3-正构烷氧基噻吩的合成工艺

Synthesis Process of 3-(n-Alkoxy)thiophene

以CuBr为催化剂,NMP为溶剂,在110°C条件下,先用3-溴噻吩与过量的甲醇钠发生取代反应合成3-甲氧基噻吩,收率为82.3%。再以无水NaHSO4为催化剂,用正戊醇与3-甲氧基噻吩反应,合成了3-戊氧基噻吩。通过正交反应研究了反应物摩尔比、反应时间、反应温度以及催化剂用量对合成3-戊氧基噻吩收率的影响,得出了最佳反应条件为:n(3-甲氧基噻吩)∶n(戊醇)=1∶1.1;反应时间3.5 h;反应温度115°C;催化剂用量:0.25%。然后根据合成3-戊氧基噻吩的最佳工艺条件并加以适当修改,合成了3-乙氧基噻吩、3-丙氧基噻吩、3-丁氧基噻吩、3-戊氧基噻吩、3-己氧基噻吩、3-辛氧基噻吩,收率分别为78.5%、73.5%、71.5%、69.7%、67.2%、64.3%。这些化合物结构都通过IR,1H NMR和MS进行了表征,并对其进行了初步香味评价。结果表明它们都具有基本肉香味的特征。

3-Methoxythiophene was synthesized from 3-bromothiophene and surplus sodium methoxide using cuprous bromide as catalyst and NMP as solvent at 110℃ with a yield of 82.3 %. Then 3-pentoxythiophene was synthesized from 3-methoxythiophene and n-pentanol with anhydrous sodium bisulfate as catalyst at 110℃. The effects of molar ratio, amount of catalyst, reaction time and reaction tempreture on the yield of 3-pentoxythiophene were investigated via orthogonal experiment. The optimum reation conditions were： n （3-methoxythiophene） ： rt （pentanol） = 1 ： 1.1, 3.5 h, 115℃, amount of catalyst 0.25%. Under the optimal reaction conditions the yield of 3-pentoxythiophene was 69.7%. According to the modified optimal reaction conditions, 3-ethoxythiophene, 3-propoxythiophene, 3-butoxythiophene, 3- pentoxythiophene, 3-hexoxythiophene and 3-octoxycthiophene were synthesized from 3-methoxythiophene and the corresponding alcohol with sodium bisulfate as catalyst between 105 - 115℃, and their yields were 78.5%, 73.5%, 71.5% ,69.7% ,67.2% and 64.3%, respectively. All these compounds were characterized by IR, MS and ^1H NMR. Their fragrance features were evaluated and they all gave meat flavour basically.