Oxidative conversion of aliphatic aldehydes to nitriles using oxoammonium salts

Oxoammonium salt-mediated oxidative conversion of aliphatic aldehydes to nitriles

This technology is a synthetic method for producing nitriles using aliphatic aldehydes and ammonium acetate (NH4OAc) as starting materials, with the oxoammonium salt 4-AcNH-TEMPO+BF4- as an oxidation mediator in an acetic acid solvent under a nitrogen atmosphere. After the reaction, the reduced TEMPO compound is re-oxidized for reuse.

The Sandmeyer and Rosenmund-von Braun reactions, widely used for nitrile production, involve the use of highly toxic metal cyanides. Alternative routes, such as amine oxidation or amide/aldoxime dehydration, require harsh reaction conditions and are limited in substrate scope and scalability.

This technology selectively produces aliphatic nitriles with yields exceeding 60% without the use of cyanides by employing stoichiometric amounts of oxoammonium salt under optimized temperature and equivalent conditions. The resulting 4-AcNH-TEMPO can be easily re-oxidized using HBF4, NaOCl, and NaBF4, allowing for the repeated use of the oxidant. It can be applied to the synthesis of pharmaceutical intermediates, pesticide raw materials, and dyes, reducing both the burden of handling toxic reagents and the cost of oxidants.

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Key Features:

• A method for producing nitriles using aliphatic aldehydes and ammonium acetate as starting materials, mediated by the oxoammonium salt 4-AcNH-TEMPO+BF4-
• Reaction conditions performed at 70°C for 12 hours in an acetic acid solvent under nitrogen, using 2.0 equivalents of oxoammonium salt relative to the aldehyde
• A step of using 2.4 to 4.0 equivalents of ammonium acetate relative to the aldehyde and creating a nitrogen atmosphere using a nitrogen balloon
• A step of regenerating the oxoammonium salt for reuse by oxidizing the reduced 4-AcNH-TEMPO after the reaction with fluoroboric acid, sodium hypochlorite, and fluoroborate

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This invention was developed with support from the Ministry of Science, ICT and Future Planning for the development of eco-friendly and economical selective aerobic oxidation reactions.

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