Dechlorinating chlorinated organic compounds

Abstract

The present invention relates to a method for dechlorinating chlorinated organic compounds in an electrochemical device comprising an undivided electrolytic cell with two electrodes acting as anode and cathode, by a) providing a composition comprising the chlorinated organic compounds, a solvent and a sacrificial electron donor, wherein the solvent can also function as the sacrificial electron donor, or alternatively, the solvent and the sacrificial electron donor are two separate components, and b) conducting an electrochemical reaction to dechlorinate the chlorinated organic compounds, characterized by alternating the polarity of the two electrodes, with both electrodes being graphite electrodes.

Description

[0001] Dechlorinating chlorinated organic compounds

[0002] The present invention relates to a method for dechlorinating chlorinated organic compounds in an electrochemical device.

[0003] Persistent Organic Pollutants (POPs) are man-made organic compounds noted for their durability in the environment and their capacity to harm ecosystems and human health. Their persistence is due to robust carbon-halogen bonds that degrade very slowly through chemical, biological, or photolytic processes, allowing these substances to build up in the environment, including soil, water, and air.

[0004] In the 20th century, POPs were massively produced for uses such as pesticides and flame retardants. As their harmful effects became known post-World War II, their manufacture was gradually reduced and largely ceased by the early 2000s in industrialized nations. Despite this, untreated POP-contaminated soils and wastes have remained, leading to further environmental contamination.

[0005] Hydrophobic by nature, POPs tend to accumulate in fatty tissues, notably within the human food chain. In areas with extensive POP use, such as Southern Spain, a majority of the population still shows detectable levels of these compounds, years after their ban. For instance, 99% of young men in that region had di chi orodiphenyltri chloroethane (DDT) and its metabolites in their blood. Similar high levels were observed for other POPs like hexachlorocyclohexanes (HCH) and dimethoxydiphenyltrichloroethane (Methoxychlor), both known carcinogens and endocrine disruptors, highlighting the urgent need for effective degradation methods.

[0006] The global urgency to address POPs resulted in the 2001 Stockholm Convention on Persistent Organic Pollutants, which now includes 186 parties. The convention mandates the ban of POP production and use, the identification of stockpiles, and the requirement that wastes be disposed of in a manner that destroys their persistent organic pollutant content. Despite these measures, scalable, efficient, and sustainable methods to remediate POPs are largely absent. The long-term inaction has often worsened situations, as seen in the Netherlands, where improper disposal of HCH waste led to widespread soil contamination, dramatically increasing clean-up costs. Presently, containment is the primary method for managing POP stockpiles. High-temperature incineration, although effective, is costly and limited in availability, while lower-temperature combustion can create dangerously toxic by-products.

[0007] EP0027745 outlines a method for the electrochemical breakdown of one or more persistent harmful or potentially hazardous organic compounds. The technique involves anodic oxidation or cathodic reduction of the organic compound in an aqueous solution where the compound is at least partially dissolvable.

[0008] US4344829 details a procedure for reclaiming benzene and chlorine from hexachlorocyclohexanes. This is achieved by reacting the waste isomers from the production of lindane with zinc, followed by electrolysis of the resultant zinc chloride. The process is carried out in the cathode compartment of an electrolytic cell, which is separated by a diaphragm, with zinc being generated in situ at the cathode.

[0009] US4702804 presents a method for the electrochemical destruction of halogenated organic compounds, reducing their levels to below 1 ppm. This is accomplished using carbonaceous cathodes primarily composed of amorphous carbon that is sufficiently graphitized to accelerate the reaction rate while maintaining significant resistance to electrochemical corrosion.

[0010] DE4407057 introduces a redox process for degrading halogenated hydrocarbons in contaminated water.

[0011] CN101810921 explains a method for the electrochemical reduction degradation of organochlorides, specifically DDT. The process employs a platinum mesh as the working and auxiliary electrodes, a saturated calomel reference electrode, a porphyrin metal compound as a catalyst, tetrabutylammonium perchlorate (TBAP) as the supporting electrolyte, and N, N-dimethylformamide (DMF) as the solvent. Under controlled voltage and time conditions, this method efficiently decomposes DDT.

[0012] Kulikov et al, “Electrochemical reductive dechlorination of chlororganic compounds on carbon cloth and metal -modified carbon cloth cathodes, Electrochimica Acta, Vol, 41, No. 4, pp. 527-531, 1996, describe a study of electrochemical reductive dehalogenation of chlorinated organic compounds in both organic and aqueous solutions. The experimental setup involved an electrolytic cell divided into two compartments by a cation or anion exchange membrane. The cathode, consisting of carbon cloth and metal-modified carbon cloth, and the anode, made of a platinum net, were placed on either side of this membrane.

[0013] EP 0 876 831 Bl discloses a process to decompose organic pollutants of various kinds, including organochlorine compounds, to CO2 via chemical oxidation using oxidants that are generated at a cathode by reduction of O2. The reaction set-up relies on the active supply of oxygen gas requiring extensive safety measures. The process generates CO2 only instead of valuable chemicals, and the reduction of O2 generates reactive peroxide species which are explosive and hazardous, especially at scale.

[0014] US 5 569 809 A discloses a process for the electrochemical reduction of organochlorine compounds at glassy-carbon and Fe electrodes using direct current at constant potential to afford the corresponding dechlorinated hydrocarbons. The anode is Pt. While providing dechlorinated compounds, the process is sensitive to electrode materials and cannot be run continuously for a prolonged period of time as the deposition of residuals deactivates electrode surfaces and makes regeneration of electrodes by mechanical electrode cleaning or in-situ electrochemical cleaning via extreme oxidation or reduction necessary.

[0015] Alternating current (AC) has recently emerged as a powerful tool in synthetic organic electrochemistry, where various waveforms are used to periodically reverse electrode polarity, distinguishing it from traditional direct current (DC). Until 2020, the use of AC in synthetic organic electrochemistry was sporadic, partly due to decreased Faradaic yields caused by energy losses to the capacitance of the electrical double layer during polarity reversals. However, recently, it was demonstrated that AC electrolysis can lead to changes in selectivity that are unattainable with conventional DC electrolysis (Kawamata, Baran, “Rapid Alternating Polarity as a Unique Tool for Synthetic Electrochemistry”, ChemRxiv August 8, 2023. https: / / doi.org / 10.26434 / chemrxiv-2023-glvvh.). Furthermore, it was shown that local pockets of electrogenerated acids around the anode that may form under a DC paradigm can be neutralized efficiently when using AC electrolysis, which can prevent electrode degradation (Kawamata, Baran et al., “Scalable Electrochemical Decarboxylative Olefination Driven by Alternating Polarity”, Angewandte Chemie International Edition (Vol. 62, No. 42, e202309157), October 16, 2023.).

[0016] The drawback of the prior art is that many existing methods for degrading persistent organic pollutants are either inefficient, costly, or environmentally detrimental, and often lack scalability for industrial applications. Another disadvantage of prior art methods is the need to regularly clean the electrodes employed to remove deposits that reduce activity, i.e. to reactivate the electrodes. Simple and cheap electrode materials, such as graphite electrodes, are prone to structural disintegration and therefore not employed in electrochemically degrading persistent organic pollutants, in particular in an undivided cell set-up (US4702804). Therefore, the present invention aims to provide scalable, cost- effective, and environmentally friendly techniques for effectively degrading chlorinated organic compounds.

[0017] The problem is solved by the method according to claim 1. Further preferred embodiments are subject of dependent claims 2 to 15.

[0018] The method according to the present invention enables an essentially complete dechlorination of chlorinated organic compounds using a mild, eco-friendly, and cost- efficient approach. In particular, it relates to a method for dechlorinating chlorinated organic compounds in an electrochemical device comprising an undivided electrolytic cell with two electrodes acting as anode and cathode, by a) providing a composition comprising the chlorinated organic compounds, a solvent, and a sacrificial electron donor, wherein the solvent can also function as the sacrificial electron donor, or alternatively, the solvent and the sacrificial electron donor are two separate components, and b) conducting an electrochemical reaction to dechlorinate the chlorinated organic compounds into hydrocarbons and inorganic chlorides (hydrochloric acid and salts thereof), characterized by alternating the polarity of the two electrodes, with both electrodes being graphite electrodes.

[0019] It was found that graphite electrodes can function as both an anode and a cathode in the dechlorination of chlorinated organic compounds when an alternating current is applied instead of a direct current. This process leads to the alternation of the polarity of the two electrodes because an alternating current (AC) periodically reverses the direction of the electric flow. As a result, the roles of the electrodes switch continuously - each electrode alternates between being the anode and the cathode. This approach ensures a neutral environment around the electrodes, preventing the build-up of electrochemically-generated acids and bases that typically occur with direct current, which can lead to: i) irreversible electrode degradation, and ii) undesired, base-mediated degradation pathways of the chlorinated compounds to generate partially dechlorinated, toxic byproducts. By using the method according to the present invention, the persistent issues of electrode destruction and incomplete dechlorination are eliminated, allowing for the continuous use and recycling of low-cost graphite electrodes to accomplish full dechlorination of POPs. Due to the method according to the present invention, the degradation of chlorinated organic compounds into useful hydrocarbons and benign, non-toxic inorganic chlorides represents a significant advantage over prior approaches. By converting harmful chlorinated compounds into valuable hydrocarbons, the invention provides a dual benefit of waste reduction and resource recovery. The production of benign and non-toxic inorganic chlorides further ensures that the by-products of the process do not pose a risk to human health or the environment.

[0020] Graphite electrodes are well known to skilled persons. The primary materials used in their production include petroleum coke, needle coke, and coal tar pitch, with varying qualities and proportions defining different types of electrodes. Examples of known graphite electrodes are Regular Power (RP), High Power (HP), and Ultra-High Power (UHP) graphite electrodes. Although all types of graphite electrodes can be used in the method according to the present invention, regular graphite electrodes are generally preferred due to their cost-effectiveness.

[0021] As the method according to the present invention can prevent the oxidation of chloride, it operates within an undivided electrolytic cell, meaning a single chamber that does not necessitate the use of a membrane to separate the anodic chamber from the cathodic chamber. The undivided cell configuration offers multiple advantages that enhance scale- up, practicality, and efficiency of the method according to the present invention. By eliminating the need for a membrane, the system becomes simpler and more cost-effective to design and operate. Membranes can be expensive and require regular maintenance or replacement, increasing operational costs and complexity. Additionally, the undivided cell allows for better mixing, improving reaction rates and overall process efficiency. This is especially important if soil or other heterogeneous matter is present because soil particles can clog or foul membranes, severely impairing their function and leading to frequent maintenance or replacement.

[0022] The electrolysis process occurs in the presence of the solvent, wherein i. the solvent can also function as the sacrificial electron donor, or ii. alternatively, the solvent and the sacrificial electron donor are two separate components.

[0023] When the solvent acts as the sacrificial electron donor, it participates directly in the redox reactions, getting oxidized in the process. This characteristic makes the solvent an active participant in the electrolysis, facilitating the overall reaction by providing the necessary electrons or accepting electrons. Examples of solvents that serve simultaneously as sacrificial electron donors include dimethyl sulfoxide, diethyl sulfoxide, and thiophene. In addition to the solvent serving as a sacrificial electron donor, one or more additional sacrificial donors may also be present. Alternatively, the solvent and the sacrificial electron donor can be two separate components. In this scenario, the solvent simply provides a medium for the ions and molecules to move and does not participate in the redox reactions. Instead, a distinct sacrificial electron donor is present in the solution. This separate sacrificial electron donor undergoes oxidation, while the solvent remains inert and merely facilitates the movement and interaction of ions within the solution. Possible solvents that do not act as sacrificial electron donor are preferably selected from the group consisting of amides, such as dimethylformamide (DMF), dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP); ethers, such as diethyl ether, tetrahydrofuran (THF), and dioxane; sulfolanes such as sulfolane, 2-methylsulfolane and hydroxysulfolane; ketones, such as acetone, methyl ethyl ketone (MEK), and cyclohexanone; esters, such as ethyl acetate, methyl acetate, and butyl acetate; carbonates, such as propylene carbonate, and dimethyl carbonate (DMC); nitriles, such as acetonitrile and benzonitrile; alcohols, such as methanol, ethanol, and isopropanol; carboxylic acids, such as acetic acid, formic acid, and propionic acid; ionic liquids, such as l-butyl-3-methylimidazolium hexafluorophosphate, and water or a mixture thereof.

[0024] The solvent should at least partially, and preferably fully, dissolve the chlorinated organic compounds as well as, if necessary, the sacrificial electron donor and / or electrolyte. As outlined below, a co-solvent can be added to further improve dissolution. By facilitating the dissociation of ionic compounds into their constituent ions, the solvent plays a crucial role in enabling the electrolysis process.

[0025] Within the context of the present invention, a sacrificial electron donor refers to a substance that provides electrons in a chemical reaction and is consumed during that process. As previously mentioned, this substance can serve multiple roles: it may function as the solvent, the electrolyte, or be a separate compound that does not act as either a solvent or an electrolyte. Compounds that can be irreversibly oxidized at a voltage below 1.5 V vs SCE (saturated calomel electrode), preferably below 1.0 V vs SCE, can act as a suitable sacrificial electron donor. The standard conditions for the “voltage vs SCE” voltammetry include a temperature of 25 °C, a pressure of 1 atmosphere, and a saturated solution of potassium chloride as the electrolyte. If liquid at room temperature, the sacrificial electron donor can simultaneously act as a solvent, and if it is a solid at room temperature, it can be dissolved in a solvent as described above.

[0026] The electrolysis process can occur in the presence of an electrolyte. The presence of an electrolyte can significantly enhance the efficiency of the electrolysis process. The constituent ions of the electrolyte can increase the conductivity of the reaction mixture and thus lower the voltage required for the electrolysis to proceed. During this dechlorination process chloride anions are generated, which act as an "in situ’’ generated electrolyte in the form of hydrochloric acid and salts thereof, such as for example NaCl. If present, the electrolyte can either i. act as the sacrificial electron donor, or ii. function separately from the sacrificial electron donor, meaning that the sacrificial electron donor and the electrolyte are two separate components.

[0027] When the electrolyte functions as the sacrificial electron donor, it directly participates in the redox reactions and is oxidized during the process. Examples of electrolytes that can concurrently serve as sacrificial electron donors include sodium acetate and sodium pivalate.

[0028] Alternatively, the electrolyte and the sacrificial electron donor can be two separate components. In this scenario, the electrolyte’s role is confined to increasing the conductivity of the reaction mixture. The sacrificial electron donor, on the other hand, supplies electrons to facilitate the redox reactions without being involved in the ionic transport. This electrolyte can be essentially any salt which is soluble in the solvent.

[0029] In one preferred embodiment of the present invention, the composition comprises the chlorinated organic compounds, a solvent which acts as a sacrificial electron donor, and an electrolyte, most preferably, wherein the solvent is DMSO and, if present, the electrolyte is sodium chloride, lithium chloride, sodium formate, sodium pivalate, or any mixture thereof. This composition results in excellent conversion rates. In the method according to the present invention, the order of adding the individual components is essentially flexible. This means the composition comprising the chlorinated organic compounds, the solvent, the sacrificial electron donor (if different from the solvent), and the electrolyte (if different from the sacrificial electron donor) can be added without following a strict sequence. One option is a stepwise addition, where each component is added sequentially. For example, one can start by adding the composition comprising the chlorinated organic compounds, followed by the solvent, and finally the sacrificial electron donor (if different from the solvent). Another approach is simultaneous addition, where all components are added at the same time. Additionally, premixed combinations of some components can be used. For instance, a mixture of the solvent and the sacrificial electron donor (if different from the solvent) can be prepared beforehand. This premix can then be added to the composition comprising the chlorinated organic compounds. The electrolysis reaction usually takes place at room temperature and normal pressure.

[0030] The method according to the present invention can be easily scaled-up, as it uses inexpensive materials, operates preferably at room temperature with electricity as its primary driving force. The utilization of inexpensive graphite electrodes contributes to significant cost reductions and ensures that large-scale operations remain financially viable. Additionally, the method’s ability to preserve electrode integrity through repeated cycles minimizes waste and enhances resource efficiency. Moreover, the inclusion of a sacrificial electron donor suppresses the oxidation of chloride to toxic chlorine gas, thereby preventing the rechlorination of the organic compounds. Additionally, the method according to the present invention employs an undivided cell configuration that enhances mixing, thereby boosting reaction rates and overall process efficiency, which is crucial for scale-up.

[0031] Preferably, the sacrificial electron donor is selected from the group consisting of C1-C4- dialkylsulfoxides, Ce-Cio-diarylsulfoxides, Ci-C4-dialkenylsulfoxides, C1-C4- dialkylsulfides, Ce-Cio-diarylsulfides, Ci-C4-dialkenylsulfides, Ci-C4-alkylcarboxylates, Ci-C4-alkyl sulfinates, Ce-Cio-hydroxyaryls, Ci-C4-alkoxy-Ce-Cio-aryls, Ci-Ce- alkylamines, Ci-C4-N-alkoxy substituted amine, carbamate-protected amines, Ce-Cio- arylamines, Ci to C4-tertiary enamines, pyrroles, indoles, hydrazines comprising one to four Ci-C4-alkyl or Ce-Cio-aryl residues, Ci-C4-alkylphosphines, Ce-Cio-arylphosphines, alkoxyphosphines and bisulfite salts. Said compounds can effectively suppress the oxidation of chloride to chlorine gas.

[0032] Throughout the present invention, the following terms are defined as follows:

[0033] The term “chlorinated organic compounds” refers to an organic chemical compound that contains at least one atom of chlorine covalently bonded to its carbon scaffold. This definition encompasses a wide range of substances, including small organic molecules, which typically have a molecular weight of less than 1,000 Daltons. However, it also includes larger chlorinated polymers, which may have significantly higher molecular weights. By covering both small molecules and larger polymeric structures, the term captures the full spectrum of chlorinated organic compounds, reflecting their diverse chemical and physical properties. These compounds are synthetic and often have high stability due to the presence of chlorine, making them resistant to degradation in the environment.

[0034] The term “Ci-C4-dialkylsulfoxides” stands for sulfoxides in which the sulfoxide group (S=O) is bonded to two linear or branched alkyl groups, each containing between one and four carbon atoms, and which can be independently selected from each other, encompassing compounds such as dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, and dibutyl sulfoxide.

[0035] The term “Ce-Cio-diarylsulfoxides” refers to sulfoxides in which the sulfoxide group (S=O) is bonded to two aryl groups, each containing between six and ten carbon atoms (Ce-Cio) in the ring. The aryl groups can be either simple aromatic rings or annulated (fused) systems, such as naphthalene (Cio). These aryl groups may carry additional substituents, such as C1-C3 alkyl groups (e.g., methyl, ethyl) or C1-C3 alkoxy groups (e.g., methoxy, ethoxy). Examples are compounds such as diphenyl sulfoxide and ditolyl sulfoxide. The term “dialkenylsulfoxide” stands for sulfoxides in which the sulfoxide group (S=O) is bonded to two alkenyl groups. These alkenyl groups may carry additional substituents, such as C1-C3 alkyl groups (e.g., methyl, ethyl) or C1-C3 alkoxy groups (e.g., methoxy, ethoxy). An example of such a compound is divinylsulfoxide.

[0036] The term “Ci-C4-dialkylsulfides” stands for sulfides in which the sulfur atom is bonded to two linear or branched alkyl groups, each containing between one and four carbon atoms (C1-C4), which can be independently selected from each other, including compounds such as dimethyl sulfide and diethyl sulfide.

[0037] The term “Ce-Cio-diarylsulfides” refers to sulfides in which the sulfur atom is bonded to two aryl groups, each containing between six and ten carbon atoms (Ce-Cio) in the ring. The aryl groups can be either simple aromatic rings or annulated (fused) systems, such as naphthalene (C10). These aryl groups may carry additional substituents, such as C1-C3 alkyl groups (e.g., methyl, ethyl) or C1-C3 alkoxy groups (e.g., methoxy, ethoxy). Examples are compounds such as diphenyl sulfide and ditolyl sulfide.

[0038] The term “dialkenylsulfide” stands for sulfides in which the sulfur atom is bonded to two alkenyl groups. These alkenyl groups may carry additional substituents, such as C1-C3 alkyl groups (e.g., methyl, ethyl) or C1-C3 alkoxy groups (e.g., methoxy, ethoxy). An example of such a compound is thiophene.

[0039] The term “Ci-C4-alkylcarboxylates” stands for carboxylate esters in which the ester linkage is bonded to a linear or branched alkyl group containing between one and four carbon atoms (C1-C4), such as methylcarboxylate or ethyl carboxyl ate.

[0040] The term “Ci-C4-alkylsulfinates” stands for sulfinate salts in which the sulfinate moiety is bonded to a linear or branched alkyl group containing between one and four carbon atoms (C1-C4), such as methyl sulfinate or ethyl sulfmate.

[0041] The term “Ce-Cio-hydroxyaryls” refers to aryl compounds, wherein the aryl group comprises between six and ten carbon atoms (Ce-Cio) in the ring and where the aryl group is bonded to a hydroxyl group ( OH). The aryl group can be either a simple aromatic ring or an annulated (fused) systems, such as naphthalene (Cio). This aryl group may carry additional substituents, such as C1-C3 alkyl groups (e.g., methyl, ethyl) or C1-C3 alkoxy groups (e.g., methoxy, ethoxy). An example of such a compound is phenol.

[0042] The term “Ci-C4-alkoxy-C6-Cio-aryls” refers to aryl compounds, wherein the aryl group comprises between six and ten carbon atoms (Ce-Cio) in the ring and where the aryl group is bonded to a Ci-C4-alkoxy group (-OR) with 1 to four carbon atoms.

[0043] The term “Ci-Ce-alkylamines” stands for amines in which the nitrogen atom is bonded to one, two, or three linear or branched alkyl group containing between one and six carbon atoms (Ci-Ce), including compounds such as triethylamine, diisopropylamine and n- butylamine.

[0044] The term "Ci-C4-N-alkoxy substituted amine" refers to an amine in which the nitrogen atom is bonded to at least one alkoxy group, where the alkyl residue of the alkoxy group can have a carbon chain length ranging from one to four carbon atoms (Ci to C4). In these compounds, the nitrogen atom can also be bonded to other alkyl groups or hydrogen atoms. Examples of N-alkoxy substituted amines include compounds like N-methoxy-N- methylamine and N-ethoxy-N-ethylamine.

[0045] The term "carbamate-protected amines" refers to an amine that has been temporarily modified with a carbamate group to protect the nitrogen atom during chemical reactions. Examples of carbamate protecting groups include Boc (tert-butyloxycarbonyl), Cbz (benzyloxycarbonyl), and Fmoc (fluorenylmethyloxy carbonyl).

[0046] The term “Ce-Cio-arylamines” refers to amines in which the nitrogen atom is bonded to a six- or ten-carbon aryl group, such as aniline, where the aryl ring can also carry additional substituents, such as C1-C3 alkyl groups (e.g., methyl, ethyl) or C1-C3 alkoxy groups (e.g., methoxy, ethoxy), and the nitrogen atom can also carry additional substituents such as Ci- Ce alkyl groups (e.g., methyl, ethyl).

[0047] The term "Ci-C4-tertiary enamines" refers to enamines nitrogen atom is connected to an enamine system (a double bond adjacent to a nitrogen atom) and bonded to two alkyl groups, where each alkyl group contains between one and four carbon atoms (C1-C4). These alkyl groups can be linear or branched and may be independently selected from each other. Examples of such compounds include N,N-dimethylvinylamine and N-ethyl-N- methylvinylamine.

[0048] The term “hydrazines” comprising one to four Ci-C4-alkyl or Ce-Cio-aryl residues refers to hydrazine derivatives where the nitrogen atoms are bonded to one to four linear or branched alkyl groups containing one to four carbon atoms (C1-C4) or aryl groups containing six (Ce) or ten (C10) carbon atoms, such as methylhydrazine or phenylhydrazine.

[0049] The term “Ci-C4-alkylphosphines” stands for phosphine compounds in which the phosphorus atom is bonded to a linear or branched alkyl group containing between one and four carbon atoms (C1-C4), such as trimethylphosphine.

[0050] The term Ce-Cio-arylphosphines refers to phosphine compounds in which the phosphorus atom is bonded to a six- or ten-carbon aryl group, such as triphenylphosphine.

[0051] The term “Ci-C4-alkoxyphosphines” refers to phosphine compounds where the phosphorus atom is bonded to an alkoxy group (-OR) with one to four carbon atoms, such as trimethylphosphite.

[0052] The term bisulfite salt refers to a salt containing the bisulfite ion (HSO3) such as sodium bisulfite (NaHSOs) or potassium bisulfite (KHSO3).

[0053] The term “fully degraded” or “completely degraded” means a conversion rate of more than 95%, preferably more than 98%, indicating that 95%, respectively 98%, of the initially present chlorinated organic compounds, measured by molar percentage (mol%), have been converted into compounds that are completely dechlorinated.

[0054] Preferably, the sacrificial electron donor is dimethyl sulfoxide (DMSO), an environmentally friendly and non-toxic solvent that effectively reduces the chlorinated organic compounds, while simultaneously serving as the solvent. During this process, while the chlorinated organic compounds undergo reduction and lose chloride anions, DMSO is oxidized to form dimethyl sulfone. This transformation not only mitigates the generation of chlorine gas, which could otherwise lead to the rechlorination of organic compounds, but also enhances the overall efficiency of the dechlorination reaction. By facilitating the removal of harmful chlorine species and promoting the degradation of toxic pollutants, DMSO thus serves a dual function, providing both an eco-friendly solvent and an electron donor in the treatment of environmental contaminants. It is worth noting that DMSO is a by-product of the wood pulp process used in paper production, which significantly decreases its ecological footprint. Similarly, the environmental impact of dimethyl sulfone, the oxidative by-product of DMSO-based processes, is minimal due to its non-toxicity. Additionally, dimethyl sulfone can be reused as a high-temperature solvent and even as a nutritional supplement, further enhancing its sustainability.

[0055] In a preferred embodiment of this invention, the reaction is carried out under neat conditions. Within the context of the present invention "neat conditions" imply that the reaction occurs without any solvent; the sacrificial electron donor itself acts as the reaction medium. Consequently, there is no additional solvent to dilute or interfere with the process. Conducting the reaction under neat conditions offers the advantage of maintaining a high concentration of the sacrificial electron donor. Neat conditions are especially preferred if the oxidation potential values of the sacrificial electron donor and the chlorinated organic compounds to be treated are close. This can help bias the oxidation profile of the reaction and prevent undesired chloride oxidation.

[0056] In another embodiment of the present invention, the reaction mixture comprises, in addition to the solvent, a co-solvent which is preferably selected from the amides, such as dimethylformamide (DMF), dimethylacetamide (DMAc), and N-methyl-2-pyrrolidone (NMP); ethers, such as diethyl ether, tetrahydrofuran (THF), and dioxane; sulfolanes such as sulfolane, 2-methylsulfolane and hydroxysulfolane; ketones, such as acetone, methyl ethyl ketone (MEK), and cyclohexanone; esters, such as ethyl acetate, methyl acetate, and butyl acetate; carbonates, such as propylene carbonate, and dimethyl carbonate (DMC); nitriles, such as acetonitrile and benzonitrile; alcohols, such as methanol, ethanol, and isopropanol; and carboxylic acids, such as acetic acid, formic acid, and propionic acid; ionic liquids, such as l-butyl-3-methylimidazolium hexafluorophosphate, and water or a mixture thereof. This co-solvent can be mixed with the solvent. A mixture of solvents can be advantageous, for instance, due to cost considerations or solubility reasons.

[0057] The chlorinated organic compounds to be dechlorinated are preferably small organic molecules having a molecular weight of less than 1000 Daltons selected from the group consisting of chlorinated organic compounds having one or more chlorine atoms, geminal trichlorides, geminal dichlorides, primary alkyl chlorides, aryl chlorides, and vicinal secondary alkyl chlorides. The term chlorinated organic compounds having one or more chlorine atoms refers to organic molecules in which at least one chlorine atom is covalently bonded to carbon atoms within the molecule. The term "geminal" refers to a configuration in which two substituents, such as chlorine atoms, are attached to the same carbon atom in the molecule. For example, in geminal trichlorides or geminal dichlorides, three or two chlorine atoms, respectively, are bonded to a single carbon atom. “Primary alkyl chlorides” describes the presence of a chlorine atom directly bonded to an aliphatic carbon, such as chlorocyclohexane. On the other hand, "aryl chlorides" are compounds where a chlorine atom is directly bonded to an aromatic ring, such as chlorobenzene. "Vicinal" describes the placement of substituents on adjacent carbon atoms. In "vicinal secondary alkyl chlorides," the chlorine atoms are attached to carbon atoms that are next to each other in the carbon chain. It was shown that these compounds can be fully degraded using the method according to the present invention. While traditional methods used in prior art often result in the formation of vinyl or aryl halides that resist further elimination steps, the present invention overcomes these limitations. The key advantage of the method described herein is its ability to achieve complete dehalogenation, thereby preventing the formation of resistant by-products. In particular, the method according to the present invention can be used to treat chlorinated organic compounds selected from the group consisting of hexachlorocyclohexanes, toxaphene, mirex (l,la,2,2,3,3a,4,5,5a,5b,6-dodecachloracta- hydro-l,3,4-metheno-lH-cyclobuta[cd]pentalene), chlordecone (1,1a, 3, 3a, 4, 5, 5, 5a, 5b, 6- decachlorooctahydro-l,3,4-metheno-2H-cyclobuta[cd]pentalen-2-one), methoxychlor (dimethoxydiphenyltrichloroethane), chlorinated paraffins, aldrin (1,2,3,4,10,10-hexachlor- l,4,4a,5,8,8a-hexahydro-l,4-endo-5,8-exo-dimethanonaphthaline), chlordane

[0058] (l,2,4,5,6,7,8,8-octachloro-3a,4,7,7a-tetrahydro-4,7-methanoindane), heptachlor (l,4,5,6,7,8,8-heptachloro-3a,4,7,7a-tetrahydro-lH-4,7-methanoindene), cis and trans dechlorane plus (1,2,3,4,7,8,9,10,13,13,14,14-dodecachloro-

[0059] 1 ,4, 4a, 5, 6, 6a, 7, 10, 1 Oa, 11 , 12, 12a-dodecahydro-l ,4,7, 10- dimethanodibenzo[a,e]cyclooctene), dieldrin ((laR,2R,2aS,3S,6R,6aR,7S,7aS)-3,4,5,6,9,9- hexachloro-la,2,2a,3,6,6a,7,7a-octahydro-2,7:3,6-dimethanonaphtho[2,3-b]oxirene), endrin (hexachlorepoxyoctahydrobis(endomethylen)naphthaline), endosulfan (6,7,8,9,10,10-hexachloro-l,5,5a,6,9,9a-hexahydro- 6,9-methano-2,4,3- benzodioxathiepine-3 -oxide), hexachlorobutadiene, dichlorodiphenyltri chloroethane, pentachlorobenzene, pentachlorophenol, hexachlorobenzene, polychlorinated dibenzofurans, polychlorinated dibenzodioxins, polyhalogenated biphenyls, p,p’ -dicofol (2,2,2-trichloro- 1 , 1 -bis(4-chlorophenyl)ethan- 1 -ol), o,p’ -dicofol (2,2,2-trichloro- 1 -(3 - chlorophenyl)- l-(4-chlorophenyl)ethan-l-ol), and polychlorinated naphthalenes. By achieving complete dechlorination, the method according to the present invention ensures that these hazardous compounds are broken down into useful hydrocarbons and benign, non-toxic inorganic chlorides (hydrochloric acid and salts thereof), thus mitigating their persistence and mitigating the risks associated with their long-term environmental and biological presence.

[0060] Alternatively, or in addition, the chlorinated organic compounds to be dechlorinated may include chlorinated polymers. The term 'chlorinated polymers' refers to a broad category of polymeric materials that incorporate chlorine atoms into their molecular structure. This group includes homopolymers like polyvinyl chloride (PVC), chlorinated copolymers such as chlorinated poly(vinyl acetate), which combines vinyl acetate and vinyl chloride, and chlorinated elastomers like chlorinated polyethylene (CPE). The molecular weight of chlorinated polymers typically ranges from 30,000 to 200,000 g / mol, with Gel Permeation Chromatography (GPC) commonly used to measure these values. By achieving complete conversion, the method according to the present invention ensures that chlorinated polymers, which are also found in microplastics, are broken down into useful hydrocarbons and benign, non-toxic inorganic chlorides, such as hydrochloric acid and its salts. This transformation not only mitigates the environmental persistence of these microplastics but also significantly reduces the risks associated with their long-term biological presence. When alternating the polarity of two electrodes, various alternating polarity waveforms, such as square and sine waves, can be utilized. In the context of the present invention, any waveform is applicable; however, the square waveform has proven to achieve particularly good results. The parameter T1 / 2 represents the interval between each polarity reversal in the square waveform.

[0061] Preferably, the polarity of the electrodes is alternated every 1 to 1800 seconds, more preferably 1 to 300 seconds, even more preferably every 10 to 60 seconds. This means that one electrode initially acts as the anode and the other as the cathode. After the set interval of preferably 1 to 1800 seconds, more preferably 300 seconds, even more preferably 10 to 60 seconds, the current reverses, causing the anode to become the cathode and vice versa. This alternation continues in synchronization with the alternating current cycle, ensuring each electrode periodically switches roles to maintain an efficient and balanced process. The selected interval also depends on the chlorinated organic compound and can be adjusted accordingly.

[0062] Preferably, in the method according to the present invention, the current is in a range of 1 mA to 100 kA. At the lab scale, the current is preferably between 10 to 100 mA, more preferably 30 to 60 mA. This current range optimizes electrolysis efficiency. On an industrial scale, the applied current is preferably within the range of 10 A to 100 kA.

[0063] The optional electrolyte is preferably selected from the group consisting of sodium chloride, sodium acetate, sodium bicarbonate, sodium sulfate, sodium citrate, sodium carbonate, potassium chloride, potassium bicarbonate, potassium sulfate, calcium chloride, calcium carbonate, magnesium sulfate, lithium chloride, sodium formate, sodium pivalate, ammonium chloride, sodium lactate, potassium acetate, sodium benzoate, sodium oxalate, sodium tartrate, preferably sodium chloride, lithium chloride, sodium formate and sodium pivalate. The use of small amounts of inexpensive electrolyte salts ensures conductivity from the start of the process. Sodium chloride, lithium chloride, sodium formate and sodium pivalate are especially preferred, all of which are inexpensive commodity chemicals. Typically, when present, the electrolyte is at a concentration of 0.03 - 3.0 M, optionally at 0.1 - 1.0 M. Preferably, the pH of the reaction is maintained between 4 and 10, and more specifically between 7.5 and 10, as the risk of chloride oxidation is significantly reduced under basic conditions. Especially good results are achieved when the pH is between 7.5 and 10. The pH can be easily controlled by using an electrolyte with adjustable basicity, such as sodium pivalate or sodium formate. Preferably, the pH of the reaction is determined by measuring the pH of an aqueous solution of a sample taken from the reaction at room temperature.

[0064] In a preferred embodiment of the present invention, particularly good results can be obtained when the solvent used is DMSO, which also acts as the sacrificial electron donor, and the electrolyte is sodium chloride, lithium chloride, sodium formate, sodium pivalate, or a mixture thereof.

[0065] The method according to the present invention can be used for treating a wide range of compositions that contain chlorinated organic compounds. In particular, the composition to be treated is selected from the group consisting of soil, sediments, groundwater, sludge, absorbers, and plastic waste, or an extract thereof.

[0066] In a preferred embodiment of the present invention, the composition to be treated comprises soil that is contaminated with the chlorinated organic compounds. This means that the chlorinated organic compounds do not have to be separated but can be treated while still in the presence of soil. This approach simplifies the remediation process by eliminating the need for pre-treatment steps to isolate the chlorinated organic compounds. Furthermore, treating the compounds in situ leads to more efficient and cost-effective decontamination.

[0067] Alternatively, the chlorinated organic compounds can be removed from the soil through a preceding extraction process. Thus, the composition to be treated is a filtrate, also called the extract, obtained after extracting the chlorinated organic compounds using an extraction agent and subsequent filtration. Subsequently, the method according to the present invention is applied to the filtrate. Even though this approach involves a preliminary treatment, it allows for the recovery of clean soil as well as the recycling of degradation products, making it a sustainable and environmentally friendly solution. The formation of useful hydrocarbons as degradation products includes compounds such as 1,1- diphenylethane, benzene, l,l-(4,4'-dimethoxyphenyl)ethane, and cyclododecatri ene (CDT) as major byproducts. These hydrocarbons are valuable to the chemical industry and integral to the manufacturing of commodity chemicals. For example, benzene is used in the large-scale synthesis of many organic compounds and their downstream applications, such as ethylbenzene, cumene, cyclohexane, and nitrobenzene. Similarly, CDT is employed in the preparation of dodecanedioic acid, which is essential for producing antiseptics, topgrade coatings, painting materials, corrosion inhibitors, surfactants, polymers, and treatments for type II diabetes.

[0068] The method according to the present invention can be carried out in an electrolysis device comprising an undivided electrolytic cell fitted with two electrodes serving alternately as anode and cathode. Two graphite electrodes are utilized in this setup, chosen for their ability to switch polarity during the reaction. The power supply to this system is a programmable power source that allows for adjustable voltage and current, with the essential feature of supporting periodic polarity reversal of the electrodes. The setup may include a mechanism for continuous stirring to ensure homogeneous mixing of the solution and efficient mass transfer to the electrode surfaces throughout the reaction.

[0069] The process according to this invention can also be conducted in a large, portable unit mounted on a truck with solar panels to harness solar energy. This mobile unit allows onsite dechlorination, eliminating the need to transport contaminated substances to a fixed facility, and uses renewable energy for a more environmentally friendly approach.

[0070] Another embodiment of the present invention relates to a method for debrominating brominated organic compounds in an electrocatalytic device comprising an undivided electrolytic cell with two electrodes acting as anode and cathode, by a) providing a composition comprising the brominated organic compounds, a solvent, and an electrolyte (if necessary), and b) conducting an electrochemical reaction to debrominate the brominated organic compounds, characterized in that one electrode is a graphite electrode acting as cathode and the other electrode is a metal electrode selected from the group consisting of magnesium, zinc, aluminum, stainless steel, copper, nickel acting as anode applying direct current. With this method, the electrochemical oxidation of the bromide anion can be avoided, which would form toxic molecular bromine (E ). Preferably, the metal electrode is a magnesium electrode, as it is inexpensive. This process also proceeds quantitatively, leading for example in case of hexabromocyclododecanes to the formation of cyclododecatriene (mixture of geometrical isomers of the alkenes) and innocuous magnesium bromide. The solvents and the electrolytes can be the same as described for the dechlorination process. The reaction preferably takes place under the following conditions: direct current electrolysis using a magnesium anode, a graphite cathode, and a mixture of hexabromocyclododecanes (POP) and sodium tetrafluoroborate or lithium chloride (electrolyte) dissolved in a solvent mixture comprised of DMSO and ethanol and / or methanol.

[0071] Figure 1

[0072] Figure 1 illustrates an electrolysis device 1 comprising an undivided electrolytic cell 2 fitted with two alternating graphite electrodes 4, 6, which serve as the anode and cathode during the electrolysis process. The programmable power source 8 is connected to the electrodes through conductive wiring 10, allowing for adjustment of both voltage and current. Additionally, a stirring mechanism 12 can be integrated into the system to maintain homogeneous mixing of the reaction solution 14 within the reservoir 16.

[0073] Figure 2

[0074] Figure 2 illustrates the condition of graphite electrodes prior to electrolysis (a) and after they have been employed in electrolysis according to the present invention, i.e. with alternating current (AC), until complete dechlorination (b). The difference in weight of the electrodes before and after AC electrolysis was < 1 mg. Further, Figure 2 shows the condition of graphite electrodes after premature termination of direct current (DC) electrolysis (c) and after completion of direct current (DC) electrolysis (d). Parts of the electrode broke during the electrolysis and graphite powder was obtained. The difference in weight of the electrodes before and after DC electrolysis was 200 mg (15% of the electrode’s initial weight, even though only one-third of it was immersed in the reaction mixture), rendering it unsuited for reuse.

[0075] Experiments

[0076] Example 1: Procedure 1 for the dechlorination of hexachlorocyclohexanes (HCH):

[0077] To a glass reaction vessel equipped with a stir bar were added HCH (1.00 g, 3.44 mmol, 1.00 eq.), sodium chloride (20 mg, 0.35 mmol, 0.10 eq.), and dimethyl sulfoxide (7.0 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 100 mA (T1 / 2: 60 s) was passed through the reaction mixture for 27 F / mol. 'H NMR analysis of an aliquot showed full conversion of HCH (>98%) and 88% yield of benzene.

[0078] Example 2: Procedure 2 for the dechlorination of hexachlorocyclohexanes (HCH):

[0079] To a glass reaction vessel equipped with a stir bar were added HCH (1.00 g, 3.44 mmol, 1.00 eq.), sodium formate (1.40 g, 20.6 mmol, 6.00 eq.), and dimethyl sulfoxide (7.0 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 100 mA (T1 / 2: 10 s) was passed through the reaction mixture for 12 F / mol. 'H NMR analysis of an aliquot showed full conversion of HCH (>98%) and 95% yield of benzene. Chloride concentration in the final reaction mixture was determined using Mohr’s titration, yielding full dechlorination (>98%).

[0080] Example 3: Procedure 1 for the dechlorination of HCH-contaminated soil:

[0081] To a glass reaction vessel equipped with a stir bar was added HCH-contaminated soil (50 wt%, 58 mg, 0.10 mmol, 1.00 eq.), sodium chloride (20 mg, 0.35 mmol, 3.50 eq.), and dimethyl sulfoxide (3.5 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 30 mA (T1 / 2: 60 s) was passed through the reaction mixture for 24 F / mol. 'H NMR analysis of an aliquot showed full conversion of HCH (>98%) and >98% yield of benzene.

[0082] Example 4: Procedure 2 for the dechlorination of HCH-contaminated soil:

[0083] To a glass reaction vessel equipped with a stir bar was added HCH-contaminated soil (50 wt%, 1.00 g, 1.72 mmol, 1.00 eq.), sodium formate (700 mg, 10.3 mmol, 6.00 eq.), and dimethyl sulfoxide (7.0 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 30 mA (T1 / 2: 10 s) was passed through the reaction mixture for 12 F / mol. 'H NMR analysis of an aliquot showed full conversion of HCH (>98%) and 94% yield of benzene. Chloride concentration in the final reaction mixture was determined using Mohr’s titration, yielding full dechlorination (>98%).

[0084] Example 5: Procedure 1 for the dechlorination of pre-extracted and filtered HCH- contaminated soil:

[0085] HCH-contaminated soil (1 wt%, 2.90 g, 0.10 mmol, 1.00 eq.) was mixed and extracted with DMSO (7.0 mL). To a glass reaction vessel equipped with a stir bar was added the extract and sodium chloride (41 mg, 0.70 mmol, 7.00 eq.). A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 30 mA (T1 / 2: 60 s) was passed through the reaction mixture for 24 F / mol. 'H NMR analysis of an aliquot showed full conversion of HCH (>98%) and >98% yield of benzene.

[0086] Example 6: Procedure 2 for the dechlorination of pre-extracted and filtered HCH- contaminated soil:

[0087] HCH-contaminated soil (1 wt%, 1.00 g, 0.03 mmol, 1.00 eq.) was mixed and extracted with DMSO (7.0 mL). To a glass reaction vessel equipped with a stir bar was added the extract and sodium formate (12.2 mg, 0.18 mmol, 6.00 eq.). A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 100 mA (T1 / 2: 10 s) was passed through the reaction mixture for 36 F / mol. 'H NMR analysis of an aliquot showed full conversion of HCH (>98%) and 95% yield of benzene. Chloride concentration in the final reaction mixture was determined using Mohr’s titration, yielding full dechlorination (>98%).

[0088] Example 7: Procedure 1 for the dechlorination of HCH-contaminated absorber:

[0089] To a glass reaction vessel equipped with a stir bar was added HCH-contaminated charcoal (50 wt%, 58 mg, 0.10 mmol, 1.00 eq.), sodium chloride (20 mg, 0.35 mmol, 3.50 eq.), and dimethyl sulfoxide (3.5 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 30 mA (T1 / 2: 60 s) was passed through the reaction mixture for 24 F / mol. 'H NMR analysis of an aliquot showed full conversion of HCH (>98%) and >98% yield of benzene.

[0090] Example 8: Procedure 2 for the dechlorination of HCH-contaminated absorber:

[0091] To a glass reaction vessel equipped with a stir bar was added HCH-contaminated charcoal (50 wt%, 1.00 g, 1.72 mmol, 1.00 eq.), sodium formate (700 mg, 10.3 mmol, 6.00 eq.), and dimethyl sulfoxide (7.0 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 100 mA (T1 / 2: 10 s) was passed through the reaction mixture for 12 F / mol. 'H NMR analysis of an aliquot showed full conversion of HCH (>98%) and 93% yield of benzene. Chloride concentration in the final reaction mixture was determined using Mohr’s titration, yielding full dechlorination (>98%).

[0092] Example 9: Procedure for the dechlorination of dimethoxydiphenyltrichloroethane (Methoxychlor) : To a glass reaction vessel equipped with a stir bar was added Methoxychlor (1.00 g, 2.89 mmol, 1.00 eq.), pivalic acid (886 mg, 8.68 mmol, 3.00 eq.), sodium hydroxide (347 mg, 8.68 mmol, 3.00 eq.), and dimethyl sulfoxide (7.0 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 60 mA (T1 / 2: 60 s) was passed through the reaction mixture for 27 F / mol. The reaction mixture was then diluted with ethyl acetate (20 mL) and an aqueous solution of LiCl (10 wt%, 30 mL) was added. The layers were separated, and the aqueous layer was extracted with ethyl acetate (2 x 20 mL). The combined organic layers were washed with the LiCl solution (10 wt%, 2 x 30 mL), dried over MgSO4 and the solvent was removed under reduced pressure. The concentrated mixture was purified by flash column chromatography (SiCL, Rf = 0.3 with a 9 / 1 mixture of hex- anes / ethyl acetate) to afford l,l-bis(4-methoxyphenyl)ethane as a white solid in 80% yield. Chloride concentration in the final reaction mixture of an identical experiment was determined using Mohr’s titration, yielding full dechlorination (>98%).

[0093] Example 10: Procedure 1 for the dechlorination of dichlorodiphenyltrichloroethane (DDT):

[0094] Experiment 10 is focused on optimizing conditions to achieve gram-scale dechlorination of DDT, all while operating under a regular atmosphere. These modifications lead to an enhanced faradaic efficiency and an increased overall yield of fully dechlorinated DDT. To a glass reaction vessel equipped with a stir bar was added DDT (355 mg, 1.00 mmol, 1.00 eq.), pivalic acid (511 mg, 5.00 mmol, 5.00 eq.), sodium hydroxide (200 mg, 5.00 mmol, 5.00 eq.), water (140 pL), and dimethyl sulfoxide (7.0 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). The reaction mixture was degassed with N2 for 30 s. An alternating current of 60 mA (T1 / 2: 10 s) was passed through the reaction mixture for 75 F / mol. The reaction mixture was then diluted with ethyl acetate (20 mL) and an aqueous solution of LiCl (10 wt%, 30 mL) was added. The layers were separated, and the aqueous layer was extracted with ethyl acetate (2 x 20 mL). The combined organic layers were washed with the LiCl solution (10 wt%, 2 x 30 mL), dried over MgSC and the solvent was removed under reduced pressure. The concentrated mixture was purified by flash column chromatography (SiCL, Rf = 0.4 with a 12 / 1 mixture of hexanes / ethyl acetate) to afford 1,1 -diphenylethane as a colorless oil in 64% yield.

[0095] Example 11: Procedure 2 for the dechlorination of dichlorodiphenyltrichloroethane (DDT):

[0096] Experiment 11 is focused on optimizing conditions to achieve gram-scale dechlorination of DDT, all while operating under a regular atmosphere. These modifications lead to an enhanced faradaic efficiency and an increased overall yield of fully dechlorinated DDT. To a glass reaction vessel equipped with a stir bar was added DDT (142 mg, 0.40 mmol, 1.00 eq.), sodium pivalate (248 mg, 2.00 mmol, 5.00 eq.), water (70 pL), and dimethyl sulfoxide (3.5 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). The reaction mixture was degassed with N2 for 30 s. An alternating current of 60 mA (T1 / 2: 10 s) was passed through the reaction mixture for 50 F / mol. The reaction mixture was then diluted with ethyl acetate (20 mL) and an aqueous solution of LiCl (10 wt%, 30 mL) was added. The layers were separated, and the aqueous layer was extracted with ethyl acetate (2 x 20 mL). The combined organic layers were washed with the LiCl solution (10 wt%, 2 x 30 mL), dried over MgSCU and the solvent was removed under reduced pressure. The concentrated mixture was purified by flash column chromatography (SiCh, Rf = 0.4 with a 12 / 1 mixture of hexanes / ethyl acetate) to afford 1,1 -diphenylethane as a colorless oil in 77% yield. Chloride concentration in the final reaction mixture of an identical experiment was determined using Mohr’s titration, yielding full dechlorination (>98%).

[0097] Example 12: Procedure 1 for the dechlorination of polyvinyl chloride (PVC):

[0098] To a glass reaction vessel equipped with a stir bar was added PVC (average molecular weight 233,000, 23 mg, 0.10 pmol, 1.00 eq.), sodium chloride (20 mg, 0.35 mmol, 3500 eq.), and dimethyl sulfoxide (3.5 mL). The reaction mixture was sonicated to assist the sol- ubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 30 mA (T1 / 2: 60 s) was passed through the reaction mixture for 24000 F / mol.1H NMR analysis of an aliquot showed full conversion of PVC (>98%) to afford a fully dechlorinated residue.

[0099] Example 13: Procedure 2 for the dechlorination of polyvinyl chloride (PVC):

[0100] Experiment 13 is focused on optimizing conditions to achieve full dechlorination of PVC. To a glass reaction vessel equipped with a stir bar was added PVC (average molecular weight 233,000, 93.2 mg, 0.40 pmol, 1.00 eq.), sodium pivalate (49.6 mg, 0.40 mmol, 1000 eq.), THF (1.2 mL), and dimethyl sulfoxide (2.3 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with two graphite electrodes (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). An alternating current of 60 mA (T1 / 2: 60 s) was passed through the reaction mixture for 24000 F / mol.JH NMR analysis of an aliquot showed full conversion of PVC (>98%). Chloride concentration in the final reaction mixture was determined using Mohr’s titration, yielding major dechlorination (75%).

[0101] Example 14: Procedure 1 for the debromination of 1,2,5,6,9,10- hexabromocyclododecanes (HBCD):

[0102] Experiment 14 is centered on optimizing conditions to facilitate gram-scale debromination of HBCD while operating under a regular atmosphere. A key focus is to either replace the electrolyte with NaCl or eliminate it altogether, instead leveraging the formation of MgB as an in situ generated electrolyte. These modifications enhance the efficiency of the debromination process. To a glass reaction vessel equipped with a stir bar were added HBCD (642 mg, 1.00 mmol, 1.00 eq.), sodium tetrafluoroborate (110 mg, 1.00 mmol, 1.00 eq.), ethanol (1.75 mL) and dimethyl sulfoxide (5.25 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with one magnesium electrode (anode) and one graphite electrode (cathode) (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). The reaction mixture was degassed with N2 for 30 s. A direct current of 60 mA was passed through the reaction mixture for 6 F / mol. The reaction mixture was then diluted with diethyl ether (20 mL) and an aqueous solution of LiCl (10 wt%, 30 mL) was added. The layers were separated, and the aqueous layer was extracted with diethyl ether (2 x 20 mL). The combined organic layers were washed with the LiCl solution (10 wt%, 2 x 30 mL), dried over MgSCh and the solvent was removed under reduced pressure. This afforded cyclododecatrienes as a colorless oil in >98% yield.

[0103] Example 15: Procedure 2 for the debromination of 1,2,5,6,9,10- hexabromocyclododecanes (HBCD):

[0104] Experiment 15 is centered on conditions to facilitate gram-scale debromination of HBCD while operating under a regular atmosphere. To a glass reaction vessel equipped with a stir bar were added HBCD (1.00 g, 1.56 mmol, 1.00 eq.), lithium chloride (29.7 mg, 0.70 mmol, 0.45 eq.), methanol (1.75 mL) and dimethyl sulfoxide (5.25 mL). The reaction mixture was sonicated to assist the solubilization of the starting materials. A cap fitted with one magnesium electrode (anode) and one graphite electrode (cathode) (8 mm wide, 50 mm length, 1 mm thickness) was screwed onto the vial (submerged electrode area: 2.0 cm2). The reaction mixture was degassed with N2 for 30 s. A direct current of 60 mA was passed through the reaction mixture for 6 F / mol. The reaction mixture was then diluted with diethyl ether (20 mL) and an aqueous solution of LiCl (10 wt%, 30 mL) was added. The layers were separated, and the aqueous layer was extracted with diethyl ether (2 x 20 mL). The combined organic layers were washed with the LiCl solution (10 wt%, 2 x 30 mL), dried over MgSCh and the solvent was removed under reduced pressure. This afforded cyclododecatrienes as a colorless oil in >98% yield.

Claims

Claims1. A method for dechlorinating chlorinated organic compounds in an electrochemical device comprising an undivided electrolytic cell with two electrodes acting as anode and cathode, by a) providing a composition comprising the chlorinated organic compounds, a solvent, and a sacrificial electron donor, wherein the solvent can also function as the sacrificial electron donor, or the solvent and the sacrificial electron donor are two separate components, and b) conducting an electrochemical reaction to dechlorinate the chlorinated organic compounds into hydrocarbons and inorganic chlorides, characterized by alternating the polarity of the two electrodes every 1 to 1800 seconds, preferably every 1 to 300 seconds, even more preferably every 10 to 60 seconds, with both electrodes being graphite electrodes.

2. Method according to claim 1, wherein the composition additionally comprises an electrolyte, whereby the electrolyte can also function as the sacrificial electron donor.

3. Method according to any of the preceding claims, wherein the sacrificial electron donor is selected from the group consisting of Ci-C4-dialkylsulfoxides, Ce-Cio- diarylsulfoxides, Ci-C4-dialkenylsulfoxides, Ci-C4-dialkylsulfides, Ce-Cio- diarylsulfides, Ci-C4-dialkenylsulfides, Ci-C4-alkylcarboxylates, C1-C4- alkyl sulfinates, Ce-Cio-hydroxyaryls, Ci-C4-alkoxy-Ce-Cio-aryls, Ci-Ce-alkylamines, Ci-C4-N-alkoxy substituted amine, carbamate-protected amines, Ce-Cio-arylamines, Ci to C4-tertiary enamines, pyrroles, indoles, hydrazines comprising one to four C1-C4- alkyl or Ce-Cio-aryl residues, Ci-C4-alkylphosphines, Ce-Cio-arylphosphines, alkoxyphosphines and bisulfite salts.

4. Method according to any of the preceding claims, wherein the solvent is DMSO which also functions as the sacrificial electron donor.

5. Method according to any of the preceding claims, wherein the reaction is conducted in neat conditions.

6. Method according to any of claims 1 to 4, additionally comprising at least one co-solvent.

7. Method according to any of the preceding claims, wherein the chlorinated organic compounds comprise compounds selected from the group consisting of chlorinated organic compounds having one or more chlorine atoms, geminal trichlorides, geminal dichlorides, primary alkyl chlorides, aryl chlorides, and vicinal secondary alkyl chlorides.

8. Method according to any of the preceding claims, wherein the chlorinated organic compounds are selected from the group consisting of hexachlorocyclohexanes, toxaphene, mirex, chlordecone, methoxychlor, chlorinated paraffins, aldrin, chlordanes, heptachlor, cis dechlorane plus, trans dechlorane plus, dieldrin, endrin, endosulfan, hexachlorobutadiene, dichlorodiphenyltrichloroethane, pentachlorobenzene, pentachlorophenol, hexachlorobenzene, polychlorinated dibenzofurans, polychlorinated dibenzodioxins, polyhalogenated biphenyls, p,p’- dicofol, o,p’ -dicofol, polychlorinated naphthalenes, polyvinyl chloride (PVC), chlorinated poly(vinyl acetate), and chlorinated polyethylene (CPE).

9. Method according to any of the preceding claims, wherein a current of 1 mA to 100 kA is applied.

10. Method according to any of the preceding claims, wherein the pH is between 4 and 10, preferably between 7.5 and 10.

11. Method according to any of the preceding claims, wherein the solvent is DMSO which also acts as sacrificial electron donor, and the electrolyte, if present, is sodium chloride, lithium chloride, sodium formate, sodium pivalate, or a mixture thereof.

12. Method according to any of the preceding claims, wherein the composition to be treated is selected from the group consisting of soil, sediments, groundwater, sludge, absorbers, and plastic waste or an extract thereof.

13. Method according to any of the preceding claims, wherein the composition is soil contaminated with chlorinated organic compounds.

14. Method according to any of claims 1 to 13, wherein the composition is a filtrate obtained after extracting the chlorinated organic compounds using an extraction agent and subsequent filtration of soil contaminated with chlorinated organic compounds.

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