Prior art — US Patent 8546449

Most Relevant Prior Art for US Patent 8546449

This section identifies and analyzes the most relevant patent prior art cited against US patent 8546449, focusing on its potential to anticipate claims under 35 U.S.C. § 102. The analysis includes the full citation, publication/filing date, a brief description of the prior art, and specific claims of US8546449 that it potentially anticipates. The claims of US8546449 generally relate to methods for generating non-equilibrium peracetic acid (PAA) solutions on-site using a hydrogen peroxide-acetyl precursor solution and a strong alkali, or solid peroxygen bleaching and stain removal compositions.

1. U.S. Patent No. 3,432,546

Full Citation: US3432546A, "Process for producing peracetic acid", Hohn et al., published March 11, 1969.
Publication/Filing Date: Published March 11, 1969.
Brief Description: This patent discloses a continuous process for producing peracetic acid by reacting hydrogen peroxide with acetic anhydride in a tubular reactor in the presence of an ammonium hydroxide catalyst. The process aims to achieve high conversion rates and product concentrations suitable for cellulosic bleaching. The process can generate up to 3.25% PAA with 78% hydrogen peroxide conversion, but also produces diacetyl peroxide as an explosion hazard and uses ammonium hydroxide, which is an undesirable contaminant for food applications.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Preamble): These claims describe methods for "continuously or intermittently generating a non-equilibrium solution of peracetic acid on a site having a point-of-use of peracetic acid for use as a disinfectant or sanitizer". While US3432546A describes a continuous process for producing PAA, it is not explicitly focused on "point-of-use" generation for "disinfectant or sanitizer" purposes, but rather for "bleaching cellulosic materials". However, the concept of continuous generation of PAA is disclosed.
- Claims 1(e) and 15(e) (Alkali Catalyst): These claims specify introducing "an aqueous source of an alkali metal or earth alkali metal hydroxide... having a concentration of at least 45% by weight." US3432546A utilizes ammonium hydroxide as a catalyst. While ammonium hydroxide is an alkali, it is not an "alkali metal or earth alkali metal hydroxide" and its concentration is not specified as "at least 45% by weight". Therefore, these specific elements are likely not anticipated.
- Claims 1(b) and 15(b) (Hydrogen Peroxide-Acetyl Precursor Solution): These claims define a "hydrogen peroxide-acetyl precursor solution" comprising aqueous hydrogen peroxide, a liquid acetyl precursor soluble in aqueous hydrogen peroxide, trace PAA, and water. US3432546A reacts hydrogen peroxide directly with acetic anhydride, implying the formation of PAA in situ but not necessarily starting with a pre-mixed "hydrogen peroxide-acetyl precursor solution" as defined, nor with a liquid acetyl precursor that is soluble in aqueous hydrogen peroxide (acetic anhydride reacts, it dissolves, but the formulation prior to reaction is different).
- Claims 1(f) and 15(f) (Non-equilibrium solution composition): These claims describe the resultant non-equilibrium solution. US3432546A produces a PAA solution, which would inherently be non-equilibrium when generated on demand, but the specific components and their "non-equilibrium concentrations" might differ. The presence of diacetyl peroxide in US3432546A is a distinguishing factor.

2. U.S. Patent No. 5,122,538

Full Citation: US5122538A, "Process for the preparation of peracetic acid solutions", Kitko, published June 16, 1992.
Publication/Filing Date: Published June 16, 1992.
Brief Description: This patent describes a method for generating non-equilibrium PAA at its point-of-use by reacting acetic acid (AA) and hydrogen peroxide in the presence of a sulfonic acid ion-exchange resin catalyst. A solution containing a 1.5:1 mole ratio of AA to hydrogen peroxide passed through a resin column produced a 15% PAA solution within 30 minutes. The patent notes the limitation of large, expensive resin beds and oxidative degradation of the resin.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Preamble - Point-of-Use Generation): These claims broadly cover continuously or intermittently generating non-equilibrium PAA at a point-of-use. US5122538A explicitly discloses generating non-equilibrium PAA at its point-of-use.
- Claims 1(b) and 15(b) (Hydrogen Peroxide-Acetyl Precursor Solution) and 1(e) and 15(e) (Alkali Catalyst): A key distinction is that US8546449 uses a hydrogen peroxide-acetyl precursor solution followed by an alkali metal or earth alkali metal hydroxide to initiate perhydrolysis. US5122538A uses acetic acid (not an acetyl precursor solution as defined in US8546449) and a sulfonic acid ion-exchange resin as a catalyst, not a strong alkali. Therefore, the specific chemical components and reaction initiation steps are different, making direct anticipation unlikely for these elements.

3. U.S. Patent No. 6,171,551

Full Citation: US6171551B1, "Method and apparatus for producing aqueous solutions of peracids", Johnson et al., published January 9, 2001.
Publication/Filing Date: Published January 9, 2001.
Brief Description: This patent discloses an electrolytic process for producing peracids, including PAA. It employs a cell divided by an ion-exchange membrane where PAA (and other oxidants) are produced in the anode compartment, which consists of an aqueous solution of acetic acid or acetate salt. The patent reports low PAA yields (less than 14 ppm PAA after 90 minutes from a potassium acetate anolyte) and difficulties with intermittent operation.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Preamble - Point-of-Use Generation): These claims cover generating non-equilibrium PAA at a point-of-use. US6171551B1 aims to produce PAA on-site using an electrolytic process.
- Claims 1 and 15 (Method Steps): The core methods of US8546449 involve mixing a hydrogen peroxide-acetyl precursor solution with water and then adding a strong alkali. US6171551B1 describes an electrolytic process, which is fundamentally different from the chemical mixing steps claimed in US8546449. The reactants (acetic acid/acetate salt) and the mechanism of PAA formation (electrolysis vs. perhydrolysis catalyzed by strong base) are distinct. Therefore, the specific method steps of claims 1-27 are not anticipated.

4. U.S. Patent No. 6,387,236

Full Citation: US6387236B1, "Method and apparatus for producing aqueous solutions of peracids", Johnson et al., published May 14, 2002.
Publication/Filing Date: Published May 14, 2002.
Brief Description: Similar to US6171551B1, this patent also describes an electrolytic process for producing peracids like PAA using a divided cell with an ion-exchange membrane. It focuses on the use of gas diffusion electrodes for cathodic reduction of oxygen to hydrogen peroxide, which then reacts with acetic acid or an acetyl precursor to form PAA. The system faces challenges with low oxygen solubility, high capital costs, and difficulty in maintaining steady-state conditions due to water movement across the membrane.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Preamble - Point-of-Use Generation): As with US6171551B1, this patent discloses on-site generation of PAA.
- Claims 1 and 15 (Method Steps): Again, the method taught by US6387236B1 is an electrolytic process, involving a multi-compartment cell, gas diffusion electrodes, and cathodic reduction, which is distinct from the chemical mixing and alkali-catalyzed perhydrolysis steps of US8546449. The specific ingredients and the order of their introduction (e.g., pre-formed hydrogen peroxide-acetyl precursor solution, then strong alkali) are not present in this electrolytic prior art.

5. U.S. Patent No. 7,012,154

Full Citation: US7012154B2, "System and method for on-site preparation of peracetic acid", Bunczek et al., published March 14, 2006.
Publication/Filing Date: Published March 14, 2006.
Brief Description: This patent describes a system for on-site production of PAA where acetic acid, hydrogen peroxide, water, and sulfuric acid are fed to a jacketed reactor. A wiped-film distillation column isolates pure PAA from the gas phase for immediate introduction to receiving water. The system is noted as capital intensive, involving safety hazards due to pure PAA production, and requiring highly trained technicians.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Preamble - Point-of-Use Generation): This patent clearly teaches a "system for on-site preparation of PAA".
- Claims 1 and 15 (Method Steps): The method in US7012154B2 involves reacting acetic acid and hydrogen peroxide with a mineral acid catalyst (sulfuric acid) in a reactor, followed by distillation to isolate pure PAA. This is fundamentally different from the US8546449 claims, which involve a pre-formed hydrogen peroxide-acetyl precursor solution and the use of a strong alkali metal or earth alkali metal hydroxide to drive the perhydrolysis reaction. The absence of a strong alkali and the presence of a distillation step in US7012154B2 differentiate it significantly.

6. U.S. Patent No. 7,651,724

Full Citation: US7651724B2, "Method and compositions for the determination of peracetic acid", Gilliard et al., published January 26, 2010.
Publication/Filing Date: Published January 26, 2010.
Brief Description: This patent describes methods and compositions for the analytical determination (measurement) of peracetic acid, particularly using a modified DPD (N,N-diethyl-p-phenylenediamine) colorimetric method. It relates to quantifying PAA, not to methods or compositions for its generation.
Potential Anticipation (35 U.S.C. § 102): This patent is directed to an analytical method for PAA, not the generation of PAA. Therefore, it does not anticipate any of the claims of US8546449, which are directed to methods and compositions for generating PAA or solid peroxygen compositions.

7. U.S. Patent Application Publication No. 2007/0082832 A1

Full Citation: US20070082832A1, "Methods for the production of peracid solutions", Ganske et al., published April 12, 2007.
Publication/Filing Date: Published April 12, 2007.
Brief Description: This publication discloses biosynthetic methods for producing peracids, including PAA, from carboxylic acids and carboxylic acid esters. These methods utilize perhydrolase enzymes to catalyze the perhydrolysis of the carboxylic acid or ester into the peracid using a solid or liquid source of hydrogen peroxide. It emphasizes enzyme-catalyzed reactions.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Method Steps): The core of US8546449 involves a chemical perhydrolysis reaction catalyzed by a strong alkali. US20070082832A1 relies on enzymatic catalysis for peracid formation. This is a fundamental difference in the reaction mechanism and components. Therefore, the methods of claims 1-27, which do not involve enzymes, are not anticipated.

8. U.S. Patent Application Publication No. 2009/0005590 A1

Full Citation: US20090005590A1, "Method and apparatus for producing aqueous solutions of peracids", Johnson et al., published January 1, 2009.
Publication/Filing Date: Published January 1, 2009.
Brief Description: This publication, similar to US6387236B1, describes an electrolytic process using cation membrane-divided cells and gas diffusion electrodes for the cathodic reduction of oxygen to hydrogen peroxide. The hydrogen peroxide then reacts with acetic acid or an acetyl precursor to form PAA. The catholyte is then directed to the acidic anode compartment to stabilize the PAA.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Method Steps): As discussed with previous electrolytic patents (US6171551B1, US6387236B1), the method of US20090005590A1 is electrolytic and involves different components and reaction mechanisms than the alkali-catalyzed perhydrolysis in US8546449. Therefore, the specific method claims 1-27 are not anticipated.

9. U.S. Patent Application Publication No. 2009/0043132 A1

Full Citation: US20090043132A1, "Methods for generating non-equilibrium peroxyacetic acid solutions", Gilliard et al., published February 12, 2009.
Publication/Filing Date: Published February 12, 2009.
Brief Description: This publication discloses a process for generating non-equilibrium PAA solutions on-site by introducing hydrogen peroxide into a sidestream of the water needing treatment, followed by introducing acetic anhydride. PAA is generated in-situ, with acetic anhydride preferentially reacting with hydrogen peroxide over hydrolysis with water. It acknowledges that acetic anhydride is expensive, corrosive, irritant, and highly flammable.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Preamble - Point-of-Use Generation): This publication directly addresses "generating non-equilibrium solutions of PAA on site, at the point-of-use".
- Claims 1(b) and 15(b) (Hydrogen Peroxide-Acetyl Precursor Solution): US20090043132A1 uses acetic anhydride as the acetyl precursor. While acetic anhydride is a liquid acetyl precursor, it's introduced separately from hydrogen peroxide, rather than as a pre-formed "hydrogen peroxide-acetyl precursor solution" as defined in US8546449. The specific characteristic of a liquid acetyl precursor that is soluble in aqueous hydrogen peroxide and then forming a pre-solution is a distinguishing feature.
- Claims 1(e) and 15(e) (Alkali Catalyst): Crucially, US20090043132A1 does not disclose the use of an aqueous source of an alkali metal or earth alkali metal hydroxide to initiate the perhydrolysis reaction. Instead, it relies on the reaction between hydrogen peroxide and acetic anhydride directly. This is a key distinguishing feature for claims 1-27 of US8546449.

10. U.S. Patent Application Publication No. 2009/0314652 A1

Full Citation: US20090314652A1, "Method and apparatus for producing aqueous solutions of peracids", Johnson et al., published December 24, 2009.
Publication/Filing Date: Published December 24, 2009.
Brief Description: This publication, similar to other Johnson et al. patents (US6171551B1, US6387236B1, US20090005590A1), describes an electrolytic method for producing peracids. It involves cation membrane-divided electrolysis cells and gas diffusion electrodes to generate hydrogen peroxide from oxygen, which then reacts with acetic acid or an acetyl precursor. The catholyte containing PAA is directed to the acidic anode compartment for stabilization.
Potential Anticipation (35 U.S.C. § 102):
- Claims 1 and 15 (Method Steps): Similar to the other electrolytic prior art by Johnson et al., this publication describes an electrolytic process, not the chemical mixing and alkali-catalyzed perhydrolysis steps of US8546449. The distinct methodology and chemical components for initiating the reaction mean that the method claims 1-27 are not anticipated.

Summary of Distinctive Features of US8546449 vs. Prior Art:

The key distinguishing features of US8546449's method claims (1-27) when compared to the cited prior art patents for PAA generation are:

The use of a pre-formed hydrogen peroxide-acetyl precursor solution (e.g., hydrogen peroxide and triacetin solution). Most prior art either reacts H2O2 with acetic acid directly or acetic anhydride separately.
The subsequent introduction of a highly concentrated aqueous source of an alkali metal or earth alkali metal hydroxide (at least 45% by weight) to drive the perhydrolysis reaction rapidly at the point-of-use. Prior art typically uses acid catalysts, enzymatic catalysts, or electrolytic processes, or does not specify such a concentrated alkali.
The generation of a non-equilibrium solution of PAA with specific components (PAA, unreacted H2O2, unreacted acetyl precursor, perhydrolysis product, alkali, and water) at non-equilibrium concentrations.

For the solid composition claims (28-40), the distinctiveness lies in:

A freely-flowable, solid peroxygen bleaching and stain removal composition comprising a liquid acetyl precursor (preferably triacetin), a water-soluble solid source of hydrogen peroxide, and a water-soluble solid source of alkalinity. Prior art, such as TAED-containing bleaches, suffered from low water solubility of the acetyl precursor and undesirable odors upon storage. The use of a liquid acetyl precursor within a solid composition is a key differentiator.

Based on this analysis, while some prior art generally teaches on-site PAA generation, none appear to fully anticipate all elements of US8546449's claims, particularly the specific combination of a pre-mixed hydrogen peroxide-acetyl precursor solution and the use of a concentrated strong alkali, or the specific solid composition with a liquid acetyl precursor.