Research Progress Of Substituting Methyl Acetate For Dimethyl Malonate To Synthesize Methyl Dihydrojasmonate

Jasmine is currently being widely recognized and cherished flavor, hedione (Methyl Dihydrojasmonate, MDJ) is one of the important compounds deployment type smell of jasmine in the field of cleaning additives, cosmetics, pesticides and so on, and have a wide range of applications. The key factors affecting the quality of the response is to choose the right materials, the process route and try to get higher quality aroma.The main purpose of this paper is to explore how to obtain high yield and high quality MDJ. Using n-valeraldehyde and cyclopentanone aldehyde condensation products of2-pentyl ketone cyclopentenone as starting material, and methyl acetate under Michael addition and microwave-assisted alkaline agent Lithium diisopropylamide (LDA) effect prepare a crude product, followed by refluxing under microwave-assisted and alkaline reagent Na2CO3effect, obtained high-quality MDJ.In the experimental process, the reaction is influenced by many factors.By examining each reaction conditions, the economy and other aspects of the theory and design several experiments optimum conditions, and by IR, GC-MS, H NMR spectra of the reaction product of qualitative and quantitative analysis, The main research achievements are as follows:(1)Cyclopentanone and n-valeraldehyde aldol condensation reaction to form two new chiral centers, are MDJ different stereochemical configuration of the main reasons is formed. Experiments using LDA as the alkaline reagent, the product was obtained cis dynamics control, process conditions: Lithium diisopropylamide at-78℃under reaction and cyclopentanone enolates, then slowly added n-valeraldehyde, a raw material input ketone aldehyde molar ratio2.2:1, LDA in an amount of30%, the reaction temperature is25℃, addition time2h, the choice of the acid catalyst p-toluenesulfonic acid, and the amount of5%. Under these conditions, cis-2-pentyl-cyclopentenone in a yield of45%.(2)Methyl acetate and2-pentyl cyclopentenone Michael plus the best process conditions of the synthesis of MDJ is: in the microwave auxiliary function, using the first drop of methyl acetate, after adding the alkaline reagent LDA, the way of feeding the last drop of2-amyl cyclopentenone, the first step in the reaction of methyl acetate under LDA pull α-H, the temperature is-78℃, Michael addition reaction temperature is-5℃, reaction time10min, methyl acetate and2-pentyl cyclopentenone ratio of raw materials is1.2:1, LDA in an amount of20%, quinine as phase transfer catalyst. Under these conditions, the yield of47.6%of MDJ. (3)Optimum technological conditions of improving the quality of the MDJ aroma is: under the effect of microwave assisted, reaction time for10min, microwave power0.5KW, using catalyst for NaCO3, dosage of10%. Under this condition, MDJ cis isomer content is14.57%.This study is still in the laboratory stage small scale, in view of the many factors that affect response effect and microwave-assisted reaction constraints on the industrial scale production, future implementations can explore amplification test, create a better efficiency.