Metal/Graphitic Carbon Nitride For Photocatalytic Oxidation Of Thioethers And Alcohols

Oxidation reaction is one of the most important types in organic synthesis.Cheap raw materials can be oxidized into high value-added products.Therefore,it has received extensive attention from chemists.Sulfoxides and ketones are important components of medicinal chemistry and fine chemistry,which can be obtained by oxidizing the cor-responding sulfides and alcohols.The traditional methods for the synthesis of sulfox-ides and ketones by the oxidation of thioethers and alcohols use peroxide and potassium permanganate as oxidants,or require high temperature and high pressure to make the reaction proceed.The reaction conditions are strict and the reaction process is compli-cated,which make it difficult to industrialize.In recent years,photochemical reaction has attracted people's attention because of mild reactions,safety,efficiency,and envi-ronmental friendliness.The photocatalyst is a necessary condition for the smooth pro-gress of the photochemical reaction.Therefore,the development of a photocatalyst with good performance is a hot field of current research.In this study,a new metal/g-C₃N₄ catalyst was assembled by metal-modified gra-phitic carbon nitride,and its conversion and selectivity in the photocatalytic oxidation of sulfide and alcohol compounds were studied.The main content and results are as follows:A method for preparing sulfoxide by photocatalytic oxidation of sulfide at room temperature using copper-loaded graphitic carbon nitride?Cu/g-C₃N₄?as photocatalyst,O₂ as oxidant and acetonitrile?Me CN?as solvent was established.The experimental results showed that under simulated sunlight conditions,the conversion of methyl phe-nyl sulfide reached 92%,with the 99%selectivity of the product sulfoxide.The exper-iments of the applicable scope of the substrate show that the electronic effect of the substituent on the benzene ring has a certain effect on the reaction,and the aryl sulfide containing electron-donating groups is more likely to react,such as-CH₃,-OCH₃.This system is also suitable for aliphatic sulfides.The catalyst circulation experiments show that the catalyst has good stability,the conversion rate can still reach 84%after five cycles of use.A mild and efficient photocatalytic system for the dehydrogenation of alcohols to ketones has been developed.Pt/g-C₃N₄ is used as a photocatalyst,Me CN is used as a solvent,and it can catalyze the smooth conversion of benzyl alcohol to the target com-pound under N₂ atmosphere at room temperature.The conversion of benzhydrol reached 97%,with the 99%selectivity.Under the optimal conditions,-Me,-Et,-F,-Cl,-Br,-CF₃,and-OCH₃ and other dozens of electron-donating and electron-withdrawing functional group-substituted alcohols can be smoothly converted into corresponding carbonyl compounds with a selectivity of 95%and a conversion of 58-99%.Through free radical trapping experiments,intermediate monitoring and other experimental methods,it is speculated that the reaction may be carried out through the benzyl alcohol radical mechanism,which is a two-electron oxidation process.The Pt/g-C₃N₄ photo-catalyst was also tested for cycle stability.After five uses,the conversion of the sub-strate benzhydrol was 91%,the catalyst activity did not decrease significantly,which indicated the stability was good.