H3O+SbF6− as a reagent in cyclotrimerization of nitriles
published: May 23, 2017, recorded: April 2017, views: 1320
Report a problem or upload filesIf you have found a problem with this lecture or would like to send us extra material, articles, exercises, etc., please use our ticket system to describe your request and upload the data.
Enter your e-mail into the 'Cc' field, and we will keep you updated with your request's status.
Cyclotrimerization of nitriles requires high temperatures and extreme pressures,  however use of catalysts greatly diminishes the need for extreme conditions. Most commonly used catalysts are SmI2/amine, trifluoromethanesulfonic acid (TfOH) and other Lewis acids.[4,5] While reaction conditions and yields are well documented, the mechanism of conversion is still relatively poorly investigated.[3,6] Focus of our research was the use of strong Lewis acids MF5 (M = As, Sb, Nb, Ta) and their products with different nitriles (R–CN). The system was investigated and reactive species were identified as well as different products. One of the obtained results was 2,4,6-trisubstituted-1,3,5-triazinium cation (1) which is a product of aforementioned cyclotrimerization. In order for reaction to proceed acidic proton (H+) is required in combination with weakly coordinating MF6 − moiety. Further optimization yielded easy-tohandle solid reagent H3O+MF6 − (M = As, Sb, Nb, Ta), which was found to produce equal results. Reaction takes place with liquid nitrile in inert conditions at room temperature, where nitrile also acts as a solvent. In addition, co-product competing to the process of 1,3,5-triazine formation was also prepared. Dissolution of 2,2-dimethylpropanenitrile (tBuCN) and H3O+SbF6 − in dichloromethane (DCM) yielded scarcely soluble 1-[(2,2-dimethylpropanoyl)amino]-2,2-dimethylpropaniminium cation (2) which is a dimer of two starting nitriles and corresponding anion. Our results will further elucidate the process of acidic activation of nitriles and formation of 2,4,6-trisubstituted-1,3,5-triazines.
Download slides: ipssc2017_zupanek_cyclotrimerization_nitriles_01.pdf (691.2 KB)
Link this pageWould you like to put a link to this lecture on your homepage?
Go ahead! Copy the HTML snippet !