Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C231/00—Preparation of carboxylic acid amides
  • C07C231/02—Preparation of carboxylic acid amides from carboxylic acids or from esters, anhydrides, or halides thereof by reaction with ammonia or amines

Definitions

• Fatty acid amides find versatile use as chemical raw materials, for
• Metal working used in the formulation of pesticides and in the extraction and processing of petroleum.
• a reactive derivative of a fatty acid such as acid anhydride, acid chloride or ester is usually reacted with an amine or it is in situ activation of the carboxylic acid by the use of coupling reagents such as N.N'-dicyclohexylcarbodiimide or worked with very special and therefore expensive catalysts.
• this leads to high production costs and, on the other hand, to undesired accompanying products, such as, for example, salts or acids, which have to be separated off and disposed of or worked up.
• equimolar amounts of common salt are formed.
• Vazquez-Tato Synlett 1993, 506, discloses the use of microwaves as a heat source for the preparation of amides from carboxylic acids and arylaliphatic amines via the ammonium salts. The syntheses were done there on a mmol scale.
• Microwave irradiation can be converted to the amide.
• the aim is to achieve as high as possible, that is to say quantitative conversion rates and yields.
• the method should further enable a possible energy-saving production of fatty acid amides, that is, the microwave power used should be absorbed as quantitatively as possible from the reaction mixture and thus offer the process a high energy efficiency. This should be incurred no or only minor amounts of by-products.
• the amides should also have the lowest possible metal content and a low intrinsic color. In addition, the process should ensure a safe and reproducible reaction.
• fatty acid amides can be prepared in technically relevant quantities by direct reaction of fatty acids with amines in a continuous process by only brief heating by irradiation with microwaves in a reaction tube whose longitudinal axis is in the propagation direction of the microwaves of a single-mode microwave applicator , In this case, the microwave energy radiated into the microwave applicator is absorbed virtually quantitatively by the reaction mixture.
• the inventive method also has a high level of safety in the implementation and provides a high reproducibility of the set reaction conditions.
• the amides prepared by the process according to the invention show a high purity and low intrinsic coloration, which are not accessible without additional process steps, compared to conventional preparation processes.
• the invention relates to a continuous process for the preparation of fatty acid amides by reacting at least one fatty acid of the formula I.
• R 3 is an optionally substituted aliphatic hydrocarbon radical having 5 to 50 carbon atoms
• R 1 and R 2 independently of one another represent hydrogen or a hydrocarbon radical having 1 to 100 C atoms
• Another object of the invention are fatty acid amides with a low metal content, prepared by reacting at least one fatty acid of formula I.
• R 3 is hydrogen or an optionally substituted aliphatic hydrocarbon radical having 5 to 50 carbon atoms, with at least one amine of the formula
• R 1 and R 2 independently of one another represent hydrogen or a hydrocarbon radical having 1 to 100 C atoms
• Suitable fatty acids of the formula I are generally compounds which have at least one carboxyl group on an optionally substituted aliphatic hydrocarbon radical having 5 to 50 carbon atoms.
• the aliphatic hydrocarbon radical is an unsubstituted alkyl or alkenyl radical.
• the aliphatic hydrocarbon radical bears one or more, for example two, three, four or more further substituents.
• Suitable substituents are, for example, halogen atoms, C r C 5 alkoxy such as methoxy, poly (C- ⁇ -C 5 alkoxy), poly (Ci-C 5 alkoxy) alkyl, carboxyl, ester, amide -, cyano, nitrile, nitro, sulfonic acid and / or aryl groups having 5 to 20 carbon atoms such as phenyl groups, with the proviso that they are stable under the reaction conditions and do not undergo side reactions such as elimination reactions.
• the C 5 -C 2 o-aryl groups can in turn substituents such as halogen atoms, halogenated alkyl radicals, CrC 2 o-alkyl, C 2 -C 2 o-alkenyl, C r C 5 alkoxy such as methoxy, ester , Amide, cyano, nitrile, and / or nitro groups.
• the aliphatic hydrocarbon radical carries at most as many substituents as it has valencies.
• the aliphatic hydrocarbon radical R 3 bears further carboxyl groups.
• the process according to the invention is also suitable for the amidation of polycarboxylic acids with, for example, two, three, four or more carboxyl groups.
• imides can also be formed.
• fatty acids (I) which carry an aliphatic hydrocarbon radical having 6 to 30 carbon atoms and in particular having 7 to 24 carbon atoms, for example having 8 to 20 carbon atoms. They can be natural or synthetic.
• the aliphatic hydrocarbon radical may also contain heteroatoms such as oxygen, nitrogen, phosphorus and / or sulfur, but preferably not more than one heteroatom per 3 C atoms.
• the aliphatic hydrocarbon radicals can be linear, branched or cyclic.
• the carboxyl group may be bonded to a primary, secondary or tertiary C atom. It is preferably bound to a primary carbon atom.
• the hydrocarbon radicals can be saturated or unsaturated.
• Preferred cyclic aliphatic hydrocarbon radicals have at least one ring with four, five, six, seven, eight or more ring atoms.
• Suitable fatty acids are, for example, pentane, pivalin, hexane, cyclohexane, heptane, octane, nonane, neononane, decane, neodecane, undecane, neoundecane, dodecane, tridecane, tetradecane, 12 Methyltridecane, pentadecane, 13-methyltetradecane, 12-methyltetradecane, hexadecane, 14-methylpentadecane, heptadecane, 15-methylhexadecane, 14-methylhexadecane, octadecane, iso-octadecane, icosan, docosan and tetracosanoic acid, as well as myristolein, palmitoleic, hexadecadiene, delta-9-cis-heptadecene
• the process according to the invention is preferably suitable for the preparation of secondary amides, ie for the reaction of fatty acids with amines in which R 1 is a hydrocarbon radical having 1 to 100 carbon atoms and R 2 is hydrogen.
• R 1 and / or R 2 are independently an aliphatic radical. This preferably has 1 to 24, more preferably 2 to 18 and especially 3 to 6 C atoms.
• the aliphatic radical may be linear, branched or cyclic. It may also be saturated or unsaturated, preferably it is saturated.
• the hydrocarbon radical may carry substituents such as, for example, C r C 5 -alkoxyalkyl, cyano, nitrile, nitro and / or C 5 -C 2 o-aryl groups, for example phenyl radicals.
• R 1 and / or R 2 independently of one another represent an optionally substituted C 6 -C 12 -aryl group or an optionally substituted heteroaromatic group having 5 to 12 ring members.
• R 1 and / or R 2 independently of one another are an alkyl radical interrupted by heteroatoms. Particularly preferred heteroatoms are oxygen and nitrogen.
• R 4 is an alkylene group having 2 to 6 carbon atoms and preferably 2 to
• R 1 and / or R 2 independently of one another are preferably radicals of the formula IV
• these amines can also be repeatedly amidated or imidated with the fatty acid (I).
• the process according to the invention is suitable for preparing fatty acid amides bearing tertiary amino groups, at least one fatty acid (I) having at least one polyamine carrying a primary and / or secondary and at least one tertiary amino group being converted into an ammonium salt and subsequently under microwave irradiation a reaction tube whose longitudinal axis is in the propagation direction of the microwaves of a single-mode microwave applicator is converted to the basic fatty acid amide.
• Tertiary amino groups here are understood as meaning structural units in which a nitrogen atom does not carry an acidic proton.
• the nitrogen of the tertiary amino group may be three
• R 1 is preferably one of the meanings given above, particularly preferably hydrogen, an aliphatic radical having 1 to 24 C atoms or an aryl group having 6 to 12 C atoms and especially for methyl, and R 2 for a tertiary Amino groups bearing hydrocarbon radical of formula V
• A is a divalent hydrocarbon radical having 2 to 50 carbon atoms, s is 0 or 1,
• Z is a group of the formula -NR 8 R 9 or a nitrogen-containing cyclic hydrocarbon radical having at least 5 ring members and
• R 8 and R 9 independently of one another represent Cr to C 2 o-hydrocarbon radicals or for polyoxyalkylene radicals of the formula (III).
• A is preferably an alkylene radical having 2 to 24 C atoms, a cycloalkylene radical having 5 to 12 ring members, an arylene radical having 6 to 12
• Ring members or a heteroarylene radical with 5 to 12 ring members A particularly preferably represents an alkylene radical having 2 to 12 C atoms. Preferably stands s for 1. Particularly preferably, A is a linear or branched alkylene radical having 1 to 6 C atoms and s is 1.
• A is a linear or branched alkylene radical having 2, 3 or 4 C atoms, in particular an ethylene radical or a linear propylene radical.
• Z is a nitrogen-containing cyclic hydrocarbon radical, compounds are particularly preferred in which A is a linear alkylene radical having 1, 2 or 3 C atoms, in particular a methylene, ethylene or a linear propylene radical.
• Z is preferably a group of the formula -NR 8 R 9 .
• R 8 and R 9 independently of one another are preferably aliphatic, aromatic and / or araliphatic hydrocarbon radicals having 1 to 20 carbon atoms.
• R 8 and R 9 are particularly preferred alkyl radicals. If R 8 and / or R 9 are alkyl radicals, they preferably carry 1 to 14 C atoms, for example 1 to 6 C atoms. These alkyl radicals can be linear, branched and / or cyclic.
• R 8 and R 9 particularly preferably represent alkyl radicals having 1 to 4 C atoms, such as, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl and isobutyl.
• the radicals R 8 and / or R 9 independently of one another are polyoxyalkylene radicals of the formula III.
• R 8 and / or R 9 particularly suitable aromatic radicals include ring systems having at least 5 ring members. They may contain heteroatoms such as S, O and N.
• R 8 and / or R 9 particularly suitable araliphatic radicals include ring systems having at least 5 ring members, which have a
• C 1 -C 6 -alkyl radical are bonded to the nitrogen. They may contain heteroatoms such as S, O and N.
• the aromatic as well as the araliphatic radicals may carry further substituents such as, for example, alkyl radicals, halogen atoms, halogenated alkyl radicals, nitro, cyano and / or nitrile groups.
• Z is a nitrogen-containing, cyclic hydrocarbon radical whose nitrogen atom is not capable of forming amides.
• the cyclic system can be mono-, di- or also polycyclic. It preferably contains one or more five- and / or six-membered rings.
• This cyclic hydrocarbon may contain one or more, such as two or three, nitrogen atoms which do not carry acidic protons, most preferably it contains an N atom.
• Particularly suitable are nitrogen-containing aromatics whose nitrogen is involved in the formation of an aromatic ⁇ -Elektronensextetts such as pyridine.
• nitrogen-containing heteroaliphatic compounds whose nitrogen atoms do not carry any protons and, for example, are all saturated with alkyl radicals.
• the linking of Z with A or the nitrogen of the formula (II) is preferably carried out here via a nitrogen atom of the heterocycle, for example in the case of 1- (3-aminopropyl) pyrrolidine.
• the cyclic hydrocarbon represented by Z may carry further substituents such as, for example, C 1 -C 2 0-alkyl radicals, halogen atoms, halogenated alkyl radicals, nitro, cyano and / or nitrile groups.
• one or more amino groups are converted into the fatty acid amide.
• the primary amino groups can also be converted into imides.
• nitrogen-containing compounds which split off ammonia gas on heating instead of ammonia.
• nitrogen-containing compounds are urea and formamide.
• Suitable amines are ammonia, methylamine, ethylamine,
• suitable amines carrying tertiary amine groups are N, N-dimethylethylenediamine, N, N-dimethyl-1,3-propanediamine, N, N-diethyl-1,3-propanediamine, N, N-dimethyl-2-methyl-1, 3-propanediamine, 1- (3-aminopropyl) pyrrolidine, 1- (3-aminopropyl) -4-methylpiperazine,
• the process is particularly suitable for the preparation of N, N-dimethylhexanoic acid amide; N, N-dimethylcyclohexanoic acid amide, N-methyloctanoic acid amide, N, N-dimethyl octanoic acid amide, N, N-dimethyl decanoic acid amide, N-methyl stearic acid amide, N, N-dimethyl stearic acid amide, N-methyl coconut fatty acid amide, N, N-dimethyl coconut fatty acid amide, N-ethyl coconut fatty acid amide, N, N-diethyl coconut fatty acid amide, N, N-dimethyl tallow fatty acid amide, N-octadecylhexanoic acid amide, and NN-dioctadecyloctanoic acid amide. Furthermore, it is particularly suitable for preparing N- (N, N'-dimethylamino) propyldicanoic
• fatty acid and amine can be reacted with one another in any ratio.
• the reaction between fatty acid and amine preferably takes place with molar ratios of from 10: 1 to 1: 100, preferably from 2: 1 to 1:10, especially from 1.2: 1 to 1: 3, in each case based on the molar equivalents of carboxyl and amino groups.
• fatty acid and amine are used equimolarly.
• the inventive preparation of the amides is carried out by reacting fatty acid and amine to form the ammonium salt and subsequent irradiation of the salt with microwaves in a reaction tube whose longitudinal axis is in the Propagation direction of the microwaves is located in a single-mode microwave applicator.
• the irradiation of the salt with microwaves preferably takes place in a largely microwave-transparent reaction tube, which is located within a waveguide connected to a microwave generator.
• the reaction tube is aligned axially with the central axis of symmetry of the waveguide.
• the waveguide acting as a microwave applicator is preferably formed as a cavity resonator. Further preferably, the microwaves not absorbed in the waveguide are reflected at its end.
• the microwave applicator as a reflection-type resonator, a local increase in the electric field strength is achieved with the same power supplied by the generator and an increased energy utilization.
• the cavity resonator is preferably operated in mode n E i 0, where n is an integer and represents the number of field maxima of the microwave along the central axis of symmetry of the resonator.
• the electric field is directed toward the central axis of symmetry of the cavity resonator. It has a maximum in the area of the central axis of symmetry and decreases to the lateral surface to the value zero.
• This field configuration is rotationally symmetric about the central axis of symmetry.
• the length of the resonator is selected relative to the wavelength of the microwave radiation used.
• N is preferably an integer from 1 to 200, particularly preferably from 2 to 100, in particular from 4 to 50 and especially from 3 to 20, for example 3, 4, 5, 6, 7 or 8.
• the irradiation of the microwave energy into the waveguide acting as a microwave applicator can take place via suitably dimensioned holes or slots.
• the irradiation of the ammonium salt with microwaves takes place in one Reaction tube, which is located in a waveguide with coaxial transition of the microwaves.
• particularly preferred microwave devices are constructed of a cavity resonator, a coupling device for coupling a microwave field in the cavity and each with an opening at two opposite end walls for passing the reaction tube through the resonator.
• the coupling of the microwaves in the cavity resonator is preferably carried out via a coupling pin, which projects into the cavity resonator.
• the coupling pin is preferably shaped as a preferably metallic inner conductor tube functioning as a coupling antenna.
• this coupling pin protrudes through one of the frontal openings into the cavity resonator.
• the reaction tube connects to the inner conductor tube of the coaxial transition and in particular it is guided through its cavity into the cavity resonator.
• the reaction tube is aligned axially with a central axis of symmetry of the cavity resonator, for which purpose the cavity resonator preferably each has a central opening on two opposite end walls for passing the reaction tube.
• Coupling antenna acting inner conductor tube can be done for example by means of a coaxial connecting cable.
• the microwave field is supplied to the resonator via a waveguide, wherein the protruding from the cavity resonator end of the coupling pin is guided into an opening which is located in the wall of the waveguide in the waveguide and the waveguide takes microwave energy and in the Resonator couples.
• the irradiation of the salt with microwaves is carried out in a microwave-transparent reaction tube which is axially symmetrical in an EOM round waveguide with coaxial transition of the microwaves.
• the reaction tube through the cavity of an acting as a coupling antenna inner conductor tube into the cavity resonator guided.
• Microwave generators such as the magnetron, the klystron and the gyrotron are known in the art.
• suitable reaction tubes Materials with tan ⁇ values measured at 2.45 GHz and 25 ° C. of below 0.01, in particular below 0.005 and especially below 0.001 are preferred.
• temperature-stable plastics such as in particular fluoropolymers such as Teflon, and engineering plastics such as polypropylene, or polyaryletherketones such as Glass fiber reinforced polyetheretherketone (PEEK) are suitable as tube materials.
• PEEK Glass fiber reinforced polyetheretherketone
• reaction tubes have an inner diameter of one millimeter to about 50 cm, especially between 2 mm and 35 cm, for example between 5 mm and 15 cm.
• Reaction tubes are understood here to be vessels whose ratio of length to diameter is greater than 5, preferably between 10 and 100,000, particularly preferably between 20 and 10,000, for example between 30 and 1,000.
• the length of the reaction tube is understood here as the distance of the reaction tube on which the microwave irradiation takes place.
• baffles and / or other mixing elements can be installed.
• Eoi cavity resonators preferably have a diameter corresponding to at least half the wavelength of the microwave radiation used.
• the diameter of the cavity resonator is preferably from 1.0 to 10 times, more preferably from 1.1 to 5 times and in particular from 2.1 to 2.6 times the half wavelength of the microwave radiation used.
• the E 0 i cavity resonator has a round cross-section, which is also referred to as Eoi round waveguide. Particularly preferably it has a cylindrical shape and especially a circular cylindrical shape.
• the reaction tube is usually provided at the inlet with a metering pump and a pressure gauge and at the outlet with a pressure holding device and a heat exchanger. This allows reactions in a very wide range of pressure and temperature.
• the conversion of amine and fatty acid to the ammonium salt can be carried out continuously, batchwise or else in semi-batch processes.
• the preparation of the ammonium salt in an upstream (semi) -Batch Process be performed as for example in a stirred tank.
• the ammonium salt is preferably generated in situ and not isolated.
• the educts amine and fatty acid, both optionally diluted with solvent, if appropriate, are mixed just shortly before they enter the reaction tube.
• the educts are fed to the process according to the invention in liquid form.
• higher-melting and / or higher-viscosity starting materials for example in the molten state and / or with solvent, for example, can be used as solution, dispersion or emulsion.
• a catalyst can be added to one of the educts or else to the educt mixture before it enters the reaction tube.
• Solid, pulverulent and heterogeneous systems can also be reacted by the process according to the invention, with only corresponding technical devices for conveying the reaction mixture being required.
• the ammonium salt may be fed into the reaction tube either at the end guided through the inner conductor tube, as well as at the opposite end.
• the reaction conditions are adjusted so that the maximum reaction temperature is reached as quickly as possible and the residence time at maximum temperature remains so short that so few side or subsequent reactions occur as possible.
• the reaction mixture can be passed through the reaction tube several times to complete the reaction, optionally after intermediate cooling. In many cases, it has proven useful if the reaction product immediately after leaving the reaction tube z. B. is cooled by jacket cooling or relaxation. 2
• the advantages of the method according to the invention lie in a very uniform irradiation of the reaction material in the center of a symmetrical microwave field within a reaction tube whose longitudinal axis is in the propagation direction of the microwaves of a single-mode microwave applicator and in particular within a E 0 i cavity resonator, for example with coaxial transition.
• the reactor design according to the invention allows reactions to be carried out even at very high pressures and / or temperatures. By increasing the temperature and / or pressure, a clear increase in the degree of conversion and yield is also observed in comparison to known microwave reactors, without causing undesired side reactions and / or discoloration.
• a very high efficiency is achieved in utilizing the microwave energy radiated into the cavity resonator, which is usually more than 50%, often more than 80%, partly over 90% and in special cases more than 95%, for example over 98% of the radiated microwave power and thus provides economic as well as environmental advantages over conventional manufacturing methods as well as prior art microwave methods.
• the inventive method also allows a controlled, safe and reproducible reaction. Since the reaction mixture is moved in the reaction tube parallel to the propagation direction of the microwaves, known overheating phenomena are compensated by uncontrollable field distributions, which lead to local overheating by changing intensities of the field, for example in wave crests and nodes, by the flow of the reaction material.
• the advantages mentioned also make it possible to work with high microwave powers of, for example, more than 10 kW or more than 100 kW, and thus in combination with only a short residence time in the Cavity resonator large production volumes of 100 and more tons per year to accomplish in a plant.
• Ammonium salt in the microwave field a very extensive amidation with conversions in general of over 80%, often over 90% such as more than 95% based on the component used in the deficit occurs, without formation of appreciable amounts of by-products.
• these ammonium salts in a flow tube of the same dimensions under thermal jacket heating extremely high wall temperatures are required to achieve suitable reaction temperatures, which led to the formation of undefined polymers and colored species, but cause only minor amide formation at the same time interval.
• the products produced by the process according to the invention have very low metal contents without the need for further processing of the crude products.
• the metal contents of the products produced by the process according to the invention based on iron as the main element are usually below 25 ppm, preferably below 15 ppm, especially below 10 ppm, such as between 0.01 and 5 ppm iron.
• the temperature rise caused by the microwave irradiation is limited to a maximum of 500 ° C., for example by controlling the microwave intensity, the flow rate and / or by cooling the reaction tube, for example by a stream of nitrogen.
• the implementation of the reaction has proven particularly useful at temperatures between 150 and 400 ° C. and especially between 180 and 300 ° C., for example at temperatures between 200 and 270 ° C.
• the duration of the microwave irradiation depends on various factors such as the geometry of the reaction tube, the radiated microwave energy, the specific reaction and the desired degree of conversion. Usually, the microwave irradiation over a Period of less than 30 minutes, preferably between 0.01 seconds and 15 minutes, more preferably between 0.1 seconds and 10 minutes and in particular between one second and 5 minutes, for example between 5 seconds and 2 minutes.
• the intensity (power) of the microwave radiation is adjusted so that the reaction material when leaving the cavity resonator has the desired maximum temperature.
• the reaction product is cooled as soon as possible after completion of the microwave irradiation to temperatures below 120 0 C, preferably below 100 0 C and especially below 60 0 C.
• the reaction is carried out at pressures between 0.01 and 500 bar and more preferably between 1 bar (atmospheric pressure) and 150 bar and especially between 1, 5 bar and 100 bar such as between 3 bar and 50 bar.
• Working under elevated pressure has proven particularly useful, the starting materials or products, the optionally present solvent and / or above the reaction water formed during the reaction being worked above the boiling point (at atmospheric pressure). More preferably, the pressure is set so high that the reaction mixture remains in the liquid state during microwave irradiation and does not boil.
• an inert protective gas such as nitrogen, argon or helium.
• the reaction is accelerated or completed in the presence of dehydrating catalysts.
• dehydrating catalysts Preferably, one works in the presence of an acidic inorganic, organometallic or organic catalyst or mixtures of several of these catalysts.
• acidic inorganic catalysts for the purposes of the present invention are sulfuric acid, phosphoric acid, phosphonic acid, hypophosphorous acid, aluminum sulfate hydrate, alum, acidic silica gel and acidic aluminum hydroxide.
• aluminum compounds of the general formula AI (OR 15 ) 3 and titanates of the general formula Ti (OR 15 ) 4 can be used as acidic inorganic catalysts, wherein the radicals R 15 may be the same or different and are independently selected from CiC-io Alkyl radicals, for example methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, iso-pentyl, sec-pentyl, neo-pentyl , 1, 2-dimethylpropyl, iso-amyl, n-hexyl, sec-hexyl, n-heptyl, n-octyl, 2-Ethylhexy, n-nonyl or n-decyl, C 3 -C 2 cycloalkyl, e.g.
• the radicals R 15 in Al (OR 15 ) 3 or Ti (OR 15 ) 4 are preferably identical and selected from isopropyl, butyl and 2-ethylhexyl.
• Preferred acidic organometallic catalysts are, for example, selected from dialkyltin oxides (R 15 ) 2 SnO, where R 15 is as defined above.
• R 15 dialkyltin oxides
• a particularly preferred representatives of acidic organometallic catalysts is di-n-butyltin oxide, which is commercially available as so-called Oxo-tin or as Fascat ® brands.
• Preferred acidic organic catalysts are acidic organic compounds with, for example, phosphate groups, sulfonic acid groups, sulfate groups or phosphonic acid groups.
• Particularly preferred sulfonic acids contain at least one sulfonic acid group and at least one saturated or unsaturated, linear, branched and / or cyclic hydrocarbon radical having 1 to 40 carbon atoms and preferably having 3 to 24 carbon atoms.
• Particularly preferred are aromatic sulfonic acids, especially alkylaromatic monosulfonic acids having one or more Ci-C2 ⁇ -alkyl radicals and especially those having C 3 -C 22 -alkyl radicals.
• Suitable examples are methanesulfonic acid, butanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, xylenesulfonic acid, 2-mesitylenesulfonic acid, 4-ethylbenzenesulfonic acid, isopropylbenzenesulfonic acid, 4-butylbenzenesulfonic acid, 4-octylbenzenesulfonic acid; Dodecylbenzenesulfonic acid, didodecylbenzenesulfonic acid, naphthalenesulfonic acid.
• Acidic ion exchangers can also be used as acidic organic catalysts, for example poly (styrene) sulfonic acid groups which are crosslinked with about 2 mol% of divinylbenzene.
• titanates of the general formula Ti (OR 15 ) 4 and especially titanium tetrabutylate and titanium tetraisopropylate are particularly preferred for carrying out the process according to the invention.
• acidic inorganic, organometallic or organic catalysts according to the invention 0.01 to 10% by weight, preferably 0.02 to 2% by weight, of catalyst is used. In a particularly preferred embodiment, working without a catalyst.
• the microwave irradiation is carried out in the presence of acidic solid catalysts.
• the solid catalyst is suspended in the optionally mixed with solvent ammonium salt or advantageously the optionally with solvent-added ammonium salt passed through a fixed bed catalyst and exposed to microwave radiation.
• suitable solid catalysts are zeolites, silica gel, montmorillonite and (partially) crosslinked polystyrenesulphonic acid, which may optionally be impregnated with catalytically active metal salts.
• Suitable acidic ion exchanger based on polystyrene sulfonic acids that can be used as solid phase catalysts are for example available from the company Rohm & Haas under the trademark Amberlyst ®.
• Suitable solvents for the process according to the invention are, in particular, solvents having ⁇ " values below 10, such as N-methylpyrrolidone, N, N-dimethylformamide or acetone, and in particular solvents having ⁇ "values below 1.
• EXAMPLES for particularly preferred solvents with ⁇ "values below 1 are aromatic and / or aliphatic hydrocarbons such as toluene, xylene, ethylbenzene, tetralin, hexane, cyclohexane, decane, pentadecane, decalin and commercial hydrocarbon mixtures such as gasoline fractions, kerosene, solvent naphtha, ® Shellsol AB, ® Solvesso 150, ® Solvesso 200, ® Exxs ol, ® isopar and ® Shellsol types.
• Solvent mixtures which have ⁇ "values preferably below 10 and especially below 1 are equally preferred for carrying out the process according to the invention.
• the process according to the invention can also be carried out in solvents having higher ⁇ "values of, for example, 5 and higher, in particular with ⁇ " values of 10 and higher.
• ⁇ values of, for example, 5 and higher
• ⁇ values of 10 and higher.
• reaction mixture is preferably between 2 and 95 wt .-%, especially between 5 and 90 wt .-% and in particular between 10 and 75 wt .-%, such as between 30 and 60 wt .-%.
• the reaction is carried out solvent-free.
• Microwaves are electromagnetic waves having a wavelength between about 1 cm and 1 m and frequencies between about 300 MHz and 30 GHz. This frequency range is suitable in principle for the method according to the invention.
• microwave radiation with the frequencies released for industrial, scientific and medical applications is preferably used, for example with frequencies of 915 MHz, 2.45 GHz, 5.8 GHz or 27.12 GHz.
• microwave power to be radiated into the cavity resonator for carrying out the method according to the invention is in particular dependent on the geometry of the reaction tube and thus of the
• Reaction volume and the duration of the required irradiation It is usually between 200 W and several 100 kW and in particular between 500 W and 100 kW such as between 1 kW and 70 kW. It can be generated by one or more microwave generators.
• the reaction is carried out in a pressure-resistant inert tube, wherein the water of reaction forming and optionally starting materials and, if present, solvents lead to a pressure build-up.
• the excess pressure can be used by relaxation for volatilization and separation of water of reaction, excess starting materials and, if appropriate, solvents and / or for cooling the reaction product.
• the water of reaction formed is after cooling and / or relaxation by conventional methods such as phase separation, distillation stripping, flashing and / or absorption separated.
• the inventive method allows a very fast, energy-saving and cost-effective production of fatty acid amides in high yields and high purity in large quantities. Due to the very uniform irradiation of the ammonium salt in the center of the rotationally symmetric microwave field, it allows a safe, controllable and reproducible reaction. It is achieved by a very high efficiency in the utilization of the radiated microwave energy, the known manufacturing process significantly superior efficiency. This process does not generate significant amounts of by-products. Such rapid and selective reactions can not be achieved by conventional methods and were not to be expected by heating to high temperatures alone.
• fatty acid amides prepared by the route according to the invention usually accumulate in sufficient purity for further use, so that no further working or post-processing steps are required. For special requirements, however, they can be further purified by customary purification methods such as, for example, distillation, recrystallization, filtration or chromatographic methods.
• the reactions of the ammonium salts under microwave irradiation were carried out in a ceramic tube (60 ⁇ 1 cm) which was axially symmetrical in a cylindrical cavity resonator (60 ⁇ 10 cm).
• a ceramic tube 60 ⁇ 1 cm
• a cylindrical cavity resonator 60 ⁇ 10 cm
• On one of the front sides of the Cavity resonator passed through the ceramic tube through the cavity of a functioning as a coupling antenna inner conductor tube.
• the microwave field generated by a magnetron with a frequency of 2.45 GHz was coupled by means of the coupling antenna in the cavity resonator (Eo-i cavity applicator, single mode).
• the microwave power was adjusted over the duration of the experiment in such a way that the desired temperature of the reaction mixture was kept constant at the end of the irradiation zone.
• the microwave powers mentioned in the test descriptions therefore represent the time average of the irradiated microwave power.
• the temperature measurement of the reaction mixture was carried out directly after leaving the reaction zone (about 15 cm distance in an insulated stainless steel capillary, 0 1 cm) by means of PtIOO temperature sensor. Microwave energy not directly absorbed by the reaction mixture was reflected at the end face of the cavity resonator opposite the coupling antenna; the microwave energy which was not absorbed by the reaction mixture during the return and was reflected back in the direction of the magnetron was conducted by means of a prism system (circulator) into a vessel containing water. From the difference between incident energy and heating of this water load, the microwave energy introduced into the reaction mixture was calculated
• reaction mixture was placed in the reaction tube under such a working pressure, which was sufficient to all educts and products or
• reaction mixtures prepared from fatty acid and amine were pumped through the reaction tube at a constant flow rate and the residence time in the irradiation zone was adjusted by modifying the flow rate.
• the mixture thus obtained was continuously pumped through the reaction tube at a working pressure of 40 bar at 6.0 l / h and subjected to a microwave power of 2.9 kW, of which 95% was absorbed by the reaction mixture.
• the residence time of the reaction mixture in the irradiation zone was approx.
• the reaction mixture had a temperature of 277 0 C.
• reaction solution in a 1 liter stirred autoclave, 500 ml of reaction solution (sample preparation see Example 1) were presented and heated in closed apparatus with maximum heating power with vigorous stirring within 8 minutes at 270 0 C (oil flow temperature 350 0 C). Under pressure, the reaction mixture was further stirred for 5 minutes and then cooled to room temperature through a Kaitölnikank.
• the product was conveyed in the manner of a very effective heat exchanger (microreactor, channel diameter 1 mm) that a residence time of 1, 5 minutes at a measured by PT 100 temperature of 275 0 C was realized.
• the total conveyor capacity was 5 liters / h.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=40667643

Family Applications (1)

Country Status (11)

Cited By (1)

Families Citing this family (17)

Family Cites Families (137)

• 2008
  • 2008-04-04 DE DE200810017216 patent/DE102008017216B4/de not_active Expired - Fee Related
• 2009
  • 2009-03-18 EP EP09728538A patent/EP2274274A1/de not_active Withdrawn
  • 2009-03-18 KR KR1020107018624A patent/KR20100135228A/ko not_active Application Discontinuation
  • 2009-03-18 WO PCT/EP2009/001987 patent/WO2009121487A1/de active Application Filing
  • 2009-03-18 BR BRPI0907820-7A patent/BRPI0907820A2/pt not_active IP Right Cessation
  • 2009-03-18 MX MX2010010764A patent/MX2010010764A/es not_active Application Discontinuation
  • 2009-03-18 CA CA2720331A patent/CA2720331A1/en not_active Abandoned
  • 2009-03-18 US US12/935,628 patent/US8884040B2/en not_active Expired - Fee Related
  • 2009-03-18 CN CN200980101757.7A patent/CN101910114B/zh not_active Expired - Fee Related
  • 2009-03-18 EA EA201001605A patent/EA020190B9/ru not_active IP Right Cessation
  • 2009-03-18 AU AU2009231122A patent/AU2009231122A1/en not_active Abandoned

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events