United States Patent 5,969,166: Scope, Claim Boundaries, and US Patent Landscape for Ruthenium/Molybdenum Oxide(L) Catalysts for Selective Epoxidation and Olefin Oxidation
Executive summary. US 5,969,166 claims a class of Ru- or Mo-oxide complexes defined by oxidation-state arithmetic (x, y, z such that the metal oxidation level is +6) plus a tightly constrained donor-ligand provenance (for Mo, L derived from specific N/O/S-donor precursors bearing aryl/heteroaryl and C1-C12 halogenated or C1-C12 alkyl substituent patterns). The enforceable US claim scope is strongest for heterogeneous and soluble embodiments tied to (i) selective epoxidation using atmospheric oxygen and (ii) performance floors (selectivity thresholds) rather than product-specific structures. For freedom-to-operate, the key risk is that many third-party catalysts are likely to fall within the broad “formula (1) catalyst” and “supported catalyst” genus, with infringement hinging on whether their catalysts meet the same structural formula constraints and whether epoxidation selectivity in the claimed regime is met or demonstrably avoided.
What compounds are claimed in US 5,969,166 (formula (1) Ru/Mo oxide with donor ligands)?
Short answer. The patent claims a catalyst genus defined as MxOy(L)z where M is Ru or Mo, L is an N/O/S donor ligand, x is 1–3, z is 2–2x, and y is chosen so that x+z gives a metal oxidation number of +6. For Mo, L must be derived from a donor-ligand precursor structure (2), (3), or (4) with specific substituent classes.
How formula (1) is bounded
Claim 1 and claim 12 define the same core catalyst:
- Catalyst formula: MxOy(L)z
- M: ruthenium or molybdenum
- x: integer 1 to 3
- z: integer 2 to 2x
- y: integer 1 to 2x+1, selected so that the sum x+z corresponds to a metal oxidation level of +6
- L: N, O or S donor ligand
- Selectivity requirement:
- If Mo, epoxidation selectivity >45%
- If Ru, epoxidation selectivity ≥30%
Enforcement implication. “Selectivity” is a functional limitation that may be critical at claim-construction and proof stages. A design-around that changes ligand set or oxidation-state arithmetic to fall outside formula (1) may still face infringement arguments if selectivity testing is argued to show the claimed functional performance is achieved.
Mo-specific ligand provenance requirement
The claims add a condition “in particular where Mo is used”: L must be derived from one of formulas (2), (3), or (4), where the ligand scaffold contains:
- X: N, O or S
- X’: N or C
- R1, R2: independently
- branched or unbranched, optionally halogenated C1–C12 alkyl, or
- optionally substituted C6–C14 aryl or heteroaryl, or
- the pair together forms C=O or C=S, or
- one of them can be H
Enforcement implication. For Mo catalysts, infringement analysis must map the third-party ligand back to a “derived from” relationship to those precursor classes. This is a narrower requirement than the generic “L is N/O/S donor” used for both metals.
What activity is claimed: selective epoxidation vs. olefin oxidation with oxygen?
Short answer. Claims 1 and 12 cover the catalyst used as such for selective epoxidation. Claim 2 covers use as a heterogeneous catalyst for selective oxidation of olefins in oxygen. Claims 5–11 cover processes that use only atmospheric oxygen and specify reaction variables.
Claim 1: “A compound … as a catalyst for selective epoxidization”
- Target reaction: epoxidization of alkenes MxOy(L)z (1)
- Performance floor: >45% (Mo) or ≥30% (Ru) selectivity.
Claim 2: “A heterogeneous catalyst … selective oxidation of olefins … in the presence of oxygen”
- Includes support material (in combination with MxOy(L)z)
- Selectivity floor: >45% if Mo compound is used (note the strict “more than 45%” in claim 2 as provided; claim 5 uses “≥40% Mo” and “≥30% Ru”).
- Supported catalyst is then further limited in claim 4.
Claim 5: process for selective epoxidization using only atmospheric oxygen
- Oxidant: only atmospheric oxygen
- Catalysts: MxOy(L)z (1) defined above
- Selectivity floor:
Key boundary. Claim 5’s “atmospheric oxygen only” restricts infringement arguments against processes that use concentrated O2, peroxides, or other oxidants (even if oxygen is present).
How broadly do the claims cover heterogeneous supported catalysts and what supports are named?
Short answer. The patent covers heterogeneous catalysts with a wide support list, with claim 4 enumerating multiple oxide supports plus several non-oxide solids including boron nitride/carbide and polymers.
Support materials in claim 4
Claim 4 lists supports selected from:
- Aluminum oxides
- Silicon dioxide
- Alumosilicates
- Titanium dioxide
- Zirconium dioxide
- Thorium dioxide
- Lanthanum oxide
- Magnesium oxide
- Calcium oxide
- Barium oxide
- Tin oxide
- Cerium dioxide
- Zinc oxide
- Boron oxide
- Boron nitride
- Boron carbide
- Boron phosphate
- Zirconium phosphate
- Silicon nitride
- Silicon carbide
- Polypyridines
- Polyacrylates
Enforcement implication. Third-party catalyst systems using common oxides (Al2O3, SiO2, ZrO2, TiO2, etc.) plus supported molybdenum or ruthenium oxide complexes face direct mapping to claim 4 unless the active component is outside formula (1) or the ligand provenance requirement for Mo is avoided.
What process parameters and substrate scope are included in claim 5 and its dependents?
Claim 5 substrate definition
Claim 5 recites epoxidization of alkenes described by an alkene formula in the patent text (provided as ##STR20##). It further defines substituents R1, R2, R3, R4:
- Each of R1–R4 is independently:
- H
- C1–C20 alkyl
- C1–C12 alkoxy
- C6–C10 aryl
- Or R1 and R2 together form a ring having 5 to 30 carbon atoms.
Claim 7: olefin types
- Aliphatic, optionally branched C2–C30 olefin
- or alicyclic C5–C12 olefin
Claim 8: oxidant form
- Oxygen is used:
- in pure form, or
- diluted with an inert gas
This does not contradict “only atmospheric oxygen” at claim 5 level; rather, claim 8 clarifies oxygen handling (pure vs diluted) within an oxygen-only regime.
Claim 9: temperature/pressure regime
- For C6–C12 alkenes: 30 to 300°C
- For C2–C5 alkenes: 120 to 230°C
- Pressure is chosen so the reaction proceeds in the liquid phase.
Claim 10: solvent-free
- Oxidation without solvent, in the pure olefin.
Claim 11: solvent systems
Solvent selected from:
- halogenated aromatics
- halogenated or non-halogenated hydrocarbons
- C1–C12 alcohols
- water
Enforcement implication. The solvent and “liquid phase” limitations are broad enough that they rarely serve as effective design-arounds. A more realistic carve-out is outside the catalyst formula (MxOy(L)z with the oxidation arithmetic and Mo ligand provenance) or using a non-atmospheric-oxygen oxidant.
Which specific donor ligands are expressly covered in the dependent claims?
Short answer. Claim 6 lists multiple named alcohol-derived donor ligands for Mo systems, each featuring a pyridyl-type heteroaryl substituent and an alkyl or perfluoroalkyl motif.
Claim 6 ligand exemplars
The claim states a donor ligand is employed that is derived from one of:
- 1,1-(C1–C6)-alkyl-1-(2-pyridyl)methanol
- 1-(2-pyridyl)-cyclohexan-1-ol
- 1-phenyl-1-(2-pyridyl)methanol
- 1,1-(C1–C6)-alkyl-1-(2-thiophenyl)methanol
- 1,1-(C1–C6)-perfluoroalkyl-1-(2-thiophenyl)methanol
- 1,1-(C1–C6)-alkyl-1-(2-pyrrolyl)methanol
- 1,1-(C1–C6)-alkyl-1-(2-imidazole)methanol
- 1,1-(C1–C6)-perfluoroalkyl-1-(2-imidazole)methanol
Enforcement implication. These exemplars strengthen evidentiary linkage from third-party Mo catalysts to the Mo “derived from formula (2), (3) or (4)” requirement. If a competitor uses a Mo catalyst with ligands structurally traceable to these classes, the ligand provenance obstacle is reduced.
What are the infringement “pressure points” in the claim set?
1) The formula (1) oxidation-state arithmetic
Claims constrain y based on the relationship: “the sum of x+z gives a metal oxidation number of +6.” This can matter in claim construction for the chemical composition of the active species. Competitors may attempt to operate at a different oxidation level or in mixed-valence states.
2) Mo ligand provenance requirement
For Mo catalysts, it is not enough that L is an N/O/S donor. It must be derived from the specified ligand precursor classes. That is a distinct narrowing that could support non-infringement if the competitor’s ligand lineage is outside the claimed precursor families.
3) Selectivity floors
- Claim 1: Mo epoxidation selectivity >45%; Ru ≥30%
- Claim 5: Mo ≥40%; Ru ≥30%
Selectivity becomes a practical proof issue: a competitor can argue different selectivity distributions under their process conditions, especially if their products differ (diol/byproducts) or if they tune conditions to improve conversion but reduce selectivity.
4) “Only atmospheric oxygen”
Using peroxides, iodosyl reagents, or other oxygen-transfer agents can provide a cleaner non-infringement pathway on the process claims, even if the catalyst system itself falls within formula (1).
How does US 5,969,166 compare across claim types: catalyst composition vs process vs supported catalyst?
| Claim |
Category |
Main limitation axis |
Practical design-around vector |
| 1, 12 |
Soluble catalyst composition (genus) |
MxOy(L)z formula + selectivity |
Change catalyst to fall outside oxidation arithmetic or ligand provenance; operate with selectivity below threshold |
| 2 |
Heterogeneous oxidation catalyst |
MxOy(L)z + support + selectivity |
Use different active metal system, oxidation state, ligand lineage; choose support if outside list for the narrower claim 4 |
| 4 |
Heterogeneous supported catalyst (enumerated supports) |
Support selection |
Use supports not in list, while still arguing no equivalence; or avoid active species mapping |
| 5 |
Process: selective epoxidation with “only atmospheric oxygen” |
Catalyst + oxidant restriction + selectivity + substrate structures |
Use different oxidant; use different catalyst mapping; show selectivity below threshold |
| 6 |
Ligand exemplars |
Derived donor ligands |
Use different donor ligand family not traceable to those exemplars/precursors |
| 7–11 |
Process parameter dependents |
Olefin class; oxygen form; T/pressure; solvent-free/solvent |
Tune process conditions alone will not avoid if catalyst mapping and selectivity/oxidant restrictions still met |
What does the patent landscape likely look like for US exclusivity and challenge risk?
Short answer. With the claim set focused on catalyst compositions and selective epoxidation/oxidation processes, the landscape risk cluster typically comes from: (i) other Mo/Ru oxide(L) catalyst systems using N/O/S donor ligands, (ii) supported heterogeneous variants using common oxides (Al2O3, SiO2, ZrO2, TiO2), and (iii) oxygen-only epoxidation processes claiming selectivity ranges.
However, a complete US “landscape” requires the patent’s full bibliographic record: assignee, filing priority, expiration/term, prosecution history, and any related continuation family and/or co-owned patents. Those bibliographic details are not present in the prompt, so a complete, accurate US-timeline and competitor-by-competitor mapping cannot be produced here.
Orange Book status, exclusivity, and regulatory linkage: is this a listed FDA drug patent?
Short answer. This patent is directed to catalysts for chemical oxidation/epoxidation, not to an FDA-approved drug product with an Orange Book listing. There is no pathway-linked FDA regulatory exclusivity analysis that can be performed from the provided claim text.
Key Takeaways
- Core claim scope is a broad Ru/Mo oxide complex genus MxOy(L)z where x = 1–3, z = 2–2x, and y is selected to make the metal oxidation level +6, with L as an N/O/S donor ligand.
- For Mo systems, the ligand provenance is a major narrowing: L must be derived from specific precursor structures (2), (3), (4) with constrained substituent classes and C=O/C=S or H allowance.
- The process claims are constrained by “only atmospheric oxygen” and selectivity thresholds (Mo ≥40% in claim 5; Ru ≥30%). Those two limitations are the main operational levers for infringement risk mitigation.
- Supported heterogeneous embodiments are broad via claim 2, and narrowed by claim 4’s enumerated supports that include common industrial oxides and some nitride/carbide/phosphate materials and certain polymers.
- Freedom-to-operate focus should be on whether a competitor’s catalyst active species satisfies the MxOy(L)z formula constraints and, for Mo, the derived-ligand requirement, and on empirical evidence of selectivity under an oxygen-only epoxidation regime.
FAQs
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Can a competitor infringe claim 5 if they use a non-atmospheric oxygen concentration or oxygen feed system?
The infringement hinge is “only atmospheric oxygen” on claim 5; oxygen dilution and pure oxygen are addressed in claim 8, but other oxygen-transfer agents or non-atmospheric oxidant systems are not within the claim framing.
-
What happens if a competing catalyst is chemically similar but the selectivity is lower than 45% (Mo) or 30% (Ru)?
Selectivity limits are explicit claim constraints in both composition and process claims; operating below those thresholds is a primary defensive strategy.
-
Do the supported-catalyst claim 4 supports limit infringement strongly?
Claim 4 is enumerated, but claim 2 covers heterogeneous catalysts more generally (support defined only by being inorganic or organic in claim 2 as provided). Risk persists unless the active species avoids formula (1) mapping.
-
Are the process solvent and temperature ranges effective non-infringement levers?
They are generally secondary; if the catalyst and oxidant and selectivity constraints are met, simply changing solvent or temperature often does not avoid composition/process claim coverage.
-
Does claim 12 add anything beyond claim 1 for soluble catalysts?
Claim 12 restates the soluble catalyst composition with the same formula (1) and selectivity constraints, adding no new structural limitations beyond “readily soluble in organic solvents.”
References (APA)
- US Patent 5,969,166. (n.d.). [Ruthenium/Molybdenum oxide(L) catalysts for selective epoxidation of alkenes and selective oxidation of olefins]. United States Patent and Trademark Office.
