Study On The Synthesis Of 2,2,4-Trimethyl-1,3-Pentanediol Penta Monoisobutyrate

2,2,4-trimethyl-1,3-pentanediol monoisobutyrate,with low freezing point,water-insoluble and high boiling point,is mainly widely used as an environmental friendly film-forming assistant for waterborne coatings.It was synthesized from isobutyraldehyde(IBD)by aldol condensation,Cannizzaro and esterification reaction in basic condition.At present,the traditional basicity catalysts present various disadvantages,such as hardly separation,corrosion for equipmen,poor recyclability.Therefore,it is urgent to find a new catalyst with high efficiency,easy separation and good reusability.In this paper,eight basic catalysts(triethylamine,sodium methoxide,sodium ethoxide,anion exchange resin,sodium hydroxide,calcium hydroxide,potassium hydroxide,calcium oxide,calcium hydroxide and sodium calcium mixture(5:2))were studied for the synthesis of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.It was found that sodium methanol dispiayed the best catalytic performance.Then,the single factor of sodium methoxide catalytic system was studied.The results showed that the product enhanced 90.38%yield under the optimum conditions of 3.5%catalyst,55?C reaction temperature and 3.0 h reaction time.The results of repeated experiment under the optimized process conditions showed that the highest yield reached 91.70%and the average yield was 90.77%,indicating that the subjective reproducibility of the experiment was well and sodium methoxide showed good catalytic performance in the synthesis.The target product was determined by GC-MS,and the purity was 97.30%.In this paper,four DBU-based monbasic site ionic liquid(MSILs)[BDBU]IM,[BDBU]OH,[ODBU]IM,[ODBU]OH and seven 1-methylimidazole-based,1,1,3,3-tetramethyl guanidine-based and DBU-based bibasic sites ionic liquids(BSILs)[Aemim]IM,[HDBU]IM,[TMG]IM,[Aemim]Pro,[Aemim]Gly,[HDBU]Pro[HDBU]Gly were designed by quaternization and ion exchange reaction.First,FT-IR,~1HNMR,GC-MS,EA,TG-TDA and pH techniques were employed to analyze the ILs.BSILs showed higher basic density and structural strength.Then,they were frist used in thesynthesisof2,2,4-trimethyl-1,3-pentanediolmonoisobutyratein water/isobutyraldehyde system.The results showed that[BDBU]IM and[Aemim]IM had better catalytic performance in the reaction process.Therefore,taking[BDBU]IM and[Aemim]IM as the model catalysts for further exploring.The[BDBU]IM catalytic system was explored in the single-factor method and the results showed that the yield of the product 63.50%under the conditions of 7.0%catalyst amount,70?C reaction temperature and 3.0 h reaction time.Furthermore,the three-factor and three-level orthogonal method was used to optimize the process conditions for the synthesis of dodecanol esters.The results showed that the reaction yield is higher than65.00%under the conditions of 7.5%catalyst amount,70?C reaction temperature and 2.0h reaction time.And the catalyst still maintains high activity after 8 cycles.DFT was applied to simulate[BDBU]IM and separation mechanism of[BDBU]IM/water-dodecanol ester were reserched.The results showed that the design of[BDBU]IM is reasonable and there is a strong hydrogen-bond between[BDBU]IM/water system,that is,"high temperature homogeneous phase,low temperature phase separation"was realized under the thermoregulated phase catalysis system composed of BSILs/water-IBD.The target product was determined by FT-IR,~1H NMR and GC-MS,and its by-product was analyzed.The[BDBU]IM catalytic system was explored in the single-factor method and the results showed that the yield reached 72.29%under the conditions of 5.0%catalyst amount,65?C reaction temperature and 2.5 h reaction time.And the catalyst still maintains high activity after 14 cycles.Finally,proposed a reasonable catalytic mechanism for[Aemim]IM.ILs exhibited the dual functions of basic catalyst and phase transfer catalyst.In the case of considerable yield of the product,it has better stability,easier separation and multiple recycling than the traditional catalyst.It is in line with the research topic of green chemistry and has a broad application prospect.