The objectives of this research were to develop an environmentally friendly synthesis route to generate bis(4-nitro-3-furazanylamino)methane (MBANF) and to test this material for skin sensitization.
This study was an in-depth evaluation of the current synthetic methods that can be used to generate MBANF. At the start of this project, the state of the art method for producing MBANF involved oxidation of 3,4-diaminofurazan to yield 3-Amino-4-nitrofurazan (ANF) which was subsequently reacted with formaldehyde to yield MBANF. The main concerns and issues associated with this synthesis method were associated with the manufacture of ANF. The process resulted in a high amount of byproducts which resulted in a low reaction yield. Additionally (and most importantly) the process employed the use of dichloromethane to acquire the ANF product from the reaction solution. While dichloromethane can be used for laboratory scale reactions, it is not an appropriate solvent to be used on the pilot or production scale due to its inherent toxicity to both humans and environment. Therefore, this project was mainly concentrated on improving the synthesis of ANF in an effort to increase the reaction yield and to eliminate the use of dichloromethane (and preferably all solvents).
This project has resulted in an improved process for the synthesis of MBANF. A scalable synthesis for ANF has been developed resulting in an increase in yield and the replacement of dichloromethane with the more environmentally friendly and scalable solvent, methyl tert-butyl ether. It is even possible that the extraction step (and use of solvent at all) may not be required if a small decrease in reaction yield can be tolerated.
A second portion of this study was to complete testing to determine if MBANF is likely to be a skin sensitizer. This testing had not been previously completed and the results would be quite relevant to the future utility of ANF. MBANF human cell line activation testing yielded a positive response for skin sensitization and was predicted to have a moderate to high oral toxicity (114 mg/kg).
The benefits of this project include the development of an ANF manufacturing process that serves to eliminate the use of dichloromethane for extraction and greatly reduces the generation of unwanted ANF byproducts, thus increasing the overall yield. The process that was developed could be viable for pilot scale production with additional optimization.