IE47653B1 - Process for producing n-carboxyalkane-aminoalkane-diphosphonic acids,n-carboxyalkane-azacycloalkane-diphosphonic acids and n-carboxyalkane-aminoarylalkane-diphosphonic acids,and products of that process - Google Patents

Abstract

1. Process for the production of N-carboxyalkane-aminoalkane diphosphonic acids, N-carboxy-alkane-azacycloalkane-diphosphonic acids and N-carboxyalkane-aminoaryl-diphosphonic acids of the general Formula I see diagramm : EP0000930,P8,F1 wherein R**1 is a hydrogen atom, or an alkyl radical of formula -(CH2 )xCH3 with x = 0 to 10, or a hydroxy ethyl radical, or a carboxy methyl radical, or a phenyl radical, or an N,N-bis-(carboxyalkyl)-aminoalkyl radical, or a methyl- or ethyl-phosphonic acid radical, or R**1 together with R**2 is an alkylene group with 3 to 5 C-atoms and forms an azacycloalkane ring with the grouping see diagramm : EP0000930,P8,F2 R**2 is a hydrogen atom, or a methyl radical, or the same radical as R**3 , or R**2 together with R**1 is an alkylene group with 3 to 5 C-atoms and forms an azacycloalkane ring with the grouping see diagramm : EP0000930,P8,F3 R**3 is a carboxy-substituted unbranched alkyl radical with the formula (CH2 )m COOH in which m = 1 to 12, or a 2-carboxy-2,2-dimethyl ethyl radical, or a 1,2-dicarboxy-ethyl radical, characterised in that an amino alkane, azacyclo alkane or aminoaryl alkane diphosphonic acid of the general Formula II see diagramm : EP0000930,P8,F4 wherein R**1 is defined as stated in Formula I and R**4 is a hydrogen atom, or a methyl radical, or R**4 together with R**1 is an alkylene group with 3 to 5 C-atoms and forms an azacyclo alkane ring with the grouping see diagramm : EP0000930,P8,F5 is heated with a corresponding unbranched or branched halogen alkane carboxylic acid or halogen succinic acid, its alkali salts, earth alkali salts or alkali-heavy metal salts or its esters in a molar ratio of 1:1 to 1:3 in aqueous medium at a temperature between 50 and 160 degrees C and at a pH value between 4.0 and 12.0 until the reaction is concluded.

Description

This invention relates to N-carboxyalkane-aminoalkanediphosphonic acids, N-carboxyalkane-azacycloalkane-diphosphonic acids and N-carboxyalkane-aminoarylalkane-diphosphonic acids and the preparation thereof.

N-carboxymethyl-aminoalkane-diphosphonic acids and N-carboxymethyl-aminoarylalkane-diphosphonic acids are described in German Patent Specification No. 2318416, and as therein described, are obtained by reacting aminoalkane- or ami noarylalkane-diphosphonic acids in an alkaline medium with formaldehyde and an alkali metal cyanide at a temperature of from 70 to 150°C. This method has the disadvantage that great care has to be taken when working with alkali metal cyanides, in particular on a technical or industrial scale, and comprehensive safety measures are essential.

It has now been found, in accordance with the present invention, that the compounds described in German Patent Specification No. 2318416, also, new N-carboxyalkane-aminoalkane-diphosphonic acids, and N-carboxyalkane-azacycloalkane diphosphonic acids and N-carboxyalkane-aminoarylalkane-diphosphonic acids can be prepared under more favourable working conditions by reacting certain aminoalkane-, azacycloalkane- or ami noarylalkane-phosphonic acids (as hereinafter defined), with halogenated alkane monoor di-carboxylic acids at a temperature from 50 to 160°C in aqueous medium and in a molar ratio of from 1:1 to 1:3. 7653 According to the invention, therefore, there is provided a process for the production of N-carboxyalkane-aminoalkane diphosphonic acids, N-carboxyalkane-azacycloalkane-diphosphonic acids and N-carboxyalkane-aminoarylalkane-diphosphonic acids of the general Formula I P03h2 P03h2 wherein R is a hydrogen atom, or an alkyl radical of formula ~(CH2)xCH3 with x = 0 to 10, or a hydroxy ethyl radical, or a carboxy methyl radical, or a phenyl radical, or an N,N-bis-(carboxyalkyl)-aminoalkyl radical, or a methyl* or 1 2 ethyl-phosphonic acid radical, or R together with R is an alkylene group with 3 to 5 C-atoms and forms an azacycloalkane ring with the grouping PO,H, ,R I 3 2 / P03H2 IT is a hydrogen atom, or a methyl radical, or the same radical as 3 ? 1 R , or R together with R is an alkylene group with to 5 C-atoms and forms an azacycloalkane ring with the grouping PO,H, R3 I 3 2 Z C — N 1 \ PO3H2 □ R is a carboxy-substituted unbranched alkyl radical with the formula (CHgJ^COOH in which m = 1 to 12, or a 2-carboxy-2,2-dimethyl ethyl radical, or a 1,2-dicarboxy-ethyl radical, characterised in that an aminoalkane, azacycloalkane or ami noaryl alkane diphosphonic acid of the general Formula II po3h2 C —N 1 \ 4 P03H2 r II 4 wherein R is defined as stated in Formula I and R is a hydrogen atom, 1 or a methyl radical, or R together with R is an alkylene group with 3 to 5 C-atoms and forms an azacycloalkane ring with the grouping ΡΟ,Η, H I32/ - rv ρο3π2 is heated with a corresponding unbranched or branched halogen alkane carboxylic acid or halogen succinic acid, its alkali salts, earth alkali salts or alkali-heavy metal salts or its esters in a molar ratio of 1:1 to 1:3 in aqueous medium at a temperature between 50 and 160°C and at a pH value between 4.0 and 12,0 until the reaction is concluded.

Examples of compounds which may be produced in accordance with the invention include N-carboxymethane-azacycloheptane-2,2-di phosphoni c acid, N-carboxypentane-1-aminoethane-1,1-diphosphonic acid, N-carboxyethane-1-aminoethane-1,1-diphosphonic acid, N-carboxy-2,2-dimethylpropane-aminomethane diphosphonic acid, N-lO-carboxydecane-aminomethane-diphosphonic acid, Ν,Ν-bis-lO-carboxydecane-aminomethane- diphosphonic acid as well as N-(1,1-diphosphonoprop-1-yl)-DL-aminosuccinic acid.

Suitable haloqenated alkane carboxylic acids for use in the process of the invention include roonochloro- or braroacetic acid, 6-brorrohexanoic acid, 3-chloropropionic acid, 3-chloro-2,2-dimethylpropionic acid φ-chloropivalic acid), 11-bromoundecanoic acid and brcmosuccinic acid.

The process of the invention may be carried out by dissolving the aminophosphonic acid in excess aqueous alkali metal hydroxide solution and then adding the halogenated carboxylic acid in such a way that the pH of the reaction mixture does not fall below 4. A more elegant method is to use initially only so much alkali metal hydroxide as is necessary to produce the desired pH of between 4 and 12, preferably 7 to 9. The further addition of alkali metal hydroxide and halogenated carboxylic acid is then controlled depending on the pH of the reaction mixture.

In many cases the phosphonic acid and halogenated carboxylic acid are preferably suspended in water and completely or partially neutralised with alkali hydroxide. The reaction time and teraperature, utilising the heat of neutralisation produced, are 0.5 to 3 tours and 50 - lfiO°C, preferably 80 to 120°C.

In this way wholly or partially neutralised salts are obtained as reaction products, and these may be converted into the free acids by means of cation exchangers.

It is also possible to use, instead of alkali hydroxide, for example alkali carbonate or, for special purposes, alkali metal and alkaline earth metal hydroxides together, e.g.sodium and calcium hydroxides or alkali metal-heavy metal hydroxides, e.g.sodium aluminate, sodium zincate or sodium stannate. lhe products prepared are in accordance with the invention particularly suitable for use in anti-corrosion agents for products used in the treatment of process and industrial waters.

Depending on the properties or the desired application, the solutions 5 are used directly, the salts are crystallised, or, after ion exchange, the acid is obtained by methods knam per se, such as evaporation concentration or precipitation or extraction with organic solvents.

Depending on the malar ratios and amirtophosphonic acid used, mono or polycarboxylated products are obtained in the carboxylation. with a molar ratio of the reactants of 1 : 1, N-carboxyalkane-aminoalkaneaminoalkane-disphosphonic acids are preferentially obtained. A molar ratio of aminophospho.nic acid: halogenated carboxylic acid of 1 : 2 to 1 : 3 preferentially produces N,N-bis-carboxyalkane-aminoalkane-disphosphonic acids. )5 ihe compounds obtained according to the present invention can be used in all cases where a good complex-forming ability with respect to divalent and polyvalent metal ions is necessary. They are also characterised in particular by their resistance to hydrolysis at high temperatures. They can be used in all media in which the hardness constituents in water interfere, or in which it is intended to eliminate all effects of polyvalent metal ions. The treatment of hard water, textile treatment baths, paper production and tanning may in particular be mentioned in this context. In addition, these phosphonic acids are suitable for stabilising water hardness in substoichions trie amounts. They can also be used as stabilisers for dispersion and suspensions.

Since the products according to the invention have the properties of phosphonic acids and aminocarboxylic acids, they have technological advantages compared with phosphonic acids and aminocarboxylic acids above, these advantages being greater than the sum of the properties of the individual components. In order that the invention may be well understood, the following examples are given by way of illustrations IQ Example 1 6.72 Kb of 50% potassium hydroxide were placed in a vessel containing a stirrer and provided with a thermometer and reflux condenser, and 2.05 Kg of 1-aminoethane-l, 1-diphosphonic acid were added thereto so that the temperature in the bottom of the vessel did not exceed 60°C. A solution of 1.89 Kg of monochloracetic acid in 2.2 Kg of water was then added dropwise within a hour and the contents of the vessel were then heated for 3 hours at 100°C.

After salting out an aliquot part of the reaction product by means of a strongly acid cation exchanger and concentrating the solutions, N,N-bis-carboxymethane-1-aminoethane-1,l-diphosphonic acid was crystallised out with methanol/ethanol in a yield of 91.3% of theory.

The product had the following analysis: Calculated: 0:22.40% N:4.36%, P:19.29% found: 0:22.6% N:4.4% P:19.3%.

Atomic ratio: C:P:N = 5.99 : 1.98 : 1.

Example 2: g of potassium hydroxide was dissolved in 100 mg of water and 20.5 g of 1-aminoethane-1, 1-diohosphonic acid was added thereto. 13.9 q of bronoacetic acid was then introduced and the whole was boiled for 3 hours under reflux.

The reaction product was treated with an acid exchanger e.g.(Lewatit S 100) and the solution was concentrated by evaporation. A bright yellow, viscous oil was produced which was crystallised from methanol/ ethanol. 25.4 g (96.6% theoretical) of N-carboxymetbane-l-aminoethane1, T -diphosphonic acid was obtained after drying under a water jet vacuum at 80°C. Analysis: calculated: C:18.26% N:5.32%, P: 23.55% found: C:17.6% N:5.2% P:23. 3% Atomic ratio: C : P : N = 3.95 : 2.02 : 1.

Example 3; 47.8 g ofamihomethane-diphosphonic acid was dissolved in 148 g of 50% potassium hydroxide at 60°C and added to a solution of 99.4 g of potassium monochloroacetate in 250 ml of water. The mixture was then heated for 3 hours at 80 - 90°C.

After working up the reaction solution as described in Example 2, 75.2 g of Ν,Ν-bis-carboxymethane-aminomethane-disphosphonic acid was obtained.

Analysis: calculated: Cr 19.56% N: 4.56% P: 20.17% found: C: 20.3% N: 4.7% P:20.3% Atomic Ratio * C : P : N= 5.04 : 1.95 : 1.

Example 4: 95.5 ofami nomethane'-diphosphonic acid was dissolved in 224 g of 50% potassium hydroxideat 60°C, and 300 ml of water and 54.3 g of methyl chloroacetate were added thereto. After boiling for 3 hours under reflux, the reaction mixture was al laved to cool.

After working up the solution with an acid exchanger, concentration by evaporation, crystallisation and drying, 115 g of N-carboxymathane-. aminomethane-diphosphonic acid was obtained, corresponding to to a yield of 92.3% of theory.

Analysis: calculated: C: 14.47% N: 5.62%, P; 24.87% found: C: 15.1% N:5.7%, P: 25.0%.

Atomic ratio: C : P : N - 3.09 : 1.98 : 1.

Example 5 : 13.4 of phenylaminomsthane-diphosphonic acid was dissolved in a solution of 8 q of NaOH in 100 ml of water in such a way that the temperature did not rise above 60°C, and 4.8 g of rrcnochloracetic acid was then added thereto. The reaction solution was then maintained for 3 hours at 110°C, and treated with a strongly acid exchanger. g of crystalline N-darboxymethane-phenylaminomethane-diphosphonic acid was obtained with methanol from the concentrated solution.

Analysis: calculated: C: 33.23% N: 4.31% P: 19.05% found: C: 32.8% N: 4.3% P: 18.6%. 15 Atomic ratio: C : P : N = 8.9 : 1.95 : 1.

Example 6 : 54.8 g of 1-amonopropane-l, 1-diphosphonic acid were stirred into 200 ml of water and 14.6 g of basic zinc carbonate was added slowly thereto.

After the end of the evolution oE gas, 140 g of 50% potassium hydroxide was aided, the mixture was cooled at 50°C, and 47.3 g of monochloracetic acid was then added in portions.

After 2 hours boiling under reflux a clear, pale yellow solution of the potassium-zinc salt of Ν,Ν-bis-carboxyroethane-l-aminoprcpane-l, 1-diphoschonie acid was obtained. Thin layer chromatography showed a minimum conversion of 90% of theory. A part of the solution was worked up as described in the preceding examples.

Analysis: calculated: C: 25.09% N: 4.18% P: 18.48% found: C: 24.5% N: 4.2% P: 18.2% Atomic ratio: C : P : N = 6.81 : 1.96 : 1.

Example 7 : 90 g of potassium hydroxide was dissolved in 250 ml of distilled water and 103.6 q of aza-cyloheptane-2, 2-diphosphonic acid were added to this solution in such a manner that the temperature did not exceed 60°C. 38 g of monocblotacetie acid was added and then the mixture was heated for 2.5 hours at 110°C. lhe mixture was allcwed to cool and 102.5 g of N-carboxymethan^e-aza-cyclcheptane-2, 2-diphosphonic acid was then recovered from the solution by the method described in Example 1.

Analysis: calculated: C: 30.49% N: 4.44% P: 19,66% found: C:30.0% N:4.5% P:20.0% Atomic ratio: C : Ν: P = 7.8 : 1 : 2.

Example 8 : g of 1-aminoethane-1, 1-diphosphonic acid was dissolved in 187 g of 30% potassium hydroxide while stirring and 39 g of 6-bromohexanoic acid was added at 60°C. To bring the reaction to comoletion the mixture was heated slowly to 100°C and kept for 3 hours at this temperature.

After working up as described in Example 1, N-carboxvpentane-1-aminoethane-1, 1-diphosphonic acid was obtained.

A conversion of 73.4% of theory was found by determining the free amino groups by Van Slyke's method.

Example 9 : 140 q of 50% potassium hydroxide was added dropwise to a mixture of 51 g of 1-aminoethane-l, 1-diphosphonic acid, 27.2 g of 3-chloropropionic acid and 150 ml of water at 70°C within 1 hour and while stirring, and the clear solution was then boiled for 2 hours under reflux.

After working up the solution, 57.5 q of W-carboxyethane-1aminoethane-1, 1-diphosphonic acid was obtained.

Analysis: calculated: C:21.67% N: 5.05% P: 22.35% found: ' C: 20.5% Ni 4.8% P: 21.3% Atomic ratio: C : H : P = 4.98 : 1 : 2.

Example 10 : 34.6 g of 3-chloro-2, 2-dimethylpropionic acid (B-chloropivalic acid) was added while stirring to a solution of 47.8 g of aminomethanediphosphonic acid in 288 g of 30% potassium hydroxide; The solution was heated within 1 hour to boiling point and maintained for 2 hours at this temperature. After working up, N-2~carboxy-2, 2-dimethylethane aminomethane-diphosphonic acid was obtained.

A conversion of 73.5% of theory was measured by determining the primary amino groups in the solution.

Example 11 ; 54.7 g of 1-arainopropane-l, 1-diphosphonic acid were dissolved in 150 g of 40% caustic soda and 49.5 g of DL-brotnosuccinic acid was added at 60°C. The mixture was boiled for 2 hours under reflux to bring the reaction to completion. g of 1-aminopropane-l, l-diphosphonic acid and 51.4 g of N-(l,l-diphosphonoprpp-l-yl)-DL-aminosuccinic acid were detected in the solution by quantitative thin layer chranatography.

Example 12 ; 47.5 of aminomethane-diphosphonic acid was dissolved in 150 g of 50% potassium hydroxide and 88.8 g of ll-bronoundecanoic acid was added to the solution at 80°C. After boiling for 2 hours under reflux and cooling the solution, approximately 30% of aminomethanediphosnhonic acid, approximately 60% of N-10-carboxydecane-araino10 methane-diphosphonic acid and approximately 10% of N, N-bis-10-carboxydecane-aminomethane-diphosphonic acid were detected by thin layer chromatoqraphy.

Examole 13 ; 127.7 kg of 1-aminoethane-l, l-diphosphonic acid were dissolved in 292.2 kg of water and 69.8 kg of 50% potassium hydroxide in a In? volume vessel provided with a stirrer, reflux condenser, heater, incorporated pK-measuring device and two dropping funnels. The solution was heated to 80°C by utilising the heat of neutralisation and 147.7 kg of 80% monochloracetic acid solution and approximately 362 kg of 50% potassium hydroxide was added from the two funnels. The addition was regulated so that the ph of the reaction medium was between 8.0 and 8.5. The reaction mixture could be maintained at 80 to 90°C by means of the heat of reaction that was evolved.

After the end of the addition, the reaction medium was adjusted to a pH of 8.5 with potassium hydroxide and the solution was stirred for 1 hour at 90 - 100°C.

The resulting solution oontaned approximately 20% of N,N-bis5 ’ carboxymethane --1-aminoethane-1, 1-diphosphonic acid.

Example 14 : 58.7 g of 3-hydroxy-l-aminopropane-l, 1-diphosphonic acid was taken up in a solution of 84 g of KOH in 300 ml of water. The salution was heated to 60°C and 56 g of 3-chloropropionic acid was added, while stirring vigorously, so that the temperature rose slowly to 80°C.

After boiling for 3 hours under reflux, a pale yellow solution was formed. After treating the solution with a strongly acid ion exchanger, concentration by evaporation, crystallisation and drying, 81 g of slightly yellowish, hygroscopic crystals were obtained. Thin layer chromatography showed a content of approximately 20% oF N-carhoxyethane-3-hydroxy 1-amino-propane-1', 1 -diphosphonic acid and approximately 80% of N, N-bis-carboxyethane-3-hydroxy-l-aminopropane-l, 1-diphosphonic acid.

Example 15 ; 24.9 of 2- carboxy-1-aminoethane-l, 1-diphosphonic acid was dissolved in 119 ml of 30% potassium hydroxide at 50°C vii ile stirring, and 19 σ of 5-brotmvalerianic acid was added at this temperature.

The reaction mixture was boiled for 3.5 hours under reflux, cooled, 47683 the solution was treated with a cation exchanger, the acid solution was concentrated bv evaporation almost to dryness, and the product was crystallised with mixtures ofmethanol, ehtanol, and acetone.

The yield of 2- carboxy-1, l-diphoschono-ethan-5-amincpentanoic acid was 24.5 g.

Analysis: calculated: C: 27.52% N: 4.01% P: 17.74% found: C: 27.5% Ns 3.9% P: 17.8% Atomic ratio: C : P : N = 8.23 : 2.06 : 1.

Example 16 : 6.9 of 1-aminodecane -1, 1-diphosphonic acid was dissolved in q of 10% potassium hydroxide, 2,5 a of 3-chloro-2, 2-dimethylprapionic acid was added at 60^C, and the reaction mixture was boiled for 3 hours under reflux. After treatinq the reaction solution with an acid cation exchanger, filtering, anc concentrating the acid solution by evaporation, 6 g of N-2-carboxy-2, 2-dimethylethane-l- ami nodecane 1-diphosphonic acid was obtained by crystallisation with methanol and water.

Analysis: calculated: C: 45.84% N: 3.14% P: 13.91% found: C: 47.8% N: 3.2% P: 14.4% Atomic- ratio: C : P : N = 17.43 : 2.03 : 1.

Claims (16)

1. Process for the production of N-carboxyalkane-aminoalkane diphosphoni c aci ds, N-carboxyalkahe-azacycloalkane-di phosphoni c acids and N-carboxyalkane-aminoarylalkane-diphosphonic acids S of the general Formula I P0 3 H 2 R — C-N P0 3 H 2 IS wherein R^ is a hydrogen atom, or an alkyl radical of formula -(CH 2 ) x CH 3 with x = 0 to 10, or a hydroxy ethyl radical, or a carboxy methyl radical, or a phenyl radical, or an N,N-bis-(carboxyalkyl)-aminoalkyl radical, or a methyl- or ethyl1 2 phosphonic acid radical, or R together with R is an alkylene group with 3 to 5 C-atoms and forms an azacycloalkane ring with the grouping P0 3 H 2 P0 3 H 2 R is a hydrogen atom, or a methyl radical, or the same radical as ο 2 1 R , or R together with R is an alkylene group with 3 to 5 C-atoms and forms an azacycloalkane ring with the grouping ΡΟ,Η, R ' 32 / po 3 h 2 R is a carboxy-substituted unbranched alkyl radical with the formula (CH 2 ) m C00H in which m = 1 to 12, or a 2-carboxy2,2-dimethyl ethyl radical, ora 1,2-di carboxy-ethyl radical, 5 characterised in that an aminoalkane, azacycloalkane or ami noaryl alkane diphosphonic acid of the general Formula II R 1 - C - N I \ 11 po 3 h 2 R 4 1 τ 4 wherein R is defined as stated in Formula I and R is a hydrogen atom, or a methyl radical, or R4 together with 10 R^ is an alkylene group with 3 to 5 C-atoms and forms an azacyclo alkane ring with the grouping ?°3 H 2 po 3 h 2 is heated with the corresponding unbranched or branched halogen alkane carboxylic acid or halogen succinic acid, its alkali salts, earth alkali salts or alkali-heavy metal salts or its esters in a molar ratio of 1:1 to 1:3 in aqueous medium at a temperature between 50 and 160°C and at a pH value between 4.0 and 12.0 until the reaction is concluded.

2. Process according to Claim 1, characterised in that the 5 pH value is kept between 7.0 ana 9.0 durinq the reaction.

3. Process according to Claim 1, characterised in that the reaction is carried out in a temperature range of 60 to 110°C.

4. An N-carboxyalkane-aminoalkane-diphosphonic acid of the general Formula I P°3 H 2 -/ \ po 3 h 2 r 12 3 in which the radicals R , R and R are as defined in Claim 1, characterised in that it is produced by a process according to any one of Claims 1 to 3.

5. Compounds according to Claim 4, wherein R^ together with 2 R is an alkylene group with 5 C-atoms and forms an azacycloheptane ring with the grouping PO 3 H 2 r 3 1 / — C — N I \ P0 3 H 2 R is a carboxy methyl group and thus the compound is N-carboxymethane-azacycloheptane-2,2-diphosphonic acid.

6. Compound according to Claim 4, wherein fU is a methyl radical, R^ is a hydrogen atom, R 1 is a carboxy pentyl radical and thus the compound is N-carboxypentane-1-ami noethane-1,1-diphosphonic acid.

7. Compound according to Claim 4, wherein pJ is a hydrogen 2 1 5 atom, R is a hydrogen atom, R is a 2-carboxy-2,2-dimethyl ethyl radical and thus the compound is N-(2-carboxy-2,2-dimethylethane) aminomethane-diphosphonic acid.

8. Compound according to Claim 4, wherein R^ is an ethyl radical, 2 3 R is a hydrogen atom, R is a group with the formula --CH -COOH I 10 CH Z —COOH and thus the compound is N-(l,1-diphosphonoprop-l-yl)-0,L-aminosuccinic acid.

9. Compound according to Claim 4, wherein R^ is a hydrogen atom, R? and R^ are carboxydecyl groups and thus the compound is 15 N,N-bis~(10-carboxydecane)-aminomethane-diphosphonic acid.

10. Compound according to Claim 4, wherein r’ is a carboxy 2 3 methyl group, R is a hydrogen atom, R is a pentane carboxylic acid radical and thus the compound is 2-carboxy-l,1-diphosphonoethane-1-aminopentane carboxylic acid. 20

11. Compound according to Claim 4, wherein R^ is an undecyl radical, R^ is a hydrogen atom, R^ is a 2-carboxy-2,2-dimethyl ethyl group and thus the compound is N-(2-carboxy-2,2-dimethylethane) -1-aminododecane-l,1-diphosphonic acid.

12. Compound according to Claim 4, wherein R 1 is a hydroxyethyl 2 Ί radical, R is a carboxyethyl group, R is likewise a carboxyethyl group and thus the compound is N,N-bis-(carboxyethane)-3-hydroxy-laminopropane-1,1-diphosphonic acid.

13. Use of the compounds according to Claim 4 in stoichiometric or sub-stoichiometric quantities for the treatment of aqueous systems.

14. A process for the production of compounds defined in Claim 1, substantially as described herein with reference to the Examples.

15. A compound as defined in Claim 4, substantially as described herein with reference to the Examples.

16. A product of general formula I which has been produced by a process according to any one of Claims 1 to 3 or 14.