WO2013030316A2 - Process for cathodic deoxygenation of amides and esters - Google Patents

Abstract

The present invention relates to a process for deoxygenating carboxamides and carboxylic esters by cathodic reduction of a solution of the carboxamide or of the carboxylic ester, which is characterized in that the solution of the carboxamide or of the carboxylic ester used for cathodic reduction comprises a salt as an additive selected from quaternary ammonium salts and quaternary phosphonium salts. R = alkyl, aryl, arylalkyl, R', R" = H, alkyl, aryl, arylalkyl.

Description

 Process for the cathodic deoxygenation of amides and esters

The present invention relates to a process for the deoxygenation of carboxylic acid amides and carboxylic acid esters by cathodic reduction of a solution of these compounds.

The reduction of carboxylic acid amides to the corresponding amines according to the reaction equation shown schematically below, hereinafter also referred to as deoxygenation of amides, is a long known, but not always easy to control reaction:

The skilled worker is fundamentally aware of various methods for the deoxygenation of amides. Typically, for this purpose, (half) metal hydrides, such as borohydrides, e.g. Sodium borohydride in the presence of activators (S.H.Xiang, Synlett 2010, 12, 1829-1832) or Diboran (H.C.Brown, J. Org. Chem. 1973, 38, 912-916), and aluminum hydrides, e.g. Assaymith et al., Synlett 2009, 17, 2777-2782) or diisobutylaluminum hydride (L.I. Zakharkin, I.M. Khorlina, Tetrahedron Letters 1962, 14, 619-620). Although these processes generally give the amines in high yields, the handling of (semi) -metal hydrides is not unproblematic because of their property in the presence of acidic protons in an exothermic reaction to form hydrogen and therefore generally requires extensive safety precautions , In addition, during the workup, oxides or hydroxides are formed whose removal from the desired product is generally complicated and which must be disposed of. These disadvantages are contrary to a use of these reactions on an industrial scale, so that these reactions have so far been found primarily in the production of complex drug molecules or in natural product syntheses application.

Several reports have been made of the catalytic hydrogenation of fatty acid amides to the corresponding fatty amines and copper chromite type catalysts - see US 5,840,985 and US 2007/0191642. WO 2005/0661 12 describes the catalytic hydrogenation of amides to amines, eg the hydrogenation of 1-acetyl pyrrolidine to 1 - Ethylpyrrolidine on bimetallic or trimetallic transition metal contacts. However, these methods are usually limited to volatile amides.

On various occasions, electrochemical processes for the preparation of amines have been described. For example, WO 2008/003620 and WO 2006/005531 describe the preparation of amines by cathodic reduction of oxime derivatives. A disadvantage of these processes is that first the corresponding oxime derivatives have to be generated and furthermore only primary amines and no secondary or tertiary amines are accessible in this way.

The object of the present invention is to provide a widely applicable process for the preparation of amines from the corresponding carboxylic acid amides, which overcomes the disadvantages of the prior art. The process should provide the corresponding amines with high selectivity and high yield.

This object is surprisingly achieved by a process in which subjecting a solution of a carboxylic acid amide in a solvent of a cathodic reduction, hereinafter also called cathodic deoxygenation, wherein the solution contains a salt as an additive, the salts under quaternary ammonium and phosphonium is selected. Surprisingly, this process can be transferred to the deoxygenation of carboxylic acid esters to the corresponding ethers according to the following reaction equation:

The present invention thus relates to a process for the deoxygenation of carboxylic acid amides and carboxylic acid esters by cathodic reduction of a solution of the carboxamide or of the carboxylic acid ester, which is characterized in that the solution used for the cathodic reduction of the carboxylic acid amide or of the carboxylic acid ester contains a salt as an additive, which quaternary ammonium salts and quaternary phosphonium salts.

In the process of the invention, an amide is converted to the corresponding amine or an ester in the corresponding ether. In this case, the carbonyl groups of the carboxamide unit of the amide and the carbonyl group of the carboxyl unit of the ester are converted into a CH 2 group. The inventive method requires no problematic or expensive reagents, as is used as a reducing agent inexpensive stream. The method allows the selective deoxygenation of the amides used, without significantly undesirable side reactions, such as a cleavage of the amide CN bond occur. Unlike the reduction with (semi) metal hydrides, there are no oxidic or hydroxidic by-products which have to be removed from the reaction mixture and disposed of. In addition, the process according to the invention not only enables the preparation of primary but also secondary and tertiary amines and the preparation of symmetrical and unsymmetrical ethers. In addition, the process of the invention allows the use of starting materials which have functional groups which are attacked in the known deoxygenation or lead to side reaction.

In the context of the present invention, the following terms have the following meanings, as far as they have no clear meaning content for the person skilled in the art.

By a quaternary ammonium group is meant an atomic group having a positively charged nitrogen atom bearing four C-bonded substituents.

By a quaternary phosphonium group is meant an atomic group having a positively charged phosphorous atom bearing four C-bonded substituents. The prefix Cn-Cm used in connection with organic radicals and organic compounds indicates the possible number of carbon atoms which the respective radical or the respective compound can have.

The term "C 1 -C 4 -alkyl" denotes a saturated, linear or branched aliphatic hydrocarbon radical having 1 to 4 carbon atoms, such as, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl or tert. butyl.

The term "C 1 -C 10 -alkyl" denotes a saturated, linear or branched aliphatic hydrocarbon radical which has 1 to 10 carbon atoms, for example methyl, ethyl, propyl, isopropyl, n-butyl, 2-butyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 2-methylbutyl, 3-methylbutyl, 1, 2-dimethylpropyl, 1, 1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, n-hexyl, 2-hexyl , 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, 1, 2-dimethylbutyl, 1, 3-dimethylbutyl, 2,3-dimethylbutyl, 1, 1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl , 1, 1, 2-trimethylpropyl, 1, 2,2-trimethyl propyl, 1-ethylbutyl, 2-ethylbutyl, 1-ethyl-2-methylpropyl, n-heptyl, 2-heptyl, 3-heptyl, 2-ethylpentyl, 1-propylbutyl, n-octyl, 2-ethylhexyl, 2-propylheptyl, Nonyl, decyl.

The term "haloalkyl" denotes a saturated, linear or branched aliphatic hydrocarbon radical having 1 to 10, in particular 1 to 6 or 1 to 4, carbon atoms and in which at least one or all, e.g. 1, 2, 3, 4, 5, 6 or 7 hydrogen atoms are replaced by halogen, in particular by fluorine, chlorine or bromine, e.g. for trifluoromethyl, chloromethyl, bromomethyl, 1, 1 -difluoroethyl, 2,2,2-trifluoroethyl, pentafluoroethyl, hexafluoropropyl or heptafluoropropyl.

The term "alkenyl" refers to a linear or branched aliphatic hydrocarbon radical which is monounsaturated or polyunsaturated and which generally has 2 to 10, in particular 2 to 6 or especially 2 to 4, carbon atoms, e.g. Ethenyl, 1-propenyl, 2-propenyl, 1-butene-1-yl, 2-butene-1-yl, 3-butene-1-yl, 1-butene-2-yl, 2-methyl-1-propene 1 -yl, 2-methyl-2-propen-1-yl, etc.

The term "alkylene" refers to a branched or unbranched, saturated, divalent aliphatic hydrocarbon radical generally having from 2 to 20, especially from 3 to 10, and especially from 3 to 6 carbon atoms, e.g. Ethane-1,2-diyl, propane-1, 3-diyl, butane-1, 4-diyl, 1-methylethane-1,2-diyl, 1,1-dimethylethane-1,2-diyl, 1 -

Methylpropane-1,3-diyl, 1,1-dimethylpropane-1,3-diyl, 2,2-dimethylpropane-1,3-diyl, pentane-1, 5-diyl, hexane-1,6-diyl, Heptane-1, 7-diyl, octane-1, 8-diyl, nonane-1, 9-diyl, decane-1, 10-diyl, dodecane-1, 12-diyl, etc. The term "alkenylene" refers to one branched or unbranched, monosaturated, bivalent aliphatic hydrocarbon radical which generally has 2 to 20, in particular 3 to 10 and especially 3 to 6 carbon atoms, for example 1, 2-ethenediyl, propene-1, 3-diyl, 2-butene-1, 4-diyl, 1-methylethene-1, 2-diyl, 1-methyl-1-propene-1, 3-diyl, 2- Methyl-1-propene-1,3-diyl, 1-pentene-1, 5-diyl, 2-pentene-1, 5-diyl, 1-hexene-1, 6-diyl, 2-hexene-1, 6- diyl, 3-hexene-1, 6-diyl, 1-hept-1, 7-diyl, 2-heptene-1, 7-diyl, 3-heptene-1, 7-diyl, etc.

The term "alkoxy" refers to a branched or unbranched, saturated alkyl radical which is linked via an oxygen atom to the remainder of the molecule. The term "C 1 -C 10 alkoxy" hereinafter refers to an alkyl radical as defined above having from 1 to 10 carbon atoms. The term "C 1 -C 4 -alkoxy" in the following denotes an alkyl radical as defined above which has 1 to 4 carbon atoms, eg methoxy, ethoxy, propyloxy, isopropyloxy, n-butyloxy, 2-butyloxy, sec-butyloxy, tert-butyl Butyloxy, n-pentyloxy, 2-pentyloxy, 2-methylbutyloxy, 3-methylbutyloxy, 1, 2 Dimethylpropyloxy, 1, 1-dimethylpropyloxy, 2,2-dimethylpropyloxy, 1-ethylpropyloxy, n-hexyloxy, 2-hexyloxy, 2-methylpentyloxy, 3-methylpentyloxy, 4-methylpentyloxy, 1, 2-dimethylbutyloxy, 1, 3-dimethylbutyloxy, 2,3-dimethylbutyloxy, 1,1-dimethylbutyloxy, 2,2-dimethylbutyloxy, 3,3-dimethylbutyloxy, 1,1,2-trimethylpropyloxy, 1,2,2-trimethylpropyloxy, 1-ethylbutyloxy, 2-ethylbutyloxy, 1-ethyl-2-methylpropyloxy, n-heptyloxy, 2-heptyloxy, 3-heptyloxy, 2-ethylpentyloxy, 1-propylbutyloxy, n-octyloxy, 2-ethylhexyloxy, 2-propylheptyloxy, nonyl, decyloxy.

The term "C3-Cio-cycloalkyl" denotes a saturated, mono- or bicyclic hydrocarbon radical containing from 3 to 10 carbon atoms, e.g. Cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, bicyclo [2.2.1] heptyl, bicyclo [3.3.0] octyl, bicyclo [3.2.1] octyl, bicyclo [2.2.2] octyl, etc ,

The term "aryl" refers to an aromatic or partially aromatic

Hydrocarbon radical which is mono- or polycyclic and usually has 6, 9, 10, 13 or 14 C atoms and which is preferably phenyl, naphthyl,

Tetrahydronaphthyl, indenyl, indanyl, fluorenyl, anthracenyl, phenanthrenyl or naphthacenyl, particularly preferably phenyl or naphthyl. The term "hetaryl" refers to an aromatic or partially aromatic heterocyclic radical which is mono- or polycyclic and usually has 5 to 14 ring members which have, in addition to carbon, at least one heteroatom as the ring atom selected from N, O and S, e.g. 1 to 4 N atoms or 1 atom selected from O and S and optionally 1, 2 or 3 further N atoms, and preferably the groups pyridyl, quinolinyl, acridinyl, pyridazinyl, pyrimidinyl, pyrazinyl, triazinyl, tetrazinyl, pyrrolyl , Pyrazolyl, isoxazolyl, imidazolyl, oxazolyl, thiazolyl, thienyl, furyl.

The term "5 to 7-membered carbocycle" denotes a saturated or unsaturated hydrocarbon radical having 5 to 7 carbon atoms as ring members.

The term "5 to 8-membered heterocycle" denotes a monocyclic or polycyclic, saturated or unsaturated heterocyclic radical having 5 to 8 ring atoms, in which the ring atoms, in addition to carbon, have at least one heteroatom, which is preferably selected from nitrogen, sulfur and oxygen, eg pyrrolidinyl, piperidinyl, morpholinyl, thiomorpholinyl, piperazinyl, hexahydroazepinyl, etc. The term "poly (oxyethylene)" denotes in a polyether radical which oxyethylene groups (OCH 2 CH 2) is constructed as a repeating unit and which is bonded via an oxygen atom. The term "alkanol" denotes an aliphatic, saturated or unsaturated alcohol which has one or more, for example 1, 2 or 3, in particular a hydroxyl group (s) and which generally has 1 to 10 carbon atoms. Accordingly, C 1 -C 10 -alkanol is understood as meaning an alkanol having 1 to 10 C atoms, such as, for example, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, pentanol, hexanol, heptanol, octanol , Nonanol and decanol, wherein the last mentioned alkanols may be linear or branched, furthermore glycol, propanediol, butanediol and glycerol.

The term "alkylene carbonate" refers to cyclic carbonates of the corresponding alkylene glycols such as ethylene carbonate (1,3-dioxolan-2-one) and propylene carbonate (4-methyl-1,3-dioxolan-2-one).

The term "alkyl phosphate" refers to an anion of the formula R-OP (O) 02 ^{2 "} where R is alkyl, eg methyl phosphate.

The term "alkylphosphonate" refers to an anion of the formula RP (O) 02 ² "in which R is alkyl, for example methylphosphonate.

The term "alkyl sulfate" refers to an anion of the formula R-OS (0) ₂ 0- wherein R is alkyl, for example methyl sulfate (= methosulfate) or ethyl sulfate.

The term "aryl sulfate" denotes an anion of the formula R-OS (0) 20 "in which R is aryl which optionally carries 1 to 3 alkyl groups, for example phenyl sulfate, toluene sulfate, mesityl sulphate.

The term "arylsulfonate" denotes an anion of the formula RS (0) 20 "in which R is aryl which optionally carries 1 to 3 alkyl groups, eg phenylsulfonate, toluenesulfonate, mesitylene sulfonate The term" carboxylate "denotes the anion of an aliphatic or aromatic carboxylic acid, such as formate, acetate, propionate or benzoate.

The term "haloalkyl sulfonate" refers to an anion of formula RS (0) 20 "wherein R is haloalkyl, eg trifluoromethyl. The term "imide" refers to anions of cyclic or acyclic carboxylic acid imides or sulfonic acid imides in which the imide nitrogen carries a negative charge. By the term "pseudohalide", for example, the following anions: cyanide (CN-), azide (N ₃ -), cyanate (OCN-), isocyanate (NCO-), fulminate (CNO),

Thiocyanate (SCN-), and isothiocyanate (NCS ^" ).

The quaternary ammonium or phosphonium salts used as additives generally have at least one, preferably at least 2, e.g. 1 to 100, in particular 2 to 100, preferably 2 to 10 and especially 2 or 3 quaternary ammonium or phosphonium groups.

The additives used in the process according to the invention are preferably salts whose cation is the F

 where k is an integer in the range from 0 to 99, in particular 1 to 99, preferably in the range from 1 to 9, in particular 1, 2, 3 or 4 and especially 1 or 2,

A is nitrogen or phosphorus and in particular nitrogen,

Z is a C 2 -C 12 -alkylene group in which optionally 1, 2 or 3 Ch - groups, which are separated from the nitrogen atoms or phosphorus atoms A and from each other by at least 2 C atoms, may be replaced by oxygen atoms, preferably an alkylene group having 2 to 6 carbon atoms, wherein optionally 1 or 2 Ch groups, which are separated from the nitrogen atoms and from each other by at least 2 C atoms, may be replaced by oxygen atoms, in particular an alkylene group having 2 to 4 carbon atoms, wherein optionally 1 Ch Group which is separated from the nitrogen atoms by at least 2 C-

Atoms separated, may be replaced by an oxygen atom; R ¹ , R ² , R ³ and R ^{4 are} each independently of the other Ci-Cio-alkyl, which is in each case unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), preferably are C 1 -C 6 -alkyl which is unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), in particular C 1 -C 3 -alkyl, each of which is unsubstituted or may be substituted with 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), or

R ¹ and R ² together with the nitrogen to which they are attached may also stand for a 5 to 8-membered heterocycle which contains 1 N-atom in the ring and is unsubstituted or with 1 to 4 substituents selected from hydroxy, C 1 -C 4 -alkoxy and C 1 -C 4 -alkyl, may be substituted,

R ⁵ and R ^{6 are} each independently of the other Ci-Cio-alkyl, which is in each case unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), preferably C 1 -C 6 -alkyl which is in each case unsubstituted or having 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), in particular C 1 -C 3 -alkyl, which is unsubstituted or contains 1 or 2 substituents, selected from hydroxyl, Alkoxy and poly (oxyethylene), may be substituted. The variables k, A, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ which occur in the formula I have the following meanings independently of one another or preferably in combination with one another.

The variable k preferably stands for an integer in a range from 1 to 9, in particular for 1, 2, 3 or 4 and especially for 1 or 2.

The variable A is preferably nitrogen.

The variable Z preferably represents a linear alkylene group having 2 to 12, in particular 2 to 6, especially 2 to 4 carbon atoms.

R ¹ , R ² , R ³ and R ⁴ are each independently of one another preferably C 1 -C 6 -alkyl, which is in each case unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), and particularly are C 1 -C 3 -alkyl, which in each case is unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene).

R ⁵ and R ⁶ are each independently of one another preferably C 1 -C 6 -alkyl, which in each case is unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene) and is preferably unsubstituted, and in particular Ci-C3-alkyl, which is in each case unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), and is preferably unsubstituted.

In particular, R ² , R ³ , R ⁵ and R ^{6 are} methyl.

In particular, R ¹ and R ⁴ are C ¹ -C ⁴ -alkyl and in particular methyl or ethyl. Particular preference is given to cations of the formula I in which k is an integer in the range from 1 to 9, preferably 1, 2, 3 or 4 and in particular 1 or 2, A is nitrogen,

Z is a linear alkylene group having from 2 to 12, preferably from 2 to 6, especially 2 to 4 carbon atoms; R ¹ , R ² , R ³ and R ^{4 are} each independently of the other Ci-C6-alkyl, which is in each case unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), preferably are C1-C3-alkyl, which is in each case unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene), or

R ⁵ and R ^{6 are} each independently of one another C 1 -C 6 -alkyl and preferably C 1 -C 4 -alkyl, each of which is unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene) and is preferably unsubstituted.

Particular preference is given to the cation of the formula I in which k is 1 to 9, preferably 1, 2, 3 or 4 and in particular 1 or 2, A is nitrogen,

Z is a linear alkylene group having 2 to 12 carbon atoms, preferably having 2 to 6 carbon atoms, in particular 2 to 4 carbon atoms,

R ¹ and R ^{4 are} each independently of the other C ¹ -C ⁴ -alkyl, preferably methyl and ethyl, and R ² , R ³ , R ⁵ and R ^{6 are} methyl.

The type of anion of the salt used as an additive is of minor importance to the process according to the invention. However, it is preferably not necessarily selected from electrochemically inert anions. Examples of suitable anions of the salt used as the additive are sulfate, hydrogensulfate, alkylsulfate, arylsulfate, arylsulfonate, haloalkylsulfonate, halide, pseudohalide such as e.g. CN, SCN, OCN and N3, carboxylate, carbonate, imide, e.g. Bis (trifluoromethylsulfonyl) imide, phosphate, alkyl phosphate, nitrate, tetrafluoroborate, hexafluorophosphate and perchlorate. Preferred are hydrogensulfate, alkylsulfate, arylsulfate, arylsulfonate, haloalkylsulfonate, arylsulfonate, especially sulfate and alkylsulfate such as e.g. Ethyl sulfate or methyl sulfate.

In preferred embodiments of the invention, salts are used whose cations of the formula I obey, in which the variables A, k, Z, R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ are each in one row of Table 1 have meanings described.

Table 1 :

Compound A kz R, R ³ , R ⁵ , R ⁶ R ² , R ⁴

1 N 1 ethanediyl methyl methyl

2 N 1 ethanediyl methyl ethyl

3 N 2 ethanediyl methyl methyl

4 N 2 ethanediyl methyl ethyl

5 N 3 ethanediyl methyl methyl

6 N 3 ethanediyl methyl ethyl

7 N 1 propanediyl methyl methyl

8 N 1 propanediyl methyl ethyl

9 N 2 propanediyl methyl methyl

10 N 2 propanediyl methyl ethyl

1 1 N 1 butanediyl methyl methyl

12 N 1 butanediyl methyl ethyl Compound A kz R, R ³ , R ⁵ , R ⁶ R ² , R ⁴

13 N 1 pentanediyl methyl methyl

14 N 1 pentanediyl methyl ethyl

15 N 1 hexanediyl methyl methyl

16 N 1 hexanediyl methyl ethyl

17 N 1 heptanediyl methyl methyl

18 N 1 heptanediyl methyl ethyl

19 N 1 hexanediyl methyl methyl

20N 1 octanediyl methyl ethyl

21 N 1 nonanediyl methyl methyl

22 N 1 nonanediyl methyl ethyl

23 N 1 decanediyl methyl methyl

24 N 1 decanediyl methyl ethyl

25 N 1 dodecanediyl methyl methyl

26 N 1 dodecanediyl methyl ethyl

27 P 1 ethanediyl methyl methyl

28 P 1 ethanediyl methyl ethyl

29 P 2 ethanediyl methyl methyl

30 P 2 ethanediyl methyl ethyl

31 P 3 ethanediyl methyl methyl

32 P 3 ethanediyl methyl ethyl

33 P 1 propanediyl methyl methyl

34 P 1 propanediyl methyl ethyl

35 P 2 propanediyl methyl methyl

36 P 2 propanediyl methyl ethyl

37 P 1 butanediyl methyl methyl

38 P 1 butanediyl methyl ethyl

39 P 1 pentanediyl methyl methyl

40 P 1 pentanediyl methyl ethyl

41 P 1 hexanediyl methyl methyl

42 P 1 hexanediyl methyl ethyl

43 P 1 heptanediyl methyl methyl

44 P 1 heptanediyl methyl ethyl

45 P 1 hexanediyl methyl methyl

46 P 1 octanediyl methyl ethyl

47 P 1 Nonanediyl methyl methyl

48 P 1 nonanediyl methyl ethyl

49 P 1 decandiyl methyl methyl Compound A k ZR, R ³ , R ⁵ , R ⁶ R ² , R ⁴

50 P 1 decanediyl methyl ethyl

51 P 1 dodecanediyl methyl methyl

52 P 1 dodecanediyl methyl ethyl

Particularly preferred salts are N, N, N, N ', N', N'-hexamethyl-1,3-propanediammonium salts, N, N'-diethyl, N, N ', N', N'-tetramethyl- 1, 3-propanediammonium salts,

N, N, N, N ', N', N'-hexamethyl-1,6-hexanediammonium salts, N, N'-diethyl, N, N ', N', N'-tetramethyl-1,6-hexanediammonium salts, N, N'-diethyl, N, N ', N', N'-tetramethyl-1, 9-nonanediammonium salts and N, N'-diethyl, N, N ', N', N'-tetramethyl-1, 12-dodecanediammonium salts especially the methosulfates and ethyl sulfates of the aforementioned salts.

The solution of the carboxylic acid amide or of the carboxylic acid ester generally contains the quaternary ammonium or phosphonium salt in a concentration in the range from 0.001 to 1000 mmol / l, frequently in the range from 0.1 to 500 mmol / l, preferably in the range from 1 to 100 mmol / l, in particular in the range of 25 to 75 mmol / l.

The ammonium and phosphonium salts described are known and sometimes commercially available or can be prepared in a conventional manner, starting from the corresponding tertiary amines or the tertiary phosphines. Tertiary amines, if not commercially available, are accessible, for example, by reacting primary amines with formaldehyde and formic acid (Eschweiler-Clark reaction). Tertiary phosphines in turn can be obtained by reaction of phosphorus trichloride with alkyl Grignard reagents or by conversion of phosphine with

Alkyl halides are produced. The tertiary amines and / or the tertiary phosphines can be converted into the corresponding quaternary ammonium or phosphonium salts with alkylating agents such as dimethyl sulfate, diethyl sulfate or trimethyl phosphate. The counterions of the salts thus obtainable are derived from the alkylating agents used. If an anion other than counterion is desired, it may easily be added e.g. be replaced by inorganic metathesis.

As a substrate for deoxygenation, it is possible in principle to use any carboxylic acid amide or carboxylic acid ester.

The substrate used is preferably a carboxylic acid amide or a carboxylic acid ester of the formula II

R _\ . CH? R

 Y "-X (III)

In formulas II and III, the variables X, Y, R ⁷ and R ^{8 have} the following meanings:

Y is a chemical bond or an alkylene group having 1 to 6 carbon atoms, X is oxygen or NR ⁹ ,

R ⁷ is selected from C 1 -C 10 -alkyl, C 2 -C 10 -alkenyl, C 1 -C 10 -alkoxy, C 1 -C 10 -alkoxy

Haloalkyl, C 1 -C 10 -haloalkoxy, C 3 -C 10 -cycloalkyl, aryl and hetaryl, where the ring in the last three groups is unsubstituted or may be substituted by up to 6 substituents which are halogen, hydroxy, C 1 -C 4 -cycloalkyl, Alkyl and C1-C4

Alkoxy are selected, and

R ^{8 is} selected from hydrogen, C ₁ -C 10 -alkyl which is unsubstituted or has 1 or 2 substituents which are selected from hydroxyl, C ₁ -C 4 -alkoxy and aryl, C ₂ -C 10 -alkenyl, C ₁ -C 10 -haloalkyl, Ci-Cio-haloalkoxy, Cs-do-cycloalkyl, aryl and

Hetaryl, wherein the ring in the last three groups is unsubstituted or may be substituted by up to 6 substituents selected from halogen, hydroxy, C 1 -C ₄ -alkyl and C 1 -C ₄ -alkoxy,

where R ^{8 is} different from hydrogen when X is O,

R ⁷ and R ⁸ may together represent C ₃ -C 20 -alkylene or C ₃ -C 20 -alkenylene which is unsubstituted or substituted by up to 6 substituents, which are hydroxy, C 1 -C ₄ -alkyl and C 1 -C ₄ -alkoxy wherein 2 substituents bonded to adjacent carbon atoms together with the carbon atoms to which they are attached can also form a 5- to 7-membered carbocycle; and

R ^{9 is} hydrogen or C 1 -C 10 -alkyl which is unsubstituted or has 1 or 2 substituents selected from hydroxy, C 1 -C ₄ -alkoxy and aryl. Preferably, the variables X, Y, R ⁷ 'R ⁸ and R ⁹ in the formulas II and III independently and in combination with one another have the following meanings. Y is preferably a chemical bond or an alkylene group having 1 to 6 carbon atoms and in particular a chemical bond,

X is preferably NR ⁹ ,

R ⁷ is preferably selected from C 3 -C 10 -cycloalkyl, aryl and hetaryl, where the ring is unsubstituted in the three groups or may be substituted by up to 6 substituents which are halogen, hydroxy, C 1 -C 4 -alkyl and C 1 -C 4 Alkoxy are selected, and in particular selected from aryl, which is unsubstituted or may be substituted with up to 6 substituents, which are selected from halogen, hydroxy, Ci-C4-alkyl and C1-C4-alkoxy.

R ⁸ is preferably selected from C 1 -C 10 -alkyl which is unsubstituted or has 1 or 2 substituents selected from hydroxy, C 1 -C 4 -alkoxy and aryl, C 1 -C 10 -haloalkyl, C 3 -C 10 -cycloalkyl, aryl and Hetaryl, wherein the ring in the last three groups is unsubstituted or may be substituted by up to 6 substituents selected from halogen, hydroxy, Ci-C4-alkyl and Ci-C4-alkoxy, and is particularly selected from Ci-Cio -Alkyl which is unsubstituted or has 1 or 2 substituents selected from hydroxy, C 1 -C 4 -alkoxy and aryl, and aryl which is unsubstituted or may be substituted by up to 6 substituents selected from halogen, hydroxy, Ci -C4-alkyl and Ci-C4-alkoxy are selected.

R ⁷ and R ⁸ may preferably together also be C 3 -C 20 -alkylene. In a preferred embodiment of the process according to the invention, a carboxamide of the formula II is used, in which

Y represents a chemical bond or an alkylene group having 1 to 6 carbon atoms,

X is NR ⁹ ,

R ^{7 is} selected from C 3 -C 10 -cycloalkyl, aryl and hetaryl, where the ring is unsubstituted in the three groups or may be substituted by up to 6 substituents which are halogen, hydroxy, C 1 -C 4 -alkyl and C 1 -C 4 -alkyl. Alkoxy and is selected from C 1 -C 10 -alkyl which is unsubstituted or has 1 or 2 substituents selected from hydroxy, C 1 -C 4 -alkoxy and aryl, C 1 -C 10 -haloalkyl, C 3 -C 10 -cycloalkyl, aryl and hetaryl, where the ring in the last three groups is unsubstituted or may be substituted by up to 6 substituents which are halogen, hydroxy, C 1 -C 4 -alkyl and C4 alkoxy are selected, or

R ⁷ and R ⁸ together are C 3 -C 20 -alkylene; and R ^{9 is} hydrogen or C 1 -C 10 -alkyl.

In a particularly preferred embodiment of the process according to the invention, a substrate according to formula II is used, in which Y stands for a chemical bond,

X is a group NR ⁹ ,

R ^{7 is} selected from aryl which is unsubstituted or may be substituted by up to 6 substituents selected from halogen, hydroxy, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, and

R ^{8 is} selected from C 1 -C 10 -alkyl which is unsubstituted or has 1 or 2 substituents selected from hydroxy, C 1 -C 4 -alkoxy and aryl, and aryl which is unsubstituted or may be substituted by up to 6 substituents which are selected from halogen, hydroxy, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy;

R ^{9 is} hydrogen or Ci-Cio-alkyl. In preferred embodiments of the process according to the invention, the substrate used is a secondary or tertiary carboxylic acid amide, ie a compound of the formula II in which X is a group NR ⁹ , where R ⁸ and optionally R ^{9 have} a meaning other than hydrogen. In a specific embodiment of the process according to the invention, the substrate used is a secondary carboxylic acid amide, ie a compound of the formula II in which X is a group NR ⁹ , where either R ^{8 has} a meaning other than hydrogen and R ^{9 is} hydrogen. In another specific embodiment of the process according to the invention, the substrate used is a tertiary carboxylic acid amide used, ie a compound of the formula II, wherein X is a group NR ⁹ , wherein R ⁸ and R ⁹ each have a meaning other than hydrogen.

The process according to the invention can be carried out in all electrolyte cells known to the person skilled in the art. The process according to the invention is preferably carried out in a divided electrolysis cell. A divided electrolytic cell is understood to mean a cell arrangement in which the cathode space and the anode space and thus the solution (catholyte) contained in the cathode space are separated from the solution (anolyte) contained in the anode space in a manner which does not transfer charge but does not transfer organic charge Substances between catholyte and anolyte allowed. The separation of cathode space and anode space can be achieved in a conventional manner by suitable separation media. As separation media, it is possible to use ion exchange membranes, microporous membranes, diaphragms, filter meshes of non-electron-conducting materials, glass frits, and porous ceramics. Preferably ion exchange membranes, in particular cation exchange membranes are used. These conductive membranes are commercially available for example under the trade name Nafion ^® (Fa. ET. DuPont de Nemours and Company) and Gore Select ^® (Messrs. WL Gore & Associates, Inc.). Preferably, the cathodic reduction of the carboxylic acid amide or carboxylic ester solution is conducted in a divided flow cell. Divided cells, in particular divided flow cells, which have a plane-parallel electrode arrangement, are preferably used. In the process according to the invention, the substrate is cathodically reduced, ie the solution containing the carboxylic acid amide or the carboxylic acid ester is introduced into the cathode half-space when the electrolysis is carried out in a divided electrolysis cell. The carboxylic acid amide or the carboxylic acid ester are then dissolved in the catholyte.

According to the invention, a solution of the carboxylic acid amide or of the carboxylic acid ester is subjected to a cathodic reduction, ie the substrate is present in dissolved form in an organic solvent. Suitable solvents are in principle all inert organic solvents customary for electrochemical reactions and mixtures thereof with water. Examples of solvents are, in particular, alkanols, for example the abovementioned C 1 -C 4 -alkanols, alkylene carbonates, such as ethylene carbonate or propylene carbonate, cyclic and acyclic ethers, for example diethyl ether, diisopropyl ether, methyl tert-butyl ether, ethyl tert-butyl ether, Tetrahydrofuran, methyltetrahydrofuran, dioxane or pyran, alkylglycols, dialkylglycols, alkyldiglycols and Dialkyl diglycols such as methyl glycol, ethyl glycol, dimethyl glycol, diethyl glycol, methyl diglycol or ethyl diglycol, polyethers such as triethylene glycol or higher polyethylene glycols and their alkyl ethers, and nitriles, for example acetonitrile or propionitrile and mixtures of these solvents. The solution used for cathodic reduction may also contain mixtures of said organic solvents with water or with C5-C7-hydrocarbons. Further suitable solvents are described in Kosuke Izutsu, "Electrochemistry in Nonaqueous Solutions", published by Wiley-VCH 2002, Chap. 1 . The catholyte preferably comprises inert solvents selected from C 1 -C 4 -alkanols, dimethyl carbonate, propylene carbonate, tetrahydrofuran, dimethoxyethane, acetonitrile, mixtures thereof and mixtures thereof with water, mixtures of these inert solvents or mixtures of these inert solvents with C 5 -C 7 -hydrocarbons.

Particularly preferred are C 1 -C 4 -alkanols, tetrahydrofuran, dimethoxyethane or mixtures thereof and mixtures with water. This can form a single- or multi-phase system.

Very particular preference is given to C 1 -C 4 -alkanols which are optionally used in mixtures with one another and / or water. Ci-C4 alkanols include monools such as methanol, ethanol, n-propanol, i-propanol, n-butanol, sec-butanol, tert-butanol, diols such as glycol and triols such as glycerol. Especially preferred as the solvent is methanol.

When carrying out the method according to the invention in a divided electrolysis cell, the catholyte and the anolyte can contain the same or different solvents.

To ensure adequate conductivity, the solution of the carboxylic acid amide or of the carboxylic acid ester usually contains a mineral acid or an inert conductive salt, mineral acids being preferred. Preferred mineral acids are hydrochloric acid, sulfuric acid or phosphoric acid, in particular sulfuric acid. When carrying out the process according to the invention in a divided electrolysis cell, the catholyte and the anolyte can contain the same or different electrolyte salts or mineral acids. The catholyte and the anolyte preferably contain, independently of one another, a mineral acid, such as hydrochloric acid, sulfuric acid or phosphoric acid, in particular sulfuric acid.

Preferably, the solution of the carboxylic acid amide or of the carboxylic acid ester (or the catholyte and the anolyte contain, independently of one another) the conductive salt or the mineral acid in a concentration in the range of 0.05 to 5 M (= mol / l), preferably in the range of 0.075 to 1 M, in particular in the range of 0.1 to 0.5 M.

The cathodes used are preferably electrodes in which the cathode surface is formed from a material with a high hydrogen overvoltage. In particular, cathodes are used in which the cathode surface consists of a material which is selected from lead, zinc, tin, nickel, mercury, cadmium, copper, an alloy of these metals or glassy carbon, graphite or diamond. Particularly preferred are cathodes in which the cathode surface consists of lead. Preferably, the cathode is polarized prior to its use.

As anodes, in principle, all conventional anode materials come into consideration. Preference is given to anodes whose surface consists of platinum, lead, zinc, tin, nickel, mercury, cadmium, copper, alloys of these metals, glassy carbon, graphite or diamond. If the anolyte contains a mineral acid, platinum, diamond, glassy carbon or graphite anodes and in particular platinum are preferably used. If the anolyte is basic, preference is given to using nickel and, in particular, platinum.

Each of the anode and the cathode can each consist entirely of the previously described materials or consist of a carrier material which is coated with the described cathode material. Suitable support materials for such coated electrodes are electrically conductive materials such as niobium, silicon, tungsten, titanium, silicon carbide, tantalum, copper, gold, nickel, iron, graphite, ceramic supports such as titanium suboxide or silver-containing alloys. The preferred carriers are metals, in particular metals with a lower standard potential, such as, for example, iron, copper, nickel or niobium.

It is preferred to use electrodes in the form of expanded metals, nets or sheets, the electrodes in particular containing the aforementioned materials. In particular, it is preferable to use a polarized lead sheet as the cathode.

The anodic reaction depends in a manner known per se on the composition of the anolyte. As a rule, the solvent used is oxidized. When using methanol as a solvent, for example, methyl formate, formaldehyde dimethyl acetal and / or dimethyl carbonate is formed. When using mixtures of methanol and Ν, Ν-dimethylformamide as a solvent, for example, N-methoxymethyl-N-methylformamide is formed. During the deoxygenation process according to the invention, an amount of charge of 4 to 12 F / mol, preferably 6 to 10 F / mol, in particular 7 to 9 F / mol is generally transferred. The current densities at which the process is carried out are generally from 1 to 1000 mA / cm ² , preferably from 10 to 100 mA / cm ² and in particular from 25 to 75 mA / cm ² .

The electrolysis according to the process of the invention is usually carried out at a temperature in a range of 0 to 100 ° C, preferably above 20 ° C, e.g. in the range of 25 to 100 ° C, in particular in the range of 25 to 80 ° C or preferably in the range of 15 to 100 ° C, in particular in the range of 15 to 80 ° C or in the range of 15 to 55 ° C, especially in Range of 25 to 55 ° C, worked.

In general, working at atmospheric pressure. Higher pressures are preferably used when operating at higher temperatures to avoid boiling of the starting compounds or solvents.

The total duration of the electrolysis naturally depends on the electrolysis cell, the substrate, the optionally added solvent, the electrode used and the current density. An optimum duration can be determined by the skilled person by routine tests, e.g. by sampling during electrolysis.

In a preferred embodiment of the invention, the contents of the electrolytic cell is mixed. For this thorough mixing of the cell contents, any mechanical stirrer known to those skilled in the art can be used. The use of other mixing methods such as the use of dynamic mixers such as Ultraturrax or liquid pumps, ultrasound or jet nozzles is also preferred. The electrolyte solution can be worked up after completion of the reaction (batch process) or continuously during the electrolysis by general separation methods. The catholyte can first be distilled and the individual compounds can be obtained separately in the form of different fractions. Suitable distillation processes are processes known to the person skilled in the art, such as direct current distillation, countercurrent distillation, short path distillation or steam distillation.

Alternatively, the product obtained can also be obtained by continuous or discontinuous extraction from the catholyte. In the case of the discontinuous extract tion, it is advantageous to work at pHs where the recovered amine is present as an uncharged species. Preference for extraction thus pH values are 9, preferably pH values> 1 1. Particularly suitable as extractants are known to those skilled organic solvents which are immiscible with water such as hydrocarbons having 5 to 12 carbon atoms such as hexane or octane, chlorinated hydrocarbons having 1 to 10 carbon atoms such as dichloromethane or chloroform, aliphatic ethers having 2 to 10 carbon atoms such Diethyl ether or diisopropyl ether, cyclic ethers such as tetrahydrofuran or aliphatic esters such as ethyl acetate or butyl acetate. Further purification after the extraction can be carried out, for example, by crystallization, distillation or by chromatography.

In addition to the products produced by cathodic reduction and unreacted substrate can be separated after completion of the reaction. This re-insulated substrate can be reused in a new electrolysis cycle. An advantage of this repeated use is that repeated amines or ethers can be recovered. Thus, the yield is significantly increased based on the amount of substrate originally used and thus increases the efficiency of the overall process. Furthermore, the repeated use of the reisolated substrate, the concentration of any sensitive products in the electrolyte per Redukti- onsvorgang be kept so low that the undesirable side reactions can be effectively suppressed, while the overall yield over the entire process (multiple electrolysis cycles) increases.

The process according to the invention can be carried out both on a laboratory scale and on an industrial scale. Furthermore, it is possible to carry out the process continuously or discontinuously. Corresponding electrolysis cells are known to the person skilled in the art. All embodiments of this invention relate to both the laboratory and industrial scale. On an industrial scale, it is preferred to carry out the process continuously.

The following examples describe the invention in more detail and are not intended to be limiting. Examples

I. Preparation of the starting materials

1 . Preparation of quaternary ammonium salts 1 .1 Preparation of N, N, N, N ', N', N'-hexamethyl-1,3-propanediammonium

 di (methylsulfate) (1) 1 .1.1 Preparation of N, N, N ', N'-tetramethyl-1,3-propanediamine

15.02 g (0.20 mol) of 1,3-propanediamine was added dropwise with stirring to 45.0 ml of 90% formic acid. Subsequently, 24.8 ml of 37% formalin solution were added. After the CO 2 evolution had ceased, the reaction solution was heated to reflux until complete conversion. In the boiling heat, the reaction mixture was then mixed with concentrated sulfuric acid. Excess water, formaldehyde and formic acid were removed by distillation after the addition of sulfuric acid. The residue was brought to a pH of> 9 with 50% sodium hydroxide solution. Thereafter, the solution was extracted three times with 60 ml of tert-butyl methyl ether. The combined organic phases were freed from the solvent under reduced pressure and then dried over NaOH.

Yield 21, 83 g (0.17 mol, 83%) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 49-1, 60 (m, 2H, 2-H); 2.13 (s, 12 H, NCH _3); 2.17-2.22 (m, 4H, 1 -H). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 26.1 (C-2); 45.5 (NCH ₃ ); 57.9 (C-1).

MS (ESI +)

m / z (lnnt.) = 131, 7 (100), [M + H] ⁺ ,

1 .1.2 Quaternization of N, N, N ', N'-tetramethyl-1,3-propanediamine

2.00 g (0.02 mol) of N, N, N ', N'-tetramethyl-1,3-propanediamine were dissolved in 20 ml of dichloromethane. At 0 ° C 4.4 ml (0.05 mol) of dimethyl sulfate were added dropwise with stirring. The reaction mixture was stirred at room temperature for 4 hours after completion of the addition. Unreacted starting materials and solvents were then removed under reduced pressure. The obtained crude product was recrystallized with methanol and ethyl acetate.

Yield 3.93 g (0.01 mol, 69%) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 2.31-2.42 (m, 2H, 2-H); 3.19 (s, 18 H, NCH _3); 3.39 - 3.45 (m, 4H, 1 -H); 3.74 (s, 6 H, OCH _3). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 17.1 (C-2); 52.9 (NCH ₃ ); 55.2 (OCH ₃ ); 62.2 (C-1). MS (ESI +)

m / z (Int.) = 271, 20 (13), [CioH27N ₂ O ₄ S] ⁺ / [Cation + Anion] ⁺ ,

653.38 (100), [C2iH ₅ 7N ₄ Oi ₂ S ₃ ] ⁺ / [2x cation + 3xAriiori] ⁺ .

The ammonium salts listed below under 1 .2 to 1 .20 were prepared in analogy to the process described under 1 .1.

1, 2 N, N'-diethyl-N, N, N ', N'-tetramethyl-1,3-propanediammonium di (methylsulfate) (2)

H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 37 (t, 6 H, 2'-H, ³ J = 7.3 Hz)); 2.20 - 2.35 (m, 2H, 2H); 3.10 (s, 12 H, NCH _3), 3.34 to 3.40 (m, 4 H, 1 H); 3.45 (q, 4-H, 1'-H, ³ J = 7.4 Hz); 3.73 (s, 5H, OCH ₃ ). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2 '); 16.2 (C-2), 49.8 (NCH ₃ ); 55.2 (OCH ₃ ); 59.2 (C-1 '); 60.2 (C-1).

MS (ESI +)

m / z (lnnt.) = 299.23 (37), [Ci ₂ H ₃ iN ₂ O ₄ S] V [cation + anion] ⁺ ,

709.45 (100) [C ₂₅ H ₆₅ N ₄ Oi ₂ S _3] ⁺ / [2xKation 3xAnion +] ^+,

1 .3 N, N, N, N ', N', N'-hexamethyl-1,4-butanediamine di (methylsulfate) (3) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1.84-1.92 (m, 4H, 2-H); 3.13 (s, 18 H, NCH _3); 3.36 - 3.45 (m, 4H, 1 -H); 3.73 (s, 6H, OCH ₃ ). ³ C NMR (75 MHz, D ₂ 0)

δ (ppm): 19.2 (C-2); 52.7 (NCH ₃ ); 55.2 (OCH ₃ ); 65.2 (C-1). MS (ESI +)

m / z (Int.) = 681, 41 (100), _[4 C23H6iN Oi2S3] ⁺ / [2xKation + 3xAnion] ^+.

1: 4 N, N'-diethyl-N, N, N ', N'-tetramethyl-1,4-butanediamine di (ethylsulfate) (4)

H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 30-1, 36 (m, 6H, 2'-H); 1, 78-1, 90 (m, 4H, 2-H); 3.04 (s, 12 H, NCH _3); 3.27 - 3.44 (m, 8H, 1 -H, 1'-H); 3.74 (s, 4H, OCH ₃ ). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2); 18.8 (C-2); 49.7 (NCH ₃ ); 55.2 (OCH ₃ ); 59.6 (C-1 '); 62.1 (C-1).

MS (ESI +)

m / z (lnnt.) = 313.22 (53), [Ci ₃ H ₃₃ N ₂ O ₄ S] V [cation + anion] ⁺ ,

737.47 (100), [C27H ₆₉ N ₄ Oi ₂ S ₃ ] ⁺ / [2x cation + 3x anion] ⁺ .

1 .5 N, N, N, N ', N', N'-hexamethyl-1, 5-pentanediammonium di (methylsulfate) (5) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 36-1, 46 (m, 2H, 3-H); 1, 82-1, 85 (m, 4H, 2-H); 3.09 (s, 18 H, NCH _3); 3.29-3.35 (m, 4H, 1 -H); 3.72 (s, 3H, OCH ₃ ). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 21, 8 (C-3): 22.2 (C-2); 52.6 (NCH ₃ ); 55.2 (OCH ₃ ); 65.9 (C-1).

MS (ESI +)

m / z (lnnt) = 299.21 (100), [Ci ₂ H ₃ iN ₂ O ₄ S] ⁺ / [Cation + Anion] ⁺ ,

709.45 (8) [C ₂₅ H ₆₅ N ₄ Oi ₂ S _3] ⁺ / [2xKation + 3xAnion] ^+. 1 .6 N, N'-diethyl-N, N, N ', N'-tetramethyl-1, 5-pentanediammonium di (ethylsulfate) (6)

2 "H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 32-1, 37 (m, 6H, 2'-H); 1, 42-1, 45 (m, 2H, 3-H); 1, 81-1, 86 (m, 4H, 2-H); 3.03 (s, 12 H, NCH _3); 3.25-3.32 (m, 4H, 1 -H); 3.37 (q, 4-H, 1'-H, ³ J = 7.3 Hz). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2 '); 14.0 (C-2 "), 21, 36 (C-3), 22.3 (C-2), 49.7 (NCH ₃ ), 59.5 (C-1 '), 62.7 ( C-1 "); 65.5 (C-1).

MS (ESI +)

m / z (Int.) = 341, 27 (100) _[2 Ci2H3iN 04S] ⁺ / [+ cation anion] ^+,

709.45 (8), [C32H79N ₄ Oi2S3] ⁺ / [2x cation + 3x anion] ⁺ .

1 .7 N, N, N, N ', N', N'-hexamethyl-1,6-hexanediammonium di (methylsulfate) (7) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 43-1, 52 (m, 4H, 3-H); 1, 78-1, 91 (m, 4H, 2-H); 3.14 (s, 18 H, NCH _3); 3.31-3.39 (m, 4H, 1 -H); 3.75 (s, 6H, OCH ₃ ). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 21, 9 (C-1); 24.8 (C-2); 52.6 (NCH ₃ ); 55.2 (OCH ₃ ); 66.2 (C-3). MS (ESI +)

m / z (lnnt.) = 313.22 (100), [Ci ₃ H ₃₃ N ₂ O ₄ S] ⁺ / [Cation + Anion] ⁺ ,

737.47 (99) [C27H ₆ 9N ₄ Oi2S _3] ⁺ / [2xKation + 3xAnion] ^+.

1 .8 N, N'-diethyl-N, N, N ', N'-tetramethyl-1,6-hexanediammonium di (ethylsulfate) (8)

2 "H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 31-1, 36 (m, 6H, 2'-H); 1, 37-1, 47 (m, 4H, 3-H); 1, 72-1, 83 (m, 4H, 2-H); 3.02 (s, 12 H, NCH _3); 3.21-3.31 (m, 4H, 1 -H); 3.32 - 3.43 (m, 4H, 1'-H). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2 '), 14.0 (C-2 "), 22.0 (C-3), 25.0 (C-2), 50.0 (NCH ₃ ) 59.4 (C-1 '); 63.0 (C-1 "); 65.5 (C-5).

HRMS (ESI +)

m / z for Ci6H39N ₂ 0 ₄ S ⁺ : calculated: 355.2631

 found: 355.2628 elemental analysis

% for Ci ₈ H ₄₄ N ₂ O ₈ S2 (480.68 g / mol):

 Calculated: C 44.98 H 9.32 N 5.83 S 13.34

Found: C 44.67 H 8.77 N 5.86 S 12.93. 1 .9 N, N, N, N ', N', N'-hexamethyl-1, 7-heptanediammonium di (methylsulfate) (9) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 33-1, 35 (m, 6H, 3-H, 4-H); 1, 70-1, 86 (m, 4H, 2-H); 3.08 (s, 18 H, NCH _3); 3.25-3.34 (m, 4H, 1 -H); 3.72 (s, 3H, OCH ₃ ). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 21, 9 (C-4); 25.0 (C-3), 27.5 (C-2), 52.5 (NCH ₃ ); 66.4 (C-1).

HRMS (ESI +)

m / z for Ci ₄ H ₃₅ N ₂ O ₄ S ⁺ : calculated: 327.2318

 found: 327,2332

1,10 N, N'-diethyl-N, N, N ', N'-tetramethyl-1,7-heptanediammonium di (methylsulfate) (10) H-NMR (300 MHz, D ₂ 0) δ (ppm): 1, 31-1, 41 (m, 12 H, 2'-H, 3-H, 4-H); 1, 66-1, 82 (m, 4H, 2-H); 3.01 (s, 12 H, NCH _3); 3.21-3.30 (m, 4H, 1 -H); 3.36 (q, 4 H, 1 '-H, ³ J = 7.3 Hz). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2 '), 21, 5 (C-4); 25.1 (C-3); 27.5 (C-2), 49.6 (NCH ₃ ); 55.2 (OCH ₃ ); 59.3 (C-1 '); 63.2 (C-1).

HRMS (ESI +)

m / z for Ci6H39N ₂ 0 ₄ S ⁺ : calculated: 355.2631

 found: 355.2619

Elemental analysis

% for Ci ₈ H ₄₄ N ₂ O ₈ S2 (480.68 g / mol):

 Calculated: C 43.75 H 9.07 N 5.83 S 13.34

Found: C 43.25 H 8.79 N 6.22 S 13.46.

1 .1 1 N, N, N, N ', N', N'-hexamethyl-1,8-octanediammonium di (methylsulfate) (11) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 31-1, 38 (m, 8 H, 4-H, 3-H); 1, 71-1, 82 (m, 4H, 2-H); 3.08 (s, 18 H, NCH _3); 3.25-3.32 (m, 4H, 1 -H); 3.72 (s, 3H, OCH ₃ ). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 22.0 (C-4); 25.1 (C-3); 27.7 (C-2); 52.5 (NCH ₃ ); 55.2 (OCH ₃ ); 66.5 (C-1).

HRMS (ESI +)

m / z for Ci ₅ H ₃₇ N ₂ O ₄ S ⁺ : calculated: 341, 2474

 found: 341, 2472

Elemental analysis

% for Ci ₆ H ₄₀ N ₂ O ₈ S ₂ (452.63 g / mol):

Calculated: C 42.46 H 8,91 N 6,19 S 14,17

Found: C 42.22 H 8.48 N 5.95 S 14.46. 1 .12 N, N'-diethyl-N, N, N ', N', - tetramethyl-1,8-octanediammonium di (methylsulfate) (12)

H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1.30-1.40 (m, 14 H, 2'-H, 4-H, 3-H); 1.67-1.79 (m, 4H, 2H); 3,00 (s, 12 H, NCH _3); 3.19-3.27 (m, 4H, 1-H); 3.34 (q, 4 H, 1'-H, ³ J = 7.3 Hz); 3.72 (s, 3H, OCH ₃ ). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2 '); 21.5 (C-4); 24.1 (C-3); 27.7 (C-2); 49.6 (NCH ₃ ); 59.3 (OCH ₃ ); 63.2 (C-1). HRMS (ESI +)

m / z for Ci4H ₃ 5N ₂ ⁺ 04S: Calculated: 383.2944

 found: 383.2946

1.13 N, N, N, N ', N', N'-hexamethyl-1,9-nonanediammonium di (methylsulfate) (13) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1.31-1.40 (m, 10H, 5H, 4H, 3H); 1.72-1.85 (m, 4H, 2H); 3.09 (s, 18 H, NCH _3); 3.24-3.33 (m, 4H, 1-H); 3.74 (s, 6 H, OCH _3). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 22.0 (C-5); 25.2 (C-4); 27.8 (C-3); 27.9 (C-2); 52.5 (NCH ₃ ); 55.2 (OCH ₃ ); 66.5 (C-1).

HRMS (ESI +)

m / z for Ci ₆ H ₃₉ N ₂ O ₄ S ⁺ : calculated: 355.2631

 found: 355.2619

Elemental analysis

% for Ci ₆ H ₃₉ N ₂ O ₈ S ₂ (451, 63 g / mol):

Calculated: C 43.75 H 9.07 N6.00 S 13.74

 Found: C 43.68 H 9.05 N 6.06 S 14.04.

1.14 N, N'-diethyl-N, N, N ', N'-tetramethyl-1,9-nonanediammonium di (sulfate) (14)

H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1.30-1.14 (m, 16 H, 2'-H, 5-H, 4-H, 3-H); 1, 67-1, 79 (m, 4H, 2-H); 3.01 (s, 12 H, NCH _3); 3.20-3.28 (m, 4H, 1 -H); 3.35 (q, 4 H, 1 '-H, ³ J = 7.3 Hz); 3.73 (s, 6H, OCH ₃ ). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2 '), 21, 5 (C-5); 25.2 (C-4); 27.8 (C-3); 28.0 (C-2); 49.6 (NCH ₃ ); 55.2 (OCH ₃ ); 59.2 (1'-C); 63.3 (C-1).

HRMS (ESI +)

m / z for Ci ₈ H ₄ 3N ₂ 04S ⁺ : calculated: 383.2944

 found: 383.2936 elemental analysis

 % for C19H46N2O8S2 (494.72 g / mol):

 Calculated: C 46.13 H 9.37 N 5.66 S 12.96

Found: C 45.68 H 9.05 N 5.64 S 12.84. 1 .15 N, N, N, N ', N', N'-hexamethyl-1, 10-decanediammonium di (methylsulfate) (15) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 29-1, 37 (m, 12 H, 5-H, 4-H, 3-H); 1, 71-1, 82 (m, 4H, 2-H); 3.08 (s, 18H, NCHs); 3.23-3.34 (m, 4H, 1 -H). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 22.0 (C-5); 25.2 (C-4); 27.9 (C-3); 28.0 (C-2); 52.5 (NCH ₃ ); 55.2 (OCH ₃ ); 66.5 (C-1). HRMS (ESI +)

m / z for C17H41 N ₂ 0 ₄ S ⁺ : calculated: 369.2787

 found: 369.2800

Elemental analysis

% for Ci ₇ H ₄ iN ₂ O ₈ S ₂ (465.65 g / mol):

Calculated: C 44.98 H 9.23 N 5.83 S 13.34 Found: C 45.32 1-1 9.18 N 5.67 S 12.97.

1 .16 N, N'-diethyl-N, N, N ', N'-tetramethyl-1, 10-decanediammonium di (ethylsulfate) (16)

H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 28-1, 40 (m, 18 H, 2'-H, 5-H, 4-H, 3-H); 1, 66-1, 78 (m, 4H, 2-H); 2.99 (s, 12 H, NCH _3); 3.18-3.26 (m, 4H, 1 -H); 3.33 (q, 4 H, 1 '-H, ³ J = 7.3 Hz). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2 '); 21, 5 (C-5); 25.2 (C-4); 27.9 (C-3); 28.1 (C-2); 49.6 (NCH ₃ ); 55.1 (OCH ₃ ); 59.2 (C-1 '); 63.3 (C-1).

HRMS (ESI +)

m / z for C2oH47N ₂ 0 ₄ S ⁺ : calculated: 41 1, 3257

 found: 41 1, 3269

Elemental analysis

% for C21 H50N2O8S2 (522.77 g / mol):

Calculated: C 48.25 H 9.64 N 5.36 S 12.27

 Found: C 47.98 H 9.34 N 5.30 S 12.24.

1 .17 N, N, N, N ', N', N'-hexamethyl-1,12-dodecanediammonium di (methylsulfate) (17) H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 28-1, 39 (m, 16 H, 6-H, 5-H, 4-H, 3-H); 1, 72-1, 84 (m, 4H, 2-H); 3.10 (s, 18H, NCHs); 3.25-3.34 (m, 4H, 1 -H); 3.74 (s, 6 H, OCH _3). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 22.0 (C-6); 25.2 (C-5); 27.9 (C-4); 28.2 (C-3); 28.4 (C-2); 52.5 (NCH ₃ ); 55.2

HRMS (ESI +)

m / z for Ci9H ₄ 5N20 ₄ S ⁺ : calculated: 397.3100

found: 397.3087 Elemental analysis

% for C20H48N2O8S2 (508.73 g / mol):

Calculated: C 48.25 H 9.64 N 5.36 S 12.27

 Found: C 47.98 H 9.34 N 5.30 S 12.24.

1.18 N, N'-diethyl-N, N, N ', N'-tetramethyl-1,12-dodecanediammonium di (ethylsulfate) (18)

 2 '

H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 29-1, 40 (m, 22 H, 2'-H, 6-H, 5-H, 4-H, 3-H); 1, 66-1, 79 (m, 4H, 2H); 3,00 (s, 12 H, NCH _3); 3.20-3.28 (m, 4H, 1 -H); 3.35 (q, 4H, 1'-H ₂ , ³ J = 7.3 Hz). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.2 (C-2 '); 14.0 (C-2 "); 21.5 (C-6); 25.3 (C-5); 28.0 (C-4); 28.2 (C-3); 28.4 ( C-2); 49.7 (NCH ₃ ); 59.2 (C-1 '); 63.3 (C-1 "); 65.5 (C-1).

HRMS (ESI +)

m / z for C2oH47N ₂ 0 ₄ S ⁺ : calculated: 439.3570

 found: 41 1, 3572.

1, 19 N, N, N, N ', N', N ", ethyl sulfate) (19)

H-NMR (300 MHz, D ₂ 0)

δ (ppm): 3.28 (s, 18H, 1'-H); 3.34 (s, 6H, 2'-H); 3.70 (s, 9H, OCH ₃ ); 4.07 (m, 8 H, 2

H, 1 -H). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 51.1 (C-2 '); 53.7 (C-1 '); 55.2 (OCH ₃ ); 57.1 (C-2); 57.9 (C-1).

HRMS (ESI +)

m / z (Int.) = 440.22 (100) [Ci4H ₃ 8N ₃ 08S2] ⁺ / [+ cation 2xAnion] ⁺ 1 .20 N, N ', N "-triethyl-N, N, N', N", N "-pentamethyl (diethylene) tri (ethylsulfate) (20)

H-NMR (300 MHz, D ₂ 0)

δ (ppm): 1, 29-1, 52 (m, 18 H, 2'-H, 2 "-H, 2"'-H); 3.03 - 3.09 (m, 4H, 1'-H); 3.1 1 (s, 12H, 3'H); 3.23 (s, 6H, 1 "'-H); 3.35 (m, 2H, 1"-H); 3.40 - 3.57 (m, 11H, 3 "-H, 2-H, 1 -H) 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 7.3 (C-2 '); 7.4 (C-2 "); 14.0 (C-2"); 45.3 (C-3 "); 50.1 (C-3 '); 54.5 (C-Γ); 59.1 (C-1'); 60.3 (C-2); 61, 4 (C-1); 65.5 (C-1 '").

HRMS (ESI +)

m / z (lnnt) = 510.33 (15) [Ci9H48N ₃ 08S2] ⁺ [cation + 2xAnion] ⁺

2. Preparation of N- (2-ethylhexyl) benzoic acid amide

52.4 ml (0.32 mol) of 2-ethylhexylamine and 82.8 ml (0.64 mol) of triethylamine were dissolved in 320 ml of dichloromethane. Then, at 0 ° C., 37.2 ml (0.32 mol) of benzoyl chloride dissolved in 320 ml of dichloromethane were added dropwise. The reaction mixture was stirred at room temperature for 12 h and then washed with saturated sodium bicarbonate solution (2 × 80 ml) and with saturated brine (2 × 80 ml). Excess solvent was removed under reduced pressure. The pure product was obtained by short path distillation (9.7 x 10 ^"3 mbar, 142 ° C).

Yield: 68.17 g (0.29 mol, 91%) -H-NMR (300 MHz, D ₂ 0)

δ (ppm): 0.87 (t, 3 H, 6-H, ³ J = 7.5 Hz); 0.91 (3 H, 8-H t, ³ J = 6.8 Hz); 1, 22-1, 41 (m, 8H, 7H, 5H, 4H, 3H, 2H); 1, 49-1, 52 (m, 2H, 2-H); 3.28- 3.46 (m, 2H, 1 -H); 6.10 (s, 1H, NH); 7.35-7.52 (m, 3H, 4'-H, 5'-H); 7.68 - 7.80 (m, 2H, 3'H). 3C-NMR (75 MHz, D ₂ 0)

δ (ppm): 10.9 (C-6); 14.0 (C-8); 23.0 (C-5); 24.4 (C-4); 28.9 (C-3); 31, 1 (C-7); 39.5 (C-2); 42.9 (C-1); 126.8 (C-5 '); 128.5 (C-4 '); 131, 3 (C-3 '); 135.0 (C-2 '); 167.6 (C-1 '). MS (ESI (+)) m / z (lnnt.) = 256.16 (100) [M + Na] ⁺ . II Cathodic deoxygenation of N- (2-ethylhexyl) benzoic acid amide to N-benzyl-N- (2-ethylhexyl) amine

Example 1 :

 Electrochemical reduction of N- (2-ethylhexyl) benzoic acid amide in the presence of N, N, N, N ', N', N'-hexamethyl-1,3-propanediammonium di (methylsulfate) (1)

The cathode and the anode compartment of a divided half by a Nation 324 ^® membrane electrolysis cells were respectively mixed with 50 ml of a 2 wt .-% methanolic sulfuric acid solution filled. In the cathode half-space, 397 mg (1.70 mmol) of N- (2-ethylhexyl) benzoic acid amide were dissolved and 325 mg (0.85 mmol) were added.

N, N, N, N ', N', N'-hexamethyl-1,3-propanediammonium di (methyl sulfate). The cathode used was a lead foil, which was polarized before immersion, and the anode used was a platinum sheet. At 45 ° C, the electrolysis was carried out galvanostatically with a current density of 55.55 mA / cm ² . After successful transfer of a charge of 1312 C (8 F), the reaction solution was removed from the cathode compartment and rinsed with methanol (40 mL). The methanol used for rinsing was combined with the reaction solution and the resulting mixture (cathode outlet) was brought to pH> 1 1 with 1N NaOH and extracted with diethyl ether (3 x 65 ml). The combined organic phases were extracted with 10% HCl (3 x 50 ml) to give the product. In order to re-isolate unreacted educt, the organic phase was dried over Na ₂ SO ₄ and freed from the solvent under reduced pressure. To obtain the product, the HCl phase was brought to pH> 1 1 with aqueous NaOH and the amine was extracted with diethyl ether (3 × 60 ml). The combined organic phases were dried over MgS0 ₄ , the solvent removed in vacuo.

Yield: 205 mg (0.93 mmol, 55%);

 Current efficiency: 23%;

Reisoliertes educt: 70 mg (0.30 mol, 18%); -H NMR (300 MHz, D ₂ 0)

δ (ppm): 0.83 (t, 3 H, 6-H, ³ J = 7.3 Hz); 0.87 (3 H, 8-H t, ³ J = 6.6 Hz); 1, 07-1, 45 (m, 111 H, 7-H, 5-H, 4-H, 3-H, 2-H, NH); 2.50 (d, 2 H, 1 H, ³ J = 6.0 Hz); 3.76 (s, 2H, 9-H); 7.13-7.48 (m, 5H, 11H, 12H, 13H). ³ C NMR (75 MHz, D ₂ 0)

 δ (ppm): 1, 0 (C-6); 14.3 (C-8); 23.3 (C-5); 24.6 (C-4); 29.1 (C-3); 31, 4 (C-7); 39.3 (C-2); 42.4 (C-1); 54.2 (C-9); 127.3 (C-1 1); 128.6 (C-12); 140.0 (C-13); 140.8 (C-10).

MS (ESI (+))

m / z (lnnt.) = 220.21 (100) [M + H] ⁺ .

Examples 2 to 7:

N- (2-ethylhexyl) benzoic acid amide was deoxygenated analogously to Example 1 in the presence of the salts described in Table A to give N-benzyl-N- (2-ethylhexyl) amine. The electrolysis conditions were as follows: Electrolyte: 50 ml of 2% H2SO4 in methanol, Q = 8 F / mol, T = 45 ° C, n (additive) = 1, 7 mmol, j = 44.1 mA / cm ² Table A:

 1) based on the reactant used

 2) based on the amount of charge used

Claims

claims

Process for the deoxygenation of carboxylic acid amides and carboxylic acid esters by cathodic reduction of a solution of the carboxylic acid amide or of the carboxylic acid ester, characterized in that the solution contains a salt as an additive which is selected from quaternary ammonium salts and quaternary phosphonium salts.

Process according to claim 1, characterized in that the cation of the salt has the formula I,

where k is an integer in the range from 1 to 99 and especially 1 or 2,

A is nitrogen or phosphorus,

Z is an alkylene group having 2 to 12 carbon atoms, in which, where appropriate, 1, 2 or 3 Ch groups which are separated from the nitrogen or phosphorus atoms A and from one another by at least 2 C atoms may be replaced by oxygen atoms,

R ¹ , R ² , R ³ and R ^{4 are} each independently of one another C 1 -C 10 -alkyl, which in each case is unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene) , or

R ¹ and R ^2, together with the nitrogen to which they are attached, may also stand for a 5 to 8-membered heterocycle containing 1 N-atom in the ring and being unsubstituted or having 1 to 4 substituents selected from hydroxy, C 1 -C 4 -alkoxy and C 1 -C 4 -alkyl, may be substituted,

R ⁵ and R ^{6 are} each independently of the other Ci-Cio-alkyl, which is in each case unsubstituted or may be substituted by 1 or 2 substituents selected from hydroxy, alkoxy and poly (oxyethylene). Process according to any one of the preceding claims, characterized in that the anions of the salt are chosen from sulphate, bisulphate, alkylsulphate, arylsulphate, arylsulphonate, haloalkylsulphonate, arylsulphonate, halide, pseudohalide, carboxylate, carbonate, imides, phosphate, alkylphosphate, nitrate, tetrafluoroborate, Hexafluorophosphate and perchlorate.

Method according to one of the preceding claims, characterized in that the solution of the carboxylic acid amide or of the carboxylic ester contain the salt in a concentration in a range of 0.001 to 1000 mmol / l, in particular in the range of 0.1 to 500 mmol / l.

Method according to one of the preceding claims, characterized in that a carboxylic acid amide or a carboxylic acid ester of the formula II is used as the substrate,

wherein

Y represents a chemical bond or an alkylene group having 1 to 6 carbon atoms,

X is oxygen or NR ⁹ ,

R ^{7 is} selected from C 1 -C 10 -alkyl, C 2 -C 10 -alkenyl, C 1 -C 10 -alkoxy, C 1 -C 10 -haloalkyl, C 1 -C 10 -haloalkoxy, C 3 -C 10 -cycloalkyl, aryl and hetaryl, where the ring is in the the last three groups are unsubstituted or may be substituted by up to 6 substituents selected from halogen, hydroxy, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, and

R ^{8 is} selected from hydrogen, C 1 -C 10 -alkyl which is unsubstituted or has 1 or 2 substituents selected from hydroxy, C 1 -C 4 -alkoxy and aryl,

C ₂ -C 10 -alkenyl, C ₁ -C 10 -haloalkyl, C ₁ -C 10 -haloalkoxy, C ₃ -C 10 -cycloalkyl, aryl and hetaryl, where the ring in the last three groups is unsubstituted or may be substituted by up to 6 substituents, which are selected from halogen, hydroxy, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, where R ^{8 is} different from hydrogen when X is O,

R ⁷ and R ⁸ together may be C 3 -C 20 -alkylene or C 3 -C 20 -alkenylene which is unsubstituted or substituted by up to 6 substituents selected from hydroxy, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy where 2 substituents attached to adjacent C atoms together with the C atoms to which they are attached can also form a 5- to 7-membered carbocycle; and is hydrogen or C 1 -C 10 -alkyl which is unsubstituted or has 1 or 2 substituents selected from hydroxy, C 1 -C 4 -alkoxy and aryl.

Method according to one of the preceding claims, characterized in that a secondary or tertiary carboxylic acid amide is used as the substrate,

Method according to one of the preceding claims, characterized in that the cathodic reduction of a solution of the carboxylic acid amide or the carboxylic ester is carried out in a divided flow cell.

Process according to one of the preceding claims, characterized in that the cathodic reduction of the solution of the carboxylic acid amide or of the carboxylic acid ester is carried out in an inert solvent selected from C 1 -C 4 -alkanols, dimethyl carbonate, propylene carbonate, tetrahydrofuran, dimethoxyethane, Acetonitrile and water, mixtures of these inert solvents or mixtures of these inert solvents with C5-C7 hydrocarbons.

Process according to any one of the preceding claims, characterized in that the solution of the carboxylic acid amide or of the carboxylic ester contains a mineral acid.

A method according to claim 9, characterized in that the solution of the carboxylic acid amide or the carboxylic acid ester contains the mineral acid in a concentration in a range of 0.05 to 5M.

A method according to any one of claims 8 to 10, characterized in that the cathodic reduction of the solution of the carboxylic acid amide or the Carboxylic acid ester in a selected from Ci-C4-alkanols or mixtures of C1-C4-alkanols inert solvent thereof, which contains a mineral acid, in particular sulfuric acid. 12. The method according to any one of the preceding claims, characterized in that the cathode used is an electrode whose surface consists of lead.

13. The method according to any one of the preceding claims, marked thereby, that as anode an electrode is used, the surface of platinum,

Lead, zinc, tin, nickel, mercury, cadmium, copper, alloys of these metals, glassy carbon, graphite or diamond.

14. The method according to any one of the preceding claims, characterized in that one carries out the electrolysis at a temperature in the range of 25 to 100 ° C.