Synthesis And Antimicrobial Activity Of Fumarate Based Ionic Liquids

Trans-but-enedioic acid esters(MRF) are widely used as antimicrobicides, which have the advantages of broad bactericidal spectrum,low-toxicity and high environmental compatibility,but their antimicrobial effects are seriously shortened because of the poor solubility in water.In this paper,α,β-unsaturated carbonyl,the antimicrobial activity functional group of trans-but-enedioic acid,was used as matrix. On the one hand,synthesis with MRF by esterification ensured lipotropy of the products;on the other hand,compounding with imidazolyl maintaind hydrophilicity of the products.That was,quaternary ammonium imidazole and mono-ester were introduced into the two sites of the carboxylic acid respectively to obtain fumarate based ionic liquids([RMIM][MRF]).Then their antimicrobial properties were studied. The main contents and some successful results have been listed as following:(1) Synthesis and characterization of MRFA series of MRF were synthesized through mixing maleic anhydride with alcohol and isomerizating with AlCl₃.The reaction conditons influencing the yield of MMF and MOF such as materials ratio,the types of isomerization catalyst, isomerization temperature,isomerization time,dosage of isomerization catalyst were investigated.Orthogonal design experiments were also carried out to optimize the synthetic technologies.Furthermore,different techniques such as melting range determination,FT/IR spectroscopy and NMR spectroscopy were adopted to characterize the products.The results showed that the optimal isomerization condictions were:isomerization temperature 80℃,isomerization time 2 h,dosage of isomerization catalyst 0.7 g for the reaction of maleic anhydride and methol with the yield of MMF of 72.3%;isomerization temperature 100℃,isomerization time 4 h, dosage of isomerization catalyst 0.2 g for the reaction of maleic anhydride and octanol with the yield of MOF of 61.9%.(2)Synthesis and characterization of[RMIM]OH[RMIM]X were synthesized by mixing N-methylimidazole and halohydrocarbon under the N₂ atmosphere,then[RMIM]OH were obtained through anion-exchange. The reaction conditons influencing the yield of[RMIM]Br such as materials ratio, reaction temperature and reaction time were investigated.Orthogonal design experiments were also carried out to optimize the synthetic technologies.Different techniques such as FT/IR spectroscopy and NMR spectroscopy were adopted to characterize the products.The results showed that the optimal synthetic conditions were:n(C₄H₇N₂)/n(C₈H₁₇Br)1.0/1.1,reaction temperature 65℃,reaction time 25 h for the reaction of C₄H₇N₂ and C₈H₁₇Br with the yield of[RMIM]Br of 98.5%.(3)Synthesis and characterization of[RMIM][MRF][RMIM][MRF]were synthesized through neutralization reaction between MRF and[RMIM]OH.A series of techniques such as FT/IR spectroscopy and NMR spectroscopy were adopted to characterize the products.All the characterization data were consistent with the expected compositions and structures.(4) Antimicrobial activity of[RMIM][MRF]Antimicrobial activity against bacteria,mold and yeast were studied by employing the photoelectricity turbidimetric method and spread-plate method.The results showed that[RMIM][MRF]could remarkably inhibit the growth of those microbial,which were better than benzoic acid and sorbic acid.Antimicrobial activity of[RMIM][MRF]with phenyl were better than that without phenyl.The minimal inhibitory concentration(MIC) for gram-positive bacteria,gram-negative bacteria, mold,S.cerevisiae and C.albicans were 0.2,0.4,0.4,0.4 and 0.6 g/L respectively.[RMIM][MRF]performed strong antimicrobial activity in pH 4～9.The antimicrobial activity of[RMIM][MRF]in pH 9 was better than that in pH 5 or pH 7, Meantime,[RMIM][MRF]demonstrated good solubility in water.Toxicity test results showed[RMIM][MRF]were non-toxic(LD＞60ml/kg Weight) and the allergic experiment indicated that it would not cause skin allergies.Therefore,[RMIM][MRF] were expected to become a new promising antimicrobial agent.