SAE-SO D stress test

(kg)

Neutralization number

Hydroxyl number

Diester content (percent by weight)

Mixed ester content
(Weight percent)

Properties of the
Distillation from the
Reaction mixture of isolated diesters:

Viscosity at
98.9 ° C

37.8 ⁰ C

Properties of the mixed ester portion of the reaction mixture:

Viscosity at
98.9 ° C

37.8 ° C

Example a)

294.9 0.19 3.6

51.7 48.3

3.36 13.00

17.86 109.5

Example b)

283.5 0.36 1.9

41.3 58.7

3.39 12.53

15.49 91.0

The two products a and b were distilled to determine any differences. The still residue of the product a produced according to the invention, d. that is, the amount of the complex ester was somewhat smaller than that of the ester product according to example b). This difference in complex ester content can be can be attributed to the fact that the diester formation in the procedure according to example a) is preferred Reaction is and that a little more diester than complex ester from the released lower boiling alcohol is formed. The starting diester of Example a) in an amount of 1278 g made 70 percent by weight of the entire initial charge, excluding the water of reaction. According to the distillation result (see table) the end product contained about 52% diester. Hence, part of the initial diester is the Represents 18% of all starting materials and differs from the diester from the released alcohol was formed, passed into the complex ester portion of the lubricant; This means that at least 25% of the simple diester has been converted to the complex ester.

ίο From the table it can be seen that according to the invention obtained ester mixture certain properties, namely a viscosity index and a pour point which make it generally useful as a lubricating oil. The lead corrosion test and the stress test gave significantly more favorable values for the ester product according to example a) than for the esterification product according to example b).

The synthetic lubricants produced according to the invention can also be combined with other known ones Mineral or synthetic lubricants are blended in order to obtain products with a better viscosity index and pour point.

The diester can be removed from the reaction product by extraction, distillation, etc., and the complex ester isolated as such and as such or in admixture with mineral and synthetic lubricating oils be used.

Special properties of the ester mixtures according to the invention can be achieved by incorporating various Lubricant additives such as oxidation inhibitors, e.g. B. phenothiazine, high pressure-resistant substances such as Tricresyl phosphate, viscosity improvers, such as polybutenes, polyacrylic or methacrylic acid esters, pour point depressants, such as polymerized fumaric and maleic acid esters, and copolymers of these esters with other polymerizable compounds, namely polyvinyl acetate, can be improved.

Claims (4)

PATENT CLAIMS: 1. A process for the preparation of mixtures of mixed esters of the lubricants which are used as lubricants general formula R_OOC - R '- COO - R "- OOC - R' - COO - R with dicarboxylic acid esters of the general formula R —OOC —R '—COO —R in which R is an alkyl radical having 6 to 10 carbon atoms, R 'is an alkylene radical having 6 to 8 carbon atoms and R "is an alkylene radical containing an oxygen atom in an ether bond, characterized in that about 2 moles of a dialkyl ester of a dicarboxylic acid are mixed with about 1 mole of a glycol and about 1 mole of a free dicarboxylic acid in the presence of an acidic or basic catalyst are reacted at a temperature of about 225 to 27O ⁰ C within about 3 to 6 hours at normal or reduced pressure. 2. The method according to claim 1, characterized in that one uses dicarboxylic acid diesters, whose alcohol components have branched chains. 3. The method according to claim 1 and 2, characterized in that di-2-ethylhexyl sebacate, Polyethylene glycol and sebacic acid are reacted with one another. 4. The method according to claim 1 to 3, characterized in that the catalyst used is sodium bisulfate or calcium oxide in an amount of 0.001 to 1 percent by weight, calculated on the theoretical weight of the mixed ester to be produced is used. © 209 518/4 «2.62