Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B13/00—Diaphragms; Spacing elements
  • C25B13/02—Diaphragms; Spacing elements characterised by shape or form
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
  • C25B1/01—Products
  • C25B1/02—Hydrogen or oxygen
  • C25B1/04—Hydrogen or oxygen by electrolysis of water
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/20—Processes
  • C25B3/23—Oxidation
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B3/00—Electrolytic production of organic compounds
  • C25B3/20—Processes
  • C25B3/29—Coupling reactions
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
  • C25B9/17—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof
  • C25B9/19—Cells comprising dimensionally-stable non-movable electrodes; Assemblies of constructional parts thereof with diaphragms
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
  • C25B9/70—Assemblies comprising two or more cells
  • C25B9/73—Assemblies comprising two or more cells of the filter-press type
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/30—Hydrogen technology
  • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P30/00—Technologies relating to oil refining and petrochemical industry
  • Y02P30/20—Technologies relating to oil refining and petrochemical industry using bio-feedstock

Definitions

• the present disclosure relates to a method of producing hydrocarbon materials such as diols. More specifically, the present disclosure provides an electrochemical decarboxylation process whereby diols, or other similar chemicals, may be formed.
• dienes such as, for example, 1 , 3- butadiene.
• Butadiene has a structure CH 2 CHCHCH 2 .
• Dienes have two double bonds in the molecule.
• diene monomers are produced by one of the four conventional methods; 1 ) by catalytic dehydrogenation of concentrate n-butylenes, 2) by catalytic dehydrogenation of n-butane, 3) as a by-product in low yields from severe high-temperature cracking of liquid hydrocarbons, and 4) from alcohols and/or diols by a combination of catalytic dehydrogenation and/or hydration.
• 3,992,471 describes the production of dienes and is incorporated herein by reference.
• One of the most widely used methods to produce dienes is the dehydration of the corresponding diol, for example 1 ,3-butadiene is obtained from the dehydration of either 1 ,4-butanediol or 2,3-butanediol.
• diol molecules are conventionally obtained using the Reppe reaction, hydrolysis of halogenated compounds, or the hydrogenation of anhydrides. All of these conventional pathways involve multiple processes which require high temperature catalytic reactions using petroleum based feedstock.
• the present embodiments relate to methods to synthesize hydrocarbons such as, for example, hydrocarbons that have at least two oxygen containing functional groups. These methods may produce such hydrocarbons from inexpensive bio-generated precursors using an electrochemical decarboxylation process.
• the decarboxylation process converts alkali salts of carboxylic acids to hydrocarbon compounds which have two or more oxygen containing substituents.
• the decarboxylation process is used to produce diols which can then be dehydrated to form dienes.
• One benefit of this process is that the final structure of the diene can be tuned by the choice of the carboxylic acid used as the precursor.
• carboxylic acids available from both natural and synthetic sources (including biomass), which allows the structure and functional group of the diene to be tailored for specific properties and functionalities.
• the diene that is produced can then be used in a variety of different applications.
• the diene may be used as a starting material for the production of synthetic rubber. The ability to control the structure and functional groups in the diene allows the rubber to be designed and tailored, as desired.
• the present embodiments provide a synthetic methodology to produce custom organic molecules from various feedstocks (including renewable bio-generated feedstocks).
• the present embodiments may operate to produce dienes from renewable feedstocks (biomass) instead of currently used petroleum based feedstocks.
• diols The production of diols is used herein as an example to demonstrate the present processes for producing hydrocarbons or other organic molecules with multiple functional groups. Conversion of the diols to dienes may produce dienes in which the double bonds are located at the terminal positions of the carbon chain. Some non-limiting examples are; 1 ,3-butadiene, 1 ,4-pentadiene, isoprene, and 1 ,5- hexadiene. Such monomers can then be used to make a variety of polymer products including acrylonitrile butadiene styrene (ABS).
• ABS acrylonitrile butadiene styrene
• the present processes may involve four (4) processing steps. These steps include: 1 ) fermentation to produce carboxylic acids from biomass, 2) saponification of the carboxylic acids to form alkali metal carboxylate salts, 3) decarboxylation of the alkali carboxylates forming diols, and 4) dehydration of the diols to form the desired diene monomer.
• the fermentation of biomass to produce carboxylic acids is a well-known and studied process that is used to produce starting materials for a variety of bio- generated products.
• the fermentation is performed on a slurry of the biomass, using specific bacteria chosen for the production of the desired carboxylic acid.
• the composition of the biomass slurry used for the fermentation depends on the feedstock and conditions that are required by the bacteria.
• carboxylic acids there are a variety of bacteria that are used in industry, permitting the carboxylic acid to be produced from a variety of biomass materials.
• lactic acid can be produced via the fermentation of glucose, molasses, corn or cheese whey.
• the pH of the resulting carboxylic stream can be low enough that the pure acid is directly obtained or it could have a pH range in which salts of the carboxylic acid are obtained.
• lactic acid is most commonly produced as calcium lactate because the low solubility allows this to be easily isolated from the fermentation bath as taught by U.S. Patent Application Publication No. 2012/0142945, which application is incorporated herein by reference.
• the calcium lactate is then acidified allowing the lactic acid to be obtained.
• the carboxylic acid may be in the acidic form and may have additional functional groups present which provide the desired functionality of the final synthesized compound.
• Lactic acid is produced commercially on hundreds of thousands metric tons annual through the fermentation of carbohydrates such as sucrose, glucose, or lactose.
• carbohydrates such as sucrose, glucose, or lactose.
• Glucose which can be converted from sucrose or directly obtained from starch is converted into two moles of lactic acid during the fermentation process.
• the fermentation of lactose, which is a dairy by-product, in the presence of water produces four moles of lactic acid.
• the saponification of carboxylic acid follows from the generally accepted procedure of reacting the carboxylic acid with an alkali metal base (MOH) at an elevated temperature.
• alkali metal bases are lithium hydroxide, sodium hydroxide, potassium hydroxide, etc.
• a generic neutralization reaction is written as follows:
• M represents an alkali metal, such as, for example sodium or lithium.
• this saponification reaction is carried out in a solvent with an alkoxide present such that the reaction forms an alkali carboxylate which precipitates out of solution.
• the alkali carboxylate salt can be easily isolated to prepare the anolyte needed for the subsequent decarboxylation step.
• the alkali carboxylate may be electrochemically decarboxylated to form a radical coupling product, because the starting carboxylate has at least one additional functional group present, the resulting coupling product will have two functional groups present, forming (for example) a diol.
• This process is performed using a two compartment electrochemical eel, which employs a ceramic membrane commercially available from Ceramatec, Inc. of Sa Lake City, Utah. Ceramatee sells this membrane under the MaSelecti) trademark.
• the electrolysis in the anotyte compartment follows the generic reaction scheme known as a modified Koibe electrolysis reaction:
• M represents an alkali metal, such as. for example sodium or lithium.
• the electrolysis in the anolyte compartment leads to products derived from a "non-Kol s electrolysis" pathway.
• a non-Koibe electrolysis is an aldehyde
• the compound obtained directly from th non-Koibe electrolysis is economically viable, as Is the case shown above in which the process produces acetoin.
• Acetoin is useful as a food additive, ⁇ In ether embodiments, the hydroxyhketone can fee reduced to a did with an additional processing step.
• the diol may then be subjected to a dehydration reaction, thereby producing water and a diene.
• the dehydration can be carried out many ways, for example in the presence of acid and a catalyst.
• Figure 1 shows a schematic drawing of method through which biomass may be converted into alkali metal salts of carboxylic acids, which in turn, may be converted into diols and further processed, if desired, into dienes;
• Figure 2 is a schematic drawing of an electrochemical cell that may be used to decarboxylate the alkali metal salt of the carboxylic acid;
• Figure 3 is a plot of the potential and current density of an electrochemical decarboxylation of sodium 3-hydroxypropionate
• Figure 4 shows a gas chromatogram of the products obtained from the electrochemical decarboxylation of sodium 3-hydroxypropionate
• Figure 5 is a plot of the potential and current density of an electrochemical decarboxylation of sodium L-lactate decarboxylation
• Figure 6 shows a gas chromatogram of the products obtained from the electrochemical decarboxylation of sodium L-lactate in methanol
• Figure 7 shows another gas chromatogram of the products obtained from the electrochemical decarboxylation of sodium L-lactate in methanol
• Figure 8 is a plot of the potential and current density of an electrochemical decarboxylation of sodium L-lactate in ethyl lactate.
• Figure 9 is a gas chromatogram of the products obtained from the electrochemical decarboxylation of sodium L-lactate in ethyl lactate.
• Bio generated or “bio-generated,” as used herein, refers to substances, either solid or fluid, which are derived from a renewable resource of biological origin.
• Hydrocarbon is defined as a compound consisting of carbon and hydrogen and can refer to saturated or unsaturated compounds.
• Die is defined as a hydrocarbon with two double bonds, these can be conjugated or non-conjugated.
• Diol is defined as a compound with two alcohol groups present.
• Carboxylic acid is a compound with the general formula RC0 2 H, where the "FT can represent saturated or unsaturated hydrocarbon chains.
• Decarboxylation refers to the process of removing C0 2 from a compound, specifically from a carboxylic acid or anion.
• Elastic as used herein, is defined as the property of a material to return to its original shape after removing an external stress that causes deformation.
• Symmetric as used herein, refers to chemical structures that have at least one mirror plan symmetry element and “non- symmetric” refers to chemical structures that do not have a mirror plan.
• Substituent and “functional group” are used interchangeably, and herein refer to an atom or group of atoms that has substituted a hydrogen atom on a carbon chain of a hydrocarbon.
• the present embodiments are generally directed to methods used to synthesize organic compounds with at least two oxygen containing functional groups, from inexpensive bio-generated precursors using an electrochemical decarboxylation process (EDP).
• EDP electrochemical decarboxylation process
• the oxygen containing organic compounds are used to produce dienes.
• Figure 1 a flow chart is illustrated which indicates how the biomass may be converted into diols, dienes and/or other useful organic molecules. More specifically, Figure 1 , shows a method by which biomass 1 may be converted into a diol 14 or diene 15. In this method, a sample of biomass 1 is obtained. Figure 1 shows a variety of different processes by which the biomass may be converted into a carboxylic acid 8. The most direct way for this conversion is through a fermentation reaction 4.
• the biomass 1 may be converted (separated) into carbohydrates 2, which may undergo hydrolysis reaction 5 to obtain the carboxylic acid 8.
• the carbohydrate 2 may undergo a conversion reaction 7 that results in the formation of a carboxylic acid 8.
• the biomass 1 may be converted (separated) into lignins, tall oil and/or resins 3. This material 3 may then undergo a conversion reaction 9 to obtain the carboxylic acid 8.
• the biomass 1 may be converted (separated) into lipids 6 which may be converted into the carboxylic acid 8, or may undergo, as needed, a conversion reaction 9 to obtain the carboxylic acid 8.
• these materials may be converted to alkali salts of carboxylic acids 10.
• These alkali salts 10 are the preferred precursor for the electrochemical decarboxylation process. This process may transform the alkali salts 10 into the diols 14. At the same time, this decarboxylation reaction may form carbon dioxide 1 1 , a hydroxyl alkalide 12 and an alkali hydroxide or an alkali methylate 13. It should be noted that once the diol 14 is obtained, it may be converted into the diene 15.
• the final structure of the oxygen functionalized organic compound is dependent on the carboxylic acid therefor dependent on the biomass used. It should be appreciated by one skill in the art that there are numerous sources of biomass and carboxylic acids derived from them, which thus, can lead to a large number of organic compounds that can be produced following the process flow given in Figure 1 .
• the dienes that are produced in the present embodiments may be dienes that can be used as monomers for the production of elastic materials.
• the large number of carboxylate substrates that can be obtained from biomass permits the monomer to be tailored in order to obtain an elastic material with the desired properties.
• Some non-limiting examples of the variances that can be tailored into the monomer are; number of carbons, degree of branching in the carbon chain, and the ability to include other functional groups.
• this invention provides a methodology to produce said monomers from a renewable feedstock instead of relying on petroleum based feedstocks.
• FIG 2 a schematic of an electrochemical cell 1 10 that may be used in the decarboxylation reaction of Figure 1 .
• the cell 1 10 comprises two separate compartments, namely an anolyte compartment 16 and a catholyte compartment 17.
• the two compartments 16, 17 may be separated by a scaffold 1 12 which houses an alkali metal ion selective membrane 18.
• the membrane may be, for example, a NaSelect® membrane from Ceramatec Inc. of Salt Lake City, Utah.
• the anolyte compartment 16 is in fluid communication with an anolyte reservoir 22.
• the anolyte reservoir houses a quantity of anolyte 1 16.
• the anolyte 1 16 may be pumped from the anolyte reservoir 22 into the anolyte compartment 16.
• the anolyte compartment 16 houses an anode 19.
• the anolyte 1 16 may comprise a solution of the alkali metal salt of the carboxylic acid 130. (As known in the art, this alkali salt RC0 2 M 130, may dissociate into its constituent ions (RC0 2 " and M + ), depending upon the particular solvent 146 that is used).
• the catholyte compartment 17 is also in fluid communication with a catholyte reservoir 21 .
• the catholyte reservoir 21 houses a quantity of catholyte 1 17.
• the catholyte 1 17 may be pumped from the catholyte reservoir 21 into the catholyte compartment 17.
• the catholyte compartment 17 houses a cathode 20.
• the catholyte 1 17 may comprise a solution of an alkali metal hydroxide 140 (MOH) or an alkali metal alkoxide 150 (MOR).
• this alkali metal hydroxide 140 may dissociate into its constituent ions (OH “ and M + ) and the alkali metal alkoxide 150 may dissociate into M + and OR " , depending upon the particular solvent 145 that is used).
• the anolyte 1 16 and the catholyte 1 17 may both comprise a solvent 145, 146, which may be the same solvent or a different solvent, depending upon the particular embodiment.
• alkali ions travel across the membrane 18 as reduction at the cathode 20 forms hydrogen 23 which evolves from the cell 1 10.
• oxidation produces radicals which form the radically-coupled product 24 as well as carbon dioxide 25.
• oxidation at surface of the anode 19 occurs causing the decarboxylation of the carboxyl functional group forming a radical and C0 2 .
• the radical then reacts directly with a second radical to form a symmetric organic molecule with at least two oxygen containing functional groups.
• the radicals combine to make a diol.
• a two electron oxidation occurs at the surface of the anode 19. This is then followed by a nucleophilic addition, making an unsymmetrical compound which has at least two oxygen containing functional groups. In one embodiment, this unsymmetrical compound can easily be converted to a diol.
• the anolyte contains multiple types of carboxylate salts, and upon oxidation the radicals form heterocoupling products. It should be noted that the heterocoupling will lead to non- symmetric compounds with oxygen containing functional groups, whereas the homocoupling leads to symmetric compounds.
• the ion conducting membrane 18 selectively transfers alkali ions (M + ), including but not limited to the ions of, sodium, lithium, and potassium, from the anolyte 1 16 to the catholyte 1 17 under the influence of an applied electrical field.
• a NaSelect® membrane 18 selectively transfers sodium ions between the anolyte 1 16 and catholyte 1 17.
• the ion conductive membrane 18 is between 10 and 5000 microns thick, or more preferably the membrane 18 is between 100 and 1000 microns thick, or even more preferably, the membrane 18 is between 200 and 700 microns thick.
• the membrane 18 is in the form of a disk with a planar configuration.
• the disk may have diameters between 0.25-25 cm.
• the disk diameter is between 1 .27-12.7 cm.
• the disk diameter is between 2.54-7.62 cm.
• the membrane 18 has a cylindrical configuration with an average diameter of the cylinder being between 0.25-25 cm.
• the diameter of the cylinder may be between 1 .27-12.7 cm.
• the diameter of the cylinder may be between 2.54-7.62 cm.
• the electrochemical cell 1 10 can be in a parallel plate configuration which uses flat membranes and electrodes, for example as shown in Figure 2.
• the electrochemical cell is in a tubular configuration which uses tubular electrodes and membranes. It should be clear to one skilled in the art that the cell configurations listed above both have advantages and disadvantages which would lead to one being chosen over the other depending on the requirements of the specific carboxylic salt being decarboxylated. It should also be clear to one skilled in the art that the process described by the present invention can be applied in a variety of cell designs.
• the anode 19 can comprise any suitable material that allows oxidation reactions to occur in the anolyte compartment 16 when an electrical potential is applied by voltage source 26 between the anode 19 and cathode 20.
• anode materials include, but are not limited to, platinum, titanium, nickel, cobalt, iron, stainless steel, lead dioxide, metal alloys, combination thereof, and other known or novel anode materials.
• the anode 19 may comprise iron-nickel alloys such as KOVAR® or INVAR®.
• the anode 19 may comprise carbon based electrodes such as boron doped diamond, glassy carbon, and synthetic carbon.
• the anode comprises a dimensionally stable anode (DSA), which may include, but is not limited to, rhenium dioxide and tantalum pentoxide on a titanium substrate.
• DSA dimensionally stable anode
• the cathode 20 may also be fabricated of any suitable cathode material that allows the reduction of water or methanol producing hydroxide or methoxide ions and hydrogen gas.
• the cathode may comprise of the materials used for the anode 19.
• the cathode 20 may be comprised of materials different from that which was used for the anode 19.
• suitable cathode materials include without limitation, nickel, stainless steel, graphite, and any other suitable cathode material that is known or novel.
• the electrodes have a smooth morphology such as a foil or thin film.
• the anode 19 and cathode 20 have a high surface area morphology, for example, but not limited to, a foam, grit, or other porous structure.
• the anode 19 and the cathode 20 have the same morphology, while in other embodiments, the electrodes may have a different morphology.
• FIG. 2 is a divided cell that comprises two distinct chambers.
• Other embodiments may be constructed in which the cell is a single-chambered cell, such that the electrolyte is fed into this chamber without an ion-selective membrane 18.
• the alkali salt 130 of the carboxylic acid may comprise one or more alcohol (OH) functional groups.
• the anolyte solution 1 16 may comprise of a polar organic solvent 146.
• suitable polar organic solvents include without limitation, methanol, ethanol, isopropanol, n-propanol, acetone, acetonitrile, dioxane, butanol, DMSO, CS 2 , diethyl carbonate, ethylene carbonate, and glycerol.
• the solvent is an ethyl ester which is formed from a carboxylic acid and ethanol, or more preferably a carboxylic acid similar in carbon number to the anion being oxidized and ethanol. Most preferably, the solvent is an ester formed from the carboxylic acid of the anion being oxidized and ethanol. An example of this type of solvent would be ethyl lactate.
• the anolyte solution 1 16 may comprise of an ionic liquid (IL).
• IL ionic liquid
• a non-limiting example is an IL with a phosphonium based cation with four substituents.
• the four substituents of the phosphonium cation are each independently an alkyl group, a cylcoalkyl group, an alkenyl group and an aryl group.
• some/all of the substituents are of a similar group.
• some/all of the substituents are the same.
• the anion of the ionic liquid is a carboxylate ion, more preferably the carboxylate ion is similar to the carboxylate anion being oxidized during the electrolysis, or most preferably the carboxylate ion is the same anion being oxidized during the electrolysis.
• Certain alkali ion conductive membranes for example NaSICON and LiSICON-type membranes, have a high temperature tolerance and thus the anolyte solution 1 16 may be heated to a higher temperature without substantially affecting the temperature of the catholyte solution 1 17 or the functionality of the membrane 18. This means molten salts or acids may be used to dissolve the carboxylate salts in the anolyte 1 16.
• the anolyte 1 16 is the molten salt of the carboxylate anion that is being oxidized.
• the anolyte solution 1 16 may optionally contain a supporting electrolyte which is soluble in the solvent and provides high electrolyte conductivity in the anolyte solution.
• a supporting electrolytes include alkali metal hydroxide, alkali metal salts, tetrafluoroborate, tetramethylammonium hexafluorophosphate, tetrabutylammonium tetrafluorobotate, tetramethylammonium perchlorate, and tetraethylammonium perchlorate. It should be appreciable to those skilled in the art that other soluble ionic compounds may be used.
• the catholyte 21 may comprise of a solvent 145 that is the same or different than the anolyte solvent 146. This is afforded because the ion conductive membrane 18 isolates the compartments from each other. Thus, the anolyte solvent 146 and the catholyte solvent 145 may be separately selected specifically for the reactions that occur in each compartment and/or the solubility of the chemicals required for the specific reactions. (A mixture of solvents may be used as the solvents 145, 146, as desired.) This permits one to design an inexpensive catholyte 1 17 which may have different properties than the anolyte 1 16, for example to have high ionic conductivity.
• the catholyte 1 17 is comprised of water and an unsaturated alkali hydroxide 140.
• the hydroxide concentration is between 0.1 -50% by weight, or more preferably between 5-25% by weight, or most preferably between 7-15% by weight.
• Another embodiment may be constructed in which the catholyte 1 17 consists of alkali methylate 150.
• the temperature of the catholyte 1 17 may or may not be the same temperature of the anolyte 1 16.
• the catholyte product stream comprises a base which may be used to neutralize the carboxylic acid to produce the alkali metal salt of the carboxylic acid 10 (as shown in Figure 1 ).
• the base consumed by the acid neutralization step may be produced in the catholyte compartment 17, recovered and re-used in future acid neutralization reactions or other chemical processes.
• oxidation occurs.
• the oxidation of a carboxylic acid or a carboxylate anion leads to decarboxylation, producing carbon dioxide and an alkyl radical.
• the radical can then combine with another radical to form alkyl-alkyl coupling products, following a modified Kolbe electrolysis process or it can react with other species present at the electrode's surface following non-Kolbe electrolysis.
• the decarboxylation leads to the formation of C0 2 and a carbocation from a two electron oxidation. Following its formation, the carbocation can then participate in nucleophilic reactions instead of coupling reactions.
• the electrolytic cell 1 10 may be operated in a continuous mode. In continuous mode, the cell 1 10 is initially filled with anolyte solution 1 16 and catholyte solution 1 17 and then, during operation, additional solution is fed into the cell 1 10, and products, by-products, and/or diluted solutions are removed from the cell 1 10 without ceasing operation of the cell.
• the electrolytic cell 1 10 is operated in batch mode. In batch mode, the anolyte solution 1 16 and catholyte solution 1 17 are fed initially into the cell 1 10 and then the cell 1 10 is operated until a desired concentration of the product is produced, then the cell 1 10 is emptied and the products are collected. The cell 1 10 is then refilled to start the process again.
• the feeding of solution may be done using a premade solution or using components that form the solution in situ. It should be noted in both continuous and batch mode, the anolyte 1 16 can be added to the solution to maintain the alkali ion concentration at a certain level.
• the anolyte solution 1 16 comprises a solvent 146, and an alkali metal salt of a carboxylic acid 130.
• carboxylic acid is dependent on the desired product and can be chosen from any class of carboxylic acids. Some non-limiting examples are fatty acids, alkyl carboxylic acids, amino acids, aryl carboxylic acids, and di- and tri- carboxylic acids.
• the carboxylic acid can also have multiple substituents present, in addition to, the carboxylic group. These additional functional groups can be located at any carbon site of the carboxylic acid, and, in some embodiments, are located in the alpha position to the carboxylate carbon. Both electron donating and withdrawing substituent can be present on the carboxylic acid.
• Some non-limiting examples of electron donating substituents are hydroxyl, amine, amide, and ether groups. Some non-limiting examples of electron withdrawing substituents are halogens, nitriles, carbonyl, nitro, and nitride groups.
• the functional group present in the alpha position to the carboxylate will determine whether the decarboxylation will follow a one electron or two electron oxidation mechanism. In one embodiment, one electron oxidation will occur, favoring radical- radical coupling because there is no substituent present in the alpha position or the substituent is an electron withdrawing group. In another embodiment, the two electron oxidation is favored, because there is an electron donating group present in the alpha position to the carboxylate group.
• the carboxylic acid may be converted into the corresponding alkali salt (RC0 2 M) via acid neutralization.
• the R group of the carboxylic acid is a hydrocarbon having a C 2 to C 2 2 hydrocarbon chain and at least one hydrogen that has been substituted for a functional group containing oxygen.
• functional groups that can be present are hydroxyl, phenyl, esters, ethers, and ketones.
• the carboxylic acid has other substituents which do not contain oxygen such as: halide, nitrile, amine, amide, and sulfide.
• the additional substituents can impart additional properties or be used to modify the elastic material after the dienes have been polymerized.
• the carboxylic acid is obtained from biomass with the additional substituent already present.
• the biomass derived carboxylic acid is first modified to include the additional functional groups.
• the alkali carboxylate is added to a suitable electrolyte which is used as the anolyte solution 1 16.
• the anolyte solution 1 16 may optionally include a supporting electrolyte if the conductivity of the alkali carboxylate is low and causes high solution resistance.
• the anolyte solution is fed either continuously or in batch mode into the electrochemical cell 1 10.
• the coupled product may be a symmetric compound containing at least two oxygen containing functional groups.
• This product can be in itself the chemical of interest, for example as a solvent, or it can be converted into a chemical of interest.
• the function groups can be converted into double bonds and the diene can be used as monomers for the production of elastic material. If the radical combines with a radical of a different carboxylate anion, then a heterocoupling product will be formed and an unsymmetrical compound will be obtained.
• Another embodiment involves decarboxylation of a carboxylate anion that has an electron donating group present in the alpha position of the carbon chain.
• the radical formed during decarboxylation may follow a different pathway and will either go through a rearrangement reaction or lose an additional electron according to the following reactions:
• [OOSSJ Ode method to promote radical-radical coupling is to perform the decarboxylation at high current densities.
• a highly conductive catholyte is used in the cathode compartment of the cell.
• Non-limiting examples of such eamoiytes are aqueous alkali h droxide and norvaqueous melhanoi/alkaji rneihoxide solutions, These solutions are reduced at the cathode leading to the formation of hydrogen gas and alkali metal hydroxides.
• the examples disclosed herein used an experimental setup which is schematically shown in Figure 2.
• the cell employed for these experiments was a micro flow cell, allowing both the anolyte and catholyte to be pumped through the cell while minimizing the distance between the electrodes and the membrane.
• the membranes used in the examples consisted of 2.54 cm diameter NaSICON disks of about 1 mm thickness which were housed on scaffolds in the center of the cells. As the scaffold and membrane physically separate the anode and cathode compartments, there was a separate reservoir and temperature controlled hotplate for the anolyte and catholyte. This allowed the chemistry and conditions of each electrolyte to be optimized for the respective electrode reactions.
• a multiple-head parasitic pump was used to pump both electrolytes into the electrolysis cell, and, depending on the temperature of the electrolytes the tubing between the cell, pump, and reservoir was insulated.
• the anolyte which contains the sodium salt of the carboxylic acid, is made by dissolving at least 10% of the salt into a polar organic solvent. This was conducted using two methods. For the first method, the sodium salt was prepared directly in the polar organic solvent by the addition of the carboxylic acid and NaOH. To ensure the complete deprotonation of the acid, the cell was operated at a pH (8- 12) indicative of excess NaOH. The second method consisted of preparing the sodium salt in a separate solution following conventional saponification reactions and then dissolving the prepared salt into a polar organic solvent. For this method, a general saponification procedure was used during which the sodium carboxylate forms as the carboxylic acid is neutralized.
• the catholyte can be made from any solution containing sodium salts, and for the examples given herein an aqueous sodium hydroxide solution was used. To obtain low solution resistance, the temperatures of the electrolytes were increased to 50 °C to improve both the solubility and conductivity.
• a power supply (BP Precision 1786B) was connected and a current density between 10 and 100 mA/cm 2 was applied.
• the voltage and current were monitored using a Data Acquisition Unit (Agilent 3490A) controlled by LabVIEW.
• the applied current density caused oxidation to occur at the anode (smooth platinum) and reduction to occur at the cathode (nickel), with each electrode having an area of 1 1 cm 2 .
• the power supply transports electrons from the anode to the cathode, a charge balance must be maintained across the cell by the diffusion of positively charge ions. Given the high selectivity of the NaSICON membrane for Na-ions, it is the only species that can provide this balance, thus a high concentration of the sodium salt was desired.
• methanol was one of the solvents used in the examples provided.
• solubility of the Na-lactate was found to be 20% after the addition of mild heat.
• a second example using ethyl lactate as the solvent is given demonstrating one of the embodiments of the present invention, and the solubility the sodium lactate in the ethyl lactate was found to be just below 20%.
• GC Gas chromatography
• the second post reaction treatment was used to remove the sodium salt from the reaction solution, via acidification with sulfuric acid.
• the addition of H 2 S0 4 acidified the carboxylate ion present and caused the Na-ions to precipitate out of the solution as Na 2 S0 4 .
• 1 -butanol was used as an internal standard to make the calibration curves.
• the electrochemical decarboxylation process disclosed in the present invention was used to convert the sodium salt of a carboxylic acid with a hydroxyl group to a diol.
• the diol produced can be used as a solvent or it can be further converted into a diene.
• the anolyte for this decarboxylation consisted of 10% by weight sodium 3-hydoxypropionate in methanol, and was prepared by dissolving the acid into methanol then adding NaOH pellets in excess. An aqueous solution containing 10% by weight sodium hydroxide was used as the catholyte.
• the electrolysis was conducted in batch mode, during which the anolyte and catholyte were cycled through the corresponding anode and cathode compartments of the cell.
• the cell was operated until enough charge passed to theoretically convert 80% of the sodium salt.
• the temperatures of the electrolytes were maintained at 50 °C, and a current density of 18.5 mA/cm 2 was employed.
• FIG. 1 contains a graph showing the potential and current density transients for the electrolysis.
• the potential started just below 8 Volts and increased to 31 Volts in 5 hours causing decarboxylation to occur.
• the potential increased from 7 Volts to 32 Volts in under 5 hours when a current density of 18 mA/cm 2 was applied.
• the conditions used in this example promoted radical-radical coupling and produced 1 ,4-butanediol according to the following reaction:
• the 1 ,4-butanediol obtained from the electrolysis of sodium 3- hydroxypropoinate has applications as a solvent or can be dehydrated to form 1 ,3- butadiene.
• the 1 ,3-butadiene is an important monomer used in the production of different types of elastic materials.
• a different carboxylic acid with a hydroxyl group was converted into a compound with multiple oxygen containing functional groups.
• the compound produced can be used as a food additive or converted into a diol, and then if desired into a diene.
• the anolyte for this decarboxylation consisted of 10% by weight sodium lactate in methanol, and was prepared by dissolving the acid into methanol then adding NaOH pellets in excess.
• An aqueous solution containing 10% by weight sodium hydroxide was used as the catholyte.
• the electrolysis was conducted in batch mode, during which the anolyte and catholyte were cycled into the corresponding anode and cathode compartments of the cell.
• the electrolysis was operated until enough charge passed to theoretically convert 80% of the sodium salt.
• the temperatures of the electrolytes were maintained at 50 °C, and a current density of 9 mA/cm 2 was employed.
• FIG. 5 contains a graph showing potential and current transients for the electrolysis.
• the potential started just below 8 Volts and increased to 31 Volts in 5 hours causing decarboxylation to occur.
• the potential decreased from 8 Volts to 7 Volts in 6 hours when a current density of 9.5 mA/cm 2 was applied.
• the conditions and the alpha-position of the hydroxyl group in the lactate anion promoted the two electron oxidation and produced acetaldehyde following the non-limiting reaction:
• the 2,3-butanediol obtained from the electrolysis of sodiumL-lactate has applications as a solvent or can be dehydrated to form 1 ,3-butadiene.
• the 1 ,3- butadiene has an application as a monomer used in the production of different types of elastic materials.
• the electrolysis was conducted in batch mode, during which the anolyte and catholyte were cycled into the corresponding anode and cathode compartments of the cell. The electrolysis was continued until enough charge passed to theoretically convert 80% of the sodium salt. During the electrolysis the temperatures of the electrolytes were maintained at 50 °C, and a current density of 9 mA/cm 2 was employed.
• the 2,3-butanediol obtained from the electrolysis of sodium L-lactate in ethyl lactate has applications as a solvent or can be dehydrated to form 1 ,3- butadiene.
• the 1 ,3-butadiene has an application as a monomer used in the production of different types of elastic materials.

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