Baeyer–Villiger oxidation of cyclohexanone by molecular oxygen with Fe–Sn–O mixed oxides as catalysts

Fe–Sn–O mixed oxides were synthesized and used as catalysts for Baeyer–Villiger oxidation of cyclohexanone, which showed both high catalytic activity and selectivity. X‐ray powder diffraction and scanning electron microscopy suggested that the Fe–Sn–O catalysts had a tetragonal structure with a grain size of 29.3 nm. An ε‐caprolactone yield as high as 98.8% was obtained in a small‐scale experiment (5 mmol of cyclohexanone). In a scale‐up test (20 mmol of cyclohexanone), the cyclohexanone conversion and ε‐caprolactone yield were 96.7 and 96.5%, respectively. In addition, the catalysts can be reused five times without any major decline in catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Asymmetric cross-aldol reaction of isatin and ketones catalyzed by crude earthworm extract as efficient biocatalyst

ABSTRACT

The asymmetric cross-aldol reaction of simple ketones (acetone, cyclohexanone) with isatin derivatives in the presence of crude extract from earthworms as green and effective biocatalyst proceeds easily in MeCN/H₂O (1:1) as solvent to afford 3-hydroxy-2-oxindoles derivatives. Ten compounds were synthesized in high yields (62–88%) and moderate ee (29–42%). Structure of the synthesized compounds has been characterized on the basis of NMR spectra and CHN analysis. The ee of the obtained compounds was determined by chiral phase HPLC analysis.     

Synthesis of hexa-, tetra-, and dihydroxanthene derivatives from salicylaldehyde aminals

Salicylaldehyde aminals react with cyclohexanone upon heating to form tetrahydroxanthene derivatives. The structure of one of these derivatives,viz., 5,7-dichloro-4a-morpholino-1,2,3,4-tetrahydro-4aH-xanthene, was established by X-ray diffraction analysis. The scheme of the reaction was suggested, which involves cycloaddition of intermediateo-methylenequinone (from aminal) and enamine (from cyclohexanone). The reactions of salicylaldehyde aminals with enamines that formed from cyclohexanone can successively afford derivatives of hexahydroxanthene, tetrahydroxanthene, and dihydroxanthene. Procedures were developed for the synthesis of these compounds.N-Substituted 4a-amino-7-nitro-1,2,3,4-tetrahydro-4aH-xanthenes were also prepared by the reactions of dialkylammonium 2-formyl-4-nitrophenoxides with the above-mentioned enamines. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 959–965, May, 1999.     

气相色谱法测定溶剂型涂料中环己酮含量

建立测定溶剂型涂料中环己酮含量的气相色谱(GC)检测方法。样品在乙酸乙酯中超声提取,以ZB–WAX毛细管柱(30 m×0.25 mm,0.25 μm)为分离色谱柱,加入十四烷作为内标物,氢火焰离子化检测器(FID)检测,内标法定量。结果表明,环己酮的质量浓度在10~250 mg/L范围内呈良好的线性关系,相关系数r=0.999 9。以阴性涂料样品为样品基质,加标平均回收率在92.5%~97.8%之间,测定结果的相对标准偏差在0.87%~1.77%(n=7)之间,方法检出限为13 mg/kg。采用该方法对15种溶剂型涂料样品进行测定,其中11种检出环己酮。该方法能使目标化合物得到有效分离,分析时间短,重复性好,灵敏度高,适用于溶剂型涂料中环己酮含量的快速测定。     

一种同时测定环己酮肟水解反应中环己酮肟和硫酸羟胺含量的方法

在环己酮肟水解反应制备硫酸羟胺过程中,环己酮肟与产物硫酸羟胺在酸性条件下难以分离,硫酸羟胺的含量测定受到环己酮肟的干扰。 本文采用高效液相色谱法和氧化还原滴定法建立了一种简便、有效的新方法同时测定硫酸羟胺与环己酮肟的含量。 结果表明,在H⁺浓度大于2.4 mol/L,Fe³⁺/环己酮肟摩尔比大于5:1的条件下,环己酮肟和硫酸羟胺测定的标准滴定曲线的线性相关系数分别为0.99998和0.99996,相对标准偏差分别为0.39%和0.50%,水解反应样品的加标回收率为97.1%~100.6%。     

Silicalite-1的后处理对其催化环己酮肟气相Beckmann重排反应性能的影响

 研究了silicalite-1分子筛的不同后处理方法对其催化环己酮肟Beckmann重排制己内酰胺性能的影响,这些方法包括水(或氨)蒸气处理以及在碱性、酸性或中性条件下用NH4NO3处理. 结合XRD,FT-IR和 29Si MAS NMR表征结果对silicalite-1催化剂的活性中心进行了探讨. 结果表明,碱性条件下用NH4NO3进行后处理对提高分子筛的催化性能最为有利. 分子筛上无规则排布的末端硅羟基数量的减少,以及具有相互氢键作用的邻式硅羟基的产生是其催化性能提升的主要原因.     

固载杂多酸PW12/C催化合成环己酮乙二醇缩酮

用固载杂多酸PW12／C催化合成了香料环己酮乙二醇缩酮．研究了酮醇摩尔比、催化剂用量、反应时间．反应温度等因素对产品收率的影响％实验表明：同载磷钨酸是合成环己酮乙二醇缩酮的优良催化剂。13(环己酮)：n(乙二醇)为1：1．5，催化剂用量为反应物料总质量的0．8％．苯作带水剂，控温110℃左右，反应时间为40min的条件下，环己酮乙二醇缩酮的收率可达89．6％。催化剂重复使用四次．收率均在80％以上。     

环己酮单加氧酶的克隆表达及酶学性质分析

为研究鞘氨醇杆菌中环己酮单加氧酶的催化特性,从N.aromaticivorans DSM 12444基因组DNA克隆表达了一个编码环己酮单加氧酶的基因chmo,并分析了该基因产物的酶学性质.该基因全长1650bp,编码550个氨基酸,理论分子量为61.6kDa.将携带此基因的重组质粒pET28a-chmo转入E.coli BL21(DE3)后,获得了62kDa左右的表达产物.重组环己酮单加氧酶(CHMO)能氧化芳香族硫醚及其衍生物、链式硫醚、其他硫醚和酮类等底物,以2-氯乙基苯基硫醚为底物时活力最高(25.65U/mg).CHMO最适反应温度和pH分别为55℃和8.87,倾向于利用NADPH作辅酶.上述结果表明,重组CHMO是一个新型的环己酮单加氧酶,推测其与硫醚及酮类物质的氧化降解有关.     

2-乙氧羰基-3-甲基-4,5-四亚甲基吡咯的合成

以乙酰乙酸乙酯(1)为原料,以醋酸为反应介质,通过与亚硝酸钠的肟化反应得到化合物N-羟基亚胺乙酰乙酸乙酯(2),化合物2在缓冲的乙酸溶液中通过锌粉还原、与环己酮(3)加成环化反应生成化合物2-乙氧羰基-3-甲基-4,5-四亚甲基吡咯(4),反应的总收率为38.95%.而采用"一锅煮"合成方法制备化合物4可使反应的总收率达到49.76%.考察了在该反应体系的pH值为3.8～4.0时,其他一些反应条件对目标化合物4合成收率的影响,确定了最佳的反应条件为:锌粉与反应物1的摩尔比为2.9:1,反应温度为95～100 ℃.所合成的化合物的结构用元素分析、IR、1H NMR等测试手段进行了表征.