Extractive Electrospray Ionization Tandem Mass Spectrometry Monitoring Four Reactions Of Synthetic Nitrogen Heterocycles

Nitrogen-containing heterocyclic compounds are often used as intermediates for synthetic medicines and pesticides,and their synthesis studies are particularly important.The reaction mechanism can guide the synthesis of organic reactions,for example,looking for new catalysts that increase the reaction yield.This reduces research time,making it more systematic and standardized.Through the changes in the ion mass of reactants and products,the beginning,end,and intermediate processes of the reaction can be accurately observed,and the reaction can be accurately grasped.The time period minimizes costs.This thesis mainly introduces three methods for the real-time monitoring and synthesis of synthetic nitrogen heterocyclic compounds by Extractive Electrospray Ionization Tandem Mass Spectrometry?EESI-MS?.?1?EESI-MS Monitoring the Friedl?nder reaction:EESI-MS online monitoring the Friedl?nder condensation reaction between 2-aminoacetophenone and acetylacetone,2-aminoacetophenone and cyclohexanone,2-aminobenzophenone and acetylacetone in methanol medium catalyzed by oxalic acid.The ion peaks of the reactants,intermediates,and products were monitored at different time intervals after initiation,and their signal intensity was recorded as a function of the reaction time.The reaction mechanism was inferred:the two reactants first undergo an addition reaction.Dehydration then produces unsaturated carbonyl compounds,and finally dehydration imidization gives quinoline derivatives.At the same time,through comparison,the scientific and practical applicability of this method is illustrated more fully.?2?EESI-MS Monitoring the Paal-Knorr Reaction:EESI-MS outline monitoring the Paal-Knorr reaction of 2,5-hexanedione and aniline catalyzed by ZrOCl₂·8H₂O in methanol medium,and recorded the changes of reactants,intermediates and products over time during the monitoring process.Reaction mechanism:Reaction path A:Formation of hemiacetal,cyclization of the hemiacetal,and dehydration of the condensed amine into a pyrrole ring.Path B:Formation of hemiacetamines,cyclization of enamines,and dehydration of enamines to pyrrole rings form product dimers when the product is increased to a certain amount.The difference from acetic acid catalysis was found:dehydrogenated intermediates appeared and simple analyses were performed?3?EESI-MS Monitoring the Doebner-Von Mille Reaction:EESI-MS online?outline?monitoring the reaction between n-butyraldehyde and anilines,p-toluidine,p-anisidine catalyzed by iodine and p-toluenesulfonic acid,and captured the the ion peaks of signals of the reactants,intermediates and products,and the reaction mechanism is presumed:the nucleophilic addition reaction of aniline and aldehyde eliminates the reaction to form an imine,and the imine undergoes a Michael addition reaction with an aldehyde of another molecule,and then Self-cyclization condensation dehydration,and finally hydrogen aromatization to produce quinoline derivatives.At the same time,the catalytic effects of two catalysts,iodine and p-toluenesulfonic acid,were compared.The results showed that p-toluenesulfonic acid had a better catalytic effect?shorter reaction time?.?4?EESI-MS Monitoring the 2-methyl quinoline and p-nitrobenzaldehyde to synthesis of 2-alkyl aza aromatic hydrocarbons:The effects of different amino acid,molar ratio of reactants,reaction temperature,solvent and catalyst amount on the reaction were screened.Under the optimal reaction conditions,the reaction was monitored by EESI-MS and the reaction mechanism was inferred:2-methylquinoline generates enamine intermediates on the catalyst pipernic acid,and an aromatic aldehyde activated by protons undergoes an addition reaction to give an alcohol intermediate,which is then cleaved by the N-H bond to give the product.