# US 5,703,259 A · Method for the preparation of pure carboxyethyl germanium sesquioxide

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- Number: US 5,703,259 A
- Document ID: US5703259A
- Status: Granted
- Kind: A
- Application number: 08/577,307
- Filed: 1995-12-22
- Granted: 1997-12-30
- Earliest claimed: 1994-03-02
- Inventors: Michael J. Arnold
- Web page: https://patentgrep.com/patent/US5703259A

## CPC

- C07F 7/30: Germanium compounds
- C07F: ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM (metal-containing porphyrins C07D487/22)

## Abstract

A synthetic method for generating pure carboxyethyl germanium sesquioxide in the absence of toxic impurities. In the method germanium dioxide and metallic germanium are not used as starting materials. The method involves steps which ensure (a) absence of any residual germanium tetrachloride to ensure none is available to form germanium dioxide, (b) removal of any germanium dioxide, (c) removal of any germanium tetrachloride later produced from any germanium dioxide and (d) final removal of any germanium dioxide. In an alternative method, intermediate TPA is prepared by direct precipitation from a concentrated solution with a halogenated solvent preferably dichloromethane when poured into a non-polar alkyl solvent preferably hexane at ambient temperature and then converted to carboxyethyl germanium sesquioxide.

## Claims

### Claim 1

A method of preparing organic germanium in the absence of any toxic level of germanium dioxide or metallic germanium composing;
preparing TPA as a crude reaction product from germanium tetrachloride including a step of solvent extraction using a halogenated solvent;
removing all but a minor amount of the original amount of halogenated solvent leaving a concentrated mixture of the TPA in mixture with a remaining minor amount of halogenated solvent;
mixing said concentrated mixture with an excess amount of a non-polar alkyl solvent at ambient temperature to form high purity crystals of TPA;
isolating the high purity crystals of TPA from the non-polar alkyl solvent;
converting the high purity crystals of TPA to carboxyethyl germanium sesquioxide.

### Claim 2 (depends on 1)

The method of claim 1 wherein said halogenated solvent is between about 3% to 60% of said concentrated mixture.

### Claim 3 (depends on 1)

The method of claim 1 wherein said halogenated solvent is between about 5% to 55% of said concentrated mixture.

### Claim 4 (depends on 1)

The method of claim 1 wherein said halogenated solvent is between about 10% to 50% of said concentrated mixture.

### Claim 5 (depends on 1)

The method of claim 1 wherein said halogenated solvent is dichloromethane.

### Claim 6 (depends on 5)

The method of claim 5 wherein said dichloromethane is between about 3% to 60% of said concentrated mixture.

### Claim 7 (depends on 5)

The method of claim 5 wherein said dichloromethane is between about 5% to 55% of said concentrated mixture.

### Claim 8 (depends on 5)

The method of claim 5 wherein said dichloromethane is between about 10% to 50% of said concentrated mixture.

### Claim 9 (depends on 1)

The method of claim 1 wherein said non-polar alkyl solvent is hexane.

### Claim 10 (depends on 9)

The method of claim 9 wherein said halogenated solvent is dichloromethane.

### Claim 11 (depends on 1)

The method of claim 1 wherein said isolating step comprises;
hydrolyzing the high purity crystals of TPA in ammonium hydroxide and;
reacting the halogenated TPA with sulfuric acid to yield carboxyethyl germanium sesquioxide.