Sodium Electrode
A room temperature method and electrode for producing sodium metal in situ is disclosed. The electrode has a sodium hydroxide, or another easily electrolyzible sodium containing material, solution on the anode side, a membrane which permits sodium ions to pass through to the cathode where the sodium ions are reduced to sodium metal. This sodium metal is then available to react with other components of the solution on the cathode side.
The present application claims benefit from earlier filed U.S. Provisional Application No. 61/793,897, filed Mar. 15, 2013, which is incorporated by reference in its entirety for all purposes.
BACKGROUND1. Field of the Invention
The present disclosure is directed to a method and an electrode for the electrochemical production of sodium at room temperature conditions.
2. Discussion of the Related Art
The production of sodium today is generally a byproduct of 0.2 production using the well-know “Downs' cell” process which involves the electrolysis of molten NaCl or a mixture of NaCl and CaCl2 heated to at least 580 C.
Sodium is also used in many basic methods for drying and purifying chemical solvents. Sonic other methods include distillation over molecular sieves, distillation over inorganic salts and distillation over sodium, potassium or an amalgam of both.
In this last process, it should be noted that the sodium does not melt at the boiling point of many solvents, and thus, potassium is used to reduce the melting point of the amalgam. Although sodium reacts violently with water, the exothermic reaction does not produce enough energy to auto-ignite any hydrogen present.
So clearly, a critical downside to the use of potassium is that the exothermic reaction of water and potassium produce enough energy to auto-ignite the resulting hydrogen if in the presence of oxygen. And, the presence of a flammable organic solvent poses an additional safety hazard. This has been the cause of many laboratory accidents, which compels scientists to consider safer options. Another consideration of academic scientists is cost. Sodium and potassium compose the primary material costs, while electricity is part of the general overhead.
For solvent purification, a small quantity of benzophenone is used. The benzophenone radical is created by the reduction of the benzophenone, and is an effective scavenger for water, oxygen, peroxides, and other contaminants. It is also an indicator of the purity of the solvent. At the point when the concentration of the radical becomes stable in solution (the concentration of impurities has been reduced to ppm levels), the solution takes on the deep blue-to-purple color of the radical, see reaction I below.
C6H5C=OC6H5+Na→Na+C6H5C=OC6H5− I
A method to safely and reliably introduce alkali metal, particularly sodium metal, into various reaction schemes and/or solvent purification schemes is of interest.
The presently disclosed electrochemical process utilizing a sodium selective membrane and electrode can be utilized in numerous applications and uses where sodium is produced, oxidized or exchanged as an ion.
The present application is directed to an electrode made up of a glass tube having an alkali metal-containing solution contained therein, a ceramic membrane located at one end of the glass tube as an interface between the alkali metal-containing solution and the outside solution, an anode located inside the glass tube and immersed in the alkali metal-containing solution, and a cathode located. outside the glass tube and immersed in the outside solution and electrically connected to the anode, wherein the ceramic membrane is permeable to alkali metal ions.
Also taught by the present disclosure is an electrochemical process carried out by providing an electrode comprising a glass tube having an alkali metal-containing solution contained therein, a ceramic membrane located at one end of the glass tube as an interface between the alkali metal-containing solution and the outside. solution, an anode located inside the glass tube and immersed in the alkali metal-containing solution, a power source connected to the anode and cathode, and a cathode located outside the glass tube and immersed in the outside solution and electrically connected to the anode, decomposing the alkali metal in the alkali metal-containing solution to form alkali metal ions, passing the alkali metal ions through the ceramic membrane to the outside solution, reducing the alkali metal ions to alkali metal at the cathode, and reacting the alkali metal with a reactant in the outside solution.
The accompanying drawing, which is included to provide a further understanding of the invention and is incorporated in and constitute a part of this specification, illustrates preferred embodiments of the invention and together with the detailed description serve to explain the principles of the invention. In the drawing:
According to the present disclosure, a room temperature method and electrode for producing sodium metal in situ is disclosed. The electrode has a sodium hydroxide (or another easily electrolyzible sodium containing material) solution on the anode side, a membrane which permits sodium ions to pass through to the cathode where the sodium ions are reduced to sodium metal. This sodium metal is then available to react with other components of the solution on the cathode side.
The present application is directed to an electrode made up of a glass tube having an alkali metal-containing solution contained therein, a ceramic membrane located at one end of the glass tube as an interface between the alkali metal-containing solution and the outside solution, an anode located inside the glass tube and immersed in the alkali metal-containing solution, and a cathode located outside the glass tube and immersed in the outside solution and electrically connected to the anode, wherein the ceramic membrane is permeable to alkali metal ions.
In some embodiments of the present disclosure, the alkali metal can be sodium. Additionally, the alkali metal-containing solution can be a solution containing an electrolyzible alkali metal containing compound. That electrolyzible alkali metal containing compound can be an alkali metal with at least one member selected from the group consisting of chloride, hydroxide, methoxide, alkoxide, tetrafluoroborate, and hexafluorophosphate.
The presently disclosed electrode further includes a power source connected to the anode and cathode. The outside solution can be, among other things, a solvent or reactant containing solution.
As illustrated in
Also taught by the present disclosure is an electrochemical process carried out by providing an electrode comprising a glass tube having an alkali metal-containing solution contained therein, a ceramic membrane located at one end of the glass tube as an interface between the alkali metal-containing solution and the outside solution, an anode located inside the glass tube and immersed in the alkali metal-containing solution, a power source connected to the anode and cathode, and a cathode located outside the glass tube and immersed in the outside solution and electrically connected to the anode, decomposing the alkali metal in the alkali metal-containing solution to form alkali metal ions, passing the alkali metal ions through the ceramic membrane to the outside solution, reducing the alkali metal ions to alkali metal at the cathode, and reacting the alkali metal with a reactant in the outside solution.
This disclosed electrochemical process can have reactants in the outside solution that include at least one member selected from the group consisting of alcohols, surfactants, fats, acids, amines, oxides, alkoxides, aryloxides, phenoxides, and halocarbons. Various of these reactants are set forth in more detail below.
The electrochemical process of the present application can further include the step of isolating the product formed by the step of reacting the alkali metal with a reactant in the outside solution. In most case, that reactant would be reducible by the alkali metal.
For some embodiments of the electrochemical process, the outside solution can be a biological system, or can be a solution that will subsequently be introduced into a biological system.
As disclosed herein, the electrochemical process can be conducted with sodium as the alkali metal, and, in some of the same or different embodiments of the electrochemical process the process can be conducted at room temperature.
From large scale use to very small, it would not be difficult to imagine the use of this process even in a biological system. One application could be based on the human body: the human brain produces 10 W of power most of which is used to transfer sodium ions, and this is possible in part due to the differences in the hydration-energy of different ions. For example the sodium ion requires 80 kJ/mol more energy than potassium to release all of the hydrated water. Given that the membrane properties do not allow water to transfer, this electrochemical system could be used in some form of a dialysis process to regulate sodium content in certain patients. Although several drugs can be found that enable the body to transfer specific ions across cell membranes and are used in “shock” cases were this transfer is not functioning properly, the potential for further applications is great.
One example of the presently disclosed process is the conversion of benzophenone to the sodium radical at the cathode of the disclosed electrode. This would be accomplished using a sodium hydroxide solution (or other economically electrolyzible material) on the anode side. If the overpotential is initially too high a small amount of a soluble sodium salt such as sodium tetrafluorohorate or hexatluorophosphate can be added to the outside solution. As long as both sides are not sealed, oxygen and hydrogen production would not yield an additional safety hazard.
The reduction of organic compounds by sodium metal includes the following typical example, the reaction of sodium metal for sodium hydride) with an alcohol.
1. 2R−OH+2Na→2RO−Na++H2
Sodium ethoxide, sodium methoxide, sodium propoxide, sodium tea-butoxide are among some of the most commonly made and used alkylates. These are used in a wide range of organic synthesis; agrochemicals; pharmaceuticals; colorants and aromas, detergents, and catalysis.
In order to eliminate the use of sodium metal for the production of sodium methylate, some producers have developed an electrochemical process using NaCl and methanol. Their process leads to the organic transfer from a sodium salt to another species with an anionic leaving group. As mentioned above the sodium alkylates are good examples of the reaction types involving substitution and/or elimination reactions:
or where substitution cannot take place:
Along these same lines, use of the Williamson synthesis would produce unsymmetrical ethers. Aryl alcohols are also frequently used in organic synthesis, so sodium phenoxide, and other derivative ring systems should be of interest, as reactants in the outside solution of the presently disclosed electrode.
Another interest for the pharmaceutical industry is the form of the final products. At times drugs are converted to a salt form in order to improve solubility and transfer within the body, for instance, naproxen sodium.
Many processes which use sodium as a metal or a counter-ion are derived from the fact that sodium is a good reducing agent but at times too reactive and non-selective. There are a few cases where more than one site on a molecule needs to be reduced. In these cases the reaction is usually run very slowly by addition of very small pieces of sodium.
Other forms of sodium are often used to reduce the rate of reactivity and to increase specificity. Examples include sodium/mercury amalgam, sodium/lead amalgam, and sodium borohydride.
The use of elemental metal and these other reducing agent examples could be replaced entirely by this system as one could set the current flow and effectively produce one atom of sodium at a time. Additionally production of extremely reactive species such as NaH or methyl sodium, which is not produced commercially due to its reactivity and shelf life could be made in situ as a short-lived intermediate during a process. A few examples of in situ production include NaH, NaCH3, or strong bases like sodium amide.
Another potential in situ process could involve the separation of enantiomerically pure materials by crystallization. One common counter ion for these separations is sodium d-tartrate. As chiral drugs are becoming more important in the pharmaceutical industry, producing the salt in situ could give better separation or a greater differential crystallization rate.
The presently disclosed method and electrode could also be used to produce many sodium oxidants, in situ or otherwise, for instance, sodium superoxide, which is used in the inorganic analysis and metal ore isolation.
Some additional sodium-containing compounds that could be produced using the presently disclosed method and electrode include dyes, anionic phase-transfer catalysts, and the components needed for two phase analysis of surfactants.
In some embodiments of the presently disclosed method, the process could be used to produce bromine and chlorine.
In yet further embodiments, the method is utilized in the saponification step in the synthesis of soaps and surfactants, as set forth schematically below.
More examples of application of the presently disclosed subject matter are to the production of non-aqueous surfactants and detergents for use in soaps, detergents, lubricating oils, and other technologies. Sodium alkylbenzene sulfonate, sodium alkyl sulfonate and sodium alkyl ethoxylates are just a few examples of compounds that can be produced using the presently disclosed subject matter.
It is known to use NaOH for the removal of naphthalic acid from jet fuel, and it should only be mentioned briefly that the existence of these types of long chain and cyclic acids are also found in many other fuels, and are usually addressed by the addition of detergents to the affected fuels. Removal of these acids by conversion to the sodium salt and subsequent filtration at the refinery could lead to reduced fuel additives.
Two final areas to which the presently disclosed method and electrode can be applied include glass manufacturing where the need to control sodium content can be critical, and also electroplating.
All publications, articles, papers, patents, patent publications, and other references cited, herein are hereby incorporated by reference herein in their entireties for all purposes.
Although the foregoing description is directed to the preferred embodiments of the present teachings, it is noted that other variations and modifications will be apparent to those skilled in the art, and which may be made without departing from the spirit or scope of the present teachings.
The foregoing detailed description of the various embodiments of the present teachings has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the present teachings to the precise embodiments disclosed. Many modifications and variations will be apparent to practitioners skilled in this art. The embodiments were chosen and described in order to best explain the principles of the present teachings and their practical application, thereby enabling others skilled in the art to understand the present teachings for various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope Of the present teachings be defined by the following claims and their equivalents.
Claims
1. An electrode comprising
- a glass tube having an alkali metal-containing solution contained therein,
- a ceramic membrane located at one end of the glass tube as an interface between the alkali metal-containing solution and the outside solution,
- an anode located inside the glass tube and immersed in the alkali metal-containing solution, and
- a cathode located outside the glass tube and immersed in the outside solution and electrically connected to the anode,
- wherein the ceramic membrane is permeable to alkali metal ions.
2. The electrode according to claim 1, wherein the alkali metal comprises sodium.
3. The electrode according to claim 1, wherein the alkali metal-containing solution comprises a solution containing an electrolyzible alkali metal containing compound.
4. The electrode according to claim 3, wherein the electrolyzible alkali metal containing compound comprises an alkali metal with at least one member selected from the group consisting of chloride, hydroxide, methoxide, alkoxide, tetrafluoroborate, and hexafluorophosphate.
5. The electrode according to claim 1, further comprising a power source connected to the anode and cathode.
6. The electrode according to claim 1, wherein the outside solution comprising a solvent or reactant containing solution.
7. An electrochemical process comprising
- providing an electrode comprising a glass tube having an alkali metal-containing solution contained therein, a ceramic membrane located at one end of the glass tube as an interface between the alkali metal-containing solution and the outside solution, an anode located inside the glass tube and immersed in the alkali metal-containing solution, a power source connected to the anode and cathode, and a cathode located outside the glass tube and immersed in the outside solution and electrically connected to the anode,
- decomposing the alkali metal in the alkali metal-containing solution to form alkali metal ions,
- passing the alkali metal ions through the ceramic membrane to the outside solution,
- reducing the alkali metal ions to alkali metal at the cathode, and
- reacting the alkali metal with a reactant in the outside solution.
8. The electrochemical process according to claim 7, wherein the reactant comprise at least one member selected from the group consisting of alcohols, surfactants, fats, acids, amines, oxides, alkoxides, aryloxides, phenoxides, and halocarbons.
9. The electrochemical process according to claim 7, further comprising isolating the product formed by the step of reacting the alkali metal with a reactant in the outside solution.
10. The electrochemical process according to claim 7, wherein the outside solution comprises a biological system.
11. The electrochemical process according to claim 7, wherein the outside solution comprises a reactant reducible by the alkali metal.
12. The electrochemical process according to claim 7, wherein the alkali metal comprises sodium.
13. The electrochemical process according to claim 7, wherein the process is conducted at room temperature.
14. An electrochemical process comprising
- providing an electrode comprising a glass tube having a sodium metal-containing solution contained therein, a ceramic membrane located at one end of the glass tube as an interface between the sodium metal-containing solution and the outside solution, an anode located inside the glass tube and immersed in the sodium metal-containing solution, a power source connected to the anode and cathode, and a cathode located outside the glass tube and immersed in the outside solution and electrically connected to the anode,
- decomposing the sodium metal in the sodium metal-containing solution to form sodium ions,
- passing the sodium ions through the ceramic membrane to the outside solution,
- reducing the sodium ions to sodium metal at the cathode, and
- reacting the sodium metal with a reactant in the outside solution.
Type: Application
Filed: Mar 18, 2014
Publication Date: Sep 25, 2014
Inventor: Dru L. DeLaet (St. Louis, MO)
Application Number: 14/218,863
International Classification: C25C 7/02 (20060101); C25C 1/22 (20060101);
