DE2400914A1 - ORTHOCIESEL ACID ESTERS, THE PROCESS FOR THEIR MANUFACTURING AND THEIR USE AS HYDRAULIC FLUID COMPONENTS - Google Patents

Description

DR. BERG DIPL.-ING. STAPF DIPL.-ING. SCHWABE DR. DR. SANDMAlR

8 MUNICH 86, POST BOX 86 02 45

Attorney File 24,695 January 9, 1974

CASTROL LIMITED Swindon, Wiltshire, England

"Orthosilicic acid esters, process for their preparation and their use as hydraulic fluid components "

The invention relates to novel, useful in ^f i hydraulic fluids compounds, in particular certain new Orthokieselsäureester (orthosilicates), a process for their preparation and their use in hydraulic fluids.

Hydraulic fluids are widely used in hydraulic systems, which are many different

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Perform functions. The combination of properties that a hydraulic fluid must possess is -von Different from case to case. The toughest requirements include those that apply to vehicle braking and braking -clutch fluids are provided. The vehicle manufacturers and other relevant bodies are very betting strict specifications for such liquids, in which very high quality standards regarding numerous properties are required.

Recently there has been an increasing tendency in vehicle construction to operate or; Actuation of aggregates, such as power steering, shock absorbers and brakes, each of which was previously equipped with its own hydraulic system to use a single hydraulic system. This has caused serious problems in the Recipe for suitable hydraulic fluids. The hydraulic fluids based on mineral oil that were previously used in power steering systems and shock absorbers have, in fact, with regard to the nitrile and chloroprene rubbers used for the seals and sleeves used in such systems have satisfactory properties, but damage the synthetic Rubbers and natural rubbers significantly, which are used in the construction of hydraulic brake and clutch systems. This leads to one being too strong Sources of the latter seals, which

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Major patching faults in the brake or clutch system can lead. Conversely, the hydraulic fluids previously used in brake and clutch systems, and usually on the Based on glycols, glycol ethers and / or glycol ether esters are built up and have worked satisfactorily in such systems, have a damaging effect on the nitrile and chloroprene rubber boots used in power steering systems and shock absorbers which can also lead to malfunctions. When operating vehicles, operational safety is important reliability, which is a desirable property in all mechanical devices represents a property which, for reasons of safety, has the meaning of an absolutely essential requirement comes to. Hence the need arose for a hydraulic fluid that would be satisfactory in a central system can be used that controls the operation or operation of a number of different units.

Among the many different types of fluids used as base materials or oils for hydraulic fluids have been proposed, certain orthosilicic acid esters are also found. These orthosilicates have been proposed for, and in some cases used, for certain types of hydraulic fluids compared to those of hydrolysis resistance

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is of little importance. Have been used by manufacturers of hydraulic fluids to be used for vehicles However, they were consistently rejected because of their completely inadequate resistance to hydrolysis for these purposes.

The invention was therefore based on the object of making new compounds available, did as the basic material or oil used for hydraulic fluids can and do not suffer from the above disadvantages of the compounds known for this purpose i.e. in particular none of the types of rubber commonly used in hydraulic systems of the most varied of types swell too much and also have good hydrolysis resistance exhibit.

It has now been found that this problem can be solved by certain new orthosilicates, the one superior Have hydrolysis resistance and due to the good balance of their for the here in Relevant properties in question, such as boiling point, hydrolysis resistance and rubber swelling properties, for use in the manufacture of hydraulic fluids for vehicle assemblies and In particular, hydraulic fluids can also be used for central hydraulic systems. These orthosilicates are characterized in that they contain at least one glycol monoether residue and at least one branched

organic group, which in some cases can be the glycol monoether residue.

The invention thus relates to orthosilicic acid esters (orthosilicates) of the general formula

R ¹ O '"OR ⁵

Si I,

R ² O

1
in which R is a propylene glycol monoalkyl ether radical with 1 to 8 carbon atoms in the alkyl terminal group or a

2 3 4 is tertiary alkyl and R, R ^ and R are the same or are different and each have an ethylene or propylene glycol monoalkyl ether radical with 1 to 8 carbon atoms in the alkyl terminal group or a tertiary alkyl radical, with the proviso that R, R and R are also propylene glycol monoalkylate radicals are, if R is a pro-

12 3 pylene glycol monoalkyl ether radical is that R, R, R ^ and R contain a total of at least 15 carbon atoms, and that

12 3-4 at least one of the radicals R, R-, R ^ and R is a glycol monoalkyl ether radical is.

The term "tertiary alkyl" denotes in the Meaning as used in the present description and the

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Claims is used, an alkyl radical having a tertiary carbon atom, i.e. a carbon atom contains, to which no hydrogen atom is bonded.

Those contained in the orthosilicates of the invention Glykolmonoalkylätherreste derive from monoalkyl ethers of mono-, di- or polyglycols, which through the general formula

ι ι

H-J-O-CH-CH-O-f-R

can be reproduced in which R and R each mean a hydrogen atom or a methyl radical, with the proviso that both R ⁷ and R are not methyl radicals, R is an alkyl radical with 1 to 8 carbon atoms) and η is a is an integer. The radicals derived from these glycol monoalkyl ethers can thus be represented by the general formula

R ⁵ R ⁶

- CH-CH-O-

-R

be reproduced.

R should preferably be 1 to 4- and especially 1- or Contains carbon atom (s). The index η is for monoglycol

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monoethers 1, diglycol monoethers 2 and polyglycol monoethers 3 or more. The boiling point of the orthosilicates of the invention is generally the higher the larger the molecule, the number of carbon atoms in the molecule being a useful parameter for it Size is. Accordingly, at least 15 carbon atoms are required for the orthosilicate to be sufficient has a high boiling point. The number of carbon atoms in the molecule depends, among other things, on the value of the index η. Preferably therefore η should be at least 2. The numerical value of the index η can be up to 20, but should be preferred be 6 at most. In general, η is particularly preferably 2 to 4-, It should be pointed out, however, that η, for example, also be 1 for some glycol monoether residues and this low value can be compensated by the fact that η is very much larger in other glycol monoalkylate residues. As Already mentioned above, the total C-atom content is a useful parameter of the molecular size, i.e., the cumulative effect of the values of the individual indices η plus the size of each of the radicals R, R, R ^ and / or R-forming alkyl radicals, the total number of carbon atoms in the molecule generally in a range of 15 to 120 and preferably 15 to 60 will be.

As already mentioned, R can optionally also be a tertiary alkyl radical, where R in this Pail is preferably 4-bis 10 and in particular. Contains 4 to 8 carbon atoms.

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2 3 As already mentioned, each of the radicals R, R or R can be a tertiary alkyl radical. In this case too, each of these alkyl radicals preferably contains 4 to 10 and especially 4 to 8 carbon atoms. At least one

the radicals R ¹ , R ² ,

and R must be a glycol monoalkyl

ether remainder of the type defined above. Before-

12 3 are preferably at least 2 of the radicals R, R, R ^y and

R Glycol monoether residues.

Accordingly, orthosilicates represent the general formula

R ⁷ O

OR

,8th

.0R

12th

Si

or

Si

R ¹⁰ O

OR '

OR

represent the two most preferred embodiments of the invention.

«7 OQ -ΛΓ)

In the general formula A, R ', R, R / and R are identical or different and each denotes a propylene glycol monoalkyl ether radical of the formula III, in which of two adjacent radicals R? and R each is a hydrogen atom and the other is a methyl radical, where-

the same or with the indices η from each other / different and you

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Total value, especially if η is a Has a value of, 2 to 4, is 8 to 16, and that the radicals R are identical or different and each represent a methyl or ethyl radical.

11 For orthosilicates of the formula B above, R is a tertiary alkyl radical with 4 to 8 G atoms, in particular

12 special a tert-butyl radical, R a glycol monoalkyl

1 · 5
ether residue of the formula III, R the same as or different

12th
that of R and also a glycol monoalkyl ether

14 - ■

remainder of the formula III "and R is a tertiary alkyl group with 4 to 8 carbon atoms, in particular a tert-butyl

11 radical, which can be the same or different from R, or a ^{glycol monoalkyl ether radical of the formula III identical to or different from R and / or R D} , where in the glycol monoalkyl ether radicals of the formula III the radicals R ⁷ and R are identical or different to one another and each denotes a hydrogen atom or one of two adjacent radicals R ⁷ and R. is a hydrogen atom and the other is a methyl radical, the indices η are the same or different and the sum

Alles

the numerical values of the indices n, if R is a branched one The alkyl radical is 4 to 8, when R, on the other hand, is a glycol monoalkyl ether radical is, is 6 to 12, and η is preferably in each case, 2 to 4, as well as the radicals R are identical or different to one another and each represent a methyl or ethyl radical.

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The orthosilicates of the invention are useful as hydraulic fluid components and can be used as a base material or base oils for this purpose. In in this case the orthosilicates make up all or substantially all of the hydraulic fluid, e.g. 70 or 99 percent by weight of each hydraulic fluid the end. When the orthosilicates. of the invention are used for this purpose, they can if desired mixed with small amounts of other known base materials or base oils.

However, the orthosilicates of the invention are particularly suitable for admixture with substantial amounts of others known base oils or base materials to modify their properties or a liquid produce which has a mixture of the properties of the individual components. In this case- can the orthosilicates may be present in a wide range of proportions, for example in amounts from 1 to 70 and especially 10 to 60 percent by weight. To this Way you can, for example, formulate hydraulic fluids for central hydraulic systems, which in high Degree in combination the good rubber swelling properties of the orthosilicates with respect to nitrile rubbers and the known synthetic base materials or base oils for brake and clutch systems with respect to the in Automotive brake and clutch systems commonly

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used synthetic rubbers and natural rubbers exhibit.

The base materials or base oils with which the orthosilicates of the invention can be mixed include the glycols, polyoxyalkylene glycols and their mono- and dialkyl esters known and widely used for this purpose. These products are commercially available, for example under the registered trademark "Ucon". Other examples of these materials are those available under the trade names "Oxitol" and "Cellosolve" . Other base materials or base oils are the boric acid esters known from British patent specification Λ 34-1 901. Further examples of known base oils that can be blended with the orthosilicates of the invention are the dicarboxylic acid esters and glycol diesters mentioned in British Patent 1 34-1901 and described in more detail in British Patent Nos. 1,083,324 and 1,24-9.

According to one embodiment, the invention relates on hydraulic fluids that are at least 70 percent • an orthosilicate according to the invention or a mixture of such orthosilicates or a mixture from one or more orthosilicate (s) according to the invention with one or more known hydraulic

contain liquid base oil (s).

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It is highly desirable that the hydraulic fluids of the invention have a kinematic viscosity of 5,000 or less, and particularly not more than 200OcSt. at -40 ⁰ C and a boiling point of at least 230 and preferably at least 260 ⁰ C.

In use, the hydraulic fluids of the invention typically contain small amounts of various additives of the types commonly used in hydraulic fluids.

Typical additives that can be used according to the invention are the lubricating additives or lubricity additives from the castor oil group or castor oils treated in various ways, for example "Firsts" castor oil,
Castor oil according to specification DTD72, blown castor oilj ie a castor oil that has been blown while being heated with air or oxygen,

special light, blown castor oil, i.e. a similarly blown castor oil, and "Hydricin 4" which is a commercially available castor oil treated with ethylene oxide and propylene oxide.

Other lubricating additives which hydraulic fluids according to the invention can be incorporated are

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i.a. Boric acid esters, e.g., tricresyl borate, and phosphorus containing esters, especially phosphates, e.g., tricresyl phosphate.

The hydraulic fluids of the invention can also contain smaller amounts of polyoxyalkylene glycols or polyoxyalkylene glycol ethers, e.g. those from Union Carbide Corporation under the registered trademark "Ucon" available, especially those of the series "LB" and "HB" included. Suitable examples of such polyoxyalkylene glycols and their ethers and esters are in British Patent 1,055,641. Other suitable lubricating additives are orthophosphates or sulfates of primary or secondary aliphatic amines with a total of 4 to 24 carbon atoms, the Alkyl citrates with an average of 3 1/2 to 13 carbon atoms in the alkyl radicals, aliphatic dicarboxylic acids and their esters. Specific examples of such additives are:

Diamylamine orthophosphate, dinonylamine orthophosphate, Diamylamine sulphate, dinonyl citrate, ..

Di (2-ethylhexyl) citrate,

from a polyoxyethylene glycol with a molecular weight polyoxyethylene sebacate derived from 200,

-azelate

or adipate,

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Polyoxyethylene / polyoxypropylene glutarate, derived from a polyoxyglycol mixture with a Average molecular weight of about 200,

Glutaric acid, azelaic acid, sebacic acid, succinic acid, diethyl sebacate, di- (2-ethylhexyl) sebacate and
Di (isooctyl) azelate.

Unsaturated aliphatic acids or their salts, e.g. oleic acid or potassium ricinoleate, can also be used.

Corrosion inhibitors which can be used for the purposes of the invention can be selected from heterocyclic nitrogen containing compounds such as benzotriazole and benzotriazole derivatives such as those in the British patent 1 061 904, or mercaptobenzothiazoles, to be selected. Many amines or amine derivatives are also suitable as corrosion inhibitors. E.g. can use hydraulic fluids as corrosion inhibitors

Di- (n-butylamine), di- (n-amylamine), cyclohexylamine,

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~ ¹⁵ ~ 24009 Η

Morpholine,

Triethanolamine -

and their soluble salts, e.g. cyclohexylamine carbonate,

Phosphites, e.g.

Triphenylphosphite and

Di (isopropyl) phosphite which is also good

Are corrosion inhibitors,

and certain inorganic salts such as sodium nitrate can be incorporated.

Other additives that make up the hydraulic fluids of the invention can be incorporated are antioxidants such as diarylamines, e.g. diphenylamine, ρ, ρ'-dioctyl-diphenylamine, phenyl-Ä-naphthylamine or Phenyl-ß-naphthylamine. Other useful antioxidants are the compounds commonly known as "hindered phenols", e.g.

2,4-dimethyl-6-t-butylphenol, 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylphenol,

1,1 -Bis- (3,5-Ä.i-t-butyl -A-- hydroxyphenyl) methane, 3,3 ', 5 »5'» - Tetra-t-butyl-A-, A- '-dihydroxy-diphenyl,

3-methyl-4,6-di-t-butylphenol and

A - methyl-2-t-butylphenol.

Still other additives that can be used are phenothiazine and its derivatives, e.g., those with

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alkyl or aryl radicals attached to the nitrogen atom or the aryl groups in the phenothiazine molecule.

Other additives that can also be used include alkylene oxide / ammonia condensation products, for example the propylene oxide / ammonia condensation product described in British patent specification 1 24-9 803, specifically as corrosion inhibitors. Complex esters, such as the products sold under the trade name “Reoplex 641” and also described in British patent specification 1,249,803, can also be used as lubricating additives. In addition, long-chain (for example C _{/ 10- y} , g-) primary amine corrosion inhibitors and polymerized quinoline resin antioxidants, as described in British Patent 1,249,803, can be used as additives. Examples of such amines or resins are the products available commercially under the name “Armeen 12D” or “Agerite resin D”.

Common additives such as those described above are normally used in small amounts, e.g. 10 and in particular 0.1 to 2 percent by weight is used.

The orthosilicates of the invention can be prepared by the methods customary for the preparation of such esters manufacture, e.g. by converting a silicon tetra-

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24009H

halides, such as SiCl ^, with four parts of a hydroxy compound, such as a glycol monoether or an alkanol, or by transesterification of a tetrahydrocarbyl silicate with corresponding amounts of a hydroxy compound. For example, to prepare an orthosilicate with four identical glycol monoether residues, silicon tetrachloride can be reacted with a glycol monoether in a molar ratio of 1: 4 or a tetraalkyl silicate with a glycol monoether in a molar ratio of 1: 4, but the reaction is preferably carried out in the presence of excess Glycol monoether, for example an excess of 10 % when using SiCl ^, or a larger excess in the case of a transesterification reaction is carried out.

For the production of an orthosilicate containing two from one glycol monoether and two from another glycol monoether contains derived residues, a step-wise process can be used, i.e. one can use SiCl. or react a tetrahydrocarbyl silicate in a molar ratio of 1: 2 with a certain glycol monoether or -esters and the reaction product then with another glycol monoether in a molar ratio from 1: 2 to implement or star. The type of Glykolmonoätherreste is thus determined by the choice of used glycol monoether and the number of each

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Remnants of a certain type determined by the molar ratio used. Examples of suitable tetrahydrocarbyl silicates are tetramethyl, tetraphenyl and tetraethyl silicate, the latter being particularly is preferred. Other suitable tetrahydrocarbyl silicates are disclosed in the British patent 1 075 236.

For the production of orthosilicates, which instead of Glycol monoether radicals containing one or more alkyl radicals can be carried out in the same manner as above are worked described, but notwithstanding this, a part of the glycol monoether used by a corresponding amount of alkanol is replaced. In this case, the alkyl radical is preferred over the glycol monoether radicals introduced, e.g. by adding SiCl ^ with an alkanol, such as t-butanol, - in the amount required to create the desired number of alkyl groups introduce, and the reaction product is then further reacted with glycol monoether. at the production of orthosilicates containing alkyl radicals by transesterification of a suitable tetraalkylsilicate, e.g. tetra- (t ^ -butyl) silicate, which contains the desired alkyl radicals contains, this can be mixed with a glycol monoether in a ratio of 1: 1, 1: 2 or 1: 3 are converted to 1, 2 or 3 Glykolmonoatherreste introduce into the molecule. Optional and preferably

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you can use a tetrahydrocarbyl silicate, such as tetraethyl silicate, transesterify with an appropriate alcohol to obtain the desired number of alkyl radicals required introduce and the compound obtained with a glycol monoether further transesterify to the remaining Replace ethyl residues with glycol monoether residues.

If the orthosilicates are produced by transesterification, this can be used as the starting material Tetrahydrocarbyl silicate and the reaction conditions should be chosen so that those released during the reaction Hydroxy compounds can be distilled off from the reaction mixture. For example, the Transesterification of tetraethylsilicate with glycol monoether, both ethanol and tetra (glycol monoether) orthosilicate. The comparatively low-boiling ethanol can be stripped off, so that the transesterification, which is an equilibrium reaction, proceed to completion can.

In the preparation of the new orthosilicates of the invention by transesterification, a catalyst is preferably used, e.g. sodium metal, which facilitates the reaction via the formation of the alkoxide of the glycol monoether, or a known transesterification catalyst such as p-toluenesulfonic acid or a tetraalkyl, e.g., tetraisopropyl titanate.

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The preparation of orthosilicates of the invention from silicon tetrahalides can be easily prepared by reacting the corresponding hydroxy compound with the tetrahalide at a temperature of -40 to 15O ⁰ C, preferably 40 to 100 ⁰ C is performed. If desired, this reaction can be carried out in the presence of an inert solvent, such as alkyl ethers, toluene, petroleum ether, etc. In addition, an acid acceptor, for example a tertiary amine, can be used to neutralize the hydrogen halide formed in the reaction.

In the preparation of orthosilicates by transesterifying a reaction temperature of, for example, 80 to 250 and preferably 120 to 200 ⁰ C and can be applied enfalls desired, an inert solvent may be used. Further details of the preparation of GlykolmonoätherorthoSilikaten can be found in "Journal of Inorganic Nuclear Chemistry", 1968, Volume 30, pages to 727.

The examples illustrate the invention.

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example 1

Manufacture of tris (triethylene glycol monomethyl ether) ib-butyl silicate

Seactants Molecular weight Deployed
lot G number
mole the Silicon tetrachloride 170 170 G • 1, 0 tert-butanol 74 74 S. 1, 0 Triethylene glycol mono-
methyl ether. 164 492 ml 3, 0 Diethyl ether 600 G Pyridine 85

The silicon tetrachloride and diethyl ether are placed in a two liter round bottom flask equipped with a stirrer, thermometer, thermocouple, nitrogen inlet, dropping funnel, condenser and water column with traps. The tertiary butanol and pyridine (the latter is used as the "acid acceptor to prevent the tertiary butanol to react with the formed during the reaction hydrogen chloride). Be filled in the dropping funnel and added gradually with an initial temperature of 20 ⁰ G in the piston The temperature is recorded by the thermocouple because the thermometer is obscured by a white precipitate which forms The addition of the tertiary butanol is completed in the course of 1 1/2 hours, the temperature being monitored as a result

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the exothermic reaction can rise to a maximum of 35 ° C at the end of the addition. The reaction mixture is then stirred for a further 30 minutes at room temperature and then filtered.

The apparatus is rebuilt as described above, whereupon the filtered reaction mixture im Piston is presented. The triethylene glycol monomethyl ether is then added to the reaction mixture through the dropping funnel The addition is initially slow, with no noticeable exothermic reaction taking place. so that the rate of addition is increased so that a temperature rise of a maximum of 5 ° C leads exothermic reaction takes place. During the addition, a vigorous stream of nitrogen is bubbled through the reaction mixture to remove hydrogen chloride.

The crude product is then heated 9 1/2 hours at 70 C as a whole, to a completion of the reaction ensure, followed by stripping it down to 17O ⁰ C at 0.05 Torr. This gives 14-0 g (23.7 percent by weight, based on the silicon tetrachloride) of a clear, brown liquid which contains 4.95 percent by weight of silicon (4.75 percent theory) and 0.17 percent by weight of residual chlorine (0 percent theory) .

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Example 2

Production of tris (triethylene glycol monomethyl ether) t-butyl silicate

Reactants' Molecular weight Used
lot Count the
mole Silicon tetrachloride 170 170 g 1.0 tert-butanol 74 74 g 1.0 Triethylene glycol mono-
methyl ether 164 542 g 3.3 Pyridine 79 g 347 g 4.4 toluene 1800 ml

The silicon tetrachloride and 250 ml of toluene are placed in a two liter round bottom flask equipped with a dropping funnel, stirrer, condenser, nitrogen inlet and thermocouple. The flask is placed on an ice bath and 87 grams of pyridine is added over 40 minutes. The temperature of the contents of the flask is kept at 15 ^ ⁰ C. Then the flask is removed from the ice bath and the contents stirred I5 minutes using its temperature to the ambient temperature is allowed to rise (about 20 ⁰ C). The tertiary butanol dissolved in 50 ml of toluene is then added to the flask in the course of 1/2 hour, the temperature being kept in a range from 20 to 25 ^° C. The contents of the flask are then heated ^{to 80 ° C. for 1 1/2 hours.}

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The contents of the flask are then transferred to a larger (three-liter) flask equipped in the same way as the original reaction vessel, and a further 500 ml of toluene are added. The remainder of the pyridine (260 g) is then added over the course of 11/2 hours, the temperature being maintained in the range from 20 to 25 ° C. Then the triethylene glycol monomethyl ether is gradually added to the reaction mixture. One third of the glycol ether is added in the course of 3/4 hour, the temperature being kept in a range from 20 to 35.degree. At this point in time the contents of the flask have thickened too much for further reaction, so that the addition is interrupted and a further 600 ml of toluene are added to the contents of the flask. Then one continues the addition of the glycol ether, wherein the temperature is maintained of the glycol ether in a range from 30 to 40 G ⁰ during the addition of the remainder. The addition is complete in a total of 2 1/2 hours, the remainder of the toluene (400 ml) being added after 3/4 of the glycol ether has been added. The reaction mixture is then stirred for 2 1/2 hours at 90 to 100 ⁰ C and then for a further 7 hours at 8O ⁰ C. Finally, the crude product is filtered, using a diatomaceous earth as a filter aid, stripped on a rotary evaporator and finally stripped up to a temperature of 170 ^° C. at a pressure of 0.4 to 0.5 Torr. This gives 236 g (40 percent by weight, based on silicon tetra-

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chloride) a deep yellow liquid that is 4.86 percent by weight Silicon (theory 4.75 percent) and 0.05 percent by weight residual chlorine (theory 0 percent) contains.

Example 3

Tris (tripropylene glycol monomethyl ether) neopentyl silicate

Reactants

Silicon tetrachloride. 17 ^ - g

Tripropylene glycol monomethyl ether (product available commercially under the name "DOWANOL TPM") 679 g

Neopentyl alcohol x 88 g

Pyridine 340 g

Toluene 2.5 liters

The toluene and silicon tetrachloride are mixed with one another in a 5 liter flask, whereupon the mixture is admixed with a mixture of the neopentyl alcohol and 79 g of pyridine while cooling. the reaction temperature rising to a maximum of 42 ° C. as a result of the exothermic reaction that takes place. The reaction mixture ^{is then heated to 100 °} C. for 4 hours and then left to cool overnight. The tripropylene glycol monomethyl ether and the remainder of the pyridine are then added over the course of half an hour, with

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the exothermic reaction that takes place is controlled by cooling with a water bath. ^{The reaction mixture is then heated to 112 to 114 °} C. for 5 hours and 20 minutes and then cooled. Then the precipitated pyridine hydrochloride is filtered off. The solvent is then stripped on a rotary evaporator and the product is finally stripped under high vacuum (200 ° C / 0.1 torr) to give 484.4 g (66.3 percent) of the final product.

Analysis: 3.74 % Si (3.84 # theory); Residual chlorine content: 0.15 #

Example 4

Tetra- (tripropylene glycol monomethyl ether

silicate

Reactants

SiGl ^ 170 g

Tripropylene glycol monomethyl

ether (as in Example 3) 906 g

Pyridine 348 g

Toluene ■ 2.5 liters + 250 ml + 250 ml

A mixture of the pyridine and the tripropylene glycol monomethyl ether is added in the course of one hour to the silicon tetrachloride dissolved in 2.5 liters of toluene, the temperature being kept below 50 C by means of a water bath. During the addition, the reaction mixture becomes increasingly viscous, which is why two subsets of

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250 ml of toluene are added in each case to facilitate stirring. The reaction mixture is then heated for 4 hours at 10O ⁰ C, cooled to this, and then filtered. Finally, the solvent is stripped off at 105 ° C./20 torr. The resulting product is then stripped under high vacuum (200 ° C./0.1 torr) to give 676.4 g (79.8 percent) of a pale yellow end product.
Analysis: 3.4 % Si (theory 3.3 #); Residual chlorine content: 0.11 %.

Example for 5

Tris- (triethylene glycol monomethyl ether) -t-'butyl-

silicate

Reactants 170 S. SiCl ^ ■ 74 S. t-butanol 542 S. Triethylene glycol monomethyl ether 347 G Pyridine

Toluene 2.5 liters + 250 ml

A mixture of the SiCl ^ and 2.5 liters of toluene is treated with a mixture of the t-butanol and 87 g of pyridine, the temperature being kept below 5O ⁰ C. The reaction mixture is heated, cooled, then 4 hours at 100 ⁰ C and then treated with a mixture of the triethylene glycol monomethyl ether and the remainder of pyridine, keeping the temperature again below 50 ⁰ C.

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is held. To facilitate stirring, more toluene (250 ml) is added and the reaction mixture is then heated to 100 ° C. for a total of 4 hours. The reaction mixture is then cooled, filtered and the toluene (100 ° C./20 Torr) is stripped off . The resulting product is then stripped under high vacuum (210 ⁰ C / 0.5 Torr) to give 34-6 g (70.4 percent ·) is the final product.

Analysis: 4-.92 # Si (theory 5.68 #); Residual chlorine content: 0.04 %.

Be ispiel 6

Bis (dipropylene glycol monomethyl ether) bis (t-butyl) silicate.

Reactants

170 g-

Dipropylene glycol monomethyl ether

(in trade under the name

"DOWAKOL DPM" available product) 326 g

t-butanol 14-8 g

Pyridine 34-8 g

Toluene _m ' 2.5 liters

A mixture
/ from the SiCl ^ and toluene is t-butanol, and 174- g of pyridine over the course of 2 hours, treated with a mixture of the, wherein the heat development is regulated so that the temperature of the reactants does not exceed ⁰ C Λ1. The reaction mixture is then heated to 100 ° C. for 4 hours.

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240Q91A

heated, whereupon it is allowed to cool and then mixed with a mixture of the dipropylene glycol monomethyl ether and the rest of the pyridine. The thus obtained mixture is heated for 4 hours at 100 ⁰ C, cooled and filtered, followed by stripping off the toluene, the reaction product mixture eineut filtered and finally stripping under high vacuum (180 ° C / 0.01 Torr) to give 248.2 g (53 percent) of the end product as a clear, yellow liquid.

Analysis: 6.02 % Si. (Theory 5.98 #); Residual chlorine content:. ·. 0.36 #.

Example 7

Bis (t-butyl) - (dipropylene glycol monomethyl ether) - (triethylene glycol monomethyl ether) silicate

Reactants 170 ε SiCl ₄ 148 G t-butanol 148 S. Dipropylene glycol monomethyl ether
("DOWANOL DPM") 197 S. Triethylene glycol monomethyl ether 2.5 liter toluene 332 G Pyridine

_{A mixture of toluene and SiCl 4 placed} in a 5 liter flask is mixed with a mixture of t-butanol and 158 g of pyridine,

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wherein the temperature is maintained by cooling with a water bath at 5O ⁰ C. The reaction mixture is then heated to 80 ° to 10 ° C. for 4 hours, whereupon it is allowed to cool and a mixture of dipropylene glycol monomethyl ether and 79 g of pyridine is added. A very weak exothermic reaction takes place. The reaction mixture is then ^{heated to 80 °} C. for 4 hours, whereupon it is allowed to cool and a mixture of the triethylene glycol monomethyl ether and the remainder of the pyridine (95 g) is added, cooling with a water bath.

Then the reaction mixture is heated for 6 hours at 100 to 104 ⁰ C, then allowed to cool, it was filtered, the toluene clips and eventually strips off the reaction mixture under high vacuum (18O ° C / O, O5 Torr). The resulting product is filtered to give 413.1 g (86 percent) of a clear, yellow liquid.

Analysis: 5.85 # Si (theory $ 5.78); Residual chlorine content: 0,

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24009U

Example 8

Tris (dipropylene glycol monomethyl ether) t-butyl silicate

Reactants

SiCl ^ 170g

t-butanol; 74 g

Dipropylene glycol monomethyl ether

("DOWANOL DPM") 488 g

Pyridine. 348 g

Toluene 1 liter + 200 ml + 200 ml +

200 ml + 400 ml + 1 liter

A premix of SiGl ₁ and 1 liter of toluene is mixed with a mixture of t-butanol and 80 g of pyridine. During the addition, taking place in this exothermic reaction is controlled by cooling Tilt a water bath. The reactants are then ^{heated to 80 °} C. for 3 hours. Then a mixture of the remainder of the pyridine and the dipropylene glycol monomethyl ether is added to the reaction mixture. During the addition, the reaction mixture becomes viscous and difficult to stir, so that further aliquots of toluene (5 × 200 ml and then 1 × 400 ml) are added as required. The heat development during the addition is regulated by cooling with a water bath. When the addition is complete, the reaction mixture is transferred to a 5 liter flask, with a further liter of toluene being added, and

-32- 409829/1074

then heated ^{to 80 °} C. for 12 hours. The product obtained in this way is filtered, then the solvent is stripped off and the product is then stripped off under high vacuum (200 ° C / 0.1 Torr). Finally, the product is again filtered to obtain 399 g _(73? 6 percent) is a clear, yellow liquid.

Analysis: $ 5.48 Si (theory $ 5.17); Residual Chlorine: $ 0.15,

Example 9

Bis- (triethylene glycol monomethyl ether) -bis- (t-butyl) -siÜkat

Reactants

170 g

t-butanol 148 g

Triethylene glycol monomethyl ether 361 g pyridine 348 g

Toluene. 2.5 liters + 250 ml

A premix of the SiCl ^ and 2.5 liters of toluene is mixed with a mixture of the t-butanol and 174 g of pyridine, the temperature being kept below 50 G during the addition. Then heating the reaction mixture 4 hours at 100 ⁰ C, cools it from hierauf- and then treated it with a mixture of the triethylene glycol monomethyl ether and the rest of the pyridine ·. A weakly exothermic reaction takes place, whereby the temperature

-33-409829 / 1074

24009H

temperature is kept below 5O ⁰ C. The reaction mixture is then heated ^{to 100 ° C. for 4 hours.} During this time, another 250 ml of toluene is added to facilitate stirring. The crude product obtained in this way is cooled and filtered, whereupon toluene is stripped off and the product is then stripped off under high vacuum, the end product being a clear, light yellow liquid in a volume of 323.1 g (64.6 percent).

Analysis: $ 5.7 Si ($ 5.6 theory); Residual chlorine content: 0.05 #.

Example 10

Bis (tripropylene glycol monomethyl ether) bis (t-butyl) silicate

Reactants

170 S. 148 S. 453 S. 348 G 2.5 liter

t-butanol tripropylene glycol monomethyl ether ("DOWANOL TPM") Pyridine toluene

A mixture of the SiCl. and the toluene is cooled with. a water bath in the course of 2 hours with a mixture of the t-butanol and 1-74 S pyridine, the temperature of the reaction mixture due to a moderately strong heat development to maxi-

-34- 409829/1074

2A009H

times 38 ° C rises. The reaction mixture is then ^{heated to 100 °} C. for 4 hours, then cooled and then a mixture of the tripropylene glycol monomethyl ether and the remaining pyridine is added over the course of 2 hours, a slight evolution of heat taking place, which increases the temperature of the reaction mixture to a maximum of 30 ^° C. leaves. Then the reaction mixture is heated for 4 hours to 100 ⁰ G, cooled and filtered, and the solvent stripped off and the product is finally stripped off under high vacuum (180 ° C / 0.1 Torr). This gives 367.2 g (63 percent) of the end product.

Analysis: 4.96 # Si (4.8 # theory); Residual chlorine content: not

certainly.

Example 11

Tris (tripropylene glycol monomethyl ether) t-butyl silicate

Reactants

₄ x 119 g

t-butanol 51.8 g

Tripropylene glycol ^{monomethyl ether (11} DOWANOL TPM ") 474 g

Pyridine 237 g

Toluene 250 ml + 300 ml + 600 ml + 200 ml

-35-409829 / 1074

A mixture of the SiCl. and 250 ml of toluene are mixed with a mixture of the t-butanol and 80 g of pyridine. The exothermic reaction which takes place increases the temperature to 30 ° C. In order to keep it flowing, a further 300 ml of toluene are added to the reaction mixture, whereupon it is heated to boiling under reflux for 2 hours. The reaction mixture is then cooled and the tripropylene glycol monomethyl ether and the remaining pyridine are added over the course of one hour, a slight evolution of heat being observed. A further 600 ml of toluene are also added. The reaction mixture is transferred by means of further 200 ml of toluene in a larger flask and then heated for 10 hours at 90 ⁰ C »Sann the crude product by filtration, stripping off the solvent on a rotary evaporator and finally stripping under high vacuum (180 ° C / 0, 1 Torr), 380 g (75 * 9 percent) of a pale yellow liquid being obtained as a by-product. ■ Analysis: $ 3.86 Si (theory 3.91 #); Residual chlorine content: 0,? 6 #.

Example 12 Tetra (dipropylene glycol monomethyl ether) silicate

Reactants

SiCl ₄ 170 g

Dipropylene glycol monomethyl ether

(• "DQWÄNOL DPM") 650 g.

Pyridine 348 g

Toluene '. 2.5 liters, g_

409829 / 107A

A premix of SiCl. and toluene is added to a mixture of the dipropylene glycol monomethyl ether, and pyridine, of which an exothermic reaction takes place by which the temperature rises to a maximum of 38 ⁰ C. The reaction mixture is then ^{heated to 10O 0} C for 3 1/2 hours, then cooled on a water bath and then filtered to remove pyridine hydrochloride, whereupon the solvent is stripped off on a rotary evaporator at 100 ° C / 20 Torr. The crude product is then under high Stripped vacuum (180 ° C / 0.1 Torr) and then filtered twice, giving 152 g (29.5 percent) of a clear, gold-colored liquid.

Analysis: $ 5.0 Si ($ 5.4-3 theory); Residual chlorine content: $ 0.05.

The infrared spectra of the products of Examples 1 to 12 above confirmed in springs EaIl that the expected product was obtained.

The utility of the orthosilicates according to the invention for use in hydraulic fluids has been confirmed by Measuring the reflux point, resistance to hydrolysis and rubber swelling of various esters proven.

The reflux point was as specified in the specification

-37-409829 / 1074

SAE J17O3c specified manner.

The rubber swell was determined in each case as follows:

In a 62.206 g bottle (2 ounce bottle) with a layer of glass beads on the bottom, a square rubber sheet with dimensions of about 2.54 × 2.54- × 0.254 cm was placed in each case. Then, the bottle was filled with the test liquid and placed in an oven at a constant temperature for 3 days, after which the rubber sheet was taken out, washed with ethanol and dried. The volume of the rubber sheet was measured exactly before and after the test by the generally known displacement method and the change in volume in percent was then calculated from the measured values. Styrene-butadiene plates were tested at 120 ⁰ C, natural rubber plates are temperature-sensitive, at 7O ⁰ G, that is, at the customary to carry out this test temperatures.

In addition, nitrile and chloroprene rubber sheets were also used, each of which was tested ^{at a temperature of 70 ° G.} It should be noted that, since nitrile and chloropreric rubbers have not previously come into contact with brake fluids and these rubbers have therefore not been tested in this way, there is no recognized or common practice in this regard.

-38- 409829/1074

24009H

The resistance to hydrolysis was determined by adding 1 g of water, 1 g of the OrthoSilicate to be tested and 9 g of a commercial glycol ether hydraulic fluid base material (Base oil) and boiling stones are placed in a boiler tube and heated to boiling over a Bunsen burner became. Then the boiler tube and its contents were allowed to cool down. The mixture to be tested became during the boiling and subsequent cooling for visually recognizable signs of non-resistance to hydrolysis, such as gelling of the mixture or formation of a precipitate or sediment is observed. According to the result of the visual The orthosilicate ester was then assessed according to the following rating scale with regard to its resistance to hydrolysis rated:

0 = test mixture gelled 3 = little sedimentation

1 = Heavy sedimentation 4- = Very weak sediment

education

2 = sedimentation 5 = clear

As the glycol ether base oil was a (presumably sodium nitrite, Agerite Resin D, and benzotriazole) partially inhibited ethylene / Fropylenglykoläthergemisch fluid used in these tests with additives having a boiling point of 288 ⁰ C. This base oil was selected after preliminary tests in which the orthosilicate with

a) water and

b) Water and glycol ether base oil without additives

was heated to boiling.

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409829/1074

24009H

These preliminary tests turned out to be not sharp enough to reduce the hydrolysis resistance of the tested To determine orthosilicate. It has been found that the presence of the additives stimulates the formation of precipitates increased.

The results of the determination of the boiling point, hydrolysis resistance tests and rubber swell tests on styrene-butadiene rubber and natural rubber are in Table I below, the results of rubber swelling tests on nitrile rubber and chloroprene rubber reproduced in Tables II and III below.

From the test results given in the tables it can be seen that the tested orthosilicates have satisfactory boiling points and superior hydrolysis resistance. They were also low Rubber swell values determined for nitrile and chloroprene rubber. The rubber swelling values at Styrene-butadiene and natural rubber were high, but they are of no great importance the low rubber swelling values of chloroprene and nitrile rubber are far more important when hydraulic fluids are used are to be produced which are compatible with all of the rubbers mentioned. If the Orthosilicates of the invention with known vehicle hydraulic fluid base oils, those relating to

409829/1074

' ^: 24009Η

Chloroprene and nitrile rubbers very poor compared to • Styrene-butadiene and natural rubber, on the other hand have good properties, are mixed, so the mixture exhibits in comparison with the values of the pure Orthosilicate with regard to styrene-butadiene rubbers and natural rubbers lower, compared to nitrile and chloroprene rubbers, on the other hand, have higher rubber swelling values.

The silicates A to C mentioned in Tables I to III below are not Teaching of the invention, but produced in the manner described in Examples 1 to 12 Glycol monoether orthosilicates tested for comparison. The silicate A was tris (triethylene glycol monomethyl ether ) i-butyl silicate with an analytically determined silicon content of 5 »0 percent by weight (Theory 4.74 percent). The silicate B was tetra (triethylene glycol monomethyl ether) silicate with a silicon content of 3.77 percent by weight (theory 4.1 percent). The silicate C was bis (tripropylene glycol monomethyl ether) bis (triethylene glycol monomethyl ether) silicate with a silicon content of 4.17 percent by weight (theory 3.78 percent).

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409829/1074

Table I.

(O

Tested orthosilicate Boiling 4th
Hydrolysis-
resistant-
ability assessment
tion 3-day rubber swelling
test {.% swelling) nature
rubber Tris- (triethylene glycol monomethyl-
ether) -t-butyl silicate 290 3 Styrene
Butadiene
rubber 3.9 3} ris- (tripropylene glycol monomethyl-
ether) neopentyl silicate * 3 . 0.5 23.7 Tetra- (tripropylene glycol monomethyl-
ether) silicate * 3 34.2 12.5 Bis- (dipropylene glycol monomethyl-
ether) -bis- (t-bu; byl) -silicate * 4th 23.5 55.5 Bis (t-butyl) - (dipropylene glycol mono-
methyl ether) - (triethylene glycol mono-
methyl ether) silicate * 4th 51.7 41.8 Tris (dipropylene glycol monomethyl
ether) -t-butylsilicate 309 4th 51.2 36.5 ■ 47.1

-fs

gabeile I (continued)

Tested orthosilicate Boil
Point
( ⁰ C) Hydrolysis-
resistant-
ability assessment
tion 3-day rubber swelling
test (# swelling) nature
rubber Bis (triethylene glycol monomethyl
ether) bis (t-butyl) silicate 303 5 Styrene
Butadiene
Ka ut sch uk 19.2 Bis (tripropylene glycol monomethyl
ether) bis (t-butyl) silicate 226 5 44.4 44.1 Tris (tripropylene glycol monomethyl
ether) -t-butylsilicate 253 5 39.9. 37.6 Silicate A 308 0 60.9 5.5 Silicate B 310 1 9.3 -0.7 Silicate C 282 1 2.4 8.0 14.2

* Not determined

Tabel

II

ίο co co

CO

Tested orthosilicate 3-day rubber swell test
Nitrilkautscb.uk (£ swelling) Tetra- (tripropylene glycol monomethyl-
ätb.er) silicate -2.4 Bis- (dipropylene glycol monometh, yl-
ätb.er) -bis- (t-butyl) -silicate O Bis (t-butyl) - (dipropylene glycol mono-
methyl ether) - (triethylene glycol mono-
methyl ether) silicate 2.6 Trig (dipropylene glycol monomethyl
ättLer) -t-butylsilicate -0.01 Bis (triethylene glycol monomethyl
ättier) bis (t-butyl) silicate 7.2 Bis (tripropylene glycol monomethyl
ether) bis (t-butyl) silicate -0.34 Silicate A 20.8 Silicate C 6.5

4?

ro

O O co

Table .III

Tested orthosilicate 3-day rubber swell test
Chloroprene rubber (^ swelling) Tris- (triethylene glycol monomethyl--
ether; -t-butylsilicate 1.5 Tris (tripropylene glycol monomethyl
ether) neopentyl silicate 0.2 Silicate A 17.4 Silicate C 11.3

Claims (14)

24009H Patent claims: 1. Orthosilicic acid ester (orthosilicate) of the general formula R ¹ O. OR- Si R ² O OR 1
in which R is a propylene glycol monoalkyl ether radical with 1 to 8 carbon atoms in the alkyl terminal group or a ter- 2-5 4 tiarer alkyl radical, and R, Ir and R are the same or are different and each have an ethylene or propylene glycol monoalkyl ether radical with 1 to 8 carbon atoms in the Alkyl closing group or a tertiary alkyl radical O "Z Il interpret, with the proviso that R, R ^ and R propylene glycol monoalkylate radicals are, if R is a pro- Λ Ρ Ί pylene glycol monoalkylatherrest is that R, R, R ^ and R contain a total of at least 15 carbon atoms, and that 1 2 -5 4 at least one of the radicals R, R, R and R is a GIy- Kolmonoalkylätherrrest is. · 2. Orthosilicate according to claim 1, characterized in that that there is at least one glycol monoalkyl ether radical of the formula 409829/1074 -CH-CH-O- (HI), has, in which R is an alkyl radical with 1 to 8 carbon atoms, η is an integer and R ⁷ and R are each a hydrogen atom or a methyl radical, with the proviso that at least one of the radicals Έ? and R is a hydrogen atom. 3. Orthosilicate according to claim 2, characterized in that R contains 1 or 2 carbon atoms. 4. Orthosilicate according to claim 2 or 3, characterized in that that η is an integer from 2 to 4 * 5- orthosilicate according to one of claims 1 to 4, 12 3 4 ' characterized in that R, R, R ^ and R in total Contain a maximum of 60 carbon atoms. 6. Orthosilicate according to one of claims Λ to 5 »characterized in that .at least one of the radicals R ¹ , R ² , R ⁵ and R ^{4 is} a tertiary alkyl radical having 4 to 8 carbon atoms. 7. orthosilicate according to one of claims 1 to 6, Ί 2 ^ 4 characterized in that R, R, R ^ and R 'are the same or are different and each have a propylene glycol mono -47- 409829/1074 24009H alkyl ether radical of the formula III, in which R ^ or R is a methyl radical, with the proviso that the indices ή are identical or different and have a total value from 8 to 16 and the alkyl radicals R are identical or different and are 1 or 2 in each case C atom (s) - included. 8. Orthosilicate according to claim 7, characterized in that E ¹ , R ² , R ⁵ and R ^{4 are the} same and each represent a di- or l'ripropylenglykolmonome.thylätherrest. 9. Orthosilicate according to one of claims 2 to 6, Ί
characterized in that R is a tertiary alkyl TL IJL rest with 4 to 8 carbon atoms, R ^v and R are identical or different and each has a glycol monoalkyl ether 2 1 denotes the remainder of the formula III and R is an equilibrium with R or a tertiary alkyl radical different from R or one identical to or different from R * and / or R Glykolmonoalkylatherrest of the formula III, with the proviso that the indices η in the Glykolmonoalkylätherresten of the formula III are identical or different and the sum of their numerical values, if P. R is a tertiary alkyl radical, 4 to 8 and, when R is a glycol monoalkyl ether radical, is 6 to 12, and that the alkyl radicals R in the glycol monoalkyl ether radicals of the formula III are identical or different and each contain 1 or 2 carbon atoms £). -48- 409829/1074 24009H 10. Orthosilicate according to claim 9, characterized in that that 1 2 3 4 a ') R is a _t-butyl radical and R, Ir and R are each Triethylene glycol monomethyl ether residue or 1 2-5 4 b) R is a neopentyl radical and R, R ^ and R are each a Tripropylene glycol monomethyl ether residue or c) R and R are each a jb-butyl radical and R and R in each case a dipropylene glycol monomethyl ether residue or Ί Ρ ^ d) R and R each a t_-butyl radical, Yr a dipro- Zj. pylene glycol monomethyl ether residue and R is a trietylene glycol monomethyl ether residue or e) R is a jfc-butyl radical and R, R ⁹ and R are each a dipropylene glycol monomethyl ether radical or f) R ¹ and R ^{2 are} each a t-butyl radical and R ⁵ and R ^ are each a triethylene glycol monomethyl ether radical or g) R and R each a t-butyl radical and R ^ and R each a tripropylene glycol monomethyl ether residue or but λ ο Χ Zl h) R is a butyl radical and R, R ^ and R are each a Is tripropylene glycol monomethyl ether residue. -49-409829 / 107 ^ 11. A method for the preparation of orthosilicates according to any one of claims 1 to 1O _1, characterized in that a silicon tetrahalide or a silicic acid tetrahydrocarbyl ester with a hydroxy compound to form an orthosilicate according to a of claims 1 to 10 converts or esters. 12. Use of orthosilicates according to any one of claims 1 to 10 as a component of hydraulic fluids. 13. Use of orthosilicates according to one of the Claims 1 to 10 according to claim 12 in an amount of 1 to 99 percent by weight. 14. Use of orthosilicates according to one of the Claims 1 to 10 according to Claim 12 or 13 as a component of at least one customary hydraulic fluid additive and / or base material or hydraulic fluids containing base oil. 409829/1074