DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA . In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.
Applicant's submission filed on 12/19/2025 has been entered.
Priority
The instant application claims domestic benefit to US provisional application no. 63/168,391 filed on 03/31/2021.
Status of the Claims
The claim amendments and remarks filed on 12/19/2025 is acknowledged. Claims 3, 12, and 17 are amended. Claims 2, 13, and 18 are cancelled. Claims 21-22 are newly added
Accordingly, claims 1, 3-12, 14-17, and 19-22 are pending and being examined on the merits herein.
Withdrawn Rejections
The 35 USC 103 rejections over Matt in view of Guadix-Montero and Rahimi for claims 1, 4-8, and 10, over Matt in view of Guadix-Montero, Rahimi, and Fartler for claims 3 and 11, over Matt in view of Guadix-Montero, Rahimi, and Luterbacher for claim 9 are withdrawn because Applicant’s arguments that an ordinary skilled artisan would not substitute the LiAlH4/NH4 hydride disclosed in Matt with the zinc powder of Rahimi was found persuasive. Here, Applicant states that the zirconium catalyzed reductive cleavage of C-O bonds disclosed in Matt requires the presence of LiAlH4 / NH4 as a reductant to form a zirconocene hydride, which then reacts with the alkene-containing substrate. Therefore, an ordinary skilled artisan would not consider substituting the hydride with zinc powder, and would not have a reasonable expectation of success because the hydride is required for the catalytic cleavage disclosed in Matt.
The 35 USC 103 rejections over Luo in view of Luterbacher for claims 17 and 19, over Nguyen for claims 17 and 19-20, and over Nguyen in view of Mobley for claim 18 is withdrawn because instant claim 18 is cancelled, and instant claim 17 now requires adding an oxalyl group to the biopolymer to form a modified biopolymer comprising the oxalyl group. Here, the previous rejections over instant claim 17 were based on adding any photoredox-active functional group to form a modified biopolymer that did not require having an oxalyl group.
The following grounds of rejection are new as necessitated by Applicant’s amendments or maintained from the previous Office Action dated 10/02/2025.
Claim Objections
Claims 1 and 17 is objected to because of the following informalities:
Claim 1 recites “… a reaction system comprising consisting of at least one catalyst …”. The “consisting of” term is a new amendment, however claim 1 does not have a proper status indicator as being amended. See 37 CFR 1.121.
Claim 17 recites “an oxayl group” and “comprising the oxayl group”. The “oxayl” appears to be a misspelling for “oxalyl”.
Appropriate correction is required.
Claim Rejections - 35 USC § 112(b)
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1, 3-11, and 21 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 1 recites “... the step of contacting the biopolymer with a reaction system comprising consisting of at least one catalyst …”.
Claim 1 is indefinite because the reaction system has both the open-ended term “comprising” and closed term “consisting”. See MPEP 2111.03. Therefore, it is unclear if the two transitional phrases were meant to be alternatives, or if Applicant intended to change the transitional phrase to either “comprising” or “consisting”,
Instant claims 3-11 and 21 depend from claim 1, but do not overcome the described indefinite issue.
For purposes of examination, instant claim 1 is being interpreted as the reaction system “comprising” at least one catalyst.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claim(s) 12 and 14-15 are rejected under 35 U.S.C. 103 as being unpatentable over Chen et al. (Environmental Progress and Sustainable Energy, 2019 in PTO-892) in view of Fartel (Master’s Thesis at the University of British Columbia, 2014 in PTO-892 dated 10/02/2025) and Fijakowski et al. (Catalysts, published March 18th 2021 in PTO-892 dated 10/02/2025).
Chen discloses an electrocatalytic method to decompose unit structures of wheat straw lignin oxidation on Pb/PbO2 and reduction on alloyed material cathode with different catalytic activity in alkaline NaOH solution (Abstract). Chen discloses that extensive research is ongoing to convert lignin to useful chemical compounds (see right column page 1). Chen discloses lignin is the second most abundant constituent in lignocellulosic biomass and contains aromatic compounds that are renewable and useful for biofuels and chemical generation (see left column last paragraph through first paragraph right column page 1). Chen demonstrates in Table 1 (page 3) the alloyed cathodes used in their method which include iron-alloyed cathodes.
Chen discloses in section “Electrocatalytic Reactions” left column page 2 that their electrocyclic reaction involved using a 500 mL reactor with an overhead mechanical stirrer, in which an alloyed material plate (cathode) and Pb/PbO2 anode with the same dimensions of 60 × 20 mm and 5 mm thickness were parallelly placed with 3 cm space from each other. Before each reaction, about 6–14 g purified wheat straw lignin was dissolved in 200 mL of sodium hydroxide solution to prepare homogeneous reaction solution (pH = 12.0–13.0). After which the reactor was placed in a specified preheated water bath (20–60C), following with a current of 10–50 mA/cm2 by a DC regulated power supply After specified reaction time, the reactor was removed into a water bath with 25C for 20 min. Then, a certain volume of solvent (dichloromethane or n-butyl alcohol) was added to the above reaction mixture, and 0.86 mol/L H2SO4 solution was added to adjust pH to 2–3 at which point unreacted lignin residue was precipitated. After standing for 20 min, the mixture was separated into solid residue, organic phase, and aqueous phase. The organic phase was condensed and then used
for analysis directly.
Here, Chen discloses the depolymerization of lignin using an electrochemical cell that comprises at least one solvent (water, dichloromethane, or n-butyl alcohol), Pb/PbO2 anode, an iron-alloyed cathode, and alkaline NaOH solution. The NaOH solution meets the limitation of an electrolyte, since NaOH breaks down into charged Na+ and OH- ions.
Chen, however, does not teach using at least one catalyst comprising a recited metallocene complex.
Fartel discloses the use of titanocene and zirconocene complexes for the selective cleavage of carbon-oxygen bonds that can be applied for the conversion of lignin to useful chemicals (see Abstract on page 2). Fartel demonstrates the titanocene-mediated carbon-oxygen bond cleavage of the α-aryloxy ketones 2-phenoxy-1-phenylethanone and 2-(2,6-dimethoxyphenoxy)-1 phenylethanone (see Abstract and Figure 5.1 on page 61). Fartel discloses that their bond cleaveage reaction occurs readily at ambient temperature and pressure (see second paragraph in Abstract, page 2).
Fijakowski et al. discloses an enhanced titanocene-based electrocatalytic system for nitrogen reduction comprising glassy carbon electrode, high level of the catechol redox mediator, optimized binary THF/MeOH solvent (see Abstract). Fijakowski et al. discloses that the activity of titanocene dichloride can be improved by using a variety of alkali metals as reductants (see end of page 2 through first paragraph of page 3). Fijakowski et al. discloses another electrochemical system for the reduction of molecular dinitrogen to ammonia using titanocene dichloride as a catalyst (see second paragraph page 3). Fijakowski et al. discloses that reduction of dinitrogen to ammonia was achieved in polar solvents, such as methanol and THF using catechol as an additive, n-Bu4NClO4 or LiClO4 as electrolytes and platinum or mercury as working electrodes (see second paragraph page 3).
It would have been prima facie obvious before the effective filing date of the claimed invention to have included the titanocene complex disclosed in Fartel and Fijakowski et al. as a catalyst in the electrochemical method of Chen to arrive at the claimed invention. One of ordinary skill in the art could have included the titanocene as a catalyst in the electrochemical method of Chen to yield predictable results because Fartel establishes the use of titanocene complexes as catalysts for bond cleavage of lignin into useful chemicals, and Fijakowski further establishes the use of titanocene complexes as an electrocatalyst in similar reductive electrochemical systems.
Claim(s) 12, 14, and 16 are rejected under 35 U.S.C. 103 as being unpatentable over Pacut et al. (J. Org. Chem, 1986 in PTO-892) in view of Du et al. (ChemSusChem, 2020 in PTO-892 dated 04/30/2025), Fartel (Master’s Thesis at the University of British Columbia, 2014 in PTO-892 dated 10/02/2025) and Fijakowski et al. (Catalysts, published March 18th 2021 in PTO-892 dated 10/02/2025).
Pacut discloses an electrochemical method to perform Birch-type reductions in aqueous solutions (see left column first paragraph page 3468).
Pacut demonstrates the reduction of either benzo[b]thiophene or diphenyl ether using their electrochemical setup. Here, reductions were carried out with mercury cathode, platinum anode, and tetrabutylammonium (TBA) electrolytes such as (TBA)PF4 (Bu4NBF4) in aqueous or mixed organic- aqueous solutions such as (TBA)OH or THF / water (see first paragraph under section “Results and Discussion” right column page 3468 and Table II page 3469). As seen in the left column page 3470, Pacut illustrates the cleavage of the diphenyl ether.
Here, Pacut teaches an electrochemical cell that comprises a solvent (THF/water), electrolyte (Bu4NBF4), anode (platinum), and cathode (mercury).
However, Pacut does not disclose a method to depolymerize a biopolymer or using at least one catalyst comprising a recited metallocene complex.
Du et al. discloses a review of various electrochemical lignin conversion strategies including electrooxidation, electroreduction, hybrid electro-oxidation and reduction, and combinations of electrochemical and other processes (e.g., biological, solar) for lignin depolymerization (see Abstract).
Du et al. discloses that lignin is the second most abundant component of lignocellulosic biomass and is the largest source of renewable aromatic compounds (see first paragraph in section 1. Introduction on page 4319). Du points to the teachings of Pacut as a method to cleave 4-O-5 lignin model compounds using the birch-type reduction described above (see right column page 4334).
Fartel discloses the use of titanocene and zirconocene complexes for the selective cleavage of carbon-oxygen bonds that can be applied for the conversion of lignin to useful chemicals (see Abstract on page 2). Fartel demonstrates the titanocene-mediated carbon-oxygen bond cleavage of the α-aryloxy ketones 2-phenoxy-1-phenylethanone and 2-(2,6-dimethoxyphenoxy)-1 phenylethanone (see Abstract and Figure 5.1 on page 61). Fartel discloses that their bond cleave reaction occurs readily at ambient temperature and pressure (see second paragraph in Abstract, page 2).
Fijakowski et al. discloses an enhanced titanocene-based electrocatalytic system for nitrogen reduction comprising glassy carbon electrode, high level of the catechol redox mediator, optimized binary THF/MeOH solvent (see Abstract). Fijakowski et al. discloses that the activity of titanocene dichloride can be improved by using a variety of alkali metals as reductants (see end of page 2 through first paragraph of page 3). Fijakowski et al. discloses another electrochemical system for the reduction of molecular dinitrogen to ammonia using titanocene dichloride as a catalyst (see second paragraph page 3). Fijakowski et al. discloses that reduction of dinitrogen to ammonia was achieved in polar solvents, such as methanol and THF using catechol as an additive, n-Bu4NClO4 or LiClO4 as electrolytes and platinum or mercury as working electrodes (see second paragraph page 3).
It would have been prima facie obvious before the effective filing date of the claimed invention to have applied the electrochemical reduction method in Pacut for lignin depolymerization as disclosed in Du and to further include the titanocene complex disclosed in Fartel and Fijakowski et al. as a catalyst to arrive at the claimed invention. One of ordinary skill in the art would have applied the method of Pacut to depolymerize lignin because Du provides guidance that the Birch-type reduction in Pacut can effectively cleave 4-O-5 lignin model compounds. Furthermore, one of ordinary skill in the art could have included the titanocene as a catalyst in the electrochemical method of Pacut to yield predictable results because Fartel establishes the use of titanocene complexes as catalysts for bond cleavage of lignin into useful chemicals, and Fijakowski further establishes the use of titanocene complexes as an electrocatalyst in similar reductive electrochemical systems.
Claim(s) 22 is rejected under 35 U.S.C. 103 as being unpatentable over Pacut et al. (J. Org. Chem, 1986 in PTO-892) in view of Du et al. (ChemSusChem, 2020 in PTO-892 dated 04/30/2025), Fartel (Master’s Thesis at the University of British Columbia, 2014 in PTO-892 dated 10/02/2025) and Fijakowski et al. (Catalysts, published March 18th 2021 in PTO-892 dated 10/02/2025), as applied to claim 12, and further in view of Huang et al. (Green Chem, published 02/19/2021 in PTO-892).
The combined teachings of Pacut, Du, Fartel, and Fijakowski are as described above and teach the method of instant claim 12 as discussed above.
The combined references, however, do not teach further including a recite reductant in instant claim 22.
Huang discloses an electrochemical system that comprises the use of Et3N as a sacrificial reductant for the cleavage of various chemicals bond including C-O (see Abstract). Huang discloses that Et3N is an inexpensive and easily available sacrificial reductant (third paragraph, left column page 2096), and suggests its use as alternative to harsher and hazardous conditions such as catalytic electro-reductive systems that involve metal hydrides, borohydrides, etc. (see first paragraph left column page 2095). Huang demonstrates several electrochemical cell setups using Et3N in Fig. 1 on page 2095, which includes a cell that comprises Et3N, platinum electrodes, Et4NClO3 as an electrolyte, and DMSO/EtOH as solvent (Fig. 1d).
It would have been prima facie obvious before the effective filing date of the claimed invention to have further included Et3N disclosed in Huang as a reductant in the electrochemical cell as disclosed by the combined teachings of Pacut, Du, Fartel, and Fijakowski described above to arrive at the claimed invention. One of ordinary skilled in the art would have been motivated to include Et3N because Huang discloses that Et3N is an inexpensive and easily available sacrificial reductant and suggests its use as an alternative to harsher and hazardous conditions such as catalytic electro-reductive systems that involve metal hydrides, borohydrides, etc. One of ordinary skill in the art would have a reasonable expectation of success because Huang disclose that Et3N can be used for the cleavage of several bonds including C-O and demonstrates the use of Et3N in similar electrochemical cell setups as seen in Pacut.
Response to Arguments
Applicant’s arguments filed on 12/19/2025 have been fully considered in so far as they apply to the rejections of the instant office action, but were not persuasive.
Applicant states that the rejection of instant claims 12 and 14-16 under 35 USC 103 should be withdrawn based on the new limitation in instant claim 12 that recites “… provided the electrochemical cell does not comprise a hydride source”. Applicant states that Wu relies on a hydride source to promote electrochemical reductive cleavage and therefore an ordinary skilled artisan would have no motivation or reasonable expectation of success in removing this hydride source.
Applicant’s argument described above was not found persuasive because the new rejections over Chen and over Pacut do not include a hydride source.
Allowable Subject Matter
Instant claims 1, 3-11, and 21 are rejected, but would be allowable if the new 35 USC 112(b) rejection over these claims are overcome.
The closest prior art is Matt (in PTO-892 dated 04/30/2025)
Matt discloses a zirconium catalyzed reductive cleavage of Csp3 and Csp2 carbon−heteroatom bond (Abstract). Matt discloses that demonstrates this reaction in Scheme 2 (see page 6985 right column), in which a zirconocene dichloride (Cp2ZrCl2) catalyst at 5 or 10 mol% in the presence of LiAlH4 /NH4 as the reductant was used for the reductive cleavage of C-O, C-N, and C-S bonds in model compounds Matt discloses that the direct homogeneous-catalyzed scission of C−O, C−N, and C−S single bonds offers new strategies for organic synthesis and the conversion of renewable feedstocks into base chemicals and that the catalytic cleavage of these bonds are particularly challenging if no activating groups are present (see page 6983, top left column).
Here, Matt does not disclose at one electron source consisting of a pure metal.
Rahimi (in PTO-892 04/30/2025) discloses a method for depolymerizing oxidized lignin under mild conditions in aqueous formic acid that resulted in more than 60 wt% yield of low-molecular-mass aromatics (see Abstract). Rahimi discloses that Rahimi et al discloses that an oxidized lignin model 2 (in Figure 2a) reacts with alkaline hydrogen peroxide to yield the aromatic monomers veratric acid (88% yield) and guaiacol (42%), and further discloses that the instability of the guaiacol prompted to consider reductive cleavage methods (see page 249 right column). Therefore, Rahimi et al. discloses the depolymerization reactivity in the presence of different reducing metals such as zinc, aluminum, magnesium, iron, and manganese (see Fig. 2A and page 249, right column second paragraph), and discloses that Zinc afforded small amounts of the O-formylated product 3 (6%), together with good yields of the aryl ethyl ketone reductive cleavage product 4 (76%) and guaiacol (69%) (see Fig 2A and page 249, right column). Rahimi et al. discloses that the zinc reducing metal was in the form of zinc powder in the cleavage reaction (see section III on page 2 of Rahimi Supplementary), which meets the limitation of a pure metal.
Here, an ordinary skilled artisan would not have substituted the hydride reductant of Matt with the zinc powder of Rahimi because the zirconium catalyzed reductive cleavage of C-O bonds disclosed in Matt requires the presence of LiAlH4 / NH4 as a reductant to form a zirconocene hydride, which then reacts with the alkene-containing substrate. Therefore, an ordinary skilled artisan would not consider this substitution and would not have a reasonable expectation of success because the hydride is required for the catalytic cleavage disclosed in Matt.
An ordinary skilled artisan would also not have considered including the zinc powder of Rahimi into the reaction system of Matt because Rahimi discloses the use of zinc powder as a reductant to depolymerize oxidized lignin using formic acid, whereas Matt discloses an entirely different hydride-based reaction system that does not involve acids or oxidized lignin. Therefore, an ordinary skilled artisan would not have considered including the zinc powder of Rahimi and would have no reasonable expectation of success in doing so.
Furthermore, the prior art does disclose reaction systems that involve metallocenes and pure metals. For example, Gansauer (in PTO-892) or WO’714 (in PTO-892, English translation provided as well) both disclose reaction systems that contain titanocene dichloride and Zn metal, however both of these prior arts disclose the applications of these reaction systems for organic synthesis or hydrogenation of polymers, respectively, and does not disclose or suggest applying this reaction system for the depolymerization of a biopolymer.
Claims 19-20 are allowable. Claim 17 is objected to for minor informalities but would be allowable.
The closest prior art is Nguyen (in PTO-892 dated 04//30/2025).
Nguyen et al. discloses a room-temperature lignin degradation strategy consisting of a chemoselective benzylic oxidation with a recyclable oxidant ([4-AcNH-TEMPO]BF4) and a catalytic reductive C–O bond cleavage utilizing the photocatalyst [Ir(ppy)2(dtbbpy)]PF6 (see Abstract). Nguyen et al. shows the two-step degradation process of model lignin compounds in Table 2 (see page 1220, bottom left column). Both DCM (dichloromethane) and MeCN (acetonitrile) were used as solvents as seen in Table 2. Nguyen et al. discloses that the two-step degradation process can be successfully performed at ambient temperatures (see page 1220, left column second paragraph). Furthermore, in the second step involving the reductive C-O bond cleavage, Nguyen et al. discloses that the cleavage mechanism involves the generation of a strong Ir2+ reductant from the excited Ir3+ state (see page 1220, right column second paragraph). The Ir2+ then performs a single electron transfer to the benzylic ketone or aliphatic aldehyde to generate a radical anion, which undergoes fragmentation to generate an alkoxy anion and the corresponding Cα-radical (see page 1220, right column second paragraph).
Here, while Nguyen discloses the addition of a photo redox active functional group to form a modified lignin (conversion process of C-OH to ketone on the lignin), Nguyen does not disclose adding an oxalyl group to form a modified biopolymer that comprises the oxalyl group. While Mobley (in PTO-892 dated 04/30/2025) discloses a Swern oxidation which uses oxalyl chloride and DMSO to oxidize lignin, this Swern oxidation does not result in an oxalyl group being added to the lignin. Rather, the oxalyl chloride activates the DMSO to produce dimethyl(chloro)sulfonium chloride which then oxides the lignin (see Swern oxidation reaction schemes on pages 13-16 of Mobley).
Conclusion
Claims 1, 3-12, 14-16, and 21-22 are rejected.
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/D.H.C./Examiner, Art Unit 1693
/SCARLETT Y GOON/Supervisory Patent Examiner, Art Unit 1693