Design And Synthesis Of Novel Allyl Ionic Liquids And Its Application In C-H Bonds Electro-oxidation

Ionic liquid is a new type of green medium in the field of chemistry and chemical industry with good stability,conductivity,designability,special solubility,non-flammability,and low vapor pressure etc..Compared with traditional alkyl ionic liquids,allyl-based ionic liquids have higher conductivity and better solubility to organics,and have potential application prospects in organic electrosynthesis.In this paper,three new allyl ionic liquids were designed and synthesized,and their structures were detected by NMR.The chemical properties of the allyl ionic liquids were investigated,and it was found that the p H value of the new allyl ionic liquid differs greatly when the anions were changed,showing the controllable designability of the ionic liquids.The conductivity of the new allyl ionic liquids was higher than that of alkyl ionic liquids at lower concentrations and the electrochemical window was wider than that of the alkyl ionic liquid at room temperature.Then,the electro-oxidation of different substrates such as p-methoxytoluene（p-MT）,p-methoxybenzyl alcohol（p-MeOB_ZOH）were studied by cyclic voltammetry and chronoamperometry.It was found that the electro-oxidation of p-MT and the electro-oxidative cyanation of p-MeOB_ZOH were controlled by diffusion process,and the diffusion coefficients were D=2.02×10^-9cm²·s^-1and D=1.69×10^-9cm²·s^-1,respectively.The electrolysis experimental of different substrates such as p-MT,p-MeOB_ZOH and p-Methoxybenzaldehyde（p-MeOBA）were studied through constant current electrolysis,and the results were listed following.（1）The electro-oxidative synthesis of p-MeOBA from p-MT were studied,and the effects of various factors such as supporting electrolyte type,supporting electrolyte content,electrode material,reaction temperature and time were explored.The yield of the target product p-MeOBA was up to 96%at 60℃for 16 h when the reaction was carried out in the undivided electrolytic cell containing 1.5 mmol p-MT,0.75 mmol AAEIMBF₄dissolved in 15 m L DMF aqueous solution,and the anode was Pt electrode,the cathode was Pb electrode,the current density was 10 m A·cm^-2.（2）The synthesis of p-meothoxybenzonitrile（p-MeOBN）through the electro-oxidative cyanation of p-MT were investigated,the influences of different reaction conditions such as the supporting electrolyte type,supporting electrolyte content,electrode material,reaction temperature and time were studied.The substrate was almost completely converted.The yield of the target product p-MeOBN was 74%at 60℃for 16 h when the reaction was carried out in the undivided electrolytic cell containing 1.5 mmol p-MT,0.75 mmol AAEIMBF₄dissolved in 15 m L DMF aqueous solution with 2.25 mmol hydroxylamine hydrochloride as the nitrogen source,and the anode was Pt,the cathode was Pb at a current density of 10 m A·cm^-2.8%p-methoxybenzaldehyde（p-MeOBA）and 10%p-methoxybenzaldehyde oxime（p-MeOBAO）were detected,indicating the electro-oxidation of methyl group to aldehydes during the process.While the formation of aldehydes was reduced directly from the methyl group,and the cyanation was prevented.（3）The synthesis of p-MeOBN through the electro-oxidative cyanation of p-MeOBA were investigated,and the reaction factors such as the supporting electrolyte type,supporting electrolyte content,reaction temperature and time were studied.The substrate was almost completely converted,but the yield of the target product p-MeOBN was decreased to 71%at a current density of 10 m A·cm^-2,60℃for 8 h.And 13%p-methoxybenzoic acid（p-MeOBAcid）was detected.It showed that the further oxidation of the high concentration of aldehyde on the electrode surface,and the yield of cyanation product decreased.（4）The synthesis of p-MeOBN through the electro-oxidative cyanation of p-MeOB_ZOH were studied,and the reaction factors such as the supporting electrolyte type,supporting electrolyte content,electrode material,reaction temperature and time were studied.The yield of the target product p-MeOBN was high up to 95%at 60℃for 16 h,when the reaction was carried out in the undivided electrolytic cell containing 1.5 mmol p-MT,0.75 mmol AAEIMBF₄dissolved in 15 m L DMF aqueous solution with 2.25 mmol hydroxylamine hydrochloride as nitrogen source,and the anode was Pt,the cathode was Pb at a current density of 10 m A·cm^-2.The results showed that the further oxidation of aldehyde was inhibited because the aldehyde was generated in situ and difficult to aggregate on the electrode surface,and the cyanation was promoted effectively.