DE102013201971A1 - Use of thiocarbamate salt or its dimers, as corrosion inhibitors or as additives for reducing the wear at equipment parts - Google Patents

Abstract

Use of thiocarbamate salt (I) or its dimers, as corrosion inhibitors or as additives for reducing the wear at equipment parts, is claimed. Use of thiocarbamate salt of formula (N-(R6)(R7)-C(=S)-S ->(K +>)) (I) or its dimers, as corrosion inhibitors or as additives for reducing the wear at equipment parts, is claimed. R6, R7 : 1-20C organic group or ring system with not > 20C; and K : organic cation. Independent claims are also included for: (1) a composition comprising thiocarbamate salt (I) or its dimer; (2) lubricant comprising (I) or its dimer as a corrosion inhibitor, and greater than 50 wt.% animal oils, vegetable oils and/or mineral oils or synthetic oils, where the lubricant is liquid at 20[deg] C; (3) (I); and (4) preparing thiocarbamate salt (I), comprising reacting a salt of formula ((K +>)(Y ->)) with carbon disulfide and an amine of formula (N-(R6)(R7)-H) (VI). Y : hydroxy, alcoholate, or thiolate.

Description

worin R_a und R_b unabhängig voneinander für eine organische Gruppe mit 1 bis 20 C-Atomen stehen oder R_a und R_b zusammen ein Ringsystem mit maximal 20 C-Atomen ausbilden und K⁺ für ein organisches Kation steht, oder von Dimeren der Salze der Formel I als Korrosionsinhibitoren oder als Additive zur Verminderung des Verschleißes an Apparateteilen.The invention the use of salts of the formula I.

wherein R _a and R _{b are} independently an organic group having 1 to 20 carbon atoms or R _a and R _b together form a ring system having a maximum of 20 carbon atoms and K ^{+ is} an organic cation, or of dimers of the salts of the formula I as corrosion inhibitors or as additives for reducing the wear on equipment parts.

Ionic liquids are useful e.g. as a lubricant, hydraulic fluid or other work equipment and come in such uses in contact with equipment or analagen parts of metals.

Many metals and alloys show signs of corrosion in the presence of ionic liquids. Corrosion in problematic extent can occur in particular in simple steels, which are often used as a material in plant and machinery.

To avoid or reduce corrosion phenomena, the addition of so-called corrosion inhibitors is known. Corrosion inhibitors, which are used in ionic liquids, are in DE-A 10 2011 005 441 described. WO 2011/110423 discloses the use of salts of thiophosphoric acid as additives in lubricants to reduce corrosion and wear on equipment parts (antiwear additives).

Particular demands are placed on corrosion inhibitors for ionic liquids, in particular they should dissolve well in the ionic liquids, be compatible with the ionic liquids and remain in the system under the conditions of later use of the ionic liquids and not evaporate, be washed out or otherwise escape the system.

In general, corrosion inhibitors which contain no metals are advantageous. When using metal salts as corrosion inhibitors, it is easy to form deposits or particulate matter, eg. B. in the form of metal oxides.

Dithiocarbamates are already known as corrosion inhibitors. In US 4560716 For example, metal salts of dithiocarbamic acid are named as corrosion inhibitors in epoxy resins. In Bulletin of Electrochemistry 10, (2-3) Feb-Mar 1994, pages 83-86 disclose V. Pandit Rao et al , Dithiocarbamates which are substituted on the nitrogen atom by two ethyl groups, a piperidine or a morpholine, as corrosion inhibitors.

Commercially, metal salts or esters of dithiocarbamic acid are available as corrosion inhibitors, e.g. B. under the trade name Additin ^® the RheinChemie.

Object of the present invention were corrosion inhibitors, which contain no metals and therefore do not have the disadvantages associated with a content of metals. Furthermore, the corrosion inhibitors should be particularly suitable as corrosion inhibitors in ionic liquids.

Accordingly, the salts according to formula I and their use as corrosion inhibitors were found.

To the salts

The salts used according to the invention are organic, metal-free salts of dithiocarbamic acid.

In formula I, R _a and R _b independently of one another represent an organic group having 1 to 20 C atoms or R _a and R _b together form a ring system having a maximum of 20 C atoms.

R _a and R _b may form a ring system with or without further heteroatoms, such as oxygen, sulfur or nitrogen; the ring system may be aromatic or non-aromatic. Overall, preferred ring systems consist of 4 to 8 ring-forming atoms (carbon atoms and heteroatoms). Ring systems of 5 or 6 ring-forming atoms are particularly preferred. Pyrrole, pyrroline, pyrrolidine, pyridine, piperidine (with only the N-atom of the thiocarbamide as heteroatom), pyrazole, imidazole, pyrazoline, imidazoline, pyrimidine, pyrazine, piperazine (with a total of two N atoms as heteroatoms) and Oxazole, oxazoline, oxazolidine, morpholine (with one N atom and one O atom as heteroatoms). The ring systems may optionally be substituted on the ring atoms by organic groups, preferably hydrocarbon groups, in particular alkyl groups. However, the total number of all C atoms of the ring system, including the C atoms in the substituents, remains a maximum of 20, in particular a maximum of 10.

R _a and R _b are preferably an organic group having 1 to 16 carbon atoms, wherein the organic group may also contain heteroatoms, for example oxygen or nitrogen, preferably in the form of a hydroxyl group, ether group, primary, secondary or tertiary amino group.

In particular, R _a and R _b in formula I are an organic group which consists exclusively of carbon and hydrogen and contains no other heteroatoms, ie for a hydrocarbon group. It may be an aliphatic or an aromatic hydrocarbon group, it may also be a hydrocarbon group consisting of both aliphatic and aromatic groups.

R _a and R _{b are} particularly preferably, independently of one another, a C 1 - to C 20 -alkyl group, in particular a C 1 - to C 16 -alkyl, very particularly preferably a C 1 - to C 8 -alkyl group.

K ⁺ stands for an organic cation.

Suitable organic cations are, in particular, organic compounds containing heteroatoms, such as nitrogen, sulfur, oxygen or phosphorus; For example, the organic cations are compounds having an oxonium group (oxonium cations), a sulfonium group (sulfonium cations) or a phosphonium group (phosphonium cations) or compounds having at least one nitrogen atom.

K ⁺ is preferably an organic cation having at least one nitrogen atom.

In particular, the organic cation contains one to three nitrogen atoms.

• – eine Verbindungen mit lokalisierter positiver Ladung an einem Stickstoffatom mit 4 Substituenten (quaternäre Ammoniumverbindungen) oder
• – eine Verbindung mit lokalisierter positiver Ladung an einem Stickstoffatom mit drei Substituenten, wobei ein Substituent durch eine Doppelbindung gebunden ist, oder
• – aromatische Verbindungen mit delokalisierter positiver Ladung und mindestens einem, vorzugsweise ein bis drei Stickstoffatomen im aromatischen Ringsystem

handeln.The organic cation may be

• A compound with localized positive charge on a nitrogen atom with 4 substituents (quaternary ammonium compounds) or
• A compound having localized positive charge on a nitrogen atom having three substituents, wherein one substituent is bound by a double bond, or
• - aromatic compounds with delocalized positive charge and at least one, preferably one to three nitrogen atoms in the aromatic ring system

act.

As quaternary ammonium compounds are preferably those having aliphatic substituents, particularly preferably those having three aliphatic substituents and an H atom as a substituent or those having four aliphatic substituents. The aliphatic substituents are, in particular, C 1 - to C 12 -alkyl groups which may optionally be substituted by one or more hydroxyl groups, preferably by at most one hydroxyl group.

As an organic cation having located positive charge on a nitrogen atom having three substituents, wherein a substituent is attached through a double bond, e.g. a guanidinium cation or non-aromatic ring systems with at least one N atom as part of the ring system called.

Preferred organic cations are quaternary ammonium compounds, the guanidinium cation and cations containing a heterocyclic ring system having one to three nitrogen atoms as part of the ring system. The latter may be monocyclic, bicyclic, aromatic or non-aromatic ring systems.

Examples include bicyclic systems, as in WO 2008/043837 are described. In the bicyclic systems of WO 2008/043837 they are diazabicyclo derivatives, preferably from a 7- and a 6-membered ring, which contain an amidinium group; in particular, the 1,8-diazabicyclo (5.4.0) undec-7-enium cation may be mentioned.

Other suitable heterocyclic cations include, for example, pyridinium cations, pyridazinium cations, pyrimidinium cations, pyrazinium cations, imidazolium cations, pyrazolium cations, pyrazolinium cations, imidazolinium cations, thiazolium cations, triazolium cations, pyrrolidinium cations. Cations and imidazolidinium cations. These cations are eg in WO 2005/113702 listed. As far as it is necessary for a positive charge on the nitrogen atom or in the aromatic ring system, the nitrogen atoms are in each case by a hydrogen atom or an organic group having generally not more than 20 C atoms, preferably a hydrocarbon group, in particular a C1 to C16 alkyl group, in particular one C1 to C10, more preferably substituted a C1 to C4 alkyl groups.

The carbon atoms of the ring system can also be substituted by organic groups having generally not more than 20 C atoms, preferably a hydrocarbon group, in particular a C1 to C16 alkyl group, in particular a C1 to C10, particularly preferably a C1 to C4 alkyl groups.

ein Pyridiniumkation der Formel III

ein Pyrazoliumkation der Formel IV

oder ein Guanidiniumkation der Formel V

wobei R und R1 bis R5 unabhängig voneinander für ein Wasserstoffatom oder eine organische Gruppe mit 1 bis 20 C-Atomen, besonders bevorzugt für ein Wasserstoffatom oder eine C1- bis C20, insbesondere eine C1- bis C12-Alkylgruppe, stehen.Most preferably, the cation is um
an imidazolium cation of the formula II

a pyridinium cation of the formula III

a pyrazolium cation of formula IV

or a guanidinium cation of the formula V

where R and R 1 to R 5 independently of one another represent a hydrogen atom or an organic group having 1 to 20 C atoms, particularly preferably a hydrogen atom or a C 1 to C 20, in particular a C 1 to C 12 alkyl group.

In the imidazolium cations of the formula II, R and R 1 are preferably, independently of one another, an organic group having 1 to 20 C atoms, in particular having 1 to 12 C atoms. The organic group is preferably a hydrocarbon group without further heteroatoms, in particular R and R 1 independently of one another are a C 1 to C 20 alkyl group, particularly preferably a C 1 to C 12 alkyl group, very particularly preferably a C 1 to C 4 alkyl group ,

The radicals R 2 to R 4 in formula II independently of one another represent a hydrogen atom or an organic group having 1 to 20 C atoms, in particular 1 to 12 C atoms, wherein in the case of an organic group the remainder is again preferably a hydrocarbon group without further heteroatoms, in particular a C1 to C20 alkyl group, more preferably a C1 to C12 alkyl group, most preferably a C1 to C4 alkyl group. The radicals R 2 to R 4 in formula II are particularly preferably a hydrogen atom or a C 1 to C 4 alkyl group. Most preferably, the radicals R 2 to R 4 in formula II are a hydrogen atom.

In the pyridinium cations of the formula III, R preferably represents an organic group having 1 to 20 C atoms, in particular having 1 to 12 C atoms. The organic group is preferably a hydrocarbon group without further heteroatoms, in particular R is a C1 to C20 alkyl group, particularly preferably a C1 to C12 alkyl group, very particularly preferably a C1 to C4 alkyl group.

The radicals R 1 to R 5 in formula III independently of one another represent a hydrogen atom or an organic group having 1 to 20 C atoms, in particular 1 to 12 C atoms, wherein in the case of an organic group the remainder is again preferably a hydrocarbon group without further heteroatoms, in particular a C1 to C20 alkyl group, more preferably a C1 to C12 alkyl group, most preferably a C1 to C4 alkyl group. The radicals R 1 to R 5 in formula III are particularly preferably a hydrogen atom or a C 1 to C 4 alkyl group. Most preferably, the radicals R 1 to R 5 in formula III are a hydrogen atom.

In the pyrazolium cations of the formula IV, R and R 1 preferably represent an organic group having 1 to 20 C atoms, in particular having 1 to 12 C atoms. The organic group is preferably a hydrocarbon group without further heteroatoms, in particular R and R 1 independently of one another are a C 1 to C 20 alkyl group, particularly preferably a C 1 to C 12 alkyl group, very particularly preferably a C 1 to C 4 alkyl group ,

The radicals R 2 to R 4 in formula IV independently of one another represent a hydrogen atom or an organic group having 1 to 20 C atoms, in particular 1 to 12 C atoms, wherein in the case of an organic group the radical is again preferably a hydrocarbon group without further heteroatoms, in particular a C1 to C20 alkyl group, more preferably a C1 to C12 alkyl group, most preferably a C1 to C4 alkyl group. The radicals R 2 to R 4 in formula IV are particularly preferably a hydrogen atom or a C 1 to C 4 alkyl group. Very particularly preferably, the radicals R 2 to R 4 in formula IV are a hydrogen atom.

In the guanidinium cations of the formula V, R and R 1 to R 5 are preferably, independently of one another, an H atom or an organic group having 1 to 20 C atoms, in particular having 1 to 12 C atoms. In the case of an organic group, preference is given to a hydrocarbon group without further heteroatoms, in particular R is a C1 to C20 alkyl group, particularly preferably a C1 to C12 alkyl group, very particularly preferably a C1 to C4 alkyl group.

Preferably, at least 2, in particular at least 4, of the radicals R and R 1 to R 5 are an organic group and the remaining radicals are an H atom. Most preferably, all of R and R 1 to R 5 are an organic group, i. Compounds of the formula V then contain no H atom as a substituent on an N atom.

The cation K + in formula I is particularly preferably an imidazolium cation of the formula II.

Examples of particularly preferred imidazolium cations include:
1-methyl-3-methylimidazolium (R and R 1 = methyl, R 2, R 3, R 4 = H), short MMIM
1-ethyl-3-methylimidazolium (R = ethyl and R 1 = methyl, R 2, R 3, R 4 = H), in short EMIM
1-ethyl-3-ethylimidazolium (R and R1 = ethyl, R2, R3, R4 = H), short EEIM
1-butyl-3-methylimidazolium (R = butyl and R 1 = methyl, R 2, R 3, R 4 = H), abbreviated to BMIM
1-Butyl-3-ethylimidazolium (R = butyl and R 1 = ethyl, R 2, R 3, R 4 = H), short BEIM
1-Butyl-3-butylimidazolium (R and R 1 = butyl, R 2, R 3, R 4 = H), BBIM for short
1-octyl-3-methylimidazolium (R = octyl and R 1 = methyl, R 2, R 3, R 4 = H), OMIM for short

oder Ib

verstanden, wobei R¹a und R¹ _b die obige Bedeutungen von Ra und Rb haben, mit der Ausnahme, dass R¹a und R¹ _b divalent sind.In a further embodiment of the invention, dimers of these salts can be used instead of the salts of the formula I. Among dimers, divalent salts of structures Ia

or Ib

wherein R ¹ a and R ¹ _{b have} the above meanings of Ra and Rb except that R ¹ a and R ¹ _{b are} divalent.

As the compound of the formula Ib is suitable, e.g. the compound Ic

Preparation of the salts

The salts according to the invention can be prepared by various known methods.

In particular, the salts according to the invention can be prepared from other salts of the organic cation, e.g. from the alkyl carbonate salts or hydroxy salts.

Salts of the above-mentioned cations and an alkyl carbonate as an anion and the preparation of such salts are, for example WO 2005/021484 known. This WO also describes the conversion of the alkyl carbonate salts into salts of other anions by adding an acid.

According to the doctrine of WO 2005/021484 For example, imidazolium alkyl carbonates or the alkyl carbonates of other cations (also abbreviated to alkyl carbonate in the following) can be converted into salts of the formula I by adding the dithiocarbamic acid. The reaction produces carbon dioxide.

Preferred starting compound is the imidazolium methyl carbonate as starting material.

As dithiocarbamic acid, the corresponding acid with the desired radicals Ra and Rb is selected.

The reaction of the alkyl carbonate with the dithiocarbamic acid may be e.g. at 0 to 100 ° C, in particular 10 to 80 ° C and atmospheric pressure, optionally in the presence of a solvent.

Suitable solvents are, in particular, alcohols, such as methanol, ethanol, isopropanol. Particularly preferred is methanol as a solvent.

The alkyl carbonate and the dithiocarbamic acid can each be used in excess. Preferred is a molar ratio of 1 to 0.8 to 0.8 to 1.

The alkyl carbonate and the dithiocarbamic acid are very particularly preferably used in an approximately stoichiometric ratio.

Alternatively, the compounds of formula I may also be prepared from the hydroxide salt of the above-mentioned cations. Here, the reaction takes place with the dithiocarbamic acid with elimination of water.

Furthermore, for the preparation of the salts according to the invention, any metathesis reactions, i. Anion exchange reactions, possible starting from any salt of a cation mentioned above and exchange of the anion for the corresponding anion of the dithiocarbamic acid. As the starting salt for anion exchange, halides, and especially chlorides, are generally undesirable in view of later use and possible residual chloride content.

umgesetzt wird.A particularly suitable process for the preparation of the salts of the formula I is characterized in that a salt of the formula K ⁺ Y ^- with carbon disulfide (CS ₂ ) and an amine of the formula VIII

is implemented.

K ⁺ , R _a and R _b have the above meaning and the anion Y ^- represents a hydroxy group, an alcoholate group or a thiolate group. Suitable alkoxide or thiolate groups are in particular groups OZ ^- or SZ ^- into consideration, in which Z is an organic group having 1 to 10 carbon atoms, preferably a hydrocarbon group and particularly preferably a C1 to C4 alkyl group. Particularly preferably, Y ^- represents a hydroxy group (OH ^-).

Imidazolium dithiocarbamates of the formula I can be obtained, for example, by reacting amines of the formula VIII, CS ₂ and imidazolium hydroxide.

The reaction is preferably carried out in a solvent, in particular water or a water-miscible, hydrophilic solvent. Particularly preferred solvents are water or alcohols, in particular water or methanol.

The reaction can preferably be carried out at atmospheric pressure and temperatures of 0 to 50 ° C. The reaction with CS ₂ is exothermic, therefore it is optionally cooled. In this process, very high sales are achieved, in general, the turnover is complete.

In one preferred embodiment, the salts according to the invention contain less than 100 ppm, in particular less than 20 ppm of halides. Most preferably, they are free of halides.

As preferred salts of the formula I are exemplary
EMIM diethyldithiocarbamate
EMIM dibutyldithiocarbamate
EMIM di-2-ethylhexyldithiocarbamat
MMIM diethyldithiocarbamate
MMIM dibutyldithiocarbamate
MMIM-di-2-ethylhexyldithiocarbamat
called.

The salt of formula I is preferably an ionic liquid, i. the salt has a melting point less than 100 ° C, especially less than 20 ° C at atmospheric pressure (1bar). After separation of the solvent, the salts can therefore be transported as liquids, stored and used in a simple manner.

use

The salts of the formula I or their dimers can be used as corrosion inhibitors in any desired compositions. They reduce the corrosion of devices or other moldings, which consist entirely or partially of metals and with which the composition comes into contact. The above metals may be any metals, e.g. to trade iron, stainless steel or copper.

The salts of the formula I or their dimers also act as additives for reducing the wear (anti-wear additives) on apparatus parts and devices, in particular of metal.

In the context of this invention and the above uses, preference is given in principle to salts of the formula I.

The salts can be used in a variety of technically used compositions; it may be in the compositions z. As to lubricants, hydraulic fluid, damping fluids or power transmission means act.

In general, the salts are used as corrosion inhibitors or antiwear additives in compositions which are liquid when used. Especially preferred in compositions that are liquid at 20 ° C.

Possible are any liquid compositions. It can be e.g. be compositions containing water or in large part, e.g. to more than 50 wt.%, In particular also more than 70% or z more than 90 wt.% Consist of water. Such compositions are for. B. as coolants of importance.

The salts of the formula I or their dimers are preferably present in the compositions in amounts of from 0.05 to 10% by weight, more preferably from 0.1 to 5% by weight, based on the composition. The salts of formula I can be used with other corrosion inhibitors, but they can also be used as sole corrosion inhibitors in compositions.

In a preferred embodiment, the compositions contain, in addition to the salt of the formula I, at least one ionic liquid which is different from the salts of the formula I.

Under an ionic liquid we, as already stated above a salt with a small 100 ° C, especially less than 20 ° C at atmospheric pressure 1 bar) understood.

In particular, salts having a cation K ⁺ , as defined in formula I, and an anion other than the thiocarbamide anion come into consideration as the ionic liquid other than salts of the formula I.

Again, it is particularly preferable that this is again a cation according to one of the formulas II to VII, very particularly preferably an ionic liquid with an imidazolium cation of the formula II.

As the anion of the ionic liquid, conventional anions which form an ionic liquid with the above cations are suitable. In particular, the anion is one of the group
the alkyl sulfates
R ^c OSO3,
wherein R ^{c is} a C1 to C12 alkyl group, preferably a C1-C6 alkyl group, the alkyl sulfonates
R ^c SO3-;
wherein R ^{c is} a C 1 to ^C 12 alkyl group, preferably a ^C 1 -C 6 alkyl group,
the halides, in particular chloride and bromide and
the pseudohalides, such as thiocyanate, dicyanamide,
the carboxylates R ^c COO-;
wherein R ^{c is} a C 1 to ^C 20 alkyl group, preferably a ^C 1 -C 8 alkyl group, in particular acetate,
the phosphates,
in particular the dialkyl phosphates of the formula R ^c R ^d PO ₄ -, wherein R ^c and R ^d independently of one another represent a ^C 1 to ^C ₆ alkyl group; in particular, R ^c and R ^{d represent} the same alkyl group, which may be mentioned dimethyl phosphate and diethyl phosphate
and the phosphonates, in particular the monoalkylphosphonic esters of the formula R ^c R ^d PO ₃ -, where R ^c and R ^d independently of one another represent a ^C _{1 to} ^C 6 alkyl group
and the TFSI anion of the formula N (-SO ₂ CF 3) ₂ - and tricyanomethamide of the formula (CN) ₃ C ^- and fluorinated anions, in particular the above anions, in which hydrogen is wholly or partly replaced by fluorine.

As anions called his e.g. Chloride, bromide, hydrogensulfate, tetrachloroaluminate, thiocyanate, dicyanamide, methylsulfate, ethylsulfate, methanesulfonate, formate, acetate, dimethylphosphate, diethylphosphate, p-tolylsulfonate, tetrafluoroborate and hexafluorophosphate, methylmethylphosphonate and methylphosphonate, the TFSI anion, tricyanomethamide and trifluoromethanesulfonate.

Particular preference is given to compositions which consist of more than 10% by weight of ionic liquids which are different from salts of the formula I.

In particular, the compositions of formula I may contain various ionic liquids in amounts of at least 30, in particular at least 50 and more preferably at least 70% by weight, based on the composition. The compositions may consist only of salts of formula I and various ionic liquids.

In general, however, the compositions will contain other ingredients such as water or organic solvents, especially organic solvents miscible with ionic liquids, e.g. Alcohols, and additives such as thickeners, stabilizers or defoamers.

The above compositions are e.g. B. used as a lubricant, hydraulic fluid, damping fluid or power transmission means.

The salts of the formula I or their dimers are particularly suitable as corrosion inhibitors and anti-wear additives in at 20 ° C (1 bar) liquid lubricants, which contain more than 50 wt.% Of animal oils, vegetable oils, mineral oils or synthetic Oils or mixtures thereof exist. Synthetic oils can be prepared from a wide variety of starting compounds, in particular also from the above animal, vegetable oils or mineral oils.

For the oils, e.g. Mineral oils may be acyclic and / or cyclic saturated and / or unsaturated hydrocarbons, optionally containing one or more heteroatoms, e.g. O, F, P, N, S may contain.

As oils without heteroatoms, for example, alkylbenzenes, cycloalkanes, polyalphaolefins and copolymers of unsaturated hydrocarbons may be mentioned;
as oils which contain oxygen as heteroatom, alcohols, esters, ketones, furans, polyethers and copolymers of olefins and, for example, acrylates, maleinates or fumarates may be mentioned;
oils containing fluorine and oxygen as heteroatoms are perfluoro ethers or esters;
as oils which contain phosphorus and oxygen as heteroatoms may be mentioned phosphoric esters;
as oils which contain phosphorus and nitrogen as heteroatoms are called phosphazenes;
Thiophenes may be mentioned as oils which contain sulfur or nitrogen as heteroatoms.

The lubricants are preferably in the temperature range of the application, which may be in the range of -80 ° C to + 450 ° C, liquid (1013mbar), but these need not be certain requirements (eg, bonded coatings). The lubricants contain the oils, for example in an amount of 1 to 99.9 wt .-%. Depending on requirements, the lubricants may contain additives which fulfill, for example, the following tasks: aging protection, wear protection, extreme pressure additives, corrosion protection, detergents, dispersants, demulsification, emulsification, antifoaming agents and other objects described in the literature (also see "Lubricant additives: chemistry and applications / editor, Leslie R. Rudnick, - 2nd Edition, 2009, CRC Press" .)

Animal or vegetable oils are e.g. Rapeseed oil, castor oil or fish oil.

As mineral oils are e.g. Petroleum fractions of spindle oils to lubricating oils SAE 30, 40 or 50 into consideration.

Synthetic oils are in particular oils which are obtainable by esterification or etherification of suitable starting materials, for example also the above animal or vegetable oils or mineral oils. Examples include diesters, such as by esterification of dicarboxylic acids such as adipic acid or sebacic acid obtained with monohydric alcohols or oligoesters which are obtainable by esterification of mixtures of di- or oligocarboxylic acids, di- or oligoalcohols and monoalcohols, for example oligoesters of sebacic or adipic acid, a polyglycol and a monohydric alcohol such as 2-ethylhexanol.

Synthetic oils are e.g. also at normal conditions (20 ° C, 1 bar) liquid oligomers, which are obtainable by polymerization, be it a free-radical polymerization, polycondensation or other Polyadduktbildung of monomers. Consider, for example, Oligomers based on ethylene oxide, propylene oxide, alkenes or iso-alkenes, such as polyethylene glycols, polypropylene glycols, polyisobutylenes or polymers and copolymers obtainable by radical polymerization of ethylenically unsaturated monomers, e.g. based on vinyl ethers, vinyl esters, acrylic esters, maleates, fumarates etc.

The lubricants find e.g. Use as engine oils (petrol and diesel engines) Transmission oils or chain lubricants.

In summary, it can be stated that the salts of the formula I work very well as corrosion inhibitors and as anti-wear additives. This effect is particularly evident in compositions with a high content of ionic liquids and in lubricants. In particular, the salts of the formula I act as corrosion inhibitors. They prevent corrosion especially on equipment parts and devices containing tin.

Examples

manufacturing

1) Preparation of 1-ethyl-3-methylimidazolium dibutyl dithiocarbamate

The EMIM chloride (1.11 mol) is initially charged in methanol (60 mL) and then slowly added dropwise at 60 ° C, the potassium dibutyl dithiocarbamate (1.11 mol, dissolved in 50 ml of methanol, slightly cloudy). During the dropping, crystals (potassium chloride) precipitate, the reaction is not exothermic. The mixture is then stirred for 4 hours under reflux (67 ° C). The next day, the solid is filtered off with suction through a frit and the filtrate is pulled dry on a rotary evaporator. The product is taken up in acetonitrile and then the undissolved solid (potassium chloride) is suctioned off. The filtrate is drawn dry on a rotary evaporator.

2) Preparation of 1-ethyl-3-methylimidazolium diethyl dithiocarbamate

The EMIM chloride (1.2 mol) is initially charged in methanol (250 mL) and then slowly added dropwise at 60 ° C, the sodium diethyl-dithio-carbamate (1.2 mol, dissolved in about 350 mL of methanol). When added dropwise, crystals (sodium chloride) precipitate, the mixture is stirred for 6 hours under reflux (67 ° C). The precipitated crystals are filtered off with suction, washed with methanol and then the filtrate is drawn dry on a rotary evaporator. The residue (suspension) is taken up in acetonitrile and then sucked the undissolved crystals (sodium chloride) and the filtrate was drawn dry.

3) Preparation of 1-ethyl-3-methylimidazolium di-2-ethylhexyl dithiocarbamate

starting compounds 0.500 mol EMIM hydroxide (7.5% in methanol - 1.0 eq) 120.7 g-0.500 mol Bis (2-ethylhexyl) amine - 1.0 eq 40.0 g-0.525 mol Carbon disulphide (boiling point: 46 ° C) - 1.05 eq.

EMIM-hydroxide is introduced and at 10 ° C (ice bath cooling), the bis (2-ethylhexyl) amine is added dropwise (becomes two-phase - not exothermic). The carbon disulfide is then slowly added at room temperature (ice bath cooling - exothermic - after addition of 2/3 of the carbon disulfide, the mixture is added dropwise in one phase) and stirred overnight at room temperature. The next day, the batch is drawn dry on a rotary evaporator. The suspension is taken up in 200 ml of acetonitrile, the solid is filtered off with suction, washed with acetonitrile and the filtrate is dried on a rotary evaporator. The filtrate acts according to H-NMR to 1-ethyl-3-methylimidazolium di-2-ethylhexyl-dithiocarbamate (yield 213.6 g, about 100%).

Application testing

A metal body (about 15 grams) was stored for 120 hours in 20 grams of an ionic liquid (IL for short) at 90 ° C under argon. It was an ionic liquid with EMIM as a cation and a sulfur-containing anion. The ionic liquid did not contain any metals or metal compounds prior to storage.

The experiment was carried out without the addition of a corrosion inhibitor, with the addition of 1 part by weight of benzotriazole (per 100 parts by weight of IL) and 1 part by weight of benzotriazole + 1 part by weight of EMIM diethyldithiocarbamate (per 100 parts by weight of IL). After storage, the content of metal in the ionic liquid was determined. The results are listed in the table below. Metal content in the ionic liquid after storage in ppm Ionic liquid without corrosion inhibitor Ionic liquid with 1 part by weight of benzotriazole Ionic liquid with 1 part by weight of benzotriazole and 1 part by weight of EMIM diethyldithio carbamate copper 19 ppm less than 3 ppm less than 3 ppm tin 142 ppm 60 ppm 7 ppm

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011005441 A [0004]
• WO 2011/110423 [0004]
• US 4560716 [0007]
• WO 2008/043837 [0025, 0025]
• WO 2005/113702 [0026]
• WO 2005/021484 [0043, 0044]

Cited non-patent literature

• Bulletin of Electrochemistry 10, (2-3) Feb-Mar 1994, pages 83-86 disclose V. Pandit Rao et al. [0007]
• "Lubricant additives: chemistry and applications / editor, Leslie R. Rudnick, - 2nd Edition, 2009, CRC Press" [0081]

Claims (14)

Use of salts of the formula I.

wherein R _a and R _{b are} independently an organic group having 1 to 20 carbon atoms or R _a and R _b together form a ring system having a maximum of 20 carbon atoms and K ^{+ is} an organic cation, or of dimers of the salts of the formula I as corrosion inhibitors or as additives for reducing the wear on equipment parts. Use according to claim 1, characterized in that R _a and R _b in formula I independently of one another is a C 1 to C 20 alkyl group. Use according to one of claims 1 or 2, characterized in that the cation K ⁺ is a quaternary ammonium cation, a guanidinium cation or a cation having a heterocyclic ring system containing one to three nitrogen atoms. Use according to one of Claims 1 to 3, characterized in that the cation is an imidazolium cation of the formula II

a pyridinium cation of the formula III

a pyrazolium cation of formula IV

or a guanidinium cation of the formula V

wherein R and R1 to R5 independently represent a hydrogen atom or an organic group having 1 to 20 C-atoms. Use according to any one of Claims 1 to 4, characterized in that the cation K ⁺ is an imidazolium cation of the formula II, R and R 1, independently of one another, being an organic group having 1 to 20 C atoms and R 2 , R3 and R4 independently represent an H atom or an organic group having 1 to 20 C atoms. Compositions containing at least one salt of the formula I or of dimers of the salts of the formula I. Compositions according to Claim 6, characterized in that they contain salts of the formula I or their dimers in amounts of from 0.05 to 10% by weight, based on the composition. Compositions according to Claim 6 or 7, characterized in that they contain ionic liquids which are different from the salts of the formula I or their dimers. Compositions according to any one of Claims 6 to 8, characterized in that they consist of more than 10% by weight of ionic liquids other than salts of formula I or their dimers. Compositions according to any one of Claims 6 to 9, characterized in that they consist of more than 10% by weight of imidazolium salts other than the salts of formula I or their dimers. Use of compositions according to one of claims 6 or 10 as lubricant, hydraulic fluid, damping fluid or force transmission means. At 20 ° C liquid lubricant containing a salt of formula I or its dimers as a corrosion inhibitor and more than 50 wt.% Animal oils, vegetable oils, mineral oils or synthetic oils or mixtures thereof. Salts of the formula I

wherein R _a and R _b independently of one another are an organic group having 1 to 20 C atoms or R _a and R _b together form a ring system having a maximum of 20 C atoms and K ^{+ is} an organic cation. Process for the preparation of the salts of the formula I, characterized in that a salt of the formula K ⁺ Y ^- with carbon disulfide (CS ₂ ) and an amine of the formula VI

is implemented, wherein K ⁺ , R _a and R _{b have} the above meaning and the anion Y ^{- is} a hydroxy group, an alcoholate or thiolate group.