H4 SiW12 O40 /C催化合成丁酮1,2-丙二醇缩酮

以丁酮和1,2-丙二醇为原料,活性炭负载硅钨酸（H4SiW12O40／C）为催化剂,催化合成了丁酮1,2-丙二醇缩酮。正交试验筛选出最佳反应条件为：丁酮200mmol,n（丁酮）：n（1,2-丙二醇）=1．0：1．4,ω（催化剂）=1．2％（以反应物质量计）,反应时间1h。在此最佳反应条件下,丁酮1,2-丙二醇缩酮的收率可达71．13％。     

磷钨杂多酸银盐催化合成缩酮(醛)

利用沉淀法制备了一系列磷钨杂多酸银盐(AgxH3-xPW12O40,0相似文献   

二氧化硅负载硅钨钼酸催化合成环己酮1,2-丙二醇缩酮

采用溶胶-凝胶法制备了二氧化硅负载硅钨钼酸催化剂。以二氧化硅负载硅钨钼酸为催化剂,环己酮和1,2-丙二醇为原料合成了环己酮1,2-丙二醇缩酮,用正交实验法研究了反应物料配比、催化剂用量、带水剂用量、反应时间等因素对反应的影响。结果表明,在n(环己酮)∶n(1,2-丙二醇)=1∶1.4,催化剂用量为反应物料总质量的0.8%,带水剂环己烷12 mL,反应时间45 min的优化条件下,环己酮1,2-丙二醇缩酮的收率可达84.93%。     

A Pd-mediated intramolecular ketalization of alkynediols: construction of the central [3.2.1]-bicyclic ketal core of cyclodidemniserinol trisulfate

A preliminary study dealing with the Pd-mediated alkynediol cycloisomerization to construct the central bicyclic ketal core of cyclodidemniserinol trisulfate is documented.     

NMR assignments of a di-pentacyclo-undecane cyclic ether

The X-ray structure of a di-pentacyclo-undecane cyclic ether was recently reported. As part of a programme to use NMR spectroscopy for the structure elucidation of cage compounds, the complete NMR assignments of the cyclic ether was attempted. Major overlap of proton and carbon signals of the two cages is observed. It was required to elucidate the fragment analogues that represent similar structural features of the cyclic ether in order to get an approximate but reasonable insight into the complex overlapping signals. Normal 2D NMR techniques were utilized to assign the various NMR signals.     

Experimental and theoretical structural study of 2,9-bis-(4-fluorophenyl)-azaadamantan-4-one ethylene ketal

The title ethylene ketal 1, C₂₃H₂₃F₂NO₂, has a tricyclic azaadamantane cage with aryl rings (4-fluorophenyl) substituted at the 2 and 9 positions. Rings A (C11-C16) and B (C17-C22) are attached to atoms C2 and C9 in axial and equatorial positions, respectively; and the presence of the five-membered 1,3-dioxolane ring attached to atom C4. The structural analysis of the title was carried out by experimental (single crystal X-ray diffraction and NMR) and confirmed by theoretical calculations (ab initio RHF, DFT and NMR-DFT-GIAO).     

新型甘露醇基凝油剂的制备及性能研究

通过甘露醇和环己酮的缩酮反应,合成了具有相选择性的新型糖基凝油剂-环己酮缩甘露醇。考察了反应时间、催化剂用量、分子筛用量、底物配比等多个因素对产物产率的影响。结果表明,分子筛用量为12g、催化剂用量为0.8g、环己酮与甘露醇摩尔比为6.2∶1的条件下反应1h,产率为52%。对所制备的环己酮缩甘露醇的凝油能力测试表明,它可以凝固汽油、硅油等多种油类,柴油、汽油和硅油凝固的最小浓度分别为0.74(wt)%、2.70(wt)%和0.39(wt)%。     

微波促进活性炭负载四氯化锡催化合成乙酰乙酸乙酯缩酮

在微波辐射下,以活性炭负载四氯化锡(SnCl4·5H2O/C)为催化剂,不用溶剂,合成了乙酰乙酸乙酯乙二醇缩酮和乙酰乙酸乙酯1,2-丙二醇缩酮。以乙酰乙酸乙酯与乙二醇缩合为模型反应进行优化,其优化条件是:负载量为20%的SnCl4·5H2O/C催化剂0.1 g,乙酰乙酸乙酯5 mL,乙二醇6 mL,微波辐射功率600 W,辐射时间2.5 min,产率达81.6%。产物经过红外光谱表征。     

H_4SiW_(12)O_(40)/C催化合成丁酮1,2-丙二醇缩酮

以丁酮和1,2-丙二醇为原料,活性炭负载硅钨酸(H4S iW12O40/C)为催化剂,催化合成了丁酮1,2-丙二醇缩酮。正交试验筛选出最佳反应条件为:丁酮200 mmol,n(丁酮)∶n(1,2-丙二醇)=1.0∶1.4,w(催化剂)=1.2%(以反应物质量计),反应时间1 h。在此最佳反应条件下,丁酮1,2-丙二醇缩酮的收率可达71.13%。     

钨硅酸的制备及其在催化合成缩酮(醛)中的应用

本文探讨了钨硅酸的制备方法,以合成环己酮1,2-内二醇缩酮为例验证钨硅酸的催化活性,并探讨了合成其它缩酮（醛）的适宜条件,得到的收率分别为：环己酮1,2-丙二醇缩酮85．5％、环己酮乙二醇缩酮89．6％、丁酮乙二醇缩酮79．5％、丁醛乙二醇缩醛89．1％、丁醛1,2丙二醇缩醛81．5％。