苯偶酰的绿色催化合成及表征

Green synthesis of benzil and its structure characterization

以金属与双水杨醛缩乙二胺合成的金属配合物Co（salen）作为均相催化剂,用空气氧化安息香合成苯偶酰,通过四因素三水平正交试验（温度、催化剂用量、KOH添加量和反应时间）的设计,探索Co（salen）催化氧化安息香的最佳条件,并以Co（salen）作为研究对象,探索最佳条件下NaY分子筛负载催化剂和不对称Schiff碱配合物对安息香的催化氧化效果,应用X射线晶体衍射（XRD）、^1H NMR核磁共振波谱、红外光谱、紫外光谱和高效液相色谱HPLC等手段对制得的席夫碱和氧化产物进行分析表征,同时考察催化剂的回收套用效果.结果表明,在35℃下反应80 min,添加1 g催化剂和1.5 g KOH时,Co（salen）催化剂产率最高可达96%以上,回收套用催化剂2次最佳,产率仍可达到77.8%.NaY分子筛和不对称希夫碱金属催化剂在最优条件下产率低于Co（salen）催化剂,Na Y分子筛作为载体能在重结晶过滤的阶段直接有效地将产物和催化剂分离,能更有效地重复利用.合成产物经HPLC和^1H NMR核磁共振波谱分析,验证了其为较高纯度的苯偶酰.

In this paper,active metal,bis-salicylaldehyde,and ethylene diamine were used for preparation of a homogeneous catalyst,metal complexes（ Co（ Salen））. Co（ Salen） was used as catalyst,and air was used as oxidant,to synthesize benzil from benzoin. Four factors（ temperature,catalyst dosage,KOH content and reaction time） and three levels orthogonal test L_9（ 3~4） was applied,to explore the optimal condition for green synthesis of benzil under catalysis of Co（ Salen）.Na Y zeolite supported catalyst and asymmetric Schiff base were used to prepare benzil under optimal condition of Co（ Salen）,to compare the catalytic efficiency for different catalysts. X-ray crystal diffraction（ XRD）,nuclear magnetic resonance（~1H NMR） spectrum,infrared spectrum,ultraviolet spectrum and high performance liquid chromatography（ HPLC） were used to analyze the structure of Schiff base and oxidation products,and recycling of catalyst was further studied. The results showedthat the optimal condition for Co（ salen） catalyst was at temperature of 35 ℃,with reaction time of 80 min,and addition of 1 g catalyst and 1. 5 g KOH,with yield up to 96%. The best recycling of catalyst was two times,with yield higher than 77.8%. The yield of Na Y zeolite supported catalyst and asymmetric Schiff base under the optimal condition of Co（ salen） catalyst is lower than Co（ salen）catalyst. However,Na Y zeolite can be directly separated with products in recrystallization filtering phase,and was more convenient for recycling. Synthesized products were characterized by ~1H NMR and HPLC analysis,and confirmed as benzil with high purity.