Method for the production of acyl glycinates by means of direct oxidation
View Patent ↗A method is described for producing acyl glycinate salts of formula (II) in which R 1 represents a saturated linear or branched alkyl radical comprising 1 to 21 carbon atoms or a monounsaturated or polyunsaturated linear or branched alkenyl radical comprising 2 to 21 carbon atoms, and B represents a cation, and/or the corresponding protonated acyl glycinic acid. Said method is characterized in that one or more fatty acid monoethanol amides of formula (I) in which R 1 has the meaning indicated above is/are oxidized with oxygen in the presence of an optionally supported bimetallic catalyst consisting of gold and a metal from group VIII of the periodic table in the alkaline medium in order to obtain one or more acyl glycinate salts of formula (II). In order to produce the protonated acyl glycinic acids, the acyl glycinate salt/s of formula (II) is/are additionally reacted with an acid.
1. A process for preparing at least one acylglycinate salt of the formula (II)
where
R 1 is a saturated linear or branched alkyl radical having from 1 to 21 carbon atoms or a monounsaturated or polyunsaturated linear or branched alkenyl radical having from 2 to 21 carbon atoms and
B is a cation,
and/or the corresponding protonated acylglycine acid, wherein the process comprises the step of oxidizing at least one fatty acid monoethanolamide of the formula (I)
where R 1 is as defined above,
with oxygen in the presence of an optionally supported bimetal catalyst consisting of gold and a metal from group VIII of the Periodic Table of Elements in alkaline medium to form at least one acylglycinate salt of the formula (II) and, in the case of the preparation of the protonated acylglycine acid, additionally reacting the at least one acylglycinate salt of the formula (II) with an acid.
2. A process as claimed in claim 1 , wherein R 1 is a saturated linear or branched alkyl radical having from 7 to 17 carbon atoms or a monounsaturated or polyunsaturated linear or branched alkenyl radical having from 7 to 17 carbon atoms.
3. A process as claimed in claim 1 , wherein the at least one fatty acid monoethanolamide of the formula (I) is selected from the group consisting of lauric acid monoethanolamide, myristic acid monoethanolamide, caprylic acid monoethanolamide, capric acid monoethanolamide, palmitic acid monoethanolamide, stearic acid monoethanolamide, isostearic acid monoethanolamide, coconut fatty acid monoethanolamide and mixtures thereof.
4. A process as claimed in claim 1 , wherein the bimetal catalyst has been applied to a support.
5. A process as claimed in claim 4 , wherein the bimetal catalyst has been applied to an oxidic support.
6. A process as claimed in claim 5 , wherein the oxidic support comprises titanium dioxide.
7. A process as claimed in claim 4 , wherein the supported bimetal catalyst contains from 0.1 to 5% by weight of gold.
8. A process as claimed in claim 4 , wherein the supported bimetal catalyst contains from 0.1 to 3% by weight of a metal from group VIII.
9. A process as claimed in claim 1 , wherein the particle size of the bimetal catalyst is from 1 to 50 nm.
10. A process as claimed in claim 1 , wherein a solution comprising at least one fatty acid monoethanolamide of the formula (I) and at least one acylglycinate of the formula (II) is subjected to the oxidizing step.
11. A process as claimed in claim 4 , wherein the supported bimetal catalyst contains from 0.5 to 3% by weight of gold.
12. A process as claimed in claim 4 , wherein the supported bimetal catalyst contains from 0.1 to 2% by weight of a metal from group VIII.
13. A process as claimed in claim 4 , wherein the supported bimetal catalyst contains from 0.1 to 3% by weight of platinum or palladium.
14. A process as claimed in claim 1 , wherein the particle size of the bimetal catalyst is from 2 to 10 nm.