Corrosion inhibitors

Abstract

Melamine derivatives and mixtures thereof with aqueous systems, a process for inhibiting corrosion of metals and metal alloys with melamine derivatives and mixtures thereof and the use of melamine derivatives and mixtures thereof as corrosion inhibitors for aqueous systems, for example water/oil mixtures, especially in the field of cleaning compositions, cooling fluids, oilfield chemicals or lubricants.

1 . A process for inhibiting corrosion of metals or metal alloys in contact with an aqueous system, the process comprising adding to the aqueous system a compound of formula (I): 
       
         
           
           
               
               
           
         
         wherein 
         A 1 , A 2 , and A 3  are each independently N—R 11 , N—R 12 , N—R 13 , S, or O, 
         R 11 , R 12 , and R 3  are each independently H, C 1 -C 20 -alkyl, or C 3 -C 15 -cycloalkyl, 
         X 12 , X 22 , and X 32  are each independently (X-a) to (X-m) groups 
       
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         * is a bond to A 1 , A 2  or A 3 , 
         ** is a bond to Y 12 , Y 22  or Y 32 , 
         R 4  is the same or different and is independently H, or CH 3 , 
         R 5  is a side chain of a natural alpha-amino acid, 
         Y 12 , Y 22 , and Y 32  are each independently carboxylate, phosphate, phosphonate, sulfonate, or a quaternary ammonium group, 
         X 12 -Y 12 , 
         X 22 -Y 22 , and 
         X 32 -Y 32  may be the same or different and may each independently also together be O—H, 
         n and m, are each independently an integer of from 1 to 20, 
         p is an integer of from 1 to 30, 
         or a salt thereof, obtained, by at least partial neutralization with a base selected from the group consisting of an alkali metal hydroxide and an amine, 
         wherein either 
         R 11 , R 12  and R 13  may each be interrupted at any position by a heteroatom, in which a number of heteroatoms is not more than 10, 
         R 11 , R 12  and R 13  and/or may each be substituted at any position, but not more than five times, by C 1 -C 10 -alkyl, OH, CO 2 H, PO(OH), PO(OH) 2 , SO 2 H or SO 3 H, in which these may likewise be substituted not more than twice by a group thereof, 
         or both. 
       
     
     
         2 . The process according to  claim 1 , wherein of from 0.001 to 5% by weight of the compound of formula (I), based on a total amount of all substances in the aqueous system, is present. 
     
     
         3 . The process according to  claim 1 , comprising inhibiting corrosion of metals or metal alloys in the field of cleaning compositions, cooling fluids, oilfield chemicals, electronics chemicals or lubricants. 
     
     
         4 . The process according to  claim 1 , wherein the metals or metal alloys comprise iron. 
     
     
         5 . The process according to  claim 4 , wherein the metals or metal alloys comprise chromium, nickel, molybdenum, aluminum, copper, zinc, or a mixture thereof. 
     
     
         6 . A compound of formula (II): 
       
         
           
           
               
               
           
         
         wherein 
         A 4 , A 5 , and A 6  are each independently N—R 41 , N—R 51 , N—R 61 , or O, 
         R 41 , R 51 , and R 61  are each independently H, C 1 -C 20 -alkyl, or C 3 -C 10 -cycloalkyl, 
         X 42 , X 52 , and X 62  are each independently (X-a′) to (X-m′) groups 
       
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
         * is a bond to A 4 , A 5  or A 6 , 
         ** is a bond to Y 42 , Y 52  or Y 62 , 
         R 6  is the same or different and is independently H, or CH 3 , 
         R 7  is a side chain of a natural alpha-amino acid, 
         Y 42 , Y 52 , and Y 62  are each independently carboxylate, phosphate, phosphonate, sulfonate, or a quaternary ammonium group, 
         X 42 -Y 42 , 
         X 52 -Y 52 , and 
         X 62 -Y 62  may be the same or different and may each independently also together be O—H, 
         q and r, are each independently an integer of from 1 to 20, and 
         s is an integer of from 1 to 30, 
         or a salt of the compound of formula (II), obtained by at least partial neutralization with a base selected from the group consisting of an alkali metal hydroxide and an amine, 
         wherein either 
         substituents R 41 , R 51  and R 61  may each be interrupted at any position by a heteroatom, in which a number of these heteroatoms is not more than 10, 
         R 41 , R 51 , and R 61  may each be substituted at any position, but not more than five times, by C 1 -C 10 -alkyl, OH, CO 2 H, PO(OH), PO(OH) 2 , SO 2 H or SO 3 H, wherein these may likewise be substituted not more than twice by a group thereof, or 
         both. 
       
     
     
         7 . An aqueous system comprising the compound according to  claim 6 . 
     
     
         8 . The aqueous system according to  claim 7 , comprising of from 0.001 to 5% by weight of the compound of formula (II), based on a total amount of all substances in the aqueous system. 
     
     
         9 . The aqueous system according to  claim 7 , further comprising phosphoric acid or at least partly neutralized phosphoric acid. 
     
     
         10 . The aqueous system according to  claim 7 , wherein the at least partial neutralization is effected with a base selected from the group consisting of an alkali metal hydroxide and an amine. 
     
     
         11 . The aqueous system according to  claim 7 , further comprising an acid or an at least partly neutralized acid. 
     
     
         12 . The aqueous system according to  claim 11 , wherein the acid is selected from the group consisting of formic acid, amidosulfonic acid, acetic acid, glycolic acid, methanesulfonic acid, lactic acid, oxalic acid, phosphoric acid, nitric acid, hydrochloric acid, sulfuric acid, citric acid, gluconic acid, salicylic acid, and carbonic acid. 
     
     
         13 - 14 . (canceled) 
     
     
         15 . The process according to  claim 1 , wherein R 11 , R 12  and R 13  may each be interrupted at any position by a heteroatom, in which a number of heteroatoms is not more than 10. 
     
     
         16 . The process according to  claim 1 , wherein R 11 , R 12  and R 13  may each be substituted at any position, but not more than five times, by C 1 -C 10 -alkyl, OH, CO 2 H, PO(OH), PO(OH) 2 , SO 2 H or SO 3 H, in which these may likewise be substituted not more than twice by a group thereof. 
     
     
         17 . The process according to  claim 1 , wherein R 11 , R 12  and R 13  may each be interrupted at any position by a heteroatom, in which a number of heteroatoms is not more than 10, and R 11 , R 12  and R 13  may each be substituted at any position, but not more than five times, by C 1 -C 10 -alkyl, OH, CO 2 H, PO(OH), PO(OH) 2 , SO 2 H or SO 3 H, in which these may likewise be substituted not more than twice by a group thereof. 
     
     
         18 . The process according to  claim 1 ,
 wherein either   R 11 , R 12  and R 13  may each be interrupted at any position by a heteroatom, in which a number of heteroatoms is not more than 8,   R 11 , R 12  and R 13  may each be substituted at any position, but not more than four times, by C 1 -C 10 -alkyl, OH, CO 2 H, PO(OH), PO(OH) 2 , SO 2 H or SO 3 H, in which these may likewise be substituted not more than twice by a group thereof, or   both.   
     
     
         19 . The process according to  claim 1 ,
 wherein either   R 11 , R 12  and R 13  may each be interrupted at any position by a heteroatom, in which a number of heteroatoms is not more than 5,   R 11 , R 12  and R 13  may each be substituted at any position, but not more than three times, by C 1 -C 10 -alkyl, OH, CO 2 H, PO(OH), PO(OH) 2 , SO 2 H or SO 3 H, in which these may likewise be substituted not more than twice by a group thereof, or   both.   
     
     
         20 . The process according to  claim 1 ,
 wherein either   R 11 , R 12  and R 13  may each be interrupted at any position by a heteroatom, in which a number of heteroatoms is not more than 3,   R 11 , R 12  and R 13  may each be substituted at any position, but not more than three times, by C 1 -C 10 -alkyl, OH, CO 2 H, PO(OH), PO(OH) 2 , SO 2 H or SO 3 H, in which these may likewise be substituted not more than once by a group thereof, or   both.   
     
     
         21 . The compound according to  claim 6 , or a salt thereof, wherein R 41 , R 51  and R 61  may each be interrupted at any position by a heteroatom, in which a number of these heteroatoms is not more than 10 
     
     
         22 . The compound according to  claim 6 , or a salt thereof, wherein R 41 , R 51 , and R 61  may each be substituted at any position, but not more than five times, by C 1 -C 10 -alkyl, OH, CO 2 H, PO(OH), PO(OH) 2 , SO 2 H or SO 3 H, wherein these may likewise be substituted not more than twice by a group thereof.