合成α-糠偶酰二肟的研究

Synthesis of α-dioximefuril

以糠醛为原料,盐酸硫胺素(VB1)为催化剂,在碱性条件,pH为8～9,采用安息香缩合反应合成中间体糠偶姻,最高收率82.7%;利用硫酸铜-吡啶氧化其为糠偶酰,最高收率91.7%;最后糠偶酰与过量盐酸羟胺缩合,生成α-糠偶酰二肟。考察了反应时间、活性炭用量和盐酸羟胺用量对产品收率的影响。结果表明,合成工艺的最佳条件为:反应时间7～8 h,活性炭3 g,n(糠偶酰)∶n(盐酸羟胺)=1∶3,最高收率60.08%。糠偶姻为白色针状晶体,熔点为138～139℃;糠偶酰为黄色针状晶体,熔点为165～166℃;产物为白色针状晶体,熔点166～168℃。中间体和产物结构用红外光谱、元素分析等方法进行表征。

Preparation of furoin using furfural as raw materials and VB1 as catalyst has been studied in alkaline conditions,pH of 8~9.The yield of the product reached 82.7%.Furoin was oxidized to furil by CuSO4-C5H5N as an oxidant.The yield of the product reached 91.7%.Finally,α-dioximefuril was synthesized by condensation from furil and NH2OH·HCl.The effect of reaction time,the amount of carbon and NH2OH·HCl on the yield of the product were researched.Optimum conditions were determined,the mixture was refluxed for 7~8 h,the amount of carbon was 3 g,n（furil）∶n（NH2OH·HCl） = 1∶3.The yield of the product reached 60.08%.The product of furoin is white needle-like crystal,the melting point was 138~139 ℃.The product of furil is yellow needle-like crystal,the melting point was 165~166 ℃.The product of α-dioximefuril is white needle-like crystal,the melting point was 166~168 ℃.Structure of objective products and intermediate products were characterized by IR and elementary analysis.