Method for the separation of acids from chemical reaction mixtures by means of ionic fluids

Abstract

A process for removing acids from reaction mixtures using an auxiliary base, in which the auxiliary base

Description

[0001] The present invention describes a process for simplified removal of acids from reaction mixtures using an ionic liquid.

[0002] The chemist skilled in the art often has the problem of scavenging acids released during a chemical reaction or removing acids from reaction mixtures. Examples of reactions in which acids are released in the course of the reaction include the silylation of alcohols or amines using halosilanes, the phosphorylation of amines or alcohols using phosphorus halides, the formation of sulfonate esters or sulfonamides from alcohols or amines and sulfonyl chlorides or sulfonic anhydrides, eliminations and substitutions.

[0003] These reactions release acids, and for this reason an auxiliary base is additionally added which in general does not take part in the actual reaction as a reactant. It is generally necessary to bind the released acids to this base by salt formation, in order to prevent side reactions and subsequent reactions, or else simply in order to remove the acid from the desired reaction product and optionally return it to the process. When the salts of the bases used are not removed at first, they may also be worked up in the presence of the product of value, e.g. by addition of a further stronger base, such as aqueous alkalis, e.g. sodium hydroxide or potassium hydroxide. This results in the formation of the salt of the stronger base added in this step. Also, the originally used base is liberated. These two components, i.e. the salt of the stronger base and the liberated initially used base (auxiliary base), generally have to be likewise removed from the product of value. This procedure often has the disadvantage that the product of value which is present in the workup may decompose as a result of the added stronger base itself or further materials in this base, e.g. the water in an aqueous alkali.

[0004] The salts of the auxiliary base with the acid are generally insoluble in organic solvents and have high melting points, so that they form suspensions in organic media which are more difficult to handle than, for example, liquids. It would therefore be desirable to be able to remove the salts of the auxiliary bases in liquid form. This would also eliminate the known process-engineering disadvantages of suspensions. These are, e.g., the formation of encrustations, reduction of heat transfer, poor mixing and stirrability, and also the formation of localized high and low concentrations and hot spots.

[0005] The prior art as it relates to industrially operated processes accordingly has the following disadvantages:

[0006] 1) the addition of two auxiliary materials, the auxiliary base and also a further strong base, and the consequent need to separate two auxiliary materials from the product of value and from each other,

[0007] 2) handling of suspensions

[0008] 3) removal of the salt of the strong base as a solid.

[0009] However, a phase separation by means of a liquid-liquid phase separation which is simple from a process-engineering point of view would be desirable.

[0010] DE-A 197 24 884 and DE-A 198 26 936 disclose processes for preparing carbonyldiimidazoles by phosgenation of imidazoles, which involve removing the resulting hydrochloride of the imidazole used as starting material as a melt from the reaction mixture. DE-A 198 26 936 discloses at page 3, line 5 that the hydrochloride of the imidazole is surprisingly liquid at temperatures of from 110 to 130° C. and melts well below the literature melting point of 158 to 161° C. The inventors suggest that the reason for this is either the formation of a eutectic mixture of the imidazole hydrochloride with the carbonyldiimidazole product of value or the formation of a ternary mixture of the imidazole hydrochloride, the carbonyldiimidazole product of value and the chlorobenzene solvent. Although the imidazole hydrochloride should not have been liquid, this was surprisingly the case in this specific case. The applicability of this concept for reactions other than phosgenation of imidazoles is not described.

[0011] It is an object of the present invention to provide a simplified process for removing acids for other chemical reactions or for the removal of acids which are present in mixtures but are not separated off during a chemical reaction by removing a salt formed from an added auxiliary base and an acid by a liquid-liquid phase separation which is simple from a process-engineering point of view.

[0012] We have found that this object is achieved by a process for removing acids from reaction mixtures using an auxiliary base, which comprises the auxiliary base

[0013] b) combining with the acid to form a salt which is liquid at temperatures at which the product of value does not significantly decompose during the removal of the liquid salt, and

[0014] c) the salt of the auxiliary base with the product of value or the solution of the product of value in a suitable solvent forming two immiscible liquid phases.

[0015] It is known to those skilled in the art that the separation of a liquid phase from a second liquid phase is considerably easier to effect from a process-engineering point of view than a solid separation.

[0016] The industrial utility of the process of the invention results from the ability to carry out the removal of the auxiliary material by a simple liquid-liquid phase separation, so that the handling of solids which is inconvenient from a process-engineering point of view is unnecessary.

[0017] The workup of the auxiliary materials may take place in the absence of the product of value, so that the latter is subject to less stress.

[0018] The stated object is achieved by the invention described here. This is accomplished by auxiliary bases being present in the reaction mixtures or being added subsequently, and their salts with acids, which are released in the course of the reaction or added, i.e. not released during the reaction under the reaction conditions and/or workup conditions, being liquid and forming a phase which is immiscible with any dissolved product of value. Such liquid salts are often referred to as ionic liquids. The acids to be bound may either be free in the reaction mixture or form a complex or an adduct with the product of value or another material present in the reaction mixture. Lewis acids in particular tend to form complexes with materials such as ketones. These complexes may be broken by the auxiliary base, which according to this invention results in the formation of the salt from the auxiliary base and the Lewis acid to be removed.

[0019] The auxiliary bases may be inorganic or organic bases, preferably organic.

[0020] Mixtures or solutions of auxiliary bases may also be used to achieve the object.

[0021] Immiscible means that at least two liquid phases, which are separated by a phase boundary, are formed.

[0022] When the pure product of value is entirely or substantially miscible with the salt formed by the auxiliary base and the acid, an auxiliary material, e.g. a solvent, may be added to the product of value, in order to achieve separation or solubility reduction. This is sensible when, for example, the solubility of the salt in the product of value or vice versa is 20% by weight or more, preferably 15% by weight or more, more preferably 10% by weight or more and most preferably 5% by weight or more. The solubility is determined under the conditions of each separation. Preference is given to determining the solubility at a temperature above the melting point of the salt and below the lowest of the following temperatures, more preferably 10° C. below the lowest and most preferably 20° C. below the lowest:

[0023] boiling point of the product of value

[0024] boiling point of the solvent

[0025] temperature of significant decomposition of the product of value

[0026] The solvent may be regarded as suitable when the mixture of the product of value and the solvent is able to dissolve the salt, or the salt is able to dissolve the product of value or a mixture of product of value and solvent, to a lesser extent than the above-stated quantities. Examples of useful solvents include benzene, toluene, o-, m- or p-xylene, cyclohexane, cyclopentane, pentane, hexane, heptane, octane, petroleum ether, acetone, isobutyl methyl ketone, diethyl ketone, diethyl ether, tert-butyl methyl ether, tert-butyl ethyl ether, tetrahydrofuran, dioxane, ethyl acetate, methyl acetate, dimethylformamide, dimethyl sulfoxide, acetonitrile, chloroform, dichloromethane, methylchloroform or mixtures thereof.

[0027] The product of value is generally a nonpolar organic or inorganic compound.

[0028] Chemical reactions which form the basis of the invention include all reactions in which acids are released, with the exception of phosgenations, more preferably with the exception of acylations, i.e. reactions of acid halides and carboxylic anhydrides.

[0029] Examples of reactions in which the process of the invention may be applied include

[0030] alkylations using alkyl or aralkyl halides, e.g. methyl chloride, methyl iodide, benzyl chloride, 1,2-dichloroethane or 2-chloroethanol,

[0031] acylations, i.e. reactions of acid halides and carboxylic anhydrides, of any desired substrates, for example alcohols or amines,

[0032] silylations, i.e. reactions with compounds which contain at least one Si-Hal bond, e.g. SiCl4, (H3C)2SiCl2 or trimethylsilyl chloride,

[0033] phosphorylations, i.e. reactions with compounds which contain at least one P-Hal bond, e.g. PCl3, PCl5, POCl3, POBr3, dichlorophenylphosphine or diphenylchlorophosphine, as likewise described, for example, by Chojnowski et al., loc cit.,

[0034] sulfurizations, i.e. sulfidations, sulfations, sulfonations and sulfatations, for example using sulfuryl chloride (SO2Cl2), thionyl chloride (SOCl2), chlorosulfonic acid (ClSO3H), sulfonyl halides, e.g. p-toluenesulfonyl chloride, methanesulfonyl chloride or trifluoromethanesulfonyl chloride, or sulfonic anhydrides, as described, e.g. by Dobrynin, V. N. et al. Bioorg. Khim. 9(5), 1983, 706-10,

[0035] eliminations, where a C═C double bond is formed with elimination of an acid, for example HCl, HBr, acetic acid or para-toluenesulfonic acid, or

[0036] deprotonations, where an acidic hydrogen atom is abstracted from the auxiliary base.

[0037] Among the mentioned reaction types, preference is given to alkylations, silylations, phosphorylations, sulfurizations, acylations with the exception of phosgenations and eliminations, and particular preference to silylations, phosphorylations and sulfurizations.

[0038] According to the invention, an acid may also be removed from reaction mixtures where an acid which was not released during the reaction was added, for example in order to adjust the pH or to catalyze a reaction. This allows, e.g. Lewis acids, which are used as catalysts for Friedel-Crafts alkylations or acylations, to be removed in a simple way.

[0039] The acids to be removed according to this invention may be Brönsted or Lewis acids. The naming of acids as Brönsted and Lewis acids is described in Hollemann-Wiberg, Lehrbuch der Anorganischen Chemie, 91st-100th edition, Walter de Gruyter, Berlin New York 1985, p. 235 and 239. The Lewis acids according to this invention also include the Lewis acids used as Friedel-Crafts catalysts, which are described in George A. Olah, Friedel-Crafts and Related Reactions, Vol. I, 191 to 197, 201 and 284-90 (1963). Examples include aluminum trichloride (AlCl3), iron(III) chloride (FeCl3), aluminum tribromide (AlBr3) and zinc chloride (ZnCl2).

[0040] In general, the Lewis acids which can be removed according to the invention comprise cationic forms of the metals of groups Ib, IIb, IIIa, IIIb, IVa, IVb, Va, Vb, VIb, VIIb and VIII of the Periodic Table of the Elements or else of the rare earths, for example lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium.

[0041] Particular examples include zinc, cadmium, beryllium, boron, aluminum, gallium, indium, thallium, titanium, zirconium, hafnium, erbium, germanium, tin, vanadium, niobium, scandium, yttrium, chromium, molybdenum, tungsten, manganese, rhenium, palladium, thorium, iron, copper and cobalt. Preference is given to boron, zinc, cadmium, titanium, tin, iron and cobalt. Useful counterions of the Lewis acid include F-, Cl-, ClO-, ClO3-, ClO4-, Br-, I-, IO3-, CN-, OCN-, SCN-, NO2-, NO3-, HCO3-, CO32-, S2-, SH-, HSO3-, SO32-, HSO4-, SO42-, S2O22-, S2O42-, S2O52-, S2O62-, S2O72-, S2O82-, H2PO2-, H2PO4-, HPO42-, PO43-, P2O74-, dithiocarbamate, salicylate, (OCnH2n+1)-; (CnH2n−1O2)-, (CnH2n−3O2)- and (Cn+1H2n−2O4)2-, where n is a number from 1 to 20, methanesulfonate (CH3SO3-), trifluoromethanesulfonate (CF3SO3-), toluenesulfonate (CH3C6H4SO3-), benzenesulfonate (C6H5SO3-), hydroxide (OH-), anions of aromatic acids such as benzoic acid, phthalic acid and the like, and 1,3-dicarbonyl compounds.

[0042] Further examples include carboxylates, and mention should be made in particular of formate, acetate, trifluoroacetate, propionate, hexanoate and 2-ethylhexanoate, stearate and also oxalate, acetylacetonate, tartrate, acrylate and methacrylate, preferably formate, acetate, propionate, oxalate, acetylacetonate, acrylate and methacrylate.

[0043] Further useful Lewis acids include borohydrides and organoboron compounds of the general formula BR″″3 and B(OR″″)3, where each R″″ is independently hydrogen, C1-C18-alkyl, or C2-C18-alkyl, C6-C12-aryl, C5-C12-cycloalkyl, each of which may optionally be interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocycle or two of them combine to form an unsaturated, saturated or aromatic ring which is optionally interrupted by one or more oxygen and/or sulfur atoms and/or by one or more substituted or unsubstituted imino groups, and the stated radicals in each case may be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles. The R″″ radicals may also be bonded to each other.

[0044] In addition to the above-cited AlCl3, FeCl3, AlBr3 and ZnCl2, preferred examples of Lewis acids include BeCl2, ZnBr2, Znl2, ZnSO4, CuCl2, CuCl, Cu(O3SCF3)2, CoCl2, Col2, Fel2, FeCl2, FeCl2(THF)2, TiCl4(THF)2, TiCl4, TiCl3, ClTi(OiPr)3, SnCl2, SnCl4, Sn(SO4), Sn(SO4)2, MnCl2, MnBr2, ScCl3, BPh3, BCl3, BBr3, BF3.OEt2, BF3.OMe2, BF3.MeOH, BF3.CH3COOH, BF3.CH3CN, B(CF3COO)3, B(OEt)3, B(OMe)3, B(OiPr)3, PhB(OH)2, 3-MeO-PhB(OH)2, 4-MeO-PhB(OH)2, 3-F-PhB(OH)2, 4-F-PhB(OH)2, (C2H5)3Al, (C2H5)2AlCl, (C2H5)AlCl2, (C8H17)AlCl2, (C8H17)2AlCl, (iso-C4H9)2AlCl, Ph2AlCl, PhAlCl2, Al(acac)3, Al(OiPr)3, Al(OnBu)3, Al(OsecBu)3, Al(OEt)3, GaCl3, ReCl5, ZrCl4, NbCl5, VCl3, CrCl2, MoCl5, YCl3, CdCl2, CdBr2, SbCl3, SbCl5, BiCl3, ZrCl4, UCl4, LaCl3, CeCl3, Er(O3SCF3), Yb(O2CCF3)3, SmCl3, Sml2, B(C6H5)3, TaCl5.

[0045] The Lewis acids may be stabilized by alkali metal or alkaline earth metal halides, for example LiCl or NaCl. To this end, the alkali metal or alkaline earth metal halides are mixed with the Lewis acid in a molar ratio of 0-100:1.

[0046] In this context, halogen or Hal refers to fluorine (F), chlorine (Cl), bromine (Br) or iodine (I), preferably chlorine.

[0047] In the case of a silylation, phosphorylation or sulfurization, compounds are generally converted which have at least one free O—H, S—H or N—H bond, optionally after deprotonation by the auxiliary base.

[0048] Useful auxiliary bases according to the invention include compounds which

[0049] b) combine with the acid released during the reaction to form a salt which is liquid at temperatures at which the product of value substantially does not decompose during the removal of the liquid salt, and

[0050] c) the salt of the auxiliary base with the product of value or the solution of the product of value in a suitable solvent forms two immiscible liquid phases.

[0051] Preference is given to such auxiliary bases which

[0052] a) do not take part as a reactant in the reaction.

[0053] It is further preferred for this auxiliary base to additionally

[0054] d) simultaneously function as a nucleophilic catalyst in the reaction, i.e. increase the reaction rate of the reaction compared to the operation in the absence of an auxiliary base by at least 1.5 times, preferably by at least two times, more preferably by about five times, most preferably by at least ten times and especially by at least twenty times.

[0055] Such compounds which may be used as bases may contain phosphorus, sulfur or nitrogen atoms, for example at least one nitrogen atom, preferably one to ten nitrogen atoms, more preferably one to five, most preferably one to three and especially one to two. Further heteroatoms, e.g. oxygen, sulfur or phosphorus atoms, may also be present.

[0056] Preference is given to such compounds which contain at least one five- to six-membered heterocycle which contains at least one nitrogen atom and also optionally an oxygen or sulfur atom, greater preference to such compounds which contain at least one five- to six-membered heterocycle which contains one, two or three nitrogen atoms and a sulfur or oxygen atom, and greatest preference is given to those with two nitrogen atoms.

[0057] Greater preference is given to such compounds which have a molecular weight below 1000 g/mol, greatest preference to below 500 g/mol and especially to below 250 g/mol.

[0058] Preference is also given to such compounds usable as bases selected from the compounds of the formulae (Ia) to (Ir), 12

[0059] and also oligomers or polymers which contain these structures,

[0060] where

[0061] R1, R2, R3, R4, R5 and R6 are each independently hydrogen, C1-C18-alkyl, or C2-C18-alkyl, C6-C12-aryl, C5-C12-cycloalkyl, each of which may optionally be interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocycle or two of them combine to form an unsaturated, saturated or aromatic ring which is optionally interrupted by one or more oxygen and/or sulfur atoms and/or by one or more substituted or unsubstituted imino groups, and the stated radicals in each case may be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles.

[0062] Therein, examples of definitions of

[0063] C1-C18-alkyl which is optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, decyl, dodecyl, tetradecyl, hexadecyl, octadecyl, 1,1-dimethylpropyl, 1,1-dimethylbutyl, 1,1,3,3-tetramethylbutyl, benzyl, 1-phenylethyl, 2-phenylethyl, α,α-dimethylbenzyl, benzhydryl, p-tolylmethyl, 1-(p-butylphenyl)-ethyl, p-chlorobenzyl, 2,4-dichlorobenzyl, p-methoxybenzyl, m-ethoxybenzyl, 2-cyanoethyl, 2-cyanopropyl, 2-methoxycarbonylethyl, 2-ethoxycarbonylethyl, 2-butoxycarbonylpropyl, 1,2-di(methoxycarbonyl)ethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, diethoxymethyl, diethoxyethyl, 1,3-dioxolan-2-yl, 1,3-dioxan-2-yl, 2-methyl-1,3-dioxolan-2-yl, 4-methyl-1,3-dioxolan-2-yl, 2-isopropoxyethyl, 2-butoxypropyl, 2-octyloxyethyl, chloromethyl, 2-chloroethyl, trichloromethyl, trifluoromethyl, 1,1-dimethyl-2-chloroethyl, 2-methoxyisopropyl, 2-ethoxyethyl, butylthiomethyl, 2-dodecylthioethyl, 2-phenylthioethyl, 2,2,2-trifluoroethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 4-hydroxybutyl, 6-hydroxyhexyl, 2-aminoethyl, 2-aminopropyl, 3-aminopropyl, 4-aminobutyl, 6-aminohexyl, 2-methylaminoethyl, 2-methylaminopropyl, 3-methylaminopropyl, 4-methylaminobutyl, 6-methylaminohexyl, 2-dimethylaminoethyl, 2-dimethylaminopropyl, 3-dimethylaminopropyl, 4-dimethylaminobutyl, 6-dimethylaminohexyl, 2-hydroxy-2,2-dimethylethyl, 2-phenoxyethyl, 2-phenoxypropyl, 3-phenoxypropyl, 4-phenoxybutyl, 6-phenoxyhexyl, 2-methoxyethyl, 2-methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 6-methoxyhexyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxypropyl, 4-ethoxybutyl or 6-ethoxyhexyl and

[0064] C2-C18-alkyl which is optionally interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups include 5-hydroxy-3-oxapentyl, 8hydroxy-3,6-dioxaoctyl, 11-hydroxy-3,6,9-trioxaundecyl, 7-hydroxy-4-oxaheptyl, 11-hydroxy-4,8-dioxaundecyl, 15-hydroxy-4,8,12-trioxapentadecyl, 9-hydroxy-5-oxanonyl, 14-hydroxy-5,10-oxatetradecyl, 5-methoxy-3-oxapentyl, 8-methoxy-3,6-dioxaoctyl, 11-methoxy-3,6,9-trioxaundecyl, 7-methoxy-4-oxaheptyl, 11-methoxy-4,8-dioxaundecyl, 15-methoxy-4,8,12-trioxapentadecyl, 9-methoxy-5-oxanonyl, 14-methoxy-5,10-oxatetradecyl, 5-ethoxy-3-oxapentyl, 8-ethoxy-3,6-dioxaoctyl, 11-ethoxy-3,6,9-trioxaundecyl, 7-ethoxy-4-oxaheptyl, 11-ethoxy-4,8-dioxaundecyl, 15-ethoxy-4,8,12-trioxapentadecyl, 9-ethoxy-5-oxanonyl or 14-ethoxy-5,10-oxatetradecyl.

[0065] When two radicals form a ring, these radicals combined may be 1,3-propylene, 1,4-butylene, 2-oxa-1,3-propylene, 1-oxa-1,3-propylene, 2-oxa-1,3-propylene, 1-oxa-1,3-propenylene, 1-aza-1,3-propenylene, 1-C1-C4-alkyl-1-aza-1,3-propenylene, 1,4-buta-1,3-dienylene, 1-aza-1,4-buta-1,3-dienylene or 2-aza-1,4-buta-1,3-dienylene.

[0066] The number of the oxygen and/or sulfur atoms and/or imino groups is not limited. In general, it is not more than 5 in the radical, preferably not more than 4 and most preferably not more than 3.

[0067] Also, at least one carbon atom, preferably at least two, are generally located between two heteroatoms.

[0068] Substituted and unsubstituted imino groups may, for example, be imino, methylimino, iso-propylimino, n-butylimino or tert-butylimino.

[0069] Furthermore, functional groups include carboxyl, carboxamide, hydroxyl, di(C1-C4-alkyl)amino, C1-C4-alkyloxycarbonyl, cyano or C1-C4-alkyloxy,

[0070] examples of C6-C12-aryl which may optionally be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles include phenyl, tolyl, xylyl, α-naphthyl, β-naphthyl, 4-diphenylyl, chlorophenyl, dichlorophenyl, trichlorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, iso-propylphenyl, tert-butylphenyl, dodecylphenyl, methoxyphenyl, dimethoxyphenyl, ethoxyphenyl, hexyloxyphenyl, methylnaphthyl, isopropylnaphthyl, chloronaphthyl, ethoxynaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, methoxyethylphenyl and ethoxymethylphenyl,

[0071] examples of C5-C12-cycloalkyl which is optionally substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles include cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, diethylcyclohexyl, butylcyclohexyl, methoxycyclohexyl, dimethoxycyclohexyl, diethoxycyclohexyl, butylthiocyclohexyl, chlorocyclohexyl, dichlorocyclohexyl, dichlorocyclopentyl and also a saturated or unsaturated bicyclic system, e.g. norbornyl or norbornenyl,

[0072] examples of a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocycle include furyl, thiophenyl, pyrryl, pyridyl, indolyl, benzoxazolyl, dioxolyl, dioxyl, benzimidazolyl, benzothiazolyl, dimethylpyridyl, methylquinolyl, dimethylpyrryl, methoxyfuryl, dimethoxypyridyl, difluoropyridyl, methylthiophenyl, isopropylthiophenyl and tert-butylthiophenyl and

[0073] examples of C1 to C4-alkyl include methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl or tert-butyl.

[0074] Preference is given to R1, R2, R3, R4, R5 and R6 independently being hydrogen, methyl, ethyl, n-butyl, 2-hydroxyethyl, 2-cyanoethyl, 2-(methoxycarbonyl)ethyl, 2-(ethoxycarbonyl)ethyl, 2-(n-butoxycarbonyl)ethyl, dimethylamino, diethylamino or chlorine.

[0075] Greater preference is given to such pyridines (la) where one of the radicals R1 to R5 is methyl, ethyl or chlorine and the rest are all hydrogen, or R3 is dimethylamino and the rest are hydrogen or all of them are hydrogen or R2 is carboxyl or carboxamide and all the others are hydrogen or R1 and R2 combined or R2 and R3 combined are 1,4-buta-1,3-dienylene and all the others are hydrogen.

[0076] Greater preference is given to such pyridazines (Ib) where one of the radicals R1 to R4is methyl or ethyl and all the rest are hydrogen or all of them are hydrogen.

[0077] Greater preference is given to such pyrimidines (Ic) where R2 to R4 are hydrogen or methyl and R1 is hydrogen, methyl or ethyl, or R2 and R4 are methyl, R3is hydrogen and R1 is hydrogen, methyl or ethyl.

[0078] Greater preference is given to such pyrazines (Id) where R1 to R4 are all methyl or all hydrogen.

[0079] Greater preference is given to such imidazoles (Ie) where, independently,

[0080] R1 is selected from methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-octyl, 2-hydroxyethyl or 2-cyanoethyl and

[0081] R2 to R4 are each independently hydrogen, methyl or ethyl.

[0082] Greater preference is given to such 1H-pyrazoles (If) where, independently,

[0083] R1 is selected from hydrogen, methyl and ethyl,

[0084] R2, R3 and R4 are each selected from hydrogen and methyl.

[0085] Greater preference is given to such 3H-pyrazoles (Ig) where, independently,

[0086] R1 is selected from hydrogen, methyl and ethyl,

[0087] R2, R3 and R4 are each selected from hydrogen and methyl.

[0088] Greater preference is given to such 4H-pyrazoles (Ih) where, independently,

[0089] R1 to R4 are each selected from hydrogen and methyl.

[0090] Greater preference is given to such 1-pyrazolines (Ii) where, independently,

[0091] R1 to R6 are each selected from hydrogen and methyl.

[0092] Greater preference is given to such 2-pyrazolines (Ij) where, independently,

[0093] R1 is selected from hydrogen, methyl, ethyl and phenyl and

[0094] R2to R6 are each selected from hydrogen and methyl.

[0095] Greater preference is given to such 3-pyrazolines (Ik) in which, independently,

[0096] R1 and R2 are each selected from hydrogen, methyl, ethyl and phenyl and

[0097] R3to R6 are each selected from hydrogen or methyl.

[0098] Greater preference is given to such imidazolines (Il) where, independently,

[0099] R1 and R2 are each selected from hydrogen, methyl, ethyl, n-butyl and phenyl and

[0100] R3 and R4 are each selected from hydrogen, methyl and ethyl and

[0101] R5 and R6 are each selected from hydrogen and methyl.

[0102] Greater preference is given to such imidazolines (Im) where, independently,

[0103] R1 and R2 are each selected from hydrogen, methyl and ethyl and

[0104] R3 to R6 are each selected from hydrogen and methyl.

[0105] Greater preference is given to such imidazolines (In) where, independently,

[0106] R1, R2 and R3 are each selected from hydrogen, methyl and ethyl and

[0107] R4to R6 are each selected from hydrogen and methyl.

[0108] Greater preference is given to such thiazoles (Io) or oxazoles (Ip) where, independently,

[0109] R1 is selected from hydrogen, methyl, ethyl and phenyl and

[0110] R2 and R3 are selected from hydrogen and methyl.

[0111] Greater preference is given to such 1,2,4-triazoles (Iq) where, independently,

[0112] R1 and R2 are each selected from hydrogen, methyl, ethyl and phenyl and

[0113] R3 is selected from hydrogen, methyl and phenyl.

[0114] Greater preference is given to such 1,2,3-triazoles (Ir) where, independently,

[0115] R1 is selected from hydrogen, methyl and ethyl and

[0116] R2 and R3 are selected from hydrogen and methyl or

[0117] R2 and R3 combined are 1,4-buta-1,3-dienylene and all others are hydrogen.

[0118] Among these, preference is given to the pyridines and the imidazoles.

[0119] Greatest preference is given to the bases 3-chloropyridine, 4-dimethylaminopyridine, 2-ethyl-4-aminopyridine, 2-methylpyridine (α-picoline), 3-methylpyridine (β-picoline), 4-methylpyridine (γ-picoline), 2-ethylpyridine, 2-ethyl-6-methylpyridine, quinoline, isoquinoline, 1-C1-C4-alkylimidazole, 1-methylimidazole, 1,2-dimethylimidazole, 1-n-butylimidazole, 1,4,5-trimethylimidazole, 1,4-dimethylimidazole, imidazole, 2-methylimidazole, 1-butyl-2-methylimidazole, 4-methylimidazole, 1-n-pentylimidazole, 1-n-hexylimidazole, 1-n-octylimidazole, 1-(2′-aminoethyl)imidazole, 2-ethyl-4-methylimidazole, 1-vinylimidazole, 2-ethylimidazole, 1-(2′-cyanoethyl)imidazole and benzotriazole.

[0120] Special preference is given to 1-n-butylimidazole, 1-methylimidazole, 2-methylpyridine and 2-ethylpyridine.

[0121] Further suitable bases include tertiary amines of the formula (XI)

NRaRbRc  (XI),

[0122] where

[0123] Ra, Rb and Rc are each independently C1-C18-alkyl, or C2-C18-alkyl, C6-C12-aryl or C5-C12-cycloalkyl, each of which may optionally be interrupted by one or more oxygen and/or sulfur atoms and/or one or more substituted or unsubstituted imino groups, or a five- to six-membered, oxygen, nitrogen and/or sulfur atom-containing heterocycle or two of them combine to form an unsaturated, saturated or aromatic ring which is optionally interrupted by one or more oxygen and/or sulfur atoms and/or by one or more substituted or unsubstituted imino groups, and the stated radicals in each case may be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles,

[0124] with the proviso that

[0125] at least two of the three radicals Ra, Rb and Rc are different and

[0126] the radicals Ra, Rb and Rc together have at least 8, preferably at least 10, more preferably at least 12 and most preferably at least 13, carbon atoms.

[0127] Ra, Rb and Rc are preferably each independently C1-C18-alkyl, C6-C12-aryl or C5-C12-cycloalkyl and more preferably C1-C18-alkyl, and the stated radicals in each case may be substituted by functional groups, aryl, alkyl, aryloxy, alkyloxy, halogen, heteroatoms and/or heterocycles.

[0128] Examples of the particular groups have already been listed above.

[0129] Preferred meanings for the Ra, Rb and Rc radicals include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl (n-amyl), 2-pentyl (sec-amyl), 3-pentyl, 2,2-dimethylprop-1-yl (neopentyl), n-hexyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, 1,1-dimethylpropyl, 1,1-dimethylbutyl, benzyl, 1-phenylethyl, 2-phenylethyl,

Claims

1. A process for removing acids from reaction mixtures using an auxiliary base, which comprises the auxiliary base b) combining with the acid to form a salt which is liquid at temperatures at which the product of value does not significantly decompose during the removal of the liquid salt, and c) the salt of the auxiliary base with the product of value or the solution of the product of value in a suitable solvent forming two immiscible liquid phases.

2. A process as claimed in claim 1, wherein the acid is released in the course of a phosphorylation, silylation, sulfurization, acylation with the exception of phosgenations, elimination or substitution.

3. A process as claimed in claim 1 or 2, wherein the auxiliary base additionally d) simultaneously functions as a nucleophilic catalyst.

4. A process as claimed in any of claims 1 to 3, wherein the salt of the auxiliary base has a melting point below 160° C.

5. A process as claimed in any of claims 1 to 4, wherein the salt of the auxiliary base has an ET(30) value of greater than 35.

6. A process as claimed in any of claims 1 to 5, wherein the base contains at least one nitrogen atom.

7. A process as claimed in any of claims 1 to 6, wherein a base is used which is selected from the group consisting of the formulae (Ia) to (Ir),

8. A process as claimed in any of claims 1 to 7, wherein the auxiliary base is 1-n-butylimidazole, 1-methylimidazole, 2-methylpyridine or 2-ethylpyridine.

9. A process as claimed in any of claims 1 to 8, wherein the acid is hydrochloric acid, acetic acid, p-toluenesulfonic acid, methanesulfonic acid or trifluoromethanesulfonic acid.

10. A process as claimed in any of the preceding claims, wherein the molar ratio of Brönsted acids to Lewis acids in the removed salt of the acid with the auxiliary base is greater than 4:1.

11. A process as claimed in any of claims 1 to 10, wherein the salt of the auxiliary base is less than 20% by weight soluble in the product of value or in the solution of the product of value in a suitable solvent.

12. A process as claimed in any of claims 1 or 3 to 11, wherein the acid was not released during the reaction.

13. A process as claimed in any of the preceding claims, wherein phosphines, phosphinic esters, phosphinous esters (phosphinites), phosphonic esters, phosphonic halides, phosphonic amides, phosphonous esters (phosphonites), phosphonous amides, phosphonous halides, phosphoric esters, phosphoric diester halides, phosphoric diester amides, phosphoric ester dihalides, phosphoric ester diamides, phosphorous esters (phosphites), phosphorous diester halides, phosphorous diester amides, phosphorous ester dihalides or phosphorous ester diamides are prepared.

14. A process for preparing phosphorus compounds from the respective reactants as claimed in claim 13, wherein the preparation is carried out continuously at a temperature of from 60° C. to 150° C. and a residence time of 1 hour.

15. The use of a phosphine, phosphinic ester, phosphinous ester (phosphinites), phosphonic ester, phosphonic halide, phosphonic amide, phosphonous ester (phosphonites), phosphonous amide, phosphonous halide, phosphoric ester, phosphoric diester halide, phosphoric diester amide, phosphoric ester dihalide, phosphoric ester diamide, phosphorous ester (phosphites), phosphorous diester halide, phosphorous diester amide, phosphorous ester dihalide or phosphorous ester diamide obtainable by a process as claimed in claim 13 or 14 as a ligand for catalysts.

16. The use of a ligand as claimed in claim 15 as a ligand for cobalt, rhodium, ruthenium, palladium, platinum, osmium, iridium or nickel catalysts.

17. The use of a catalyst as claimed in claim 16 in a hydrocyanation, hydrogenation or hydroformylation.

18. A process as claimed in claim 1, wherein the auxiliary base is used in nonionic form.

19. A process as claimed in any of claims 1 to 9 or 11 to 14, wherein the acid is a Lewis acid.

20. A process as claimed in claim 19, wherein the molar ratio of Brönsted acids to Lewis acids in the removed salt of the acid with the auxiliary base is not greater than 1:1.

21. A process as claimed in claim 19, wherein the reaction mixture stems from a Friedel-Crafts alkylation or acylation, phosphorylation or sulfurization of aromatics.

22. A process as claimed in claim 21, wherein an aromatic of the formula (X) is used

23. A process as claimed in claim 21, wherein the product is ethylbenzene, acetophenone, 4-methylacetophenone, 4-methoxyacetophenone, propiophenone, benzophenone, dichlorophenylphosphine, diphenylchlorophosphine, tosyl chloride, 1,2-, 1,3- or 1,4-diethylbenzene, 1,2,3-, 1,2,4- or 1,3,5-triethylbenzene, cumene (isopropylbenzene), tert-butylbenzene, 1,3- or 1,4-methylisopropylbenzene, 9,10-dihydroanthracene, indane, cresol, 2,6-xylenol, 2-sec-butylphenol, 4-tert-butylphenol, octylphenol, nonylphenol, dodecylphenol, thymol or 2,6-di-tert-butyl-4-methylphenol.

24. A process as claimed in any of claims 1 to 6, wherein the auxiliary base is a tertiary amine of the formula (XI)

25. A process as claimed in claim 24, wherein Ra, Rb and Rc are selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl (n-amyl), 2-pentyl (sec-amyl), 3-pentyl, 2,2-dimethylprop-1-yl (neopentyl), n-hexyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, 1,1-dimethylpropyl, 1,1-dimethylbutyl, benzyl, 1-phenylethyl, 2-phenylethyl, α,α-dimethylbenzyl, phenyl, tolyl, xylyl, α-naphthyl, β-naphthyl, cyclopentyl and cyclohexyl.

26. A process as claimed in claim 24 or 25, wherein the tertiary amine is selected from diisopropylethylamine, diethyl-tert-butylamine, diisopropylbutylamine, di-n-butyl-n-pentylamine, N,N-di-n-butylcyclohexylamine and tertiary amines of pentyl isomers and triallylamine.