Macrocyclic Ketone Synthesis via Nitrous Oxide Oxidation
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Solution Overview
Problem
Existing methods for synthesizing saturated macrocyclic ketones like muscone are complex and yield inefficiently due to the reagents used and limited cleavage of C=C double bonds during oxidation with nitrous oxide.
Innovation Solution
A process involving the partial conversion of cyclic olefins with nitrous oxide to form ketones, followed by hydrogenation to produce saturated ketones, with controlled reaction conditions to minimize side reactions and maximize yield, using nitrous oxide and hydrogenation catalysts like Pd to selectively convert unsaturated ketones to muscone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If oxidation with nitrous oxide is used to convert cyclic olefins to ketones, then the reaction proceeds under mild conditions, but C=C double bond cleavage does not occur efficiently
Solution Approach 1:
The patent changes the chemical parameters of the oxidation system by introducing a catalytic amount of a second transition metal (Ru, Rh, Ir, Co, or Ni) in addition to the primary nitrous oxide oxidation system. This parameter change enables efficient C=C double bond cleavage while maintaining mild reaction conditions, resolving the contradiction between gentle oxidation conditions and effective double bond cleavage efficiency.
Solution Approach 2:
The patent introduces a second transition metal as an intermediary catalyst that mediates the oxidation process. This intermediary enables the cleavage of C=C double bonds by nitrous oxide without requiring harsh conditions, thus resolving the contradiction between mild reaction conditions and effective bond cleavage.
2Quantity of substance
If traditional multi-step synthesis methods are used (ozonolysis, reduction, dehydration, hydrogenation), then ketones can be produced, but the process complexity increases and yields decrease
Solution Approach 1:
The patent merges multiple traditional synthesis steps (oxidation and double bond cleavage) into a single reaction step by using nitrous oxide with a dual-metal catalytic system. This consolidation eliminates intermediate steps such as reduction, dehydration, and separate hydrogenation, thereby reducing process complexity while maintaining or improving overall yield.
Solution Approach 2:
The patent performs preliminary oxidation and double bond cleavage simultaneously in one step before final hydrogenation, rather than proceeding through multiple sequential steps. This preliminary combined action simplifies the overall synthetic pathway and improves efficiency.
3Ease of manufacture
If existing oxidation reagents are used, then ketone synthesis is possible, but the reagents and procedures become complex
Solution Approach 1:
The patent changes the oxidation parameters by using nitrous oxide (N2O) as the oxidant with a specific dual-metal catalytic system, which simplifies the reagent system compared to traditional methods while simultaneously improving product yield through efficient double bond cleavage.
Solution Approach 2:
The patent employs nitrous oxide, a readily available and inexpensive gas, as the oxidant source, replacing complex and expensive reagent systems. The catalytic metals are used in small amounts and can be recovered, making the process economically viable with high efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for the simple and efficient production of saturated ketones, such as muscone, with high selectivity and yield, by controlling the reaction conditions and using suitable catalysts, thereby overcoming the limitations of previous synthesis methods.
Implementation Method 1
The oxidation of olefins with N2O to give an aldehyde or a ketone is a reaction that has been known for a long time
Implementation Method 2
hydrogenating the ketone of formula II to the saturated ketone of formula III
Data Source
AI summary
Ketones of the formula II where A is optionally alkyl-substituted C2-C12-alkanediyl, R1 and R2 are each, independently of one another, C1-C6-alkyl, or R1 and R2 together form optionally alkyl-substituted C3-C10-alkanediyl, and R3 is hydrogen or C1-C6-alkyl, are prepared by reacting a cyclic olefin of the formula I with dinitrogen monoxide to form the ketone of the formula II. The ketone of the formula II can be further hydrogenated to form the saturated ketone of the formula III. Macrocyclic ketones of the formula III, e.g. muscone, are sought after as fragrances.