Patent Application
20140100363
A wide variety of potentially practical and useful embodiments will be more readily understood through the following detailed description of certain exemplary embodiments, with reference to the accompanying exemplary drawings in which:
Certain exemplary embodiments can provide a composition of matter comprising chlorine dioxide complexed with a cyclodextrin.
Chlorine dioxide (“ClO2”) can be an excellent disinfectant, and/or can be effective against a wide range of organisms. For example, ClO2 can provide excellent control of viruses and bacteria, as well as the protozoan parasites Giardia, Cryptosporidium, and/or amoeba Naegleria gruberi and their cysts.
In addition to disinfection, ClO2 can have other beneficial uses in water treatment, such as color, taste and odor control, and removal of iron and manganese. There are also important uses outside of water treatment, such as bleaching pulp and paper (its largest commercial use), disinfection of surfaces, and sanitization/preservation of fruits and vegetables.
ClO2 can present certain challenges, which can stem largely from its inherent physical and chemical instability. ClO2 in pure form is a gaseous compound under normal conditions. As a gas, it can be sensitive to chemical decomposition, exploding at higher concentrations and when compressed. Because ClO2 can be highly soluble in water, ClO2 can be used as a solution of ClO2 gas dissolved in water.
However, the gaseous nature of ClO2 means that it can be volatile, thus ClO2 tends to evaporate rapidly from solutions when open to the atmosphere (physical instability). This tendency can limit the practically useful concentrations of ClO2 solutions. With concentrated solutions, this rapid evaporation can generate gaseous ClO2 concentrations that can present an unpleasantly strong odor, and can pose an inhalation hazard to users. A closed container of the solution can quickly attain a concentration in the headspace of the container that is in equilibrium with the concentration in the solution. A high concentration solution can have an equilibrium headspace concentration that exceeds the explosive limits in air (considered to be approximately 10% by weight in air).
For these and other reasons, virtually all commercial applications to date have required that ClO2 be generated at the point of use to deal with these challenges. However, on-site generation also can have significant draw-backs, particularly in the operational aspects of the equipment and the need to handle and store hazardous precursor chemicals. It can be desirable to have additional forms of ready-made ClO2.
Certain exemplary embodiments can provide a composition of matter comprising a solid form of chlorine dioxide complexed with a cyclodextrin. When stored, a concentration of the chlorine dioxide in the composition of matter can be retained at, for example, greater than 12% for at least 14 days and/or greater than 90% for at least 80 days, with respect to an initial concentration of chlorine dioxide in said composition of matter. Certain exemplary embodiments can provide a method comprising releasing chlorine dioxide from a solid composition comprising chlorine dioxide complexed with a cyclodextrin.
Certain exemplary embodiments can provide a solid complex formed by combining ClO2 with a complexing agent such as a cyclodextrin, methods of forming the complex, and/or methods of using the complex as a means of delivering ClO2, such as essentially instantly delivering ClO2.
ClO2 is widely considered to be inherently unstable. Also, ClO2 is widely considered to be reactive with a fairly wide range of organic compounds, including glucose, the basic building block of cyclodextrins such as alpha-cyclodextrin. It is reasonable to assume that ClO2 will react with cyclodextrins in solution. Additionally, relatively impure ClO2 systems containing chlorite and/or chlorate impurities might be expected to destroy cyclodextrins due to the reactivity of chlorite/chlorate with organic compounds.
Chlorine dioxide can be generated by the method described in the OxyChem Technical Data Sheet “Laboratory Preparations of Chlorine Dioxide Solutions—Method II: Preparation of Reagent-Grade Chlorine Dioxide Solution”. Nitrogen has generally been used in our laboratory as the stripping and diluting gas, but it is expected that any inert gas can be used. It is believed that the combined ClO2/nitrogen gas stream can be used in any convenient concentration between 0% and the explosive limit.
That method specifies the following equipment and reagents:
That method specifies, inter alia, the following procedure:
We have unexpectedly discovered that, by bubbling sufficiently pure gaseous ClO2 diluted in nitrogen (as generated by this method) at a rate of, for example, approximately 100 ml/minute to approximately 300 ml/minute, through a near-saturated solution of alpha-cyclodextrin (approximately 11% to approximately 12% w/w) in place of plain water, at or below room temperature, a solid precipitate formed. The minimum ClO2 concentration required to obtain the solid precipitate lies somewhere in the range of approximately 500 ppm to approximately 1500 ppm. A 1:1 molar ratio of ClO2 to cyclodextrin—approximately 7600 ppm ClO2 for approximately 11% alpha-cyclodextrin—is presumed to be needed in order to complex all the alpha-cyclodextrin. We believe that the use of even more ClO2 will maximize the amount of precipitate that forms. Precipitation may begin before ClO2 addition is complete, or may take up to approximately 2 to approximately 3 days, depending on the amount of ClO2 added and the temperature of the system.
Another method of preparing this solid material is as follows. A solution of alpha-cyclodextrin is prepared. That solution can be essentially saturated (approximately 11%). A separate solution of ClO2 can be prepared by the method referenced above, potentially such that it is somewhat more concentrated than the alpha-cyclodextrin solution, on a molar basis. Then the two solutions can be combined on approximately a 1:1 volume basis and mixed briefly to form a combined solution. Concentrations and volumes of the two components can be varied, as long as the resultant concentrations in the final mixture and/or combined solution are sufficient to produce the precipitate of the complex. The mixture and/or combined solution then can be allowed to stand, potentially at or below room temperature, until the precipitate forms. The solid can be collected by an appropriate means, such as by filtration or decanting. The filtrate/supernatant can be chilled to facilitate formation of additional precipitate. A typical yield by this unoptimized process, after drying, can be approximately 30 to approximately 40% based on the starting amount of cyclodextrin. The filtrate/supernatant can be recycled to use the cyclodextrin to fullest advantage.
The collected precipitate then can be dried, such as in a desiccator at ambient pressure, perhaps using Drierite desiccant. It has been found that the optimum drying time under these conditions is approximately 24 hours. Shorter drying times under these conditions can leave the complex with unwanted free water. Longer drying times under these conditions can result in solid containing a lower ClO2 content.
Since we have observed that the residence time of the complex in a desiccating chamber has a distinct effect on the resulting ClO2 content of the dried complex, it is expected that the use of alternate methods of isolating and/or drying the complex can be employed to alter yield rates and obtain a ClO2 cyclodextrin complex with specific properties (stability, ClO2 concentration, dissolution properties, etc.) suitable for a particular application. Lyophilization and spray-drying are examples of these kinds of alternate methods, which can dry the precipitated complex, and/or isolate the complex as a dry solid from solution-phase complex, and/or from the combined precipitate/solution mixture.
Based on methods used to form other complexes with cyclodextrins, it is believed that any of several additional methods could be utilized to form the ClO2 cyclodextrin complex. Slurry complexation, paste complexation, solid phase capture, and co-solvent systems are examples of additional preparatory options. In one unoptimized example of a modified slurry process, 11 g of solid alpha-cyclodextrin was added directly to a 100 g solution of 7800 ppm ClO2 and mixed overnight. While a majority of the cyclodextrin went into solution, approximately 20% of the powder did not. This was subsequently found to have formed a complex with ClO2 that upon isolation, contained approximately 0.8% ClO2 by weight. In one unoptimized example of a solid phase capture process, ClO2 gas was generated by the method described in the OxyChem Technical Data Sheet. The ClO2 from the reaction was first passed through a chromatography column packed with a sufficient amount of Drierite to dry the gas stream. Following this drying step, 2.0 g of solid alpha-cyclodextrin was placed in-line and exposed to the dried ClO2 in the vapor phase for approximately 5 hours. The alpha-cyclodextrin was then removed, and found to have formed a complex with ClO2 containing approximately 0.75% ClO2 by weight.
This precipitate is assumed to be a ClO2/alpha-cyclodextrin complex. Cyclodextrins are known to form complexes or “inclusion compounds” with certain other molecules, although for reasons presented above it is surprising that a stable complex would form with ClO2. Such a complex is potentially characterized by an association between the cyclodextrin molecule (the “host”) and the “guest” molecule which does not involve covalent bonding. These complexes are often formed in a 1:1 molecular ratio between host and guest, but other ratios are possible. One portion of this putative ClO2/alpha-cyclodextrin complex has been subjected to X-ray crystallography. The results of this study indicate a regular crystalline array in which one ClO2 molecule occupies the cavity of each cyclodextrin molecule, in said 1:1 molecular ratio.
There are a number of reaction conditions that affect the process leading to the formation of the complex. Any of these conditions can be optimized to enhance the yield and/or purity of the complex. Several of these conditions are discussed below.
The pH at which the complexation takes place between ClO2 and cyclodextrin has been observed to affect the yield and ClO2 content of the resulting ClO2 complex. Therefore, this parameter might affect the stability and/or properties of the resulting complex. An approximately 11% alpha-cyclodextrin solution was combined with an approximately 9000 ppm ClO2 solution on a 1:1 molar basis and the pH immediately adjusted from approximately 3.5 to approximately 6.7 with approximately 10% NaOH. A control was set up in the same fashion with no pH adjustment after combining the approximately 11% cyclodextrin and approximately 9000 ppm ClO2 solution. The resulting yield of the pH adjusted preparation was approximately 60% lower than the control and had approximately 20% less ClO2 content by weight.
The temperature at which the complexation takes place between ClO2 and cyclodextrin has been observed to affect the yield and ClO2 content of the resulting ClO2 complex. Therefore, this parameter might affect the stability and/or properties of the resulting complex. An approximately 11% alpha-cyclodextrin solution was combined with an approximately 7800 ppm ClO2 solution on a 1:1 molar basis in 2 separate bottles. One of these was placed in a refrigerator at approximately 34° F. and the other was left at room temperature. Upon isolation and substantial dry down of the resulting complexes, the refrigerated preparation produced approximately 25% more complex by weight and a lower ClO2 concentration.
The stirring rate and/or level of agitation during the formation of a ClO2 cyclodextrin complex has been observed to affect the yield and ClO2 content of the resulting ClO2 complex. Therefore, this parameter might affect the stability and/or properties of the resulting complex. An approximately 11% alpha-cyclodextrin solution was combined with an approximately 7800 ppm ClO2 solution on a 1:1 molar basis in 2 separate bottles. One of the bottles was placed on a magnetic stir plate at approximately 60 rpm, while the other remained undisturbed. After approximately 5 days, the precipitated complex from each was isolated and dried down. The preparation that was stirred resulted in an approximately 20% lower yield and approximately 10% lower ClO2 concentration by weight.
The addition of other compounds to the complexation mixture has been observed to affect the yield and/or ClO2 content of the resulting ClO2 complex. Therefore, the use of additives in the preparation process might affect the stability and/or properties of the resulting complex and/or lead to a ClO2 complex with properties tailored to a specific application. For example, we have found that very low concentrations of water soluble polymers (approximately 0.1% w/v), such as polyvinylpyrrolidone and carboxymethylcellulose, have resulted in ClO2 concentrations higher and lower, respectively, than that observed in a control preparation containing only cyclodextrin and ClO2. In both cases however, the yield was approximately 10% lower than the control. In another example, we found that the addition of approximately 0.5% acetic acid to the complexation mixture resulted in approximately 10% higher yield and approximately 40% lower ClO2 content.
When isolated and dried, the resulting solid typically has a granular texture, appears somewhat crystalline, with a bright yellow color, and little or no odor. It can be re-dissolved in water easily, and the resulting solution is yellow, has an odor of ClO2, and assays for ClO2. The ClO2 concentration measured in this solution reaches its maximum as soon as all solid is dissolved, or even slightly before. The typical assay method uses one of the internal methods of the Hach DR 2800 spectrophotometer designed for direct reading of ClO2. The solution also causes the expected response in ClO2 test strips such as those from Selective Micro Technologies or LaMotte Company. If a solution prepared by dissolving this complex in water is thoroughly sparged with N2 (also known as Nitrogen or N2), the solution becomes colorless and contains virtually no ClO2 detectable by the assay method. The sparged ClO2 can be collected by bubbling the gas stream into another container of water.
One sample of the dried solid complex was allowed to stand in an uncovered container for approximately 30 hours before being dissolved in water, and appeared to have lost none of its ClO2 relative to a sample that was dissolved in water immediately after drying. Four portions from one batch of solid complex left in open air for periods of time ranging from approximately 0 to approximately 30 hours before being re-dissolved in water all appeared to have approximately the same molar ratio of ClO2 to alpha-cyclodextrin. Other batches appeared to have somewhat different ratios of ClO2 to alpha-cyclodextrin. This difference may simply reflect differences in sample dryness, but it is known that cyclodextrin-to-guest ratios in other cyclodextrin complexes might vary with differences in the process by which the complex was formed. However, samples of the present complex prepared by an exemplary embodiment tended to contain close to, but to date not greater than, a 1:1 molar ratio of ClO2 to cyclodextrin. That is, their ClO2 content approached the theoretical limit for a 1:1 complex of approximately 6.5% by weight, or approximately 65,000 ppm, ClO2. Assuming that a 1:1 molar ratio represents the ideal form of the pure complex, the ratio of ClO2 to cyclodextrin can be targeted as close to 1:1 as possible, to serve as an efficient ClO2 delivery vehicle. However, solid complexes with a net ClO2 to cyclodextrin ratio of less than 1:1 can be desirable in some cases. (We believe such a material is probably a mixture of 1:1 complex plus uncomplexed cyclodextrin, not a complex with a molar ratio of less than 1:1.)
An aqueous solution of ClO2 having such a high concentration (e.g., approaching approximately 65,000 ppm) can pose technical and/or safety challenges in handling, such as rapid loss of ClO2 from the solution into the gas phase (concentrated and therefore a human exposure risk), and/or potentially explosive vapor concentrations in the headspace of a container in which the solution is contained. The solid appears not to have these issues. Release into the gas phase is relatively slow, posing little exposure risk from the complex in open air. The lack of significant odor can be an important factor in the users' sense of safety and/or comfort in using the solid. For example, a small sample has been left in the open air for approximately 72 hours, with only an approximately 10% loss of ClO2. At such a slow rate, users are unlikely to experience irritation or be caused to feel concern about exposure. Gas-phase ClO2 concentration in the headspace of a closed container of the complex can build up over time, but appears not to attain explosive concentrations. Even solid complex dampened with a small amount of water, so that a “saturated” solution is formed, to date has not been observed to create a headspace ClO2 concentration in excess of approximately 1.5% at room temperature. It is commonly believed that at least a 10% concentration of ClO2 in air is required for explosive conditions to exist.
The freshly-prepared complex is of high purity, since it is obtained by combining only highly pure ClO2 prepared by OxyChem Method II, cyclodextrin, and water. Some cyclodextrins are available in food grade, so the complex made with any of these is suitable for treatment of drinking water and other ingestible materials, as well as for other applications. Other purity grades (technical, reagent, pharmaceutical, etc.) of cyclodextrins are available, and these could give rise to complexes with ClO2 that would be suitable for still other applications.
In certain embodiments, the solid complex can be quickly and conveniently dissolved directly in water that is desired to be treated. Alternatively, the solid can be dissolved, heated, crushed, and/or otherwise handled, processed, and/or treated to form, and/or release from the solid, a solution, such as an aqueous chlorine dioxide solution, and/or another form of ClO2, such as a ClO2 vapor, that then can be used for disinfecting surfaces, solids, waters, fluids, and/or other materials. For example, solutions of ClO2 prepared by dissolving the complex in water, either the water to be treated or an intermediate solution, can be used for any purpose known in the art for which a simple aqueous solution of comparable ClO2 concentration would be used, insofar as this purpose is compatible with the presence of the cyclodextrin. These uses can include disinfection and/or deodorization and/or decolorization of: drinking water, waste water, recreational water (swimming pools, etc.), industrial reuse water, agricultural irrigation water, as well as surfaces, including living tissues (topical applications) and foods (produce, meats) as well as inanimate surfaces, etc.
It is anticipated that the complex can be covalently bound, via the cyclodextrin molecule, to another substrate (a polymer for example) for use in an application where multiple functionality of a particular product is desired. For example, such a complex bound to an insoluble substrate can, upon contact with water, release its ClO2 into solution while the cyclodextrin and substrate remain in the solid phase.
It has been found that this solid complex ordinarily experiences a slow release of ClO2 gas into the air. Conditions can be selected such that the concentration level of the ClO2 released into the air is low enough to be safe (a condition suggested by the lack of conspicuous odor) but at a high enough concentration to be efficacious for disinfection and/or odor control in the air, and/or disinfection of surfaces or materials in contact with the air.
The solid complex can release ClO2 directly, via the gas phase, and/or via moisture that is present, into other substances. The solid can be admixed with such substances, such as by mixing powdered and/or granular solid complex with the other substances in powdered and/or granular form. The solid complex can be applied to a surface, such as skin and/or other material, either by “rubbing in” a sufficiently fine powder of the complex, and/or by holding the solid complex against the surface mechanically, as with a patch and/or bandage. The substance receiving the ClO2 from the complex can do so as a treatment of the substance and/or the substance can act as a secondary vehicle for the ClO2.
In some instances, the complex can impart different and/or useful reactivity/properties to ClO2. By changing its electronic and/or solvation environment, the reactivity of complexed ClO2 will almost certainly be quantitatively, and perhaps qualitatively, different.
Early indications are that ClO2 retention can be greatly enhanced by cold storage.
The solid complex can be packaged and/or stored in a range of forms and packages. Forms can include granulations/powders essentially as recovered from the precipitation process. The initially obtained solid complex can be further processed by grinding and/or milling into finer powder, and/or pressing into tablets and/or pucks and/or other forms known to the art. Other materials substantially unreactive toward ClO2 can be combined with the solid complex to act as fillers, extenders, binders, and/or disintegrants, etc.
Suitable packages are those that can retain gaseous ClO2 to a degree that provides acceptable overall ClO2 retention, consistent with its inherent stability, as discussed above, and/or that provide adequate protection from moisture. Suitable materials to provide high ClO2 retention can include glass, some plastics, and/or unreactive metals such as stainless steel. The final form of the product incorporating the solid complex can include any suitable means of dispensing and/or delivery, such as, for example, enclosing the solid in a dissolvable and/or permeable pouch, and/or a powder/solid metering delivery system, and/or any other means known in the art.
Other Cyclodextrins:
Most of the above material relates to alpha-cyclodextrin and the complex formed between it and ClO2. This is the only ClO2/cyclodextrin complex yet isolated. We believe that beta-cyclodextrin may form a complex with ClO2, which techniques readily available to us have not been able to isolate. Whereas the complex with alpha-cyclodextrin is less soluble than alpha-cyclodextrin alone, leading to ready precipitation of the complex, it may be that the ClO2/beta-cyclodextrin complex is more soluble than beta-cyclodextrin alone, making isolation more difficult. Such solubility differences are known in the art surrounding cyclodextrin complexes. Techniques such as freeze-drying may be able to isolate the complex in the future.
However indirect evidence for the complex has been observed. Beta-cyclodextrin has a known solubility in water. If the water contains a guest substance that produces a cyclodextrin complex more soluble than the cyclodextrin alone, more of the cyclodextrin will dissolve into water containing that guest than into plain water. This enhanced solubility has been observed for beta-cyclodextrin in water containing ClO2. Two separate 100 g slurries of beta-cyclodextrin solutions were prepared. The control solution contained 5% beta-cyclodextrin (w/w) in ultrapure water, and the other contained 5% beta-cyclodextrin (w/w) in 8000 ppm ClO2. Both slurries were mixed at 200 rpm for 3 days, at which time the undissolved beta-cyclodextrin was isolated from both solutions and dried for 2 days in a desiccator. The weight of the dried beta-cyclodextrin from the ClO2 containing slurry was 0.32 g less than the control slurry indicating that a soluble complex might exist between the beta-cyclodextrin and ClO2 in solution. It is believed, by extension, that ClO2 might form complexes with gamma-cyclodextrin and/or chemically derivatized versions of the natural (alpha- (“α”), beta- (“β”), and gamma- (“γ”)) cyclodextrins. In the case of beta- and/or gamma-cyclodextrin and/or other cyclodextrins having internal cavities larger than that of alpha-cyclodextrin, it might be that the complex(es) formed with ClO2 will incorporate numbers of ClO2 molecules greater than one per cyclodextrin molecule.
Related Inclusion Complex Formers:
It is expected by extension of the observed cyclodextrin complexes that some other molecules known to form inclusion compounds will also complex ClO2. In particular, cucurbiturils are molecules known primarily for having ring structures that accommodate smaller molecules into their interior cavities. These interior cavities are of roughly the same range of diameters as those of the cyclodextrins. It is anticipated that combining the appropriate cucurbituril(s) and ClO2 under correct conditions will produce cucurbituril/ClO2 complex(es), whose utility can be similar to that of cyclodextrin/ClO2 complexes.
ClO2 generated by the OxyChem Method II referenced above was bubbled as a stream mixed with nitrogen, at a rate of approximately 100-300 ml per minute, into an approximately 120 mL serum bottle containing approximately 100 g of approximately 11% (by weight) alpha-cyclodextrin solution at RT. Precipitation of the complex was observed to begin within approximately 1 hour, with ClO2 ultimately reaching a concentration of approximately 7000 ppm or more in the solution. Precipitation occurred very rapidly, and over the course of approximately 10 minutes enough complex was formed to occupy a significant volume of the bottle. The bottle was capped and placed in the refrigerator to facilitate further complex formation. After approximately 1 week the solid was removed from the solution onto filter paper and dried in a desiccator with Drierite for approximately 4 days. Yield was approximately 50% (by weight of starting cyclodextrin), and ClO2 concentration in the complex was approximately 1.8%.
The general method used was as follows. See
Other experiments showed a wide variety in initial ClO2 concentrations in freshly prepared complex. For example, in several experiments, complex formed by the combining solutions approach yielded ClO2 concentrations such as 1.8% and 0.9%. In other experiments, complex formed by the generation method in which the ClO2 was captured in an ice-chilled cyclodextrin solution yielded 0.2% ClO2.
Additional experiments at room temperature resulted in a wide variety of ClO2 retention results. For example, when complex formed by the combining solutions approach was sealed in approximately 10 ml vials with a nitrogen blanket, approximately 56% of the original ClO2 concentration was retained after 35 days, and approximately 31% was retained after 56 days. As another example, when complex formed by the generation method was left open to the air in a dark storage area, approximately 42% of the original ClO2 concentration was retained after 35 days, and approximately 25% was retained after 56 days. As yet another example, when complex formed by the generation method was sealed in approximately 10 ml clear glass vials with a nitrogen blanket and stored under white fluorescent light, approximately 13% of the original ClO2 concentration was retained after 14 days. As still another example, when complex formed by the generation method was stored in an approximately 2 ounce jar covered with Parafilm, approximately 6% of the original ClO2 concentration was retained after 59 days.
Further experiments at refrigerator temperature (approximately 1 degree C.) also resulted in a wide variety of ClO2 retention results with respect to the original ClO2 concentration, including 91% after 30 days, 95% after 85 days, and 100% after 74 days.
It is believed that uncomplexed cyclodextrin can be present in the product due to 1) co-precipitation of uncomplexed cyclodextrin along with the complex, and/or 2) loss of ClO2 from a portion of the complex. It is believed that loss of ClO2 from the complex can occur more rapidly when the complex is wet. Thus, drying the complex rapidly, under the correct conditions, might help increase the amount of ClO2 retained in the complex.
To test these beliefs, an alternative method can be conducted as follows: A laboratory scale ClO2 generator can provide a gaseous stream of ClO2 in nitrogen. The gaseous stream can be bubbled into 500 g of an aqueous solution of α-cyclodextrin (from approximately 5% to approximately 12% by weight). This method has been conducted at room temperature, but also can be performed at any reduced temperature above the freezing point of the solution. The cyclodextrin solution can be agitated throughout the ClO2 injection period by mixing with an approximately 45 mm diameter disperser blade attached to an overhead laboratory stirrer, operating at approximately 600 rpm. After approximately 45 minutes, and/or as the ClO2 concentration in the cyclodextrin solution reaches approximately 6000-7000 ppm, the product complex can begin to precipitate. Usually within approximately 30 minutes of commencement of heavy precipitation the reaction is complete. The precipitate can be isolated at once, or the slurry of precipitate can be stored for separation later.
The precipitate can be isolated by vacuum filtration. After the filter cake has reached the consistency of a dry paste, the product can be washed with a solvent in which water is soluble, but in which the product is not appreciably soluble. For example, the product filter cake can be transferred to a screw cap bottle containing approximately 400 ml of acetone. (We have found that ethanol also gives acceptable results, and reasonably predict that solvents that can dissolve substantial quantities of water (preferably miscible with water), don't dissolve appreciable amounts of the product complex, and/or evaporate completely relatively quickly (generally having a boiling point≦80° C.), such as any of methanol, isopropanol, n-propanol, t-butanol, methyl ethyl ketone, acetonitrile, diethyl ether, 1,2-dimethoxy-ethane, ethyl acetate, and/or tetrahydrofuran might also give acceptable results.) The bottle can be shaken on a laboratory bench top shaker for approximately 10 minutes at a setting high enough to achieve a vigorous mix. Once again vacuum filtration can be used to isolate the solid. When the filter cake is free of excess solvent, an additional approximately 50 ml of fresh acetone can be added and pulled through. Vacuum can be pulled through the filter cake until the odor of acetone is no longer discernable. The product thus obtained generally can be found to be dry to the desired degree.
This method of product isolation and drying by solvent washing can be preferred on the basis of brevity. However, it is believed that other means of drying the product beneficially can be used instead of or in conjunction with the solvent washing and vacuum filtration method. For example, the product obtained before or after solvent washing might be freeze dried, or it might be dried in a desiccator with a drying agent such as Drierite, at atmospheric pressure and room temperature, and/or under vacuum refrigeration.
The degree of dryness can be determined by a heated weight loss test. Before heating, an approximately 0.4 g portion of the solid can be weighed. Then, the portion can be heated in a suitable heatproof dish in a muffle furnace at approximately 125° C. for approximately 30 minutes (meaning that the ambient temperature in the furnace is 125° C. when the product is placed in the furnace and that ambient temperature is held at 125° C. for the entirety of that 30 minutes). Then, after cooling in a desiccator to approximately room temperature, the sample can be re-weighed. The weight loss can be in the range of approximately 9 to approximately 15.5%, such as in the range of approximately 9 to approximately 12%. If the weight loss is higher than approximately 12%, the product can be further dried by additional solvent washing and/or by drying in a desiccator with a drying agent such as Drierite.
The resulting product can be a yellow powder, similar in character to that obtained by other processes described herein, although it can contain a significantly higher ClO2 concentration. This powder can be relatively fine in texture, can dry relatively rapidly and thoroughly, can dissolve relatively rapidly in water (which can provide for rapid release and availability of ClO2), and/or can be relatively amenable to tableting or other bulk forming operations.
In addition to being stored, transported, and/or used as is, the product can be combined with beneficial additives. In particular, it is believed that the product can be combined with a range of beneficial additives that are also in solid form, by simply dry-blending the product with the solid additive, where the solid additive has a suitable powder/granular form. These can be additives which enhance the aesthetics of the product as is or in use, such as colorants and/or powder flow-control agents, or which add secondary performance benefits, such as cleaning agents, rheology-modifiers, etc. In many cases these additives can be substantially incompatible with ClO2 if combined in aqueous solution. However, such combinations of solids can provide little opportunity for the ClO2 to interact with the additives, due to the absence of any common medium (solvent) in which the two can commingle and interact, resulting in effectively compatible mixtures.
The product also can be combined with beneficial additives that are normally liquids. Liquid additives that are compatible with ClO2 can be directly mixed with the product by known methods. Liquid additives that are normally incompatible with ClO2 can cause mutual destruction if mixed directly with the product. However, these additives can be combined with the product with greater compatibility if complexed, adsorbed, absorbed, or otherwise disposed in a solid medium, including complexation in cyclodextrins, prior to dry-blending with the product. Such additives can be those that enhance the aesthetics of the product as is and/or in use, such as colorants and/or fragrance materials, and/or that add secondary performance benefits, such as cleaning agents, rheology-modifiers, etc.
The product can be sensitive to light. To protect it from degradation by light, the product can be: stored in the dark, stored in packaging that protects it from short wavelength light, such as light below 500 nm, and/or combined with suitable “UV absorbers” and/or “UV blockers” that are effective in the proper wavelength range, such as, for example:
This alternative method can follow the OxyChem method described herein, such as beginning at paragraph 16 and/or illustrated in
ClO2 was generated by the alternative method described above and bubbled as a stream mixed with nitrogen, at a rate of approximately 250 mL per minute into a 1 L reaction kettle. The kettle was placed in an ice bath and contained approximately 500 g of approximately 11.5% (by wt) alpha-cyclodextrin. The cyclodextrin solution was agitated throughout the ClO2 injection period by mixing with an approximately 45 mm diameter disperser blade attached to an overhead laboratory stirrer, operating at approximately 600 rpm. Precipitation of the product complex began approximately 40 minutes after the onset of ClO2 generation and at a ClO2 concentration of approximately 4500 ppm. Generation of ClO2 was continued for approximately 10 minutes beyond the onset of precipitation of the product complex. The slurry of precipitate was quickly transferred to a 500 mL bottle and placed into a refrigerator. The bottle of precipitated product was removed from the refrigerator after approximately 3 hours and then the precipitate was collected on a filter paper using vacuum filtration and dried to a dry paste. One portion (1A) of the product was then placed into a 250 mL bottle containing approximately 200 mL of cold acetone and capped, while the other portion (1B) was placed into a 250 mL bottle containing approximately 200 mL of cold ethanol and capped. Both bottles were placed on a laboratory shaker for approximately 10 minutes of vigorous mixing. In both cases the majority of the product was insoluble in the solvent. Vacuum filtration was then used to remove the bulk of the acetone from the product complex 1A in that bottle, followed by two additional washes with approximately 50 mL of fresh acetone. The filtration was continued until no acetone odor was detectable over the dried product. The same vacuum filtration procedure was then applied to the product 1B in the ethanol bottle as well, using ethanol for the additional washes with fresh solvent. Heating the acetone dried product 1A to approximately 125° C. for approximately 30 minutes showed a weight loss of approximately 11%. The ClO2 concentration was approximately 5.8% (by wt). The ethanol dried product 1B showed a weight loss of approximately 12% and had a ClO2 concentration of approximately 6.3% (by wt).
ClO2 was generated as in Experiment 1 above and bubbled into a 1 L reaction kettle containing approximately 500 g of approximately 11.5% (by wt) alpha-cyclodextrin in an ice bath. Agitation was provided as in Experiment 1. Precipitation of the product complex began approximately 35 minutes after the onset of ClO2 generation and at a ClO2 concentration of approximately 6500 ppm. Generation of ClO2 was continued for approximately 10 minutes beyond the onset of precipitation of the product complex. The slurry of precipitate was immediately vacuum filtered to a dry paste. The product was then dried using the procedure described in Experiment 1 above using both acetone and ethanol. Heating the acetone dried product (2A) to approximately 125° C. for approximately 30 minutes showed a weight loss of approximately 12.8%. The ClO2 concentration was approximately 5.94% (by wt). The ethanol dried product (2B) showed a weight loss of approximately 13.5% and had a ClO2 concentration of approximately 6.2% (by wt).
ClO2 was generated as in Experiments 1 and 2 above and bubbled into a 1 L reaction kettle containing approximately 500 g of approximately 11.5% (by wt) alpha-cyclodextrin, with the same mode of agitation. For this experiment, the reaction kettle was not placed in an ice bath, so the product was formed at room temperature. Precipitation of the product complex began approximately 40 minutes after the onset of ClO2 generation and at a ClO2 concentration of approximately 7500 ppm. Generation of ClO2 was continued for approximately 25 minutes beyond the onset of precipitation of the product complex. The slurry of precipitate was immediately vacuum filtered to a dry paste. The product was then dried using the procedure described in Experiments 1 and 2 above, except that approximately 380 mL of acetone was used and the solvent was at room temperature. Heating the acetone dried product to approximately 125° C. for approximately 30 minutes showed a weight loss of approximately 15%. The ClO2 concentration was approximately 6.3% (by weight).
ClO2 was generated as in Experiments 1, 2, and 3 above, and bubbled into a 1 L reaction kettle containing approximately 500 g of approximately 11.5% (by wt) alpha-cyclodextrin, with the same mode of agitation. As in Experiment 3 above, the reaction kettle was not placed in an ice bath. Precipitation of the product complex began approximately 45 minutes after onset of ClO2 generation and at a ClO2 concentration of approximately 7800 ppm. Generation of ClO2 was continued for approximately 20 minutes beyond the onset of precipitation of the product complex. The product was then dried using the procedure described in Experiments 1, 2, and 3 above, except that approximately 460 mL of acetone was used and the solvent was at room temperature. Heating the acetone dried product to approximately 125° C. for approximately 30 minutes showed a weight loss of approximately 15.4%. The product complex was then placed in a dessicator for additional drying for approximately 16 hours in a refrigerator. Heating the acetone dried product to approximately 125° C. for approximately 30 minutes showed a weight loss of approximately 11.2%. The ClO2 concentration was approximately 6.5% (by weight).
The alternative method can result in:
When the following terms are used substantively herein, the accompanying definitions apply. These terms and definitions are presented without prejudice, and, consistent with the application, the right to redefine these terms during the prosecution of this application or any application claiming priority hereto is reserved. For the purpose of interpreting a claim of any patent that claims priority hereto, each definition (or redefined term if an original definition was amended during the prosecution of that patent), functions as a clear and unambiguous disavowal of the subject matter outside of that definition.
Various substantially and specifically practical and useful exemplary embodiments of the claimed subject matter are described herein, textually and/or graphically, including the best mode, if any, known to the inventor(s), for implementing the claimed subject matter by persons having ordinary skill in the art. Any of numerous possible variations (e.g., modifications, augmentations, embellishments, refinements, and/or enhancements, etc.), details (e.g., species, aspects, nuances, and/or elaborations, etc.), and/or equivalents (e.g., substitutions, replacements, combinations, and/or alternatives, etc.) of one or more embodiments described herein might become apparent upon reading this document to a person having ordinary skill in the art, relying upon his/her expertise and/or knowledge of the entirety of the art and without exercising undue experimentation. The inventor(s) expects skilled artisans to implement such variations, details, and/or equivalents as appropriate, and the inventor(s) therefore intends for the claimed subject matter to be practiced other than as specifically described herein. Accordingly, as permitted by law, the claimed subject matter includes and covers all variations, details, and equivalents of that claimed subject matter. Moreover, as permitted by law, every combination of the herein described characteristics, functions, activities, substances, and/or structural elements, and all possible variations, details, and equivalents thereof, is encompassed by the claimed subject matter unless otherwise clearly indicated herein, clearly and specifically disclaimed, or otherwise clearly contradicted by context.
The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate one or more embodiments and does not pose a limitation on the scope of any claimed subject matter unless otherwise stated. No language herein should be construed as indicating any non-claimed subject matter as essential to the practice of the claimed subject matter.
Thus, regardless of the content of any portion (e.g., title, field, background, summary, description, abstract, drawing figure, etc.) of this document, unless clearly specified to the contrary, such as via explicit definition, assertion, or argument, or clearly contradicted by context, with respect to any claim, whether of this document and/or any claim of any document claiming priority hereto, and whether originally presented or otherwise:
The use of the terms “a”, “an”, “said”, “the”, and/or similar referents in the context of describing various embodiments (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.
The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted.
When any number or range is described herein, unless clearly stated otherwise, that number or range is approximate. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value and each separate subrange defined by such separate values is incorporated into the specification as if it were individually recited herein. For example, if a range of 1 to 10 is described, that range includes all values therebetween, such as for example, 1.1, 2.5, 3.335, 5, 6.179, 8.9999, etc., and includes all subranges therebetween, such as for example, 1 to 3.65, 2.8 to 8.14, 1.93 to 9, etc.
When any phrase (i.e., one or more words) appearing in a claim is followed by a drawing element number, that drawing element number is exemplary and non-limiting on claim scope.
No claim of this document is intended to invoke paragraph six of 35 USC 112 unless the precise phrase “means for” is followed by a gerund.
Any information in any material (e.g., a United States patent, United States patent application, book, article, etc.) that has been incorporated by reference herein, is incorporated by reference herein in its entirety to its fullest enabling extent permitted by law yet only to the extent that no conflict exists between such information and the other statements and drawings set forth herein. In the event of such conflict, including a conflict that would render invalid any claim herein or seeking priority hereto, then any such conflicting information in such material is specifically not incorporated by reference herein.
Within this document, and during prosecution of any patent application related hereto, any reference to any claimed subject matter is intended to reference the precise language of the then-pending claimed subject matter at that particular point in time only.
Accordingly, every portion (e.g., title, field, background, summary, description, abstract, drawing figure, etc.) of this document, other than the claims themselves and any provided definitions of the phrases used therein, is to be regarded as illustrative in nature, and not as restrictive. The scope of subject matter protected by any claim of any patent that issues based on this document is defined and limited only by the precise language of that claim (and all legal equivalents thereof) and any provided definition of any phrase used in that claim, as informed by the context of this document.
This application claims priority to, and incorporates by reference herein in its entirety, pending U.S. Provisional Patent Application 61/346,112 (Attorney Docket 1009-037), filed 19 May 2010.
| Number | Date | Country | |
|---|---|---|---|
| 61346112 | May 2010 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13111083 | May 2011 | US |
| Child | 14104123 | US |
