N-heterocyclic compounds and their use as surfactants

Abstract

The present invention relates to N-heterocyclic compounds of the formula (I) and the salts thereof. The present invention also relates their use as surfactants, in particular as emulsifiers, as foam regulators and / or as wetting agents. Formula (I) and the salts thereof, where k is 0 or 1; R1 is selected from C7-C29-alkyl and C7-C29-alkenyl; X and Y are identical or different and selected from CH2, O, S, SO, SO2 or NR3, provided that at least one of X and Y is CH2, R2 is hydrogen or C1-C4-alkyl, R3 is hydrogen or C1-C4-alkyl, where k is if both X and Y are CH2 and where COOH replaces one of the hydrogen atoms of a CH2 group in positions a or b.

Description

[0001] N-heterocyclic compounds and their use as surfactants

[0002] The present invention relates to N-heterocyclic surfactants wich bear a carboxyl group and the salts thereof. The present invention also relates their use as surfactants, in particular as emulsifiers, as foam regulators and / or as wetting agents.

[0003] TECHNICAL BACKGROUND

[0004] Surfactants are compounds which lower the surface tension between two phases, in particular between two liquids. Surfactants generally are organic amphiphilic compounds, i.e., compounds comprising both hydrophobic (= lipophilic) and hydrophilic groups. Such compounds find use, e.g., as detergents, wetting agents, foaming agents, emulsifiers, and dispersants.

[0005] Being commodities, surfactants are produced on a large scale and used universally on industrial / institutional as well as on private level. After use, residual surfactants are generally discharged into sewage systems or directly into surface waters, and most of them end up dispersed in different environmental compartments such as soil, water or sediment, at least if the wastewater has not undergone a secondary treatment in wastewater treatment plants. The problems related with surfactants, especially with those not derived from natural sources, such as toxic effects on various aquatic and other organisms, are well known.

[0006] Furthermore, one of the presently most pressing needs worldwide is the reduction of the carbon footprint of all sorts of products, processes and activities.

[0007] Currently, most surfactants, such as linear alkylbenzene sulfonates (LAS), sulfosuccinates, alcohol alkoxylates or alcohol alkoxylate sulfates are produced starting exclusively or at least predominantly from petrochemical starting materials, i.e. from material gained from fossil carbon sources.

[0008] It is the object of the present invention to provide compounds which are suitable as surfactants. Advantageously they should have a reduced carbon footprint, especially by being at least partially available from renewable sources, and / or should be readily biodegradable, or ideally both available from renewable sources and readily biodegradable. Furthermore, the compounds should be accessible by simple and robust production methods which can be carried out on production scale.

[0009] PCT / EP2023 / 058273 discloses the production of surfactants having a betaine structure by reductive amination of amino acids including cyclic alpha-amino acids, namely proline, hydroxyproline or pipecolic acid (piperidine-2-carboxylic acid) with fatty C8-C18aldehydes to obtain N-alkylated amino acids bearing a C8-C18alkyl or C8-C18alkenyl moiety on the nitrogen atom of the amino acid.

[0010] EP 345927 relates to N-substituted 3-piperidine carboxylic acids which are suitable for treating several neurological disorders. EP 345927 mentions the hydrochlorides of 1-(1-(3-propylnonyl) 3-piperidine carboxylic acid and 1-(1-(4-propyldecyl)-3- piperidinecarboxylic acid.

[0011] Chemical Abstracts Service, Columbus, Ohio, database accession no. 1156635-26-4, of June 14, 2009 mentions 1-nonyl 3-piperidinecarboxylic acid.

[0012] EP 340755 mentions 1-decyl-4-piperidinecarboxylic acid as an intermediate in the production of monopersulfate bleaching agents WO 2020 / 160054 mentions 1-hexadecyl-4-piperidinecarboxylic acid as an intermediate in the production of a pharmaceutical active from the group of imidazoquinoline amine compounds.

[0013] SUMMARY OF THE INVENTION

[0014] The above mentioned objects are achieved by the compounds of formula (I), in particular by the compounds of formulae (I. a), (l.b) and (l.c) depicted below, and the salts of the compounds of formulae (I), (l.a), (l.b) and (l.c). Therefore, the present invention relates to compounds of general formula (I) and the salts thereof, where k is 0 or 1; R1is selected from C7-C29-alkyl and C7-C29-alkenyl;

[0015] X and Y are identical or different and selected from CH2, O, S, SO, SO2or NR3, provided that at least one of X and Y is CH2,

[0016] R2is hydrogen or Ci-C4-alkyl, R3is hydrogen or C C4-alkyl, where k is 1 if both X and Y are CH2and where COOH replaces one of the hydrogen atoms of a CH2group in positions a or b as surfactants, in particular as emulsifiers, as foam regulators and / or as wetting agents, and especially as a surfactant for stabilizing oil-in-water emulsions or aqueous dispersions.

[0017] The present invention also relates to compounds of the general formula (I) and the salts thereof, where k is 0 or 1;

[0018] R1is selected from C7-C29-alkyl and C7-C29-alkenyl;

[0019] X and Y are identical or different and selected from CH2, O, S, SO, SO2or NR3, provided that at least one of X and Y is CH2,

[0020] R2is hydrogen or CrC4-alkyl,

[0021] R3is hydrogen or Ci-C4-alkyl, where k is 1 if both X and Y are CH2and where COOH replaces one of the hydrogen atoms of a CH2group in positions a or b. except for the following compounds and their salts:

[0022] 1-(1-(3-propylnonyl)-3-piperidinecarboxylic acid, which is a compound of the formula (I), where COOH replaces one of the hydrogen atoms of a CH2group in position a, k is 1, both X and Y represent CH2, R2is hydrogen, and where the moiety, CH2-R1represents 1-(3-propylnonyl),

[0023] 1-(1-(4-propyldecyl)-3-piperidinecarboxylic acid, which is a compound of the formula (I), where COOH replaces one of the hydrogen atoms of a CH2group in position a, k is 1, both X and Y represent CH2, R2is hydrogen, and where the moiety, CH2-R1represents 1-(1-(4-propyldecyl),

[0024] 1-nonyl-3-piperidinecarboxylic acid, which is a compound of the formula (I), where COOH replaces one of the hydrogen atoms of a CH2group in position a, k is 1, both X and Y represent CH2, R2is hydrogen, and where the moiety, CH2-R1represents 1- nonyl, 1-decyl-4-piperidinecarboxylic acid, which is a compound of the formula (I), where COOH replaces one of the hydrogen atoms of a CH2group in position b, k is 1, both X and Y represent CH2, R2is hydrogen, and where the moiety, CH2-R1represents 1-decyl, and

[0025] 1-hexadecyl-4-piperidinecarboxylic acid, which is a compound of the formula (I), where COOH replaces one of the hydrogen atoms of a CH2group in position b, k is 1, both X and Y represent CH2, R2is hydrogen, and where the moiety, CH2-R1represents 1-hexadecyl.

[0026] In particular, the present invention relates to compounds of the formulae (I. a), (l.b) and (l.c) and the salts thereof, where R1and R2are as defined herein for formula (I) and where

[0027] Y in formula (l.a) is as defined herein for formula (I) and in particular CH2;

[0028] X in formula (l.b) is as defined herein for formula (I) and in particular CH2;

[0029] X' in formula (l.c) is O or S.

[0030] The compounds of formulae (I), (l.a), (l.b) and (l.c) can be prepared from aldehydes of the formula (III) and cyclic amino acid compounds of the formulae (III), (III. a), (lll.b) or (lll.c), respectively, by a reductive amination. Therefore, a further aspect of the invention relates to a process for producing the compounds of formula (I), in particular of formulae (l.a), (l.b) and (l.c), which comprises a reductive amination of an aldehyde of general formula (II) wherein R1is as defined in the context of formulae (I), (l.a), (l.b) and (l.c); with an amino acid compound of general formula (III) in particular with an amino acid compound of the general formulae ), (III. a), (lll.b) or (lll.c), respectively or a salt thereof, wherein k, R2, X, X' and Y are as defined in the context of formulae (I), (I. a), (l.b) and (l.c), and where COOH in formula (Illi) replaces one of the hydrogen atoms of a CH2group in positions a or b; in the presence of molecular hydrogen and a heterogeneous catalyst comprising a group 8, group 9 or group 10 element of the periodic table of the elements.

[0031] Due to the presence of both a basic amino nitrogen and the carboxyl group, the compounds of formulae (I), (I. a), (l.b) and (l.c) are zwitterionic. If incorporated into water or aqueous liquids, the compounds of the formulae (I), (I. a), (l.b) and (l.c) efficiently reduce the surface tension. Therefore, they are particularly suitable as surfactants. Therefore, a further aspect of the present invention relates to the use of the compounds of formulae (I), (I. a), (l.b) and (l.c) as well as salts of the compounds of the formulae (I), (I. a), (l.b) and (l.c) as surfactants or in surfactant compositions. In particular, the compounds of formulae (I), (I. a), (l.b) and (l.c) as well as salts of the compounds of the formulae (I), (I. a), (l.b) and (l.c) can be used as emulsifiers, as foam regulators and / or as wetting agents.

[0032] In particular, the compounds of formulae (I), (I. a), (l.b) and (l.c) as well as salts thereof can be used in the following applications: In detergents, including laundry detergents, dishwashing detergents and l&l cleaners, in surfactant formulations for cleaning hard surfaces, in humectants, in cosmetic and pharmaceutical formulations, in crop protection formulations, in paints, in coating agents, in adhesives, in leather degreasing agents, in formulations for the textile industry, in fiber processing, in metal processing, in the food industry, for water treatment, in paper industry, in fermentation processes, for mineral processing and in emulsion polymerizations.

[0033] Yet, further aspects of the of the present invention relate to surfactant compositions containing at least one compound selected from the compounds of formulae (I), (l.a), (l.b) and (l.c) and / or a salt of the compounds of formulae (I), (l.a), (l.b) and (l.c) as defined herein and and at least one further component which is different from the compounds of formula (I) and its salts, which is in particular selected from the group consisting of carriers, surfactants different from the compounds (I), fragrance, antimicrobial agents, sequestrants, enzymes, enzyme stabilizers, hydrotropic agents, bleaching agents, dyes, pigments, pH adjusting agents, pearlescent, opacifiers, viscosity modifiers, dispersants and inorganic salts; and the use of the compounds of the formulae (I), (l.a), (l.b) or (l.c) as defined herein for stabilizing oil-in-water emulsions or aqueous dispersions, methods for stabilizing oil-in-water emulsions or aqueous dispersions which comprises the incorporation of at least one compound of the formulae (I), (l.a), (l.b) or (l.c) as defined herein into the oil-in-water emulsions or aqueous dispersions.

[0034] The invention is associated with several benefits. Due to the zwitterionic structure, the compounds of the formulae (I), (l.a), (l.b) and (l.c) are suitable as surfactants. In particular, efficiently reduce surface tension and interfacial tension of aqueous emulsions and suspensions of hydrophobic matter and the contact angle of water on surfaces. The compounds of the formulae (I), (l.a), (l.b) and (l.c) can be easily produced from the amino acid compounds of the formulae (II), (II. a), (II. b) or (II. c), respectively and the aldehydes of the formula (III), by a reductive amination which can be carried out on lab scale and on industrial production scale. As both the compounds of formulae (II) and (III) and, in particular, the compounds of formulae (II. a), (II. b) or (II. c) are readily available from renewable resources, in particular by biochemical processes using carbohydrates as starting materials, the provision of the compounds of the formulae (I), (l.a), (l.b) and (l.c) allow for efficiently reducing the carbon footprint associated with the provision of conventional anionic surfactants, e. g. from the group of alkysulfates, alkylether sulfates, alkyl sulfonates, alkylbenzene sulfonates and alkylphenol ether sulfonates. Last but not least, the compounds of the formulae (I), (La), (Lb) and (l.c) are readily biodegradable due to the aminoacid base structure, in particular if the moiety R1is linear alkyl or alkenyl.

[0035] DETAILED DESCRIPTION OF THE INVENTION

[0036] The term "Cn-Cm" as used herein refers to the range of the number of carbon atoms a moiety may have. The term "alkyl" is used in the usual sense and stands for saturated straight-chain or linear and branched aliphatic non-cyclic hydrocarbon radicals. Cn-Cm-alkyl has n to m carbon atoms. "C1-C30-Alkyl" is a saturated aliphatic non-cyclic hydrocarbon radical having 1 to 30 carbon atoms. "C6-C30-alkyl" is a saturated straight-chain or branched aliphatic non-cyclic hydrocarbon radical having 6 to 30 carbon atoms. "C8-C30-alkyl" is a saturated straight-chain or branched aliphatic non-cyclic hydrocarbon radical having 8 to 30 carbon atoms. "C10-C18- alkyl" is a saturated straight-chain or branched aliphatic non-cyclic hydrocarbon radical having 10 to 18 carbon atoms. "C10-C14-alkyl" is a saturated straight-chain or branched aliphatic non-cyclic hydrocarbon radical having 10 to 14 carbon atoms. Examples for C10-C14- alkyl are n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl and structural isomers thereof. Examples for C10-C18-alkyl are, in addition to those mentioned for C10-C14-alkyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl and structural isomers thereof. Examples for C8-C30- alkyl are, in addition to those mentioned for C10-C18-alkyl, n-octyl, n-nonyl, n-nonadecyl, n- eicosyl, n-henicosyl, n-docosyl, n-tricosyl, n-tetracosyl, n-pentacosyl, n-hexacosyl, n-octacosyl, n-nonacosyl, n-triacontyl and structural isomers thereof. Examples for C6-C30-alkyl are, in addition to those mentioned for C8-C30-alkyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3- methylpentyl, 4- methyl pentyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,2- di methyl butyl, 2,3-dimethylbutyl, 3, 3 -di methyl butyl, 1-ethylbutyl, 2-ethylbutyl, 1,1,2- trimethylpropyl, 1,2,2-tri methyl propyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl, n- heptyl and (other) structural isomers thereof. Examples for Ci-C30-alkyl are, in addition to those mentioned for C6-C30-alkyl, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, 1- methyl butyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-di methyl propyl and other structuryl isomers thereof.

[0037] Strictly speaking, the term "alkenyl" indicates monounsaturated (i.e. containing one C-C double bond) straight-chain or branched aliphatic non-cyclic hydrocarbon radicals. In terms of the present invention, the term "alkenyl" however also encompasses polyunsaturated straight-chain or branched aliphatic non-cyclic hydrocarbon radicals having 2 (alkadienyl), 3 (alkatrienyl) or more (a I ka polyenyl) C-C double bonds. Examples for C2-C30-alkenyl in the strict sense (just one C-C double bond) are ethenyl, 1-propenyl, 2-propenyl, 1-methylethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl, 2-methyl-1-propenyl, 1-methyl-2- propenyl, 2-methyl-2-propenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-methyl-1- butenyl, 2-methyl-1-butenyl, 3-methyl-1-butenyl, 1-methyl-2-butenyl, 2-methyl-2-butenyl, 3-methyl-2-butenyl, 1-methyl-3-butenyl, 2-methyl-3-butenyl, 3-methyl-3-butenyl, 1,1-dimethyl-2-propenyl, 1,2-dimethyl-1-propenyl, 1,2-dimethyl-2-propenyl, 1-ethyl-1- propenyl, 1-ethyl-2-propenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl, 5-hexenyl, 1-methyl- 1-pentenyl, 2-methyl-1-pentenyl, 3-methyl-1-pentenyl, 4-methyl-1-pentenyl, 1-methyl-2- pentenyl, 2-methyl-2-pentenyl, 3-methyl-2-pentenyl, 4-methyl-2-pentenyl, 1-methyl-3- pentenyl, 2-methyl-3-pentenyl, 3-methyl-3-pentenyl, 4-methyl-3-pentenyl, 1-methyl-4- pentenyl, 2-methyl-4-pentenyl, 3-methyl-4-pentenyl, 4-methyl-4-pentenyl, 1,1-dimethyl-2- butenyl, 1,1-dimethyl-3-butenyl, 1,2-dimethyl-1-butenyl, 1,2-dimethyl-2-butenyl, 1,2-dimethyl- 3-butenyl, 1,3-dimethyl-1-butenyl, 1,3-dimethyl-2-butenyl, 1,3-dimethyl-3-butenyl, 2,2-dimethyl-3-butenyl, 2,3-dimethyl-1-butenyl, 2,3-dimethyl-2-butenyl, 2,3-dimethyl-3- butenyl, 3,3-dimethyl-1-butenyl, 3,3-dimethyl-2-butenyl, 1-ethyl-l-butenyl, 1-ethyl-2-butenyl,

[0038] 1-ethyl-3-butenyl, 2-ethyl-1-butenyl, 2-ethyl-2-butenyl, 2-ethyl-3-butenyl, 1,1,2-trimethyl-2- propenyl, 1-ethyl-1-methyl-2-propenyl, 1-ethyl-2-methyl-1-propenyl, 1-ethyl-2-methyl-2- propenyl, 1-heptenyl, 2-heptenyl, 3-heptenyl, 4-heptenyl, 5-heptenyl, 6-heptenyl, 1-octenyl,

[0039] 2-octenyl, 3-octenyl, 4-octenyl, 5-octenyl, 6-octenyl, 7-octenyl, 1-nonenyl, 2-nonenyl, 3- nonenyl, 4-nonenyl, 5-nonenyl, 6-nonenyl, 7-nonenyl, 8-nonenyl, 1-decenyl, 2-decenyl, 3- decenyl, 4-decenyl, 5-decenyl, 6-decenyl, 7-decenyl, 8-decenyl, 9-decenyl, 1-undecenyl, 2- undecenyl, 3-undecenyl, 4-undecenyl, 5-undecenyl, 6-undecenyl, 7-undecenyl, 8-undecenyl, 9-undecenyl, 10-undecenyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10- and 11-dodecenyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11- and 12-tridecenyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12- and 13- tetradecenyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-, 13- and 14-pentadecenyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-, 13-, 14- and 15-hexadecenyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-, 13-, 14-, 15- and 16-heptadecenyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, 11-, 12-, 13-, 14-, 15-, 16- and 17-octadecenyl, the nonadecenyls, the eicosenyls, the henicosenylss, the docosenylss, the tricosenyls, the tetracosenyls, the pentacosenyls, the hexacosenyls, the heptacosenyls, the octacosenyls, the nonacosenyls, the triacontenyls and the structural isomers thereof. Alkadienyls have at least 4 carbon atoms and 2 C-C double bonds. Examples are buta-1,3-dien-1-yl, buta-1,3-dien-2-yl, penta-1,3-dien-1-yl, penta-1,3-dien-2-yl, penta-1,3- dien-3-yl, penta-1,3-dien-4-yl, penta-1,3-dien-5-yl, penta-1,4-dien-1-yl, penta-1,4-dien-2-yl, penta-1,4-dien-3-yl, and the higher homologues with up to 30 carbon atoms. Al katrienyls have at least 6 carbon atoms and 3 C-C double bonds. Examples are 1,3,5-hexatrien-1-yl, 1,3,5-hexatrien-2-yl, 1,3,5-hexatrien-3-yl, 1,3,5-heptatrien-1-yl, 1,3,5-heptatrien-2-yl, 1,3,5- heptatrien-3-yl, 1,3,5-heptatrien-4-yl, 1,3,5-heptatrien-5-yl, 1,3,5-heptatrien-6-yl, 1,3,5- heptatrien-7-yl, and the higher homologues with up to 30 carbon atoms.

[0040] The term "stereoisomers" as used in context with the present invention relates specifically to optical isomers, such as enantiomers or diastereomers, the latter existing due to more than one stereogenic center in the molecule, but also to Z / E isomers. The compounds of formula (I) and likewise the compounds of formulae (I. a), (l.b) and (l.c) may have at least one stereogenic center, namely the carbon atoms carrying the carboxyl group and optionally the carbon atom carrying R2, provided that R2is different from hydrogen. In the letter case, the compounds may have E- or Z configuration with respect to the relative arrangement of R2and the carboxyl group. In terms of the present invention, the term "pure enantiomer" is understood as a non-racemic mixture of a specific compound, where the desired enantiomer is present in an enantiomeric excess of > 90 %ee.

[0041] In terms of the present invention, the term "pure diastereomer" is understood as a mixture of the diastereomers of a specific compound, where the desired diastereomer is present in an amount of > 90 %, based on the total amount of diastereomers of said compound.

[0042] In the present context, the formulae (I), (I. a), (l.b) and (l.c), when not defined as a specific stereoisomer or a specific mixture of stereoisomers, refer to pure enantiomers, pure diastereomers and also to the mixtures of enantiomers and mixtures of diastereomers. When not defined as a specific stereoisomer or a specific mixture of stereoisomers, formulae (I), (I. a), (l.b) and (l.c) refers to mixtures of stereoisomers as obtained in a non-stereoselective method used for its production or obtained from mixtures of stereoisomers of the staring materials of the formulae (II) or (III) respectively.

[0043] The remarks made below concerning preferred definitions of the variables are valid on their own as well as preferably in combination with each other concerning the compounds of formulae (I), (I. a), (l.b) and (l.c), as defined herein, where applicable, as well as concerning the compositions, uses and methods of the invention as defined herein.

[0044] The moiety R1in formulae (I), (I. a), (l.b) and (l.c) is preferably selected from linear C7-C29-alkyl and linear C7-C29-alkenyl, in particular from linear C7-C21-alkyl and linear C7-C21-alkenyl or from linear C8-C19-alkyl and linear C8-C19-alkenyl, more particular from linear CiCi7-alkyl and linear CirC17— alkenyl, especially from linear CirC13-alkyl and linear Cn-C13-alkenyl. This will further improve the biodegradability of the compounds of formulae (I), (I. a), (l.b) and (l.c).

[0045] With regard to the surfactant properties, the moiety R1in formulae (I), (I. a), (l.b) and (l.c) is preferably selected from C7-C21-alkyl, in particular from C8-C19-alkyl or from Cn-C17-alkyl, especially from Cn-C13-alkyl, e. g. C8-alkyl, Cn-alkyl or C13-alkyl. In particular, R1is selected from linear C7-C21-alkyl, more particularly from linear C8-C19-alkyl or from linear Cn-C17-alkyl, especially from linear CiCi3-alkyl, e. g. n-octyl, n-undecyl or n-tridecyl.

[0046] The moiety R2in formulae (I), (I. a), (l.b) and (l.c) is preferably hydrogen or methyl, especially hydrogen.

[0047] A preferred group (1) of embodiments relates to compounds of the formulae (I), (I. a), (l.b) and (l.c) and their salts, wherein R1is selected from linear C7-C2i-alkyl and linear C7-C21-alkenyl or from linear C8-C19-alkyl and linear C8-C19-alkenyl, more particular from linear CirC17-alkyl and linear CiC17— alkenyl, especially from linear C-ii-C13-alkyl and linear Cn-C13-alkenyl, and

[0048] R2is hydrogen or methyl, especially hydrogen.

[0049] A particularly preferred group (2) of embodiments relates to compounds of the formulae (I), (l.a), (l.b) and (l.c) and their salts, wherein

[0050] R1is selected from linear C7-C2i-alkyl and linear C7-C21-alkenyl or from linear C8-C19-alkyl and linear C8-C19-alkenyl, more particular from linear CiCi7-alkyl and linear CiCi7— alkenyl, especially from linear Cn-C^-alkyl and linear Cn-C13-alkenyl, and

[0051] R2is hydrogen or methyl, especially hydrogen.

[0052] A particularly preferred group (3) of embodiments relates to compounds of the formulae (I), (l.a), (l.b) and (l.c) and their salts, wherein

[0053] R1is linear C7-C2i-alkyl, in particular linear C8-C19-alkyl, more particularly linear CiCi7-alkyl, especially linear Cn-C^-alkyl, e. g. n-octyl, n-undecyl or n-tridecyl, and

[0054] R2is hydrogen or methyl, especially hydrogen.

[0055] According to a preferred group (4) of embodiments, the variable k in formula (I) is 1. In this case, formula (I) is in particular represented by one of the formulae (l.a) and (l.b), respectively. In this group (4) of embodiments, R1and R2are as defined herein and preferably as defined in groups (1), (2) or (3) of embodiments.

[0056] According to a preferred subgroup (4a) of group (4) of embodiments, both X and Y are Y are CH2. In this case, formula (I) is in particular represented by one of the formulae (l.a) and (l.b), respectively, where both X and Y are Y are CH2. In this subgroup (4a) of embodiments, R1and R2are as defined herein and preferably as defined in groups (1), (2) or (3) of embodiments.

[0057] According to further preferred subgroup (4b) of group (4) of embodiments, Y is NR3, O or S, in particular O or S, and X is CH2. In this case, formula (I) is in particular represented by the formula (l.a), respectively, where Y is NR3, O or S, in particular O or S, and X is CH2. In this subgroup (4b) of embodiments, R1and R2are as defined herein and preferably as defined in groups (1), (2) or (3) of embodiments.

[0058] According to another preferred subgroup (4c) of group (4) of embodiments, X is NR3, O or S, in particular O or S, and Y is CH2. In this case, formula (I) is in particular represented by one of the formulae (l.a) and (l.b), respectively, where X is NR3, O or S, in particular O or S, and Y is CH2. In this subgroup (4c) of embodiments, R1and R2are as defined herein and preferably as defined in groups (1), (2) or (3) of embodiments. Examples of compounds according to group (4) of embodiments include N-n-nonyl-piperidine-3-carboxylic acid, which is also referred to as N-n-nonyl-3- piperidinecarboxylic acid, N-n-dodecyl-piperidine-3-carboxylic acid, which is also referred to as N-n-dodecyl-3-piperidinecarboxylic acid, N-n-tetradecyl-piperidine-3-carboxylic acid, which is also referred to as N-n-tetradecyl-3-piperidinecarboxylic acid, N-n-nonyl-piperidine-4-carboxylic acid, which is also referred to as N-n-nonyl-4- piperidinecarboxylic acid, N-n-dodecyl-piperidine-4-carboxylic acid, which is also referred to as N-n-dodecyl-4-piperidinecarboxylic acid, N-n-tetradecyl-piperidine-4-carboxylic acid, which is also referred to as N-n-dodecyl-4-piperidinecarboxylic acid, the salts of the aforementioned compounds, mixtures of the aforementioned compounds, in particular enantiomeric mixtures of the first three mentioned compounds and their salts, e.g. the racemates and their salts, and the pure enantiomers of the first three mentioned compounds and their salts, e.g. the R-enantiomers of the of the first three mentioned compounds and their salts, as well as the S-enantiomers of the of the first three mentioned compounds and their salts.

[0059] According to a further preferred group (5) of embodiments, the variable k in formula (I) is 0 and where X is O or S, in particular S, and Y is CH2. In this case, formula (I) is in particular represented by formula (l.c). In this group (5) of embodiments, R1and R2are as defined herein and preferably as defined in groups (1), (2) or (3) of embodiments.

[0060] Examples of compounds according to group (5) of embodiments include N-n-nonylthioproline, N-n-dodecylthioproline, N-n-tetradecylthioproline, N-n-nonyl-L-thioproline, N-n-dodecyl-L-thioproline, N-n-tetradecyl-L-thioproline, the salts of the aforementioned compounds, mixtures of the aforementioned compounds, in particular enantiomeric mixtures of the first three mentioned compounds and their salts, e.g. the racemates of the first three mentioned compounds and their salts.

[0061] The compounds of formulae (I), (I. a), (l.b) and (l.c) are depicted in their undissociated form. As they are amino acids, they may form internal (zwitterionic) salts having no net charge as depicted in formula (l-z) below. However, they may also be provided in the form of external salts with anionic or cationic counter ions, depending on the net charge of the compound of the formula (I). For example, the compound of formula (I) may be protonated by an acid to form a cation of formula (l-cat), where the net charge is compensated by an anion. The compound of formula (I) may be provided deprotonated by a base forming an anion of formula (l-an), where the net charge is compensated by a cation.

[0062] Suitable cations include alkali metal ions, such as sodium or potassium, ammonium and substituted ammonium. Suitable anions include, but are not limited to the corresponding base of mineral acids, e. g. halide ions, such as chloride or bromide, sulfate, hydrogen sulfate, phosphate, mono- and dihydrogen phosphate and linear or cyclic polyphosphates, such as diphosphate or triphosphate, and the corresponding base of organic acids, e. g. anions of mono- or dicarboxylic acids or aminocarboxylic acids, such as formiate, acetate, hydroxypropionate, lactate, malate, maleate, succinate, tartrate, citrate, isocitrate, glutamate, aconitate, phosphonates and sulfonates.

[0063] Salts of the compounds of formula (I), where the compound of formula (I) is present in the anionic form (l-an) or its cationic form (l-cat) are also termed "external salts". These "external salts" may be obtained under acidic or basic conditions, e. g. by neutralizing the compound of formula (I) with a suitable base or a suitable acid.

[0064] Suitable organic acids include carboxylic acids, sulfonic acids, carbonic acid, organic phosphonic acids, and aminocarboxylic acids. Preferably, the organic acid is selected from carboxylic acids, most preferably from formic acid, acetic acid, oxalic acid, propionic acid, hydroxypropionic acid, lactic acid, malic acid, maleic acid, succinic acid, tartaric acid, aconitic acid, citric acid and glutamic acid.

[0065] The base may be selected from metal hydroxides and amines. Suitable metal hydroxides include alkali metals, in particular sodium hydroxide and potassium hydroxide. Sodium hydroxide is particularly preferred. Suitable amines include ammonia; aliphatic amines such as monomethylamine, dimethylamine, monoethylamine, diethylamine, monopropylamine, dipropylamine, decylamine, dodecylamine and tetradecylamine; alkanolamines such as ethanolamine and diethanolamine; and lysine. External salts obtained under basic conditions generally display improved solubility at higher pH values.

[0066] Neutralization of the amine surfactant of general formula (I) is typically performed at room temperature, i.e., 25 °C, and under atmospheric pressure. Neutralization is typically carried out in a solvent, preferably a solvent as described above. The neutralized reaction product may be purified by typical means, such as evaporation of the solvent to obtain a crude material, which may be further purified by, e.g., recrystallization.

[0067] As said, the compounds of formulae (II) and (III), respectively, used for the production of the compounds of formula (I) can be obtained from renewable sources, in particular from biological sources. As said, it is desired to provide surfactants which are obtained at least partly from renewable sources, especially from bio-based sources.

[0068] Renewable sources are sources that theoretically may be inexhaustible. They are natural and self-replenishing, and usually have a low- or zero-carbon footprint. Among these, bio-based sources, i.e. non-fossil materials of vegetal or animal origin, are of major importance.

[0069] However, also upcycled CT "exhaust gases" which would otherwise be released into the atmosphere, such as CO2or methane, are considered as a renewable source. Preference is however given to bio-based sources.

[0070] Preferably, the compounds of formulae (I), (I. a), (l.b) and (l.c) are obtained from the cyclic amino acids (III) or (III. a), (lll.b) or (lll.c), respectively, which are obtained from a renewable, preferably bio-based, source. Preferably, the compounds of formulae (I), (I. a), (l.b) and (l.c) are obtained from the aldehydes of formula (II) which are obtained from a renewable, preferably bio-based, source. In particular, the compounds of formulae (I), (I. a), (l.b) and (l.c) are obtained from the cyclic amino acids of the formulae (III) or (III. a), (lll.b) or (lll.c), respectively, which are obtained from a renewable, preferably bio-based, source and from the aldehydes of formula (II) which are obtained from a renewable, preferably bio-based, source.

[0071] More preferably in the compounds of formulae (I), (I. a), (l.b) and (l.c) at least 20 mol-% in particular at least 30 mol-%, especially at least 50 mol% or up to 100 mol-% of the carbon atoms, relative to the total amount of carbon atoms in the compounds of formulae (I), (I. a), (l.b) and (l.c), stem from a renewable source. Even more preferably, in the compounds of formulae (I), (I. a), (l.b) and (l.c) at least 20 mol-% in particular at least 30 mol-%, especially at least 50 mol% or up to 100 mol-% of the carbon atoms, relative to the total amount of carbon atoms in the compounds of formulae (I), (I. a), (l.b) and (l.c), are bio-based.

[0072] The cyclic amino acids of the formulae (III) or (III. a), (lll.b) or (lll.c), respectively, can be obtained for example obtainable from fermentation processes, especially from the fermentation of sugars or other digestible carbohydrates according to well established methods. Likewise aldehydes of the formula (II), in particular those where R1is linear alkyl or alkenyl having an odd number of carbon atoms, can be obtained from biological sources, e. g. from plant oils.

[0073] The origin of the compounds of formulae (I), (I. a), (l.b) and (l.c) from a renewable, to be more precise a bio-based source can be verified, for example, by radiocarbon dating. Radiocarbon dating is based on the fact that radiocarbon (14C) is constantly created in the earth's atmosphere by the interaction of cosmic rays with atmospheric nitrogen: The cosmic rays generate neutrons in the atmosphere which can strike nitrogen-14 (14N) atoms. These, in turn, decay to14C under release of a proton. The resulting14C combines with atmospheric oxygen to form radioactive carbon dioxide, which is incorporated into plants by photosynthesis, subsequently into herbivorous animals feeding on plants and ultimately into the complete biosphere by carnivorous animals feeding on herbivorous animals. Upon death of the animal or plant, carbon exchange with its environment is stopped, whereupon the amount of14C begins to decrease as the14C undergoes radioactive decay.

[0074] Measuring the amount of14C in a sample of a compound of formulae (I), (I. a), (l.b) or (l.c), respectively, is thus an indicator of its origin: In compounds of formulae (I), (I. a), (l.b) and (l.c), respectively, which are derived completely from a renewable, to be more precise from a biobased source, the amount of14C will be the same or not essentially lower than found in presently living organisms.

[0075] Generally, the molar ratio of the12C isotope to the14C isotope is used as an indicator. In living organisms, the molar ratio of the12C isotope to the14C isotope is approximately 1 x1012: 1 (to be more precise 1x1012: 1.25).

[0076] Thus, the content of the14C isotope in the compounds of formulae (I), (I. a), (l.b) and (l.c), respectively, will be at a detectable level if at least part of the compounds of formulae (I), (I. a), (l.b) and (l.c), respectively, is derived from a renewable, to be more precise from a bio-based source. Suitable methods for determining the content of the14C isotope are known in the art and deliver generally comparable results. For example, the method according to ASTM D6866-21 can be used; this method was specifically developed for determining the content of bio-based / biogenic carbon in bioproducts. However, other methods are suitable as well. The detection level of the available methods of the content of the14C isotope is such that it allows radiocarbon dating between ca. 300 and 60000 before the present time, which is very remote from the age of fossil carbon sources. Thus, any detected14C isotope is an indicator of a renewable origin of the compound (I. a) or (l.b). In a preferred embodiment, the molar ratio of the12C isotope to the14C isotope in the compounds of formulae (I), (l.a), (l.b) and (l.c), respectively, is less than 3x1012: 1, i.e. it is from ca. 1 x1012: 1 (to be more precise from 1 x1012: 1.25) to less than 3x1012: 1.

[0077] The process for the production of the compound of formula (I) comprises reductive amination of an aldehyde of formula (II) with a cyclic amino acid compound of general formula (III) or a salt thereof. It is apparent that using a cyclic amino acid compound of general formula (III. a) or a salt thereof will yield a compound of the formula (l.a) while using a cyclic amino acid compound of general formula (lll.b) or (I I l.c) or a salt thereof, will yield a compound of the formula (l.b) or (l.c), respectively, depending on the type of the cyclic amino acid compound.

[0078] The aldehyde of general formula (II) is an aliphatic aldehyde. Examples of aliphatic aldehydes of general formula (II) include octanal, nonanal, decanal, undecanal, dodecanal, tetradecanal, hexadecanal, 2-ethylhexanal and citral, in particular citral, dodecanal and tetradecanal. Citral is understood as a mixture of two geometric isomers, specifically geranial (citral A) and neral (citral B).

[0079] Examples of cyclic amino acids are in particular nipecotic acid (piperidine-3-carboxylic acid, compound III. a, where R2is H and where Y = CH2), isonipecotic acid (piperidine-4-carboxylic acid, compound lll.b, where R2is H and where X = CH2) and thioproline (1,3-thiazolidine-4- carboxylic acid, compound lll.c, where R2is H and where X' = S).

[0080] The molar ratio of the total amount of the aldehyde of formula (II) to the total amount of the cyclic amino acid compound of formula (III) is preferably in the range of 0.8:1 to 1.3:1, more preferably 0.9:1 to 1.2:1, most preferably 0.95:1 to 1.15:1.

[0081] The reductive amination is performed in the presence of a heterogeneous catalyst comprising a transition metal of group 8, group 9 or group 10 of the periodic table of the elements (IUPAC numbering). Examples of preferred transition metals include cobalt (Co), nickel (Ni), ruthenium (Ru), palladium (Pd) and platinum (Pt). Preferably, the transition metal is selected from ruthenium and platinum and is especially platinum,

[0082] The metals can be used as such, or else applied to supports. Preferred supports are selected from aluminum oxide, silicon dioxide, titanium dioxide, zirconium dioxide and activated carbon. Particular preference is given to the supported metals. Preferred supports are activated carbon, aluminum oxide, silica and titanium dioxide as well as mixtures thereof. A very particularly preferred support is activated carbon. Very especially preferred hydrogenation catalysts include platinum on activated carbon, ruthenium on activated carbon, ruthenium on aluminum oxide or silicon dioxide and palladium on activated carbon. In a preferred embodiment, the heterogeneous catalyst is selected from Raney nickel, ruthenium on aluminum oxide or silicon dioxide and platinum on activated carbon (Pt / C). When the heterogeneous catalyst is platinum on activated carbon, the catalyst may comprise a binder such as polytetrafluoroethylene (PTFE).

[0083] The catalyst is typically present in an amount of at most 2.5 wt.-%, such as 0.01 to 2.5 wt.-%, preferably 0.01 to 1.5 wt.-%, more preferably 0.01 to 1.5 wt.-%, e.g., 0.3 to 1.2 wt.-% or 0.5 to 1.1 wt.-%, calculated as elemental transition metal relative to the weight of the amino compound of general formula (III). The inventive process thus requires relatively low amounts of catalyst.

[0084] The reductive amination is preferably carried out at a pressure of molecular hydrogen of at least 1 bara, preferably in the range of at least 1 bara to less than 50 bara, in particular more than 1 bara to less than 50 bara. Preferably, the pressure of molecular hydrogen is in the range of 3 to 30 bara, more preferably 3 to 25 bara, most preferably 4 to 21 bara. A pressure of molecular hydrogen of more than 1 bara allows for a favorably low reaction time, thus increasing the efficiency of the process.

[0085] On the other hand, if the pressure of molecular hydrogen is too high, the aldehyde (III) is reduced to the corresponding alcohol, rather than participating in the reductive amination. The corresponding alcohol is notably difficult to separate from the reaction mixture. Thus, working at a pressure of molecular hydrogen within the claimed range allows for high selectivity and high efficiency of the process.

[0086] The reductive amination is preferably carried out at a temperature of at least 25 °C. Preferably, the temperature is in the range of 25 to 120 °C, more preferably 30 to 90 °C, most preferably 40 to 50 °C. A temperature in this range allows for the reductive amination reaction to proceed at an adequate rate under mild conditions.

[0087] The reductive amination is preferably carried out in the presence of a solvent having a Hildebrand solubility parameter 5 in the range of 18 to 38 MPa1 / 2, preferably in the range of 30 to 37 MPa1 / 2, more preferably 31 to 37 MPa1 / 2, most preferably 32 to 35 MPa1 / 2. It was found that a solvent having a Hildebrand solubility parameter 5 in this range allows for a high solubility of both the starting materials and the obtained surfactant. The solvent may be in the form of a single solvent or a mixture of two or more solvents. The Hildebrand solubility parameter 5 provides a numerical estimate of the degree of interaction between compounds, and thus be used as an indicator of solubility. Compounds having similar values of 5 are likely miscible. The Hildebrand solubility parameter 5 is well-known in literature. The following table provides exemplary solvents and their Hildebrand solubility parameter from Barton, Allan F. M. (1983), Handbook of Solubility Parameters and Other Cohesion Parameters, CRC Press. The Hildebrand solubility parameter 5 of a solvent mixture may be determined by averaging the Hildebrand values of the individual solvents by volume. For example, the Hildebrand solubility parameter of a mixture of two parts ethanol and one part water may be calculated as:

[0088] 5 = ((2 x 26.2 MPa1 / 2+ 48.0 MPa1 / 2) / 3) = 33.5 MPa1 / 2.

[0089] Selection of a solvent having a Hildebrand solubility parameter 5 in the above range ensures that the solvent has solubility characteristics suitable for the amino compound of general formula (III), and that the reductive amination reaction proceeds at an adequate rate.

[0090] In a preferred group of embodiments, the solvent comprises a protic solvent and / or an aprotic solvent comprising an ether moiety, in particular a protic solvent. A protic solvent is understood to be a solvent which is able to donate a proton (H+) to a solute, e.g., via an O-H or N-H bond, typically via hydrogen bonding. An aprotic solvent is unable to donate a proton to a solute.

[0091] Preferably, the solvent comprises at least one protic solvent selected from water and an aliphatic alcohol. Preferred aliphatic alcohols include methanol, ethanol and isopropanol, in particular ethanol. More preferably, the solvent comprises an aliphatic alcohol or a mixture of an aliphatic alcohol and water. In a preferred embodiment, the solvent is a mixture of an aliphatic alcohol and water in a volume ratio in the range of 1:1 to 4:1, preferably 1.25:1 to 3:1, most preferably 1.5:1 to 2:1. In a particularly preferred embodiment, the solvent is a mixture of ethanol and water in a volume ratio in the range of 1:1 to 4:1, preferably 1.25:1 to 4:1, more preferably 1.5:1 to 2:1, most preferably 1.5:1 to 2:1. The volume ratio is understood to relate to the ratio of the individual solvent volumes prior to mixing, i.e., disregarding any volume contraction which may occur upon mixing.

[0092] In another preferred group of embodiments, the solvent comprises at least one aprotic solvent comprising an ether moiety, such as tetra hydrofuran, 2-methyltetrahydrofuran, 1,4- dioxane, or tetra hydro pyran, in particular tetrahydrofuran. In one embodiment, the solvent is tetrahydrofuran.

[0093] In a further preferred group of embodiments, the solvent comprises at least one aprotic solvent comprising an ether moiety and at least one protic solvent. For example, the solvent may comprise a mixture of tetrahydrofuran with at least one protic solvent, in particular water or an alcohol. In a preferred embodiment, the solvent is a mixture of tetra hydrofuran with water or ethanol, in particular a mixture of tetra hydrofuran with water. The reductive amination is preferably carried out at a solvent dilution ratio of not more than 20.0 L per kg, preferably at most 15.0 L per kg, more preferably at most 12.5 L per kg.

[0094] Typically, the reductive amination is performed at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kg. A concentration of the aldehyde of general formula (II) and the amino compound of general formula (III) in this range allows for efficiently reacting the amino compound with the aldehyde at high selectivity.

[0095] In one embodiment, the reductive amination is preferably carried out at a pressure of molecular hydrogen in the range of 3 to 30 bara, at a temperature in the range of 25 to 120 °C, and in a solvent having a Hildebrand solubility parameter 5 in the range of 18 to 38 MPa1 / 2, at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kg.

[0096] In a further embodiment, the reductive amination is preferably carried out at a pressure of molecular hydrogen in the range of 3 to 25 bara, preferably 4 to 21 bara, at a temperature in the range of 25 to 120 °C, and in a solvent having a Hildebrand solubility parameter 5 in the range of 18 to 38 MPa1 / 2, at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kg..

[0097] In a further embodiment, the reductive amination is performed at a pressure of molecular hydrogen in the range of 3 to 30 bara, at a temperature in the range of 30 to 90 °C, more preferably 40 to 50 °C, and in a solvent having a Hildebrand solubility parameter 5 in the range of 18 to 38 MPa1 / 2, at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kg..

[0098] In a further embodiment, the reductive amination is performed at a pressure of molecular hydrogen in the range of 3 to 30 bara, at a temperature in the range of 25 to 120 °C, and in a solvent having a Hildebrand solubility parameter 5 in the range of 30 to 37 MPa1 / 2, preferably 31 to 37 MPa1 / 2, more preferably 32 to 35 MPa1 / 2, at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kg..

[0099] In a further embodiment, the reductive amination is performed at a pressure of molecular hydrogen in the range of 3 to 30 bara, at a temperature in the range of 25 to 120 °C, and in a solvent having a Hildebrand solubility parameter 5 in the range of 18 to 38 MPa1 / 2, at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kg. In a further embodiment, the reductive amination is performed at a pressure of molecular hydrogen in the range of 3 to 30 bara, at a temperature in the range of 25 to 120 °C, and at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kg, wherein the solvent is a mixture of an aliphatic alcohol, in particular ethanol, and water in a volume ratio of 1:1 to 4:1, preferably 1.25:1 to 3:1, most preferably 1.5:1 to 2:1.

[0100] In a further embodiment, the reductive amination is performed at a pressure of molecular hydrogen in the range of 3 to 30 bara, at a temperature in the range of 25 to 120 °C, and in a solvent having a Hildebrand solubility parameter 5 in the range of 18 to 38 MPa1 / 2, at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kg, wherein the heterogeneous catalyst is present in an amount of at most 2.5 wt.-%, such as 0.01 to 2.5 wt.-%, preferably 0.01 to 1.5 wt.-%, more preferably 0.01 to 1.5 wt.-%, e.g., 0.3 to 1.2 wt.-% or 0.5 to 1.2 wt.-%, calculated as the proportion of group 10 element relative to the total amount of the amino compound of general formula (III).

[0101] In a further embodiment, the reductive amination is performed at a pressure of molecular hydrogen in the range of 3 to 30 bara, at a temperature in the range of 25 to 120 °C, and at a solvent dilution ratio in the range of 1.0 to 20.0 L per kg, in particular in the range of 1.0 to 15.0 L per kg, especially in the range of 1.0 to 12.5 L per kgv, wherein the solvent is a mixture of an aliphatic alcohol and water, in particular ethanol and water, in a volume ratio of 1 : 1 to 4 : 1, preferably 1.25 : 1 to 3 : 1, most preferably 1.5:1 to 2:1, and wherein the heterogeneous catalyst is present in an amount of at most 2.5 wt.-%, such as 0.01 to 2.5 wt.-%, preferably 0.01 to 1.5 wt.-%, more preferably 0.01 to 1.5 wt.-%, e.g., 0.3 to 1.2 wt.-% or 0.5 to 1.2 wt.-%, calculated as the proportion of group 10 element relative to the total amount of the amino compound of general formula (III).

[0102] The process of the invention may be carried out in any reactor suitable for maintaining the pressure of molecular hydrogen in the desired range and at the desired temperature, such as an autoclave.

[0103] The process of the invention is preferably conducted in feed operation, wherein the amino compound of general formula (III) is provided (i.e., initially charged), and the aldehyde of general formula (II) is metered thereto. It is understood that providing the amino compound of general formula (III) also includes providing a solution of the amino compound of general formula (III). Likewise, metering the aldehyde of general formula (II) thereto includes metering a solution of the aldehyde of general formula (II) thereto. The solvent contained in the solution of the amino compound of general formula (III) and the solvent contained in the solution of the aldehyde of general formula (II) together constitute the solvent in the presence of which the reductive amination occurs. The solvents comprised in the two solutions may be identical or different. In the latter case, the solvent in the presence of which the reductive amination occurs will be a mixture of solvents.

[0104] In particular, the aldehyde of general formula (II) is added at constant feed rate. This allows for avoiding undesired side reactions. Thus, on the one hand, the reduction of the aldehyde to the corresponding alcohol is suppressed, obtaining the compound of general formula (I) at higher selectivity and avoiding the removal of the difficult to separate corresponding alcohol. On the other hand, aldol condensation of the aldehyde with itself to form the aldehyde dimer is avoided. This again allows for higher selectivity and moreover suppresses the formation of dimer-based surfactants with less advantageous properties.

[0105] The reaction product obtained in the process of the invention may be purified by typical means, such as filtration of the reaction mixture to remove the heterogeneous catalyst and subsequent evaporation of the solvent from the filtrate to obtain a crude material. In order to fully solubilize the reaction product in the obtained reaction mixture prior to filtration, a suitable additional solvent, in particular ethanol, may be added. The crude material may be further purified by, e.g., recrystallization.

[0106] In one embodiment, the aldehyde of general formula (II) and / or the cyclic amino acid compound of formula (III) are bio-based compounds. In this embodiment, the process allows for obtaining surfactants in a particularly environmentally friendly fashion.

[0107] The compounds of general formula (I) are preferably at least partially biodegradable. Biodegradation is preferably at least 20%, more preferably at least 60% (all percentages in wt.-% based on the total solid content) within 28 days according to OECD 301.

[0108] It is believed that while the present process allows for avoiding a detrimentally high degree of aldol condensation of the aldehyde with itself to form the aldehyde dimer, and thus allows for higher selectivity, dimerization cannot be avoided altogether. It has now been found that a small amount of dimer-based surfactants has an advantageous effect on important surfactant properties, such as foam volume, wetting time, surface tension and contact angle.

[0109] As said, the compounds of the formulae (I), (I. a), (l.b) and (l.c) and their salts are suitable as surfactants, in particular as emulsifiers, as foam regulators and / or as wetting agents. They can be used as surfactants in a wide variety of applications, including, but not limited to detergents, including laundry detergents, dishwashing detergents and l&l cleaners, surfactant formulations for cleaning hard surfaces, in humectants, in cosmetic and pharmaceutical formulations, in crop protection formulations, in coating agents, in adhesives, in sealant compositions, in leather degreasing agents, in formulations for the textile industry, in fiber processing, in metal processing, in the food industry, for water treatment, in paper industry, in fermentation processes, for mineral processing and in emulsion polymerizations. They may be used in any composition which typically contain at least one surfactant. In these compositions, the may partly or completely replace conventional surfactants, in particular anionic surfactants.

[0110] Therefore, the compositions of the invention are understood to mean any composition which contains at least one compound of the invention, i. e. at least one compound selected from the compounds of formulae (I), (I. a), (l.b) and (l.c) and their salts and mixtures thereof.

[0111] Such compositions include homecare compositions, including detergent formulations, such as laundry detergents, dishwashing detergents and household cleaners, compositions for cleaning or disinfecting on an industrial scale (also called industrial and institutional cleaning or l&l cleaning), personal care compositions, compositions for metal processing, such as metal working fluids, compositions for fibre processing, compositions for paper production processes, leather degreasing agents, humectants, aqueous polymer dispersions (polymer latexes or polymer emulsions), slurries of inorganic or organic matter, such as pigment compositions, coating compositions, such as paint formulations, varnishes and stains, crop protection compositions, adhesive formulations, sealant formulations etc.

[0112] Therefore, the present invention in particular relates to homecare compositions, cleaning agents, including household cleaners and l&l cleaners, in wetting agents, coating compositions, adhesive compositions, leather degreasing agents, humectants, textile treatment agents, pigment compositions, sealant formulations, and cosmetic, pharmaceutical or crop protection formulations containing a compound of formulae (I), (I. a), (l.b) or (l.c) or a salt of the compounds of the formulae (I), (I. a), (l.b) and (l.c). The compounds of the formulae (I), (I. a), (l.b) and (l.c) and their salts are particularly suitable as surfactants in homecare compositions, l&l cleaning compositions, personal care compositions and crop protection compositions.

[0113] Household care products are generally understood to be compositions for cleaning or washing goods and objects. Homecare compositions and compositions for cleaning or disinfecting on an industrial scale (also called industrial and institutional cleaning or l&l cleaning) overlap largely, only that l&l compositions are adapted to the use on a larger scale and are thus often more aggressive (e.g. by being more concentrated and / or by having a distinctly higher or lower pH than the respective homecare composition) and / or are less "pleasant", e.g. in the sense of odor or aspect or touch. Moreover, they are suitable for clean- in-place (Cl P), which is a method of automated cleaning the interior surfaces of pipes, vessels, equipments, filters and associated fittings and the like without major disassembly. Examples for homecare and l&l compositions are dishwashing compositions (in liquid or gel form), laundry compositions (in liquid or gel form; for example laundry detergents, fabric softeners, rinsing compositions, bleacher compositions, stain remover compositions and the like), surface cleaning compositions (also termed hard surface cleaners; for example glass, floor, counter, bath(room), toilet bowl, sink, kitchen, appliance and furniture cleaning compositions; all-purpose cleaners; sanitary cleaners), non-cosmetic deodorants (e.g. air and / or surface deodorants), disinfectants (for example spray air disinfectants, and spray, liquid and paste / gel surface disinfectants), surface protecting and / or polishing compositions, rug shampoos, descaling agents, and compositions for wet wipes (e.g. for cleaning the floor, furniture, bath room surfaces etc.).

[0114] Personal care compositions are used for cleaning, washing, disinfecting, nurturing, grooming, protecting or embellishing the human body (and thus also include cosmetics). Examples are creams, lotions, ointments, other o / w or w / o emulsions, liquid or gel-like soaps, shampoos, make-up and other decorative cosmetics, and compositions for wet wipes (e.g. for cleaning the nappy area). More specific examples are skin-washing and cleansing preparations in the form of soaps, syndets, washing gels, soapless detergents or washing pastes, bath preparations, e.g. foam baths, milks, oils, shower preparations; skin-care preparations, e.g. skin emulsions, multi-emulsions, powders, sprays or skin oils; cosmetic preparations, e.g. facial make-up in the form of day creams or powder creams, face powder (loose or pressed), rouge or cream make-up, eye-care preparations, e.g. eyeshadow preparations, mascara, eyeliner, eye creams or eye-fix creams; lip-care preparations, e.g. lipsticks, lip gloss, lip contour pencils, nail-care preparations, such as nail varnish, nail varnish removers, nail hardeners or cuticle removers; foot-care preparations, e.g. foot baths, foot powders, foot creams or foot balsams, special deodorants and antiperspirants or callus-removing preparations; light-protective preparations, such as sun milks, lotions, creams or oils, sunblocks or tropicals, pre-tanning preparations or after-sun preparations; skin-tanning preparations, e.g. self-tanning creams; depigmenting preparations, e.g. preparations for bleaching the skin or skin-lightening preparations; insect-repellents, e.g. insect-repellent oils, lotions, sprays or sticks; deodorants, such as deodorant sprays, deodorant aerosols, pump-action sprays, deodorant gels, sticks or roll-ons, also water-free deodorant aerosols or sticks; antiperspirants, e.g. antiperspirant sticks, creams or roll-ons; preparations for cleansing and caring for blemished skin, e.g. synthetic detergents (solid or liquid), peeling or scrub preparations or peeling masks; hairremoval preparations in chemical form (depilation), e.g. liquid hair-removing preparations, cream- or paste-form hair-removing preparations, hair-removing preparations in gel form or aerosol foams; shaving preparations, e.g. shaving soap, foaming shaving creams, nonfoaming shaving creams, foams and gels, pre-shave preparations for dry shaving, aftershaves or aftershave lotions; fragrance preparations, e.g. fragrances (eau de Cologne, eau de toilette, eau de parfum, parfum de toilette, perfume), perfume oils or perfume creams; cosmetic hairtreatment preparations, e.g. hair-washing preparations in the form of shampoos and conditioners, hair-care preparations, e.g. pre-treatment preparations, hair tonics, styling creams, styling gels, pomades, hair rinses, treatment packs, intensive hair treatments, hairstructuring preparations, e.g. hair-waving preparations for permanent waves (hot wave, mild wave, cold wave), hair-straightening preparations, liquid hairsetting preparations, hair foams, hairsprays, bleaching preparations, e.g. hydrogen peroxide solutions, lightening shampoos, bleaching creams, bleaching powders, bleaching pastes or oils, temporary, semi-permanent or permanent hair colorants, preparations containing self-oxidising dyes, or natural hair colorants, such as henna or camomile; antidandruff preparations in the form of shampoos, conditioners, hair tonics, styling creams or gels or treatments packs; oral care preparations such as (tooth) pastes, gels, mouth washes and sprays; disinfectants for mouth or skin.

[0115] Crop protection compositions, which are often also termed plant protection compositions, are compositions which are effective against various harmful microorganisms, harmful invertebrate pests or undesired plants relevant for agriculture, e.g. harmful fungi, harmful invertebrate pests, such as harmful insects, arachnids, nematodes or molluscs, and weeds, which cause damage to agricultural plants, plant propagation materials, such as seeds, or harvested crops. Examples for crop protection compositions are fungicidal, insecticidal, acaricidal, nematicidal, moluscicidal or herbicidal compositions and pesticide adjuvant compositions. Crop protection compositions also encompass plant growth regulating compositions. Plant growth regulators are plant protection products used to influence plant growth and are used, for example, for increasing the stability of cereals by shortening the stalk length, thus reducing or preventing lodging, for improving the rooting of cuttings, reducing plant height in horticulture, preventing the germination of potatoes and the like. The term encompasses moreover compositions used in material protection for combating various harmful microorganisms and invertebrate pests, such as compositions for the treatment of lumber or the surroundings of lumber material against termites or compositions fo the treatment of mosquito nets against harmful insects, such as Anopheles mosquitoes, and the like.

[0116] Typically, the compositions of the present invention contain at least one further component in addition to the at least one compound of the formulae (I), (I. a), (l.b) and (l.c) and their salts depending on the desired purpose. Such additional components include e. g. carriers, which may be liquid or solid, surfactants different from the compounds (I), fragrance, antimicrobial agents, sequestrants, enzymes, enzyme stabilizers, hydrotropic agents, bleaching agents, dyes, pigments, pH adjusting agents, pigments, dyes, pearlescent, opacifiers, viscosity modifiers and inorganic salts.

[0117] In particular, the homecare compositions, l&l cleaning compositions. Such compositions include in particular detergents such as granular laundry detergents, liquid laundry detergents, liquid dishwashing detergents; and in miscellaneous formulations such as all purpose cleaning agents, liquid soaps, shampoos, shower gels, and liquid scouring agents. Moreover, the compounds and compositions of the invention may be used as surfactants in institutional and industrial cleaning formulations such as kitchen cleaners, industrial laundry detergents, vehicle cleaners, and disinfection cleaners.

[0118] The compounds and compositions of the invention find particular use as surfactants in detergents, specifically laundry detergents and manual dishwashing products. These are generally comprised of a number of components besides the compound(s) of the invention. The composition typically comprises a total amount of 0.1 to 15 wt.-% of the compound(s) of the invention, relative to the weight of the composition. Typical compositions are known to the experts.

[0119] Laundry detergents typically comprise other surfactants of the anionic, nonionic, amphoteric or cationic type; builders such as phosphates, aminocarboxylates and zeolites; organic cobuilders such as polycarboxylates; bleaching agents and their activators; foam controlling agents; enzymes; anti-greying agents; optical brighteners; and stabilizers.

[0120] Liquid laundry detergents generally comprise the same components as granular laundry detergents, but generally contain less of the builders. Moreover, liquid detergent formulations often comprise hydrotropic substances. All-purpose cleaning agents may comprise other surfactants, builders, foam suppressing agents, hydrotropes and solubilizer alcohols.

[0121] Builders may be comprised in amounts of up to 90% by weight, preferably about 5 to 35% by weight, to intensify the cleaning action. Examples of common inorganic builders are phosphates, polyphosphates, alkali metal carbonates, silicates and sulfates. Examples of organic builders are polycarboxylates, aminocarboxylates such as ethylenediaminetetraacetates, nitrilotriacetates, hydroxycarboxylates, citrates, succinates and substituted and unsubstituted alkanedi- and polycarboxylic acids.

[0122] Another type of builder, useful in granular laundry and built liquid laundry agents, includes various substantially water-insoluble materials which are capable of reducing the water hardness, e.g., by ion exchange processes. In particular, complex sodium aluminosilicates, known as type A zeolites, are useful for this purpose.

[0123] The laundry detergents may also contain bleaching agents, e.g., percompounds such as perborates, percarbonates, persulfates and organic peroxy acids. Formulations containing percompounds may also contain stabilizing agents, such as magnesium silicate, sodium ethylenediaminetetraacetate or sodium salts of phosphonic acids. In addition, bleach activators can be used to increase the efficiency of the inorganic persalts at lower washing temperatures. Particularly useful for this purpose are substituted carboxylic acid amides, e.g., tetraacetylethylenediamine, substituted carboxylic acids, e.g., isononyloxybenzenesulfonate and sodium cyanamide.

[0124] Examples of suitable hydrotropic substances are alkali metal salts of benzene, toluene and xylene sulfonic acids; alkali metal salts of formic acid, citric and succinic acid, urea, mono-, di-, and triethanolamine. Examples of solubilizer alcohols are ethanol, isopropanol, mono- or polyethylene glycols, monopropylene glycol and ether alcohols.

[0125] Examples of foam controlling agents are high molecular weight fatty acid soaps, paraffinic hydrocarbons, and silicon containing defoamers. In particular, hydrophobic silica particles having silicon adsorbed thereon are efficient foam control agents in these laundry detergent formulations.

[0126] Examples of known enzymes which are effective in laundry detergent agents are, among others, proteases, amylases, cellulases, mannanases, and lipases. Preference is given to enzymes which have their optimum performance at the design conditions of the detergent.

[0127] A large number of fluorescent whiteners are described in the literature. For laundry detergent formulations, the derivatives of diaminostilbene disulfonates and substituted distyrylbiphenyl are particularly suitable.

[0128] As anti-greying agents, water-soluble colloids of an organic nature are preferably used. Examples are water-soluble polyanionic polymers such as polymers and copolymers of acrylic and maleic acid, cellulose derivatives such as carboxymethyl cellulose, methyl- and hydroxyethylcellulose.

[0129] In addition to one or more of the aforementioned other surfactants and other detergent composition components, laundry detergent compositions typically comprise one or more inert components. For instance, the balance of liquid detergent composition is typically an inert solvent or diluent, most commonly water.

[0130] Manual dishwashing products may comprise, besides the compounds obtained in the process of the invention, other surfactants of the anionic, nonionic, amphoteric or cationic type; solvents; diamines; carboxylic acids or salts thereof; polymeric suds stabilizers; enzymes; builders; perfumes; and / or chelating agents.

[0131] Suitable solvents include diols, polymeric glycols, and mixtures thereof. Preferred diols include propylene glycol, 1,2 hexanediol, 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol. Polymeric glycols, which comprise ethylene oxide (EO) and propylene oxide (PO) groups, may also be included in the present invention. These materials are formed by adding blocks of ethylene oxide moieties to the ends of polypropylene glycol chains. A preferred polymeric glycol is a polypropylene glycol having an average molecular weight in the range of 1,000 to 5,000 g / mol. When polymeric glycols are present, it may be beneficial to include either a diol and / or an alkali metal inorganic salt, such as sodium chloride, so as to obtain satisfactory physical stability. Suitable amounts of diols to provide physical stability are in the amounts in the ranges found above.

[0132] Further suitable solvents include glycols or alkoxylated glycols, ethers and diethers having from 4 to 14 carbon atoms, preferably from 6 to 12 carbon atoms, aromatic alcohols, alkoxylated aromatic alcohols, aliphatic branched alcohols, alkoxylated aliphatic branched alcohols, linear CrC5alcohols, alkoxylated linear -C5 alcohols, C8-C14alkyl and cycloalkyl hydrocarbons and halo hydrocarbons, C6-C16glycol ethers, and mixtures thereof.

[0133] Suitable alkoxylated glycols are methoxy octadecanol and / or ethoxyethoxyethanol. Suitable aromatic alcohols include benzyl alcohol. Suitable aliphatic branched alcohols include 2- ethylbutanol and / or 2-methylbutanol. Suitable alkoxylated aliphatic branched alcohols include 1-methylpropoxyethanol and / or 2-methylbutoxyethanol. Suitable linear CrC5alcohols include methanol, ethanol, and / or propanol.

[0134] Manual dishwashing compositions typically comprise 0.01 to 20 wt.-% of solvent, based on the total weight of the composition. The solvents may be used in conjunction with an aqueous liquid carrier, such as water, or they may be used without any aqueous liquid carrier being present.

[0135] Manual dishwashing compositions may further comprise one or more diamines.

[0136] The composition preferably comprises 0.1 to 15 wt.-% of at least one diamine, based on the total weight of the composition.

[0137] Suitable diamines include organic diamines in which p 1 and p 2 are in the range of 8.0 to 11.5, such as 1,3-bis(methylamine)-cyclohexane (pKa = 10 to 10.5), 1,3-propane diamine (pK1=10.5; p 2=8.8), 1,6-hexane diamine (pK1 = 11; p 2 = 10), 1,3-pentane diamine (pK1 = 10.5; p 2 = 8.9), 2-methyl-1,5-pentane diamine (Dytek A) (pK1 = 11.2; p 2 = 10.0). pKa values referenced herein may be obtained from literature, such as from "Critical Stability Constants: Volume 2, Amines" by Smith and Martel, Plenum Press, NY and London, 1975. The pKa of the diamines is specified in an all-aqueous solution at 25°C and for an ionic strength between 0.1 to 0.5 M. Other preferred materials are primary diamines having two primary amino groups with alkylene spacers ranging from C4to C8.

[0138] The compositions according to the present invention may comprise a linear or cyclic carboxylic acid or salt thereof. Where the acid or salt thereof is present and is linear, it preferably comprises from 1 to 6 carbon atoms whereas where the acid is cyclic, it preferably comprises greater than 3 carbon atoms. The linear or cyclic carbon-containing chain of the carboxylic acid or salt thereof may be substituted with a substituent group selected from the group consisting of hydroxyl, ester, ether, aliphatic groups having from 1 to 6, more preferably 1 to 4 carbon atoms and mixtures thereof.

[0139] Preferred carboxylic acids are those selected from the group consisting of salicylic acid, maleic acid, acetyl salicylic acid, 3-methyl salicylic acid, 4-hydroxy isophthalic acid, di hydroxyfumaric acid, 1,2,4-benzene tricarboxylic acid, pentanoic acid and salts thereof and mixtures thereof. Where the carboxylic acid exists in the salt form, the cation of the salt is preferably selected from alkali metal, alkaline earth metal, monoethanolamine, diethanolamine or triethanolamine and mixtures thereof.

[0140] The carboxylic acid or salt thereof is preferably present in an amount from 0.1% to 5 wt.-%, based on the total weight of the composition.

[0141] The composition may comprise a polymeric suds stabilizer. These polymeric suds stabilizers provide extended suds volume and suds duration without sacrificing the grease cutting ability of the liquid detergent compositions. Suitable polymeric suds stabilizers include homopolymers of (N,N-di(CrC8alkyl)amino)(C1-C8)alkyl acrylate esters; and copolymers thereof.

[0142] The molecular weight of the polymeric suds stabilizers is preferably in the range of 1,000 to 2,000,000 g / mol, most preferably from 20,000 to 500,000 g / mol. Polymeric suds stabilizer may be present in the form of a salt, for example the citrate, sulfate, or nitrate salt of (N,N- dimethylamino)alkyl acrylate ester. One preferred polymeric suds stabilizer is (N,N- dimethylamino)alkyl acrylate ester. Polymeric suds stabilizers are preferably present in an amount of 0.01% to 15 wt.-%, based on the total weight of the composition.

[0143] Suitable builders include aluminosilicate materials, silicates, polycarboxylates and fatty acids, materials such as ethylene-diamine tetraacetate, metal ion sequestrants such as aminopolyphosphonates, particularly ethylenediamine tetramethylene phosphonic acid and diethylene triamine pentamethylene-phosphonic acid. Though less preferred for obvious environmental reasons, phosphate builders can also be used. Suitable polycarboxylate builders include citric acid, preferably in the form of a water-soluble salt, and derivatives of succinic acid. Specific examples include lauryl succinate, myristyl succinate, palmityl succinate 2-dodecenylsuccinate, 2-tetradecenyl succinate. Succinate builders are preferably used in the form of their water-soluble salts, including sodium, potassium, ammonium and alkanolammonium salts. Other suitable polycarboxylates are oxodisuccinates and mixtures of tartrate monosuccinic and tartrate disuccinic acid, as described in US 4,663,071.

[0144] Suitable fatty acid builders include saturated and unsaturated C10-i8fatty acids, as well as the corresponding soaps. Preferred saturated species have from 12 to 16 carbon atoms in the alkyl chain. The preferred unsaturated fatty acid is oleic acid. Other preferred builder system for liquid compositions is based on dodecenyl succinic acid and citric acid.

[0145] Builders are preferably present in amounts of 0.5 % to 50 wt.-%, more preferably 5 to 25 wt.- %, based on the total weight of the composition.

[0146] Suitable enzymes include enzymes selected from cellulases, hemicellulases, peroxidases, proteases, gluco-amylases, amylases, lipases, cutinases, pectinases, xylanases, reductases, oxidases, phenoloxidases, lipoxygenases, ligninases, pullulanases, tannases, pentosanases, malanases, p-glucanases, arabinosidases or mixtures thereof. Enzymes may be present in amounts of 0.0001% to 5 wt.-% of active enzyme, based on the total weight of the composition.

[0147] Preferred proteolytic enzymes, then, are selected from the group consisting of Alcalase® (Novo Industri A / S), BPN', Protease A and Protease B (Genencor), and mixtures thereof. Protease B is most preferred. Preferred amylase enzymes include TERMAMYL®, DURAMYL® and the amylase enzymes those described in WO 9418314 to Genencor International and WO 9402597 to Novo.

[0148] Suitable chelating agents include iron and / or manganese chelating agents. Such chelating agents can be selected from the group consisting of amino carboxylates, amino phosphonates, polyfunctionally-substituted aromatic chelating agents and mixtures thereof. Suitable amino carboxylates include ethylenediaminetetraacetates, N-hydroxyethylethylenediaminetriacetates, nitrilo-tri-acetates, ethylenediamine tetraproprionates, triethylenetetraaminehexaacetates, diethylenetriaminepentaacetates, and ethanoldiglycines, alkali metal, ammonium, and substituted ammonium salts thereof, and mixtures thereof. Suitable amino phosphonates include ethylenediaminetetrakis (methylenephosphonates). Suitable polyfunctionally-substituted aromatic chelating agents include dihydroxydisulfobenzenes such as 1,2-dihydroxy-3,5-disulfobenzene. Chelating agents may be present in amounts of 0.00015% to 15 wt.-%, based on the weight of the composition.

[0149] The invention is described in further detail by the subsequent examples.

[0150] Examples

[0151] Abbreviations:

[0152] EtOH Ethanol n.d. not determined

[0153] PT / C Platinum on carbon black

[0154] THE Tetrahydrofurane wt.% percent by weight

[0155] General Information

[0156] Analysis was performed via gas chromatography (after silylation), and structures were confirmed by nuclear magnetic resonance (NMR) spectroscopy.

[0157] Hildebrandt solubility parameters if solvent mixtures were calculated on the basis of the Hildebrandt solubility parameters of the individual solvents as described herein.

[0158] The foam volume was measured according to EN 12728 at 2 g / L and 40°C at pH 9 in tap water with a hardness of 10 °d or in deionized water (DI water) .

[0159] The cotton wetting time was measured according to EN 1772 at 1 g / L in deionized water with 10 wt.-% of Na2CO3.

[0160] The surface tension was measured at 23 °C after 0.10 s, at 1 g / L in deionized water at pH 9 or in water having a hardness of 10°d at pH 9 in accordance with DIN EN 14370:2004.

[0161] The interfacial tension vs. hexadecane was measured at 23 °C after 10 min, at 1 g / L in deionized water with a DataPhysics instrument OCA25 (pendant drop method).

[0162] The contact angle was measured on polyethylene at 40 °C after 10.0 s, at 0.2 g / L in deionized water with a DataPhysics instrument OCA25.

[0163] Reductive aminations of an aldehyde with an amino compound were performed at a temperature of 25 to 90 °C and at a hydrogen pressure of 5 to 20 bar in a 300 mL autoclave in accordance with Table 1 below. Example 1

[0164] Platinum on carbon black (3 wt.%, 1 g, PT / C) was added to a solution of nipecotic acid (100%, 10 g) in a mixture of ethanol (50 mL) and water (40 mL) in an autoclave. The reaction vessel was closed and subsequently purged with nitrogen gas (thrice at 5 bar) and hydrogen gas (thrice at 5 bar). At an initial hydrogen pressure of 20 bar, stirring (700 U / min) was applied. The reaction mixture was warmed to 60 °C. Subsequently, dodecanal (95%, 16 g) as a solution in ethanol (20 mL) was metered continuously to the reaction mixture over the course of 5 h. The temperature (60 °C) and hydrogen pressure (20 bar) were maintained.

[0165] After complete addition of the aldehyde solution, the reaction mixture was stirred at a temperature of 60 °C and a hydrogen pressure of 20 bar for 1 h, then cooled to room temperature and purged with nitrogen gas (thrice at 5 bar). Afterwards, the catalyst was filtered off and the filter cake was washed twice with ethanol. The solvent was removed by evaporation, yielding the crude material as a solid (19 g, purity: 83%, yield: 68%).

[0166] Examples 2 to 3

[0167] The compounds (I) of examples 2 to 3 were performed by analogy to Example 1, as indicated in Table 1. The properties of the compounds (I) are summarized in table 2. Dodecylsarcosine was tested as a comparative.

[0168] Table 1: Reactants and reaction conditions Table 1 (continued): Reactants and reaction conditions

[0169] 1volume contractions were taken into account for mixtures of two solvents

[0170] 2Hildebrandt solubility parameter 3 time for continuous dosing of the aldehyde, plus additional stirring time

[0171] 45wt.% ruthenium on carbon black instead of 3wt.% of Platinum on carbon black

[0172] Table 2: Properties of the inventive compounds:

[0173] 1) C1: Dodecylsarcosin

Claims

Claims1. The use of a compound of general formula (I)or a salt thereof, where k is 0 or 1;R1is selected from C7-C29-alkyl and C7-C29-alkenyl;X and Y are identical or different and selected from CH2, O, S, SO, SO2or NR3, provided that at least one of X and Y is CH2,R2is hydrogen or CrC4-alkyl,R3is hydrogen or CrC4-alkyl, where k is 1 if both X and Y are CH2and where COOH replaces one of the hydrogen atoms of a CH2group in positions a or b; as a surfactant, in particular as a surfactant for stabilizing oil-in-water emulsions or aqueous dispersions.

2. A compound of general formula (I) as defined in claim 1 except for the following compounds and the salts thereof: 1-(1-(3-propylnonyl)-3-piperidinecarboxylic acid, 1-(1-(4-propyldecyl)-3-piperidinecarboxylic acid, 1-nonyl-3-piperidinecarboxylic acid, 1-decyl-4-piperidinecarboxylic acid and 1-hexadecyl-4-piperidinecarboxylic acid.

3. The use of claim 1 or the compound of claim 2, where R1is C7-C21-al kyl, in particular C8-C19-alkyl, more particularly CiCi7-alkyl, especially C-ii-C13-alkyl, e. g. Cialkyl.

4. The use or the compound of any one of the preceding claims where R2is hydrogen or methyl, especially hydrogen.

5. The use or the compound of any one of the preceding claims where k = 1.

6. The use or the compound of claim 5, where both X and Y are CH2.

7. The use or the compound of claim 5, where Y is O or S and X is CH2.

8. The use or the compound of any one of claims 1 to 4, where k is 0, X is O or S andY is CH2.

9. The use of claim 1, where the compound of the formula (I) is selected from the group consisting ofN-n-nonyl-piperidine-3-carboxylic acid, N-n-dodecyl-piperidine-3-carboxylic acid, N-n-tetradecyl-piperidine-3-carboxylic acid, N-n-nonyl-piperidine-4-carboxylic acid, N-n-dodecyl-piperidine-4-carboxylic acid, N-n-tetradecyl-piperidine-4-carboxylic acid the mixtures thereof and the salts thereof.

10. The compound of claim 2 selected from the group consisting ofN-n-dodecyl-piperidine-3-carboxylic acid, N-n-tetradecyl-piperidine-3-carboxylic acid, N-n-nonyl-piperidine-4-carboxylic acid, N-n-dodecyl-piperidine-4-carboxylic acid, N-n-tetradecyl-piperidine-4-carboxylic acid the mixtures thereof and the salts thereof.

11. The use of claim 1 or the compound of claim 2, where the compound of the formula (I) is selected from the group consisting ofN-n-nonylthioproline, N-n-dodecylthioproline, N-n-tetradecylthioproline, N-n-nonyl-L-thioproline,N-n-dodecyl-L-thioproline, N-n-tetradecyl-L-thioproline, the mixtures thereof and the salts thereof.

12. The use or the compound of any one of the preceding claims, wherein the relative amount of bio based carbon, based on the total amount of carbon atoms in the compound of formula (I) is at least 20 mol-%.

13. A composition containing at least one compound of formula (I) or a salt thereof as defined in any one of claims 2 to 12 and and at least one further component different from the compound of formula (I) or a salt thereof, which is in particular selected from the group consisting of carriers, surfactants different from the compounds of formula (I), fragrance, antimicrobial agents, sequestrants, enzymes, enzyme stabilizers, hydrotropic agents, bleaching agents, dispersants, pH adjusting agents, pigments, dyes, pearlescent, opacifiers, viscosity modifiers and inorganic salts.

14. A process for preparing a compound of general formula (I), the process comprising reductive amination of an aldehyde of general formula (II)wherein R1is defined as in claims 1 or 2; with an amino compound of general formula (III)or a salt thereof, wherein k, R2, X and Y are defined as in any one of claims 1, 3, 4, 5 6 or 7, andwhere COOH replaces one of the hydrogen atoms of a CH2group in positions a or b; in the presence of molecular hydrogen and a heterogeneous catalyst comprising a group 8, group 9 or group 10 element of the periodic table of the elements.

15. The process of claim 14 which meets at least one of the following requirements (a),(b), (c), (d), (e), (f), (g), (h or (i)):(a) the reductive amination is conducted in feed operation, wherein the amino compound of general formula (III) is provided, and the aldehyde of general formula (II) is metered thereto;(b) the reductive amination is performed at a pressure of molecular hydrogen of at least 1 bara;(c) the reductive amination is performed at a temperature of at least 25 °C;(d) the reductive amination is performed in a solvent having a Hildebrand solubility parameter 5 in the range of 18 to 38 MPa1 / 2,(e) at a solvent dilution ratio of at most 20.0 L per kg, the solvent dilution ratio being the total volume of solvent to the total weight of the aldehyde of general formula (II) and the amino compound of general formula (III);(f) the reductive amination is performed in a solvent comprising at least one protic solvent and / or an aprotic solvent comprising an ether moiety(g) the heterogeneous catalyst is present in an amount of at most 2.5 wt.-%, calculated as group 8, group 9 or group 10 element relative to the weight of the amino compound of general formula (III);(h) the group 8, group 9 or group 10 element is selected from ruthenium, cobalt, nickel, palladium and platinum, preferably ruthenium and platinum, most preferably platinum;(i) the heterogeneous catalyst is platinum on activated carbon or ruthenium on activated carbon.

16. The process according to any one of claims 14 or 15, wherein the aldehyde of general formula (II) and / or the amino compound of general formula (III) are biobased compounds.

17. The process according to any one of claims 14 to 16, where the amino compound of the general formula (II) is selected form the group consisting of pi peridi ne-3 - carboxylic acid, piperidine-4-carboxylic acid and thioproline and the salts thereof.

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