US 8,809,576 B2  10  9  The organic acid is preferably selected from the group of  succinic acid, oxalic acid, malonic acid, glutaric acid, adipic  acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,  fumaric acid, itaconic acid, methylmalonic acid, phthalic  acid, terephthalic acid, isophthalic acid.  In a further alternative process the organic acid is a tricar› boxylic acid of the general formula  le:  where R  12  is an organic radical selected from the group com› prising unsubstituted and mono- or polysubstituted, branched  and straight-chain alkyl radicals, cycloalkyl radicals, alkenyl  radicals having one or more double bonds, alkynyl radicals  having one or more triple bonds, aryl radicals, alkylaryl radi› cals, arylalkyl radicals, arylalkenyl radicals, alkyloxyalkyl  radicals, hydroxyalkyl radicals and alkylthioalkyl radicals.  where Z is an organic radical selected from the group com› prising unsubstituted and mono- or polysubstituted, branched  and straight-chain alkanetriyl radicals, cycloalkanetriyl radi› cals, alkenetriyl radicals having one or more double bonds,  alkynetriyl radicals having one or more triple bonds, aryltriyl  radicals, alkylaryltriyl radicals, arylalkanetriyl radicals, ary› lalkenetriyl radicals, alkyloxyalkanetriyl radicals, hydroxy› alkanetriyl radicals andalkylthioalkanetriyl radicals. The suf- fix "-triy l" indicates here that the three carboxy lie acid groups  of the tricarboxylic acid are bonded to this radical. The car› boxylic acid groups may each independently be bonded to  any carbon atoms of the organic radical, for example gemi› nally, vicinally or to nonadjacent carbon atoms, where the  carbon atoms to which the carboxylic acid groups are bonded  may either be in terminal positions or within the radical.  Moreover, it is preferred that Z is defined as follows:  unsubstituted and mono- or polysubstituted, branched and  straight-chain (C 1 -C 18 )-alkanetriyl radicals, (C 3 -C 18 )-cy› cloalkanetriyl radicals, (C 2 -C 26 )-alkenetriyl radicals having  one or more double bonds, (C 2 -C 26 )-alkynetriyl radicals hav› ing one or more triple bonds, (C 6 -CIO)-aryltriyl radicals,  especially phenyltriyl radicals,  (C 1  -C 18 )-alkyl-(CcCIO)- aryltriyl radicals, (CcCIO)-aryl-(C 1  -C 18 )-alkanetriyl radi› cals, (CcCIO)-aryl-(C 1 -C 18 )-alkenetriyl radicals, (C 1  -C 18 )› alkyloxy-(C1 -C 18 )-alkanetriyl  radicals,  (C 1 -C 6 )› hydroxyalkanetriyl radicals and (C 1  -C 18 )-alkylthio-(C 1  - C 18 )-alkanetriyl radicals, any substituents being selected  from the group comprising OH, ORIO", NH 2 , NHRIO",  NRIO"R 20 ", Cl, Br, I and F, where RIO", R 20 " are each inde› pendently selected from the group comprising H, unsubsti› tuted and mono- or polysubstituted, branched and straight› chain (C 1  -C 18 )-alkyl radicals, (C 3 -C 18 )-cycloalkyl radicals,  (C 2 -C 26 )-alkenyl radicals having one or more double bonds,  (CcCIO)-aryl radicals, especially phenyl radicals, (C 1  -C 18 )› alkyl-(C6-CIO)-aryl radicals, (C 6 -CIO)-aryl-(C 1  -C 18 )-alkyl  radicals, especially benzyl radicals, (C 1  -C 18 )-alkyloxy-(C 1  - C 18 )-alkyl radicals, (C 1  -C 18 )-hydroxyalkyl radicals and (C 1  - C 18 )-alkylthio-(C 1  -C 18 )-alkyl radicals.  In a preferred embodiment, the organic acid is selected  from the group of citric acid, cyclopentane-1,2,3-tricarboxy- lic acid, cyclopentane-1,2,4-tricarboxylic acid, 2-methylcy› clopentane-1,2,3-tricarboxylic acid, 3-methylcyclopentane- 1,2,4-tricarboxylic acid.  In a further process, the organic acid corresponds to a  sulphonic acid of the general formula II:  II  In a preferred process, R 13  is defined as follows: unsubsti- tuted and mono- or polysubstituted, branched and straight› chain (C 1 -C 18 )-alkyl radicals, (C 3 -C 18 )-cycloalkyl radicals,  (C 2 -C 26 )-alkenyl radicals having one or more double bonds,  (C 2 -C 26 )-alkynyl radicals having one or more triple bonds,  (CcCIO)-aryl radicals, especially phenyl radicals, $^{(C}$1 -C 18 )› alkyl-(C6-CIO)-aryl radicals, (C 6 -CIO)-aryl-(C 1  -C 18 )-alkyl  radicals, (CcCIO)-aryl-(C 2 -C 18 )-alkenyl radicals, (C 1  -C 18 )› alkyloxy-(C1 -C 18 )-alkyl  radicals,  (C 1  -C 18 )-hydroxyalkyl  radicals and (C 1  -C 18 )-alkylthio-(C 1  -C 18 )-alkyl radicals, any  substituents being selected from the group comprising OH,  OR 23 , NH 2 , NHR 23 , NR 23 R 33 , Cl, Br, I andF, whereR 23  and  R 33  are each independently selected from the group compris- where R  13  is an organic radical selected from the group com› prising unsubstituted and mono- or polysubstituted, branched  and straight-chain alkyl radicals, cycloalkyl radicals, alkenyl  radicals having one or more double bonds, alkynyl radicals  having one or more triple bonds, aryl radicals, alkylaryl radi- cals, arylalkyl radicals, arylalkenyl radicals, alkyloxyalkyl  radicals, hydroxyalkyl radicals and alkylthioalkyl radicals.  III  In a preferred process, the organic acid is selected from the  group of p-toluenesulphonic acid, camphor- I 0-sulphonic  acid, benzenesulphonic acid, dodecylbenzenesulphonic acid,  naphthalenesulphonic acids, phenolsulphonic acids.  In a further process according to the present invention, the  organic acid is a phosphonic acid of the general formula III:  It is preferred that R  12  is defined as follows: unsubstituted  and mono- or polysubstituted, branched and straight-chain  (C 1  -C 18 )-alkyl radicals, (C 3 -C 18 )-cycloalkyl radicals, (C 2 - C26)-alkenyl radicals having one or more double bonds, (C 2 - C26)-alkynyl radicals having one or more triple bonds, (C 6 - C IO)-ary 1 radicals, especially pheny 1 radicals, ( C  1 -C 18 )-alkyl- (CcCIO)-aryl  radicals,  (CcCIO)-aryl-(C 1  -C 18 )-alkyl  radicals, (C 6 -CIO)-aryl-(C 2 -C$_{18}$)-alkenyl radicals, (C 1  -C 18 )› alkyloxy-(C1 -C 18 )-alkyl  radicals,  (C 1  -C 18 )-hydroxyalkyl  radicals and (C 1  -C 18 )-alkylthio-(C 1  -C 18 )-alkyl radicals, any  substituents being selected from the group comprising OH,  $_{OR}$22, NH 2 , NHR 22 , NR 22 R 32 , Cl, Br, I and F, where R 22  and  R 32  are each independently selected from the group compris› ing H, unsubstituted and mono- or polysubstituted, branched  and straight-chain (C 1  -C 18 )-alkyl radicals, (C 3 -C 18 )-cy› cloalkyl radicals, (C 2 -C 26 )-alkenyl radicals having one or  more double bonds, (C 6 -CIO)-aryl radicals, especially phenyl  radicals, (C 1  -C 18 )-alkyl-(CcCIO)-aryl radicals, (CcCIO)› aryl-(C1 -C 18 )-alkyl radicals, especially benzyl radicals, (C 1  - C$_{18}$)-alkyloxy-(C 1  -C 18 )-alkyl radicals, (C 1  -C 18 )-hydroxy- alkyl  radicals  and  (C 1  -C 18 )-alkylthio-(C 1  -C 18 )-alkyl  radicals.  le 10  0  II  R $^{13}$-P-OH  I  OH  0  II  R $^{12}$-S-OH  II  0 