WO1981000848A1 - Selective metal chelating compounds - Google Patents

Selective metal chelating compounds Download PDF

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Publication number
WO1981000848A1
WO1981000848A1 PCT/AU1980/000071 AU8000071W WO8100848A1 WO 1981000848 A1 WO1981000848 A1 WO 1981000848A1 AU 8000071 W AU8000071 W AU 8000071W WO 8100848 A1 WO8100848 A1 WO 8100848A1
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compound
copper
mercury
compounds
formula
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PCT/AU1980/000071
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French (fr)
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J Hodgkin
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Commw Scient Ind Res Org
J Hodgkin
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Priority to AU63383/80A priority Critical patent/AU6338380A/en
Publication of WO1981000848A1 publication Critical patent/WO1981000848A1/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D295/00—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms
    • C07D295/04—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms
    • C07D295/08—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms substituted by singly bound oxygen or sulfur atoms
    • C07D295/096—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms substituted by singly bound oxygen or sulfur atoms with the ring nitrogen atoms and the oxygen or sulfur atoms separated by carbocyclic rings or by carbon chains interrupted by carbocyclic rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D295/00—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms
    • C07D295/04—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms
    • C07D295/08—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms substituted by singly bound oxygen or sulfur atoms
    • C07D295/084—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms substituted by singly bound oxygen or sulfur atoms with the ring nitrogen atoms and the oxygen or sulfur atoms attached to the same carbon chain, which is not interrupted by carbocyclic rings
    • C07D295/088—Heterocyclic compounds containing polymethylene-imine rings with at least five ring members, 3-azabicyclo [3.2.2] nonane, piperazine, morpholine or thiomorpholine rings, having only hydrogen atoms directly attached to the ring carbon atoms with substituted hydrocarbon radicals attached to ring nitrogen atoms substituted by singly bound oxygen or sulfur atoms with the ring nitrogen atoms and the oxygen or sulfur atoms attached to the same carbon chain, which is not interrupted by carbocyclic rings to an acyclic saturated chain

Definitions

  • This invention is concerned with selective metalchelating agents which are useful in the selective removal of metal Ions from (or their addition to) biological systems in contact with water.
  • organic chelating agents are designed to selectively chelate copper and mercury ions and act as carriers of these ions in biological organic matrices.
  • 8-hydroxy quinoline derivatives have been used to remove toxic metals in cases of metal poisoning by mercury or lead salts.
  • Other applications include the addition of cobalt or copper salts to animal diets where these metals are deficient in the local environment.
  • Metal chelation compounds such as organo-mercurials are used for the treatment of fungus problems in paints and plastics.
  • Very selective metal-chelating agents would therefore be very useful in a number of applications, especially in relation to the ions of copper and mercury. For example, they could be used in the extraction of poisonous mercury salts from the body without the removal of beneficial ions, and in the addition of copper ions to animal diets without upsetting the balance of other metal ions in the animal.
  • the most preferred polymers are those prepared using piperazine and have the following structure, as confirmed by nuclear magnetic resonance and infrared measurements.
  • R' and R''' are independently lower (C 1 -C 3 ) alkyl groups or hydrogen atoms and R'' is a hydrogen atom or a crosslinking group.
  • R 1 and R 2 are the same or different groups and each is C 1 to C 6 alkyl or hydroxyalkyl;
  • R 3 is hydrogen, halogen, a C 1 to C 4 alkoxy group or a C 1 to C 18 alkyl group.
  • R 1 and R 2 are the same .
  • R 1 and/or R 2 is hydroxyalkyl
  • the preferred group is the 2-hydroxyethyl group.
  • the specific physical properties of the chelating material (1) will vary according to the substituent R 3 on the phenol ring.
  • R 3 is a relatively long chain alkyl, such as the nonyl group
  • R 3 is halogen, e.g., chlorine.
  • groups may be selected for R 3 in order to modify properties of the compounds (or their metal complexes) such as their solubility or dispersability in water or other liquid or solid medium or their biological compatibility.
  • R 3 contains less than 9 carbon atoms.
  • hydroxyalkyl substituents such as -CH 2 CH 2 OH, for R 1 and R 2 confer greater water solubility on the uncomplexed chelating agent.
  • R 1 and R 2 are the same, may be produced in accordance with another aspect of the invention, by the Mannich condensation of a phenolic component (formula II) with excess formaldehyde and two moles of a piperazine component (formula III under neutral conditions.
  • the selective copper and mercury chelating agents of formula (I) are prepared by reacting one mole of the phenol (II) with slightly over two moles of the piperazine compound (III) and about three moles of formaldehyde under neutral Mannich reaction conditions in aqueous ethanol solvent. [M. Tramontini, Synthesis, 1973, p. 703 to 775]. The mixture is heated under reflux for up to 16 hours to ensure full substitution at both ortho positions of the phenol ring. Mono-substituted compounds are formed if the amounts of the piperazine derivative or formaldehyde are insufficient or if the reaction conditions are not vigorous enough.
  • the compounds (I) formed in the Mannich reaction can be isolated by evaporation of the bulk of the solvent, addition of water to remove polar inpurities and extraction with water insoluble solvents such as chloroform or benzene.
  • the invention also includes the copper and mercury chelate complexes of the compounds of formula I.
  • This example illustrates the preparation and properties of a copper and mercury chelating agent prepared from 4-chlorophenol, 1-methylpiperazine and formaldehyde.
  • 1-methylpiperazine (21 g, 0..21 mole) was dissolved in 150 ml of ethanol; formaldehyde solution (35 ml of 33%, 0.35 mole) was added slowly with stirring. After complete addition 4-chlorophenol (12.8 g. 0.1 mole) was added and the mixture heated at reflux for 10 hours. The ethanol solution was then evaporated down to about 60 ml and 150 ml of water and 150 ml of chloroform added. The mixture was then shaken thoroughly and the chloroform layer separated off, washed with a small amount of water and dried over sodium sulphate.
  • Compound IA formed a picrate salt, which was recrystallized from acetone as yellow needles which decomposed at about 220°C.
  • This example illustrates the preparation and properties of a chelating agent prepared from nonylphenol, 1-methylpIperazine and formaldehyde.
  • a water soluble chelating agent was obtained by the general methods of Example 1, using 1(2'-hydroxyethyl) piperazine and p-cresol.
  • This example illustrates the preparation and properties of a chelating agent prepared from an alkoxy substituted phenol, 1-methylpiperazine and formaldehyde, Using the general method of Example 1, a chelating compound was formed from l-methylpiperazlne, formaldehyde and 4-methoxy phenol. It was obtained as a brown oil. Its proton NMR spectrum in chloroform [D] was ⁇ (ppm from TMS) 2.29s (singlet N-CH 3 ); 2.53s (piperazine ring);
  • This example illustrates the preparation and properties of copper complex of compound IA.
  • the chelating agent IA was dissolved in chloroform and shaken with slightly less than 1 mole % of aqueous copper sulphate solution. The water layer immediately changed from blue to dark green as the complex formed. The chloroform layer was removed and the water washed with fresh chloroform to remove any excess chelating agent. The water solution was then freeze dried to give the copper complex as a dark green hydroscopic powder. Analysis: Found C, 40.42; H, 5.84; N, 10.52; S, 6.0; Cl, 6.6. C 18 H 29 N 4 OCl.CuSO 4 . H 2 O requires C, 40.75; H, 5.89; N,10.56; S, 6.03; Cl, 6.68%.
  • the mercury complexes can be formed in a very similar manner but these are much less water soluble than the copper complexes.
  • the mercury complex formed from compound IB and aqueous mercuric chloride solution is a pale yellow solid which, is slightly soluble in water and chloroform. Analysis indicates that it contains one mercury atom per unit structure.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)

Abstract

Selective metal chelating compounds of the general formula I (FORMULA) wherein R1 and R2 are the same or different groups and each is C1 to C6 alkyl or hydroxyalkyl; and R3 is hydrogen, halogen, a C1 to C4 alkoxygroup or a C1 to C18 alkyl group. These organic chelating agents selectively chelate copper and mercury ions. The chelate complexes of the compounds with copper and mercury act as carriers of these ions in biological organic matrices.

Description

SELECTIVE METAL CHELATING COMPOUNDS
This invention is concerned with selective metalchelating agents which are useful in the selective removal of metal Ions from (or their addition to) biological systems in contact with water. These organic chelating agents are designed to selectively chelate copper and mercury ions and act as carriers of these ions in biological organic matrices.
The use of strong metal-chelating organic molecules to transfer traces of metal ions into or out of biological systems is well known. For example, EDTA salts or
8-hydroxy quinoline derivatives have been used to remove toxic metals in cases of metal poisoning by mercury or lead salts. Other applications include the addition of cobalt or copper salts to animal diets where these metals are deficient in the local environment. Metal chelation compounds such as organo-mercurials are used for the treatment of fungus problems in paints and plastics.
Many of these commercial chelating agents are, however, strong complexing agents for a great range of polyvalent metal ions. Although they often have some selectivity for a particular metal ion, this usually is not sufficient to prevent the occurrence of serious side effects in the use of such materials, for example, the removal of other elements essential to the body when chelating agents are used as detoxifying agents.
Very selective metal-chelating agents would therefore be very useful in a number of applications, especially in relation to the ions of copper and mercury. For example, they could be used in the extraction of poisonous mercury salts from the body without the removal of beneficial ions, and in the addition of copper ions to animal diets without upsetting the balance of other metal ions in the animal.
Our copending Australian Patent Application No. 36269/78 describes a series of selective metal-chelating resins, which are polymers produced by the condensation of a phenolic component comprising one or more phenols, formaldehyde, and a diamino component comprising one or more di-(secondary amino); compounds, under neutral (Mannich reaction) conditions.
The most preferred polymers are those prepared using piperazine and have the following structure, as confirmed by nuclear magnetic resonance and infrared measurements.
Figure imgf000004_0001
where R' and R''' are independently lower (C1-C3) alkyl groups or hydrogen atoms and R'' is a hydrogen atom or a crosslinking group.
Although these resins have a high selectivity for mercury and copper their usefulness is limited because they are water insoluble polymers. Thus while they may be used in the removal of low concentrations of copper and mercury from effluents and water, they cannot be used in the manner suggested above, i.e., as carriers of copper and mercury in biological systems.
According to one aspect of the present invention there are provided compounds of the general formula I
(I)
Figure imgf000005_0001
wherein R1 and R2 are the same or different groups and each is C1 to C6 alkyl or hydroxyalkyl;
and R3 is hydrogen, halogen, a C1 to C4 alkoxy group or a C1 to C18 alkyl group.
Preferably R 1 and R2 are the same .
When R 1 and/or R2 is hydroxyalkyl, the preferred group is the 2-hydroxyethyl group.
The specific physical properties of the chelating material (1) will vary according to the substituent R3 on the phenol ring. For example, those compounds in which R3 is a relatively long chain alkyl, such as the nonyl group, will give a more fat soluble copper chelate. Compounds in which R3 is halogen, e.g., chlorine., will give fungicidal chelates. Thus groups may be selected for R3 in order to modify properties of the compounds (or their metal complexes) such as their solubility or dispersability in water or other liquid or solid medium or their biological compatibility.
The strongest chelating structures are those with the shortest R 1 or R2 chains (e.g., R1 = R2 = methyl) and in which R3 contains less than 9 carbon atoms. The use of hydroxyalkyl substituents, such as -CH2CH2OH, for R1 and R2 confer greater water solubility on the uncomplexed chelating agent.
The compounds of this invention wherein R 1 and R2 are the same, may be produced in accordance with another aspect of the invention, by the Mannich condensation of a phenolic component (formula II) with excess formaldehyde and two moles of a piperazine component (formula III under neutral conditions.
Figure imgf000006_0001
(II) (III)
wherein R 1 (=R2) and R3 are as defined above.
More specifically, the selective copper and mercury chelating agents of formula (I) are prepared by reacting one mole of the phenol (II) with slightly over two moles of the piperazine compound (III) and about three moles of formaldehyde under neutral Mannich reaction conditions in aqueous ethanol solvent. [M. Tramontini, Synthesis, 1973, p. 703 to 775]. The mixture is heated under reflux for up to 16 hours to ensure full substitution at both ortho positions of the phenol ring. Mono-substituted compounds are formed if the amounts of the piperazine derivative or formaldehyde are insufficient or if the reaction conditions are not vigorous enough. Where substituents are not present in the para position of the starting phenol disubstituted derivatives can be formed where one of the substituted piperazine rings goes to this para position. Neither the mono-substituted derivatives (some of which have been previously synthesized, e.g., A. Bucherle, F. Ducluzeau, F. Haimovici, Chim. Ther., 2. 410 (1967): W.L. Nobles, R.F. Tietz, Y.S. Koh, J.M. Burkhalter, J. Pharm. Sci. 52, 600 (1963)) nor the ortho-para substituted derivatives have the strong selective chelating properties of the compounds of the present invention.
The compounds (I) formed in the Mannich reaction can be isolated by evaporation of the bulk of the solvent, addition of water to remove polar inpurities and extraction with water insoluble solvents such as chloroform or benzene. The compounds are generally only slightly soluble in water except where R1 and R1 =
-CH2CHOH. However, when added to an aqueous solution of copper salts at pH between about 3 and 9 they form very soluble dark green copper complexes. The equivalent mercury salt complexes are much less soluble in water and are only a pale yellow colour.
The invention also includes the copper and mercury chelate complexes of the compounds of formula I.
The invention is further described and elucidated in the following examples. These should not be construed, however, as limiting the invention in any way.
EXAMPLE- 1
This example illustrates the preparation and properties of a copper and mercury chelating agent prepared from 4-chlorophenol, 1-methylpiperazine and formaldehyde.
1-methylpiperazine (21 g, 0..21 mole) was dissolved in 150 ml of ethanol; formaldehyde solution (35 ml of 33%, 0.35 mole) was added slowly with stirring. After complete addition 4-chlorophenol (12.8 g. 0.1 mole) was added and the mixture heated at reflux for 10 hours. The ethanol solution was then evaporated down to about 60 ml and 150 ml of water and 150 ml of chloroform added. The mixture was then shaken thoroughly and the chloroform layer separated off, washed with a small amount of water and dried over sodium sulphate. On evaporation of the chloroform an almost pure sample of IA the target compound (formula I, R 1, R2 = CH3 R3 = 4-chloro) was obtained. This was further purified by chromatography on alumina in benzene to give the desired chelating agent as a low melting, pink solid soluble in hydrocarbon solvents, chloroform and ethanol but only slightly soluble in water. 'H NMR (Chloroform); δ (ppm from TMS) 2.29s (singlet,
N-CH3); δ2.52s (piperazine ring); δ3.60s (exocyclic CH2); δ7.03s (aromatic).
Compound IA formed a picrate salt, which was recrystallized from acetone as yellow needles which decomposed at about 220°C.
Analysis: Found C, 41.44; H, 3.67; N, 17.42; Cl, 3.4. C18H29N4OCl requ ires C, 41.60; H, 3.68; N, 17.52; Cl,
3.4% . EXAMPLE 2
This example illustrates the preparation and properties of a chelating agent prepared from nonylphenol, 1-methylpIperazine and formaldehyde.
1-methylpiperazine (2.1 g, 0.21 mole) was dissolved in 150 ml of ethanol; formaldehyde solution (35 ml of 33%, 0.35 mole) was added slowly with, stirring. After. complete addition commercial nonylphenol (22 g, 0.1 mole) was added and the mixture heated at reflux for 16 hours. The product IB (formula I, R 1, R2 = CH3, R3 = nonyl) was obtained by the work-up procedure of Example 1 and was a pale yellow oil soluble in hydrocarbon solvents and ethanol.
H NMR (Chloroform) ; δ0.8m (multiplet, chain CH3; δ1.2m (chain CH2); δ2.26s (N-CH3) ; δ2.48s (piperazine ring) ; δ3.60s(exocyclic CH2) ; δ6.9m (aromatic) .
EXAMPLE 3
A water soluble chelating agent was obtained by the general methods of Example 1, using 1(2'-hydroxyethyl) piperazine and p-cresol. The product IC (formula 1, R1, R2 = -CH2CH2OH, R3 = 4-CH3.) was obtained as viscous pale yellow oil.
"H NMR (Chloroform) ; δ2.28s(CH3) ; δ2.60s (piperazine ring) ; δ2.62s + m (exocyclic CH2) ; δ4.78m CH2OH) ; δ6.95s (aromatic) .
EXAMPLE 4
This example illustrates the preparation and properties of a chelating agent prepared from an alkoxy substituted phenol, 1-methylpiperazine and formaldehyde, Using the general method of Example 1, a chelating compound was formed from l-methylpiperazlne, formaldehyde and 4-methoxy phenol. It was obtained as a brown oil. Its proton NMR spectrum in chloroform [D] was δ(ppm from TMS) 2.29s (singlet N-CH3); 2.53s (piperazine ring);
3.60 (multiplet NCH2Ar); 3 . 67 (0-CH3); 6.60s (aromatic).
This compound ID (formula I, R 1, R2 = CH3, R3 =
4-OCH3) formed a tripicrate salt which was recrystallized from acetone as yellow needles with a melting point about 210°C. Its analysis was C 43.06%, H = 4.08%,
N,17.57%; calculated for tripicrate C=42.90%, H=3.99%,
N=17.58%.
EXAMPLE 5
This example illustrates the preparation and properties of copper complex of compound IA.
The chelating agent IA was dissolved in chloroform and shaken with slightly less than 1 mole % of aqueous copper sulphate solution. The water layer immediately changed from blue to dark green as the complex formed. The chloroform layer was removed and the water washed with fresh chloroform to remove any excess chelating agent. The water solution was then freeze dried to give the copper complex as a dark green hydroscopic powder. Analysis: Found C, 40.42; H, 5.84; N, 10.52; S, 6.0; Cl, 6.6. C18H29N4OCl.CuSO4. H2O requires C, 40.75; H, 5.89; N,10.56; S, 6.03; Cl, 6.68%.
EXAMPLE 6
The mercury complexes can be formed in a very similar manner but these are much less water soluble than the copper complexes. For example,, the mercury complex formed from compound IB and aqueous mercuric chloride solution is a pale yellow solid which, is slightly soluble in water and chloroform. Analysis indicates that it contains one mercury atom per unit structure.

Claims

THE CLAIMS : -1. Compounds of the general formula I
(I)
Figure imgf000012_0001
characterised In that R 1 and R2 are the same or different groups and each is C1 to C6 alkyl or hydroxyalkyl;
and R 3 is hydrogen, halogen, a C1 to C4 alkoxy group, or a C1 to C18 alkyl group.
2. A compound as claimed in Claim 1, characterised in that R 1 and R2 are the same group.
3. A compound as claimed in Claim 1 or Claim 2, cchhaarraacctteerriisseedd iinn 1that one or both of the groups R 1 and R2 is 2-hydroxyethyl,
4. A compound as claimed in Claim 1 or Claim 2 characterised in that one or both of the groups R 1 and R2 is methyl.
5. A compound as claimed in Claim 1, characterised in that R 1 and R2 are both methyl groups and R3 is
4-chloro,4-methoxy or 4-nonyl.
6. A compound as claimed in Claim 1,. characterisedin that R1and R2 are both 2-hydroxyethyl groups and R3 is 4-methyl.
7. A method for the preparation of compounds of the formula I stated in Claim 1, wherein R 1 and R2 are the same group, characterised in that a phenolic compound of the formula II is condensed with, excess formaldehyde and two moles of a piperazine compound of the formula III, under neutral, Mannich condensation conditions
Figure imgf000013_0001
(Il) (III)
wherein R 1 (=R2) and R3 are as defined in Claim 1.
8. A method as claimed in Claim 7, characterised in that one mole of the phenolic compound of formula II is reacted with slightly over two moles of the piperazine compound of formula III and about three moles of formaldehyde under neutral Mannich reaction conditions in aqueous ethanol solvent and the mixture is heated under reflux for a period sufficient to ensure full substitution at both ortho positions of the phenol ring.
9. A method for the selective chelation of copper and/or mercury ions which comprises adding to an aqueous system containing copper and/or mercury a. compound claimed in any one of Claims 1 to 6.
10. A method for the selective removal of copper and/or mercury ions from a biological system which comprises contacting the system with a medium containing a compound claimed In any one of Claims 1 to 6.
11. The copper chelate complex of any one of the compounds claimed in any one of Claims 1 to 6.
12. The mercury chelate complex of any one of the compounds claimed in any one of Claims 1 to 6.
13. A method for the selective addition of copper and/or mercury ions to a biological system which comprises contacting the system with a copper and/or mercury chelate complex as claimed in Claim11 or Claim 12.
PCT/AU1980/000071 1979-09-27 1980-09-26 Selective metal chelating compounds WO1981000848A1 (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB787008A (en) * 1955-07-13 1957-11-27 Hoffmann La Roche Novel bis(piperidinomethyl)-phenols and a process for the manufacture of same
AU285631B2 (en) * 1963-10-14 1966-04-21 Science Union Et Cie, Societe Francaise De Recherche Medicale New derivatives of dihydroxybenzoic acid and process for preparing them

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB787008A (en) * 1955-07-13 1957-11-27 Hoffmann La Roche Novel bis(piperidinomethyl)-phenols and a process for the manufacture of same
AU285631B2 (en) * 1963-10-14 1966-04-21 Science Union Et Cie, Societe Francaise De Recherche Medicale New derivatives of dihydroxybenzoic acid and process for preparing them

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