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 .
Claim Rejections - 35 USC § 103
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.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-6 are rejected under 35 U.S.C. 103 as being unpatentable over Lee et al. “Preparation of Extremely Active Ethylene Tetramerization Catalyst [iPrN(PAr2)2−CrCl2] + [B(C6F5)4] – (Ar = −C6H4-p-SiR3)” Catalysts 11, 1122 (2021) (“Lee”) in view of Chabbra et al., “First experimental evidence for a bis-ethene chromium(I) complex forming from an activated ethene oligomerization catalyst”, Science Advances 6, eabd7057 (2020) (“Chabbra”).
Lee discloses an ethylene oligomerization method employing:
a cationic chromium complex bearing a tridentate PNP ligand, of the form[PNP–CrCl2]+[B(C6F5)4]−[PNP–CrCl_2]^+[B(C_6F_5)_4]^-[PNP–CrCl2]+[B(C6F5)4]−,wherein the chromium center bears two halogen ligands, satisfying the definitions of X¹ and X² in claim 1;
a discrete weakly coordinating anion [B(C6F5)4]−[B(C_6F_5)_4]^-[B(C6F5)4]−, wherein A = boron and Y¹–Y⁴ are fluorinated aryl groups, fully corresponding to Chemical Formula 1 for the boron embodiment;
an organoaluminum compound Al(iBu)3_33 used concurrently with the chromium complex, wherein iBu is a C₄ alkyl, satisfying Chemical Formula 2 where R¹¹ = C₄–C₈ alkyl;
reacting the chromium complex and organoaluminum compound with ethylene, in an organic solvent, at temperatures of about 20–50 °C, which fall within the claimed requirement of less than 60 °C.
Accordingly, Lee teaches every limitation of Claim 1 except the alternative embodiment in which A = aluminum in the counter-anion and the specific requirement that R11 is n-octyl.
Chabbra discloses the use of aluminate weakly coordinating anions of the formula
[Al(OC(CF3)3)4]−[Al(OC(CF_3)_3)_4]^-[Al(OC(CF3)3)4]−,
wherein:
A = aluminum, and
Y¹–Y⁴ are fluorinated alkoxy substituents, falling squarely within the scope of Claim 1.
Chabbra teaches that these aluminate anions abstract halide from PNP-ligated chromium complexes to generate cationic Cr–PNP species that are catalytically competent in ethylene oligomerization.
Thus, Chabbra expressly teaches the exact alternative anion embodiment of Chemical Formula 1 that is not disclosed by Lee.
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of Leen by substituting the borate anion of Lee with the aluminate anion taught by Chabbra because:
Both references concern the same catalytic species—cationic chromium complexes bearing PNP ligands used for ethylene oligomerization.
Borate and aluminate weakly coordinating anions are recognized functional equivalents in organometallic catalysis, both serving to stabilize cationic transition-metal centers without coordinating to the metal.
Chabbra provides direct experimental evidence that aluminate weakly coordinating anions successfully generate catalytically active cationic Cr–PNP species, establishing a reasonable expectation of success if substituted into the Lee system.
The substitution of one weakly coordinating anion for another represents a predictable design choice, not a change to the catalytic mechanism or ligand framework.
Accordingly, it would have been obvious to use either boron- or aluminum-based weakly coordinating anions in the method of Lee to arrive at the full scope of Claim 1.
Substituting Al(iBu)₃ with Al(n-octyl)₃
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of Lee by employing organolauminum compound as claimed because the substitution of one C₄–C₈ trialkylaluminum compound for another is a routine and predictable variation, as all trialkylaluminum compounds of this class perform the same cocatalyst function in Cr-based olefin oligomerization.
A person of ordinary skill in the art would have had a reasonable expectation of success
because:
Chabbra demonstrates that aluminate WCAs successfully generate active cationic Cr–PNP species;
the catalytic mechanism remains unchanged;
the role of AlR₃ cocatalysts is well understood and unaffected by alkyl chain length.
Claim 3 (30–60 °C; 10 min–2 h)
Lee 2021 teaches ethylene oligomerization at 20–50 °C, overlapping the claimed temperature range. Reaction times of minutes to hours are conventional and represent result-effective variables. Claim 4 (Cr:Al = 1:10–300)
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of by having the ratio as claimed because Lee employs an excess of trialkylaluminum relative to chromium. Selecting a specific ratio within a known operable range constitutes routine optimization. Claim 5 (hydrogen present)
The introduction of hydrogen during ethylene oligomerization to influence chain transfer
and suppress polymer formation is well known in olefin catalysis.
Claim 6 (ethylene:hydrogen ratio 1:0.001–3.0)
Once hydrogen addition is known, the amount of hydrogen constitutes a result-effective variable. It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified Lee by utilizing the claimed ratio because such ratio spans conventional trace-to-moderate hydrogen levels used in olefin oligomerization.
Response to Arguments
Applicant’s arguments have been fully considered but are not persuasive.
Applicant contends that Lee does not disclose the use of trinoctylaluminum (Al(n-octyl)₃). This is acknowledged; however, the rejection is based on 35 U.S.C. §103, not §102. Lee teaches the use of a trialkylaluminum cocatalyst (Al(iBu)₃) in a Cr–PNP ethylene oligomerization system. It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified Lee by substituting Al(iBu)₃ with another trialkylaluminum compound such as Al(n-octyl)₃, because trialkylaluminum compounds constitute a known class of interchangeable cocatalysts that perform the same Lewis acidic alkylating function, and variation of alkyl group is a routine design choice to adjust steric and solubility properties. The claimed selection therefore represents a predictable use of prior-art elements according to their established functions (KSR).
Applicant further argues that neither Lee nor Chabbra suggests trinoctylaluminum. However, obviousness does not require an express teaching of the exact species where the claimed compound is a member of a known genus of functionally equivalent alternatives. The prior art provides motivation to use AlR₃ cocatalysts generally, and selection of a specific alkyl substituent within that class would have been routine.
Applicant’s evidence of reduced polyethylene byproduct formation when using trinoctylaluminum has been considered but is not persuasive. The showing is limited to a single example and is not commensurate in scope with the breadth of Claim 1, which encompasses a wide range of PNP ligands, X¹/X² substituents, and anion systems. Moreover, polyethylene formation is a known result-effective variable influenced by cocatalyst structure, and changes in alkyl group are expected to affect such outcomes. The observed difference therefore reflects routine optimization rather than an unexpected property sufficient to overcome the rejection.
Accordingly, the rejection of Claim 1 under 35 U.S.C. §103 is maintained. Claims 3–6 fall with Claim 1.
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to TAM M NGUYEN whose telephone number is (571)272-1452. The examiner can normally be reached Mon - Frid.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Prem C Singh can be reached at 571-273-6381. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/TAM M NGUYEN/Primary Examiner, Art Unit 1771
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