Synthesis of 4-Methyl-2-Isopropyl- 1,3 -Dioxolane by TiSiW12O40/ TiO2 as Catalyst

Acetals and ketals are a kind of the important compounds and used to protect carbonyl,middle material of the organic synthesis. What's more, they are a sort of the widely use flavor substance. 4-Methyl-2-isopropyl-1,3-dioxolane has fresh fruit odor and apple note. It is used to producing many sorts of essence. And the conventional method to synthesize 4-methyl-2-isopropyl-1,3-dioxolane makes use of sulfuric acid as catalyst in factories. But it causes many problems, such as the erosion of production equipment, difficulty after-treatment, low quality of the products, etc. HPA and its salts shows excellent catalytic activity to the esterification and have recently attracted much attention as catalysts for various industrial processes, because their acidic and redox properties can be controlled at atomic/molecular levels. Misono, Pope [1], and Wang [2]have reviewed the homogeneous catalysis and fine organic synthesis catalyzed by heteropoly compounds. However, there is no report on the synthesis of 4-methyl-2-isopropyl-1,3-dioxolane catalyzed by TiSiW12O40/TiO2. TiSiW12O40/TiO2 was prepared according to reference [3] and identified by means of IR and XRD. The reaction was carried out in a three-neck flask equipped with a stirrer, a reflux condenser, and a thermometer. A certain amounts of isobutyraldehyde,1,2-propanediol and the catalyst was heated to boiling and refluxed until no water flowed off. The purified product was analyzed by IR spectra and 1HNMR.In this paper, we report 4-methyl-2-isopropyl-1,3-dioxolane was synthesized from isobutyraldehyde and 1,2-propanediol in the presence of TiSiW12O40/TiO2. The factors influencing the yield of product and the optimum reaction conditions were discussed. The optimum conditions are molar ratio of isobutyraldehyde to 1,2-propanediol was 1:1.5, the quantity of catalyst was equal to 0.5% feed stock, and the reaction time was 1.0 h. TiSiW12O40/TiO2 was an excellent catalyst to synthesize 4-methyl-2-isopropyl-1,3-dioxolane and the yield can be up to 92.1%. IR spectra of 4-methyl-2-isopropyl- 1,3-dioxolane shows peaks at 1191,1100,1022,950 cm-1; 1HNMR (δH, ppm):4.65-4.67 (d, 1H, CH), 4.02-4.20 (m, 1H, CH), 3.81-3.92 (d, 1H, CH), 3.35-3.43 (t, 1H, CH),1.61～1.85 (m, 1H, CH), 1.14-1.29 (d, 3H, CH3), 0.96 (m, 6H, CH3); nD20=1.4135; b.p. 127-130 ℃.And we found that the catalyst can be utilized repeatedly, moreover, the catalytic activities of the catalyst are almost unchanged after it has been used five times. From the above results and discussion, we can see that the synthesis of 4-methyl-2-isopropyl-1,3-dioxolane catalyzed by TiSiW12O40/TiO2 instead of sulfuric acid has a great prospect of application.     

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％。     

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%。     

Oxidation of 1,3-Dioxacycloalkanes with Complexes of Potassium Chlorochromate and Chlorodiperoxochromate with 15-Crown-5, Catalyzed with 2,2,5,5-Tetramethyl- 4-phenyl-3-oxo-3λ5-imidazolin-1-yloxyl

2,2,5,5-Tetramethyl-4-phenyl-3-oxo-3⁵-imidazolin-1-yloxyl catalyzes oxidation of 2-isopropyl-1,3-dioxolane, 2-phenyl-1,3-dioxolane, 2-phenyl-4-chloromethyl-1,3-dioxolane, and 2-phenyl-1,3-dioxane with 15-crown-5 complexes of potassium chlorodiperoxochromate (KCrO₅Cl·2C₁₀H₂₀O₅) and potassium chlorochromate (KCrO₃Cl·2C₁₀H₂₀O₅). 2-Isopropyl-1,3-dioxolane is oxidized to the corresponding monoester in quantitative yield, and the 2-phenyl derivatives yield benzaldehyde. The spiro ketal, 2,2-pentamethylene-4-methyl-1,3-dioxane, is decomposed to cyclohexanone.     

高岭土负载SO42-/ZrO2-TiO2催化剂的制备及其在缩酮合成中的应用

以经H2SO4处理焙烧的高岭土为载体,制备了以其负载的SO2-4/ZrO2-TiO2固体酸催化剂。 用FT-IR、XRD和NH3-TPD等测试技术表征了催化剂的微观结构及酸强度,考察了对环己酮乙二醇缩酮反应的催化活性及稳定性。 结果表明,酸化处理使高岭土表面酸量增加,但酸强度变化不大,而其负载SO2-4/ZrO2-TiO2后,经500 ℃焙烧3 h其酸量及酸强度显著升高。 环己酮用量为0.2 mol、乙二醇0.24 mol、催化剂1.2 g、带水剂环己烷15 mL,回流反应70 min后,缩酮收率可达96.8%,催化剂重复使用5次收率保持在90%以上。     

Oxidation of 1,3-Dioxacyclanes with Oxone and Potassium Persulfate Catalyzed by 2,2,5,5-Tetramethyl-4-Phenyl-3-Imidazoline-3-Oxide-1-Oxyl

The catalytic effect of 2,2,5,5-tetramethyl-4-phenyl-3-imidazoline-3-oxide-1-oxyl on the oxidation of 2-isopropyl-1,3-dioxolane, 2-phenyl-1,3-dioxolane, 2-phenyl-4-chlormethyl-1,3-dioxolane, 2-isopropyl-1,3-dioxane, 2-isopropyl-4-methyl-1,3-dioxane, 2-phenyl-1,3-dioxane, 2-phenyl-4-methyl-1,3-dioxane with oxone and potassium persulfate is reported. The corresponding glycol monoesters were obtained with yields of 90-100%.     

磷钨酸铜绿色催化合成缩醛(酮)及其催化活性测定

合成了绿色杂多酸盐催化剂磷钨酸铜;将环己酮、苯甲醛同乙二醇、1,2-丙二醇的缩合反应作为探针反应,测定了催化剂的催化活性,比较系统地考察了催化剂用量、物料配比、反应时间、带水剂用量等因素对反应产率的影响.结果表明:在底物醛(酮)用量0.2 mol、醛(酮)/乙二醇(1,2-丙二醇)摩尔比1.0/1.5、催化剂用量0.5 g、带水剂环己烷用量18 mL、一定温度下回流反应2.0 h,1,4-二氧螺[4,5]癸烷产率为83.3%,3-甲基-1,4-二氧螺[4,5]癸烷产率为89.7%,2-苯基-1,3-二氧环戊烷产率为66.7%,4-甲基-2-苯基-1,3-二氧环戊烷产率为78.5%.     

硅钨酸掺杂的聚苯胺：实物模板法制备及催化性能

以不同形态的实物为模板,硅钨酸为掺杂剂,过硫酸铵为氧化剂合成了不同微观形貌掺杂态聚苯胺,并用红外光谱、气相色-质联用仪及扫描电镜对其进行了表征。考察了所制备的聚苯胺催化合成环己酮1,2-丙二醇缩酮的性能,探讨了不同微观形貌掺杂态聚苯胺催化剂对缩酮反应的催化活性,研究了催化剂用量、反应时间等因素对产品收率的影响,以及不同沸程的产物。结果表明:硅钨酸掺杂聚苯胺是合成环己酮1,2-丙二醇缩酮的良好催化剂,其中微观结构为球状的聚苯胺催化性能最佳。在n环己酮∶n1,2-丙二醇=1∶1.4,催化剂用量为反应物总质量的1.6%,反应时间为40 min的最佳条件下,环己酮1,2-丙二醇缩酮的收率为89.2%。     

酸化铝锌复合交联蒙脱土催化合成缩酮和缩醛

缩酮(醛)是一类有天然花香、果香或特殊香味的香料,也常用于有机合成的羰基保护或作为反应中间体[1].其工业合成一般是在无机质子酸的催化下进行[2],这类催化剂存在副反应多、产品纯度不高、设备腐蚀严重、后处理中含有大量酸性废水及造成环境污染等缺点.     

Keggin型钨锗酸联咪唑盐催化合成环己酮乙二醇缩酮

设计合成了Keggin型钨锗酸联咪唑盐(H4biim)[H2GeW12O40]·18H2O(1b,H2biim=2,2′-联咪唑), 并将其用于催化合成环己酮乙二醇缩酮反应。 通过X射线单晶衍射、红外光谱(FT-IR)、紫外光谱(UV)、热重-差热(TG-DTA)、粉末衍射(XRD)等技术手段对催化剂1b进行了表征。 较系统地研究了反应物料比、催化剂用量、反应时间等因素对催化反应的影响。 在n(环己酮)∶n(乙二醇)=1∶1.4,n(1b,以W计)∶n(环己酮)=1∶260,反应2 h的优化反应条件下,目标化合物产率达90%,催化剂可循环使用,表现出良好的催化稳定性。     

Synthesis of 1,2,4-triazole and thiazole analogs of ketoconazole

The synthesis of 1,2,4-triazole and thiazole analogs of ketoconazole is described in which one of the α azole ring carbons is linked to C-2 of the ketal by means of a three methylene tether. Lithiation of 1-methyl-1,2,4-triazole and thiazole and subsequent alkylation with 2-(2,4-dichlorophenyl)-2-(3-iodopropyl)-1,3-dioxolane produced, after an aqueous acidic workup, 2,4-dichlorophenyl 3-[5-(1-methyl-1,2,4-triazolyl) and 2-thiazolyl]propyl ketones, respectively. Ketalization with glycerol furnished the corresponding diastereomeric pairs of cis and trans 1,3- dioxolanes. The reaction of 2,4-dichlorophenyl 3-[5-(1-methyl-1,2,4-triazolyl)]propyl ketone with 3-mercapto-1,2-propanediol produced the corresponding diastereomeric cis and trans hydroxymethyl 1,3-oxathiolanes. The diastereomeric racemates were separated by column chromatography and their stereochemistry established by nOe nmr experiments. Some of these racemic cis ketal alcohols were converted by benzyl bromide to the corresponding benzyl ethers. Several of these racemic cis-ketals were reacted, first with methanesulfonyl chloride, then with 1-acetyl-4-(4-hydroxyphenyl)piperazine, to furnish the title compounds.     

碘催化合成环己酮乙二醇缩酮

环缩酮类香料性能优良,在日用香精和食品香精中用途广泛。合成缩酮的传统催化剂为硫酸,反应时间长,副反应多,对反应设备腐蚀严重,废液排放量大,后处理工艺复杂,人们一直在寻求更优良的催化剂。本文利用单质碘催化剂合成了环己酮缩乙二醇。     

Preparation and Catalytic Activity of PW_(12)/PAn Material in Synthesis of 2-Methyl-2-Ethyl Acetoacetate-1,3-Dioxolane

Acetals and ketals are among the most important perfume materials and industrial materials of organic synthesis. Up to now, there are many methods to synthesize them. Conventionally H2SO4 is used as catalyst in factories, but it causes many problems, such as the erosion of equipment, difficulty for after-treatment, low quality of the products, etc. Heteropolyacids (HPA) and their salts have been extensively studied because of their interesting catalytic properties. Significant research effo…     

Dawson型磷钨钒杂多酸催化合成环己酮乙二醇缩酮

环己酮乙二醇缩酮又称1,4-二氧杂螺[4,5]癸烷,系缩酮类化合物,是重要的化工中间体,可作为特殊的反应溶剂及羰基保护基团。由于缩酮具有优于母体羰基化合物特殊的香气,其作为新型香晶、香料在日用化工和食品工业中已得到广泛应用。环己乙二醇缩酮通常在腐蚀酸无机酸如硫酸作用下     

Oxidation of 1,3-Dioxacycloalkanes with Dimethyldioxirane

The kinetic regularities of the reactions of dimethyldioxirane with 1,3-dioxane, 2-propyl-, 2-isopropyl-, 2-phenyl-, 2,2-pentamethylene-, 2,2-dimethyl-, and 4-(hydroxymethyl)-2,2-dimethyl-1,3-dioxolanes, as well as with 2-isopropyl-, 2-phenyl-, 2,2,4-trimethyl-, 2-isopropyl-4-methyl-, 4-methyl-, 4-methyl-2-phenyl-, and 5,5-dimethyl-2-phenyl-1,3-dioxanes in acetone were studied by spectrophotometry. The reaction kinetics are described by a second-order equation (first order in dioxirane and first order in dioxacycloalkane). The reaction rate is independent of the concentration of oxygen in the reaction mixture. The activation parameters of the reactions were determined.     

固体超强酸SO2-4-MoO3-TiO2的制备及其催化酯化性能研究

In this paper a new solid superacid catalyst SO2-4-MoO3-TiO2 was prepared.The activity of the catalyst in esterification of acetic acid and iso-amyl alcohol was measured and compared with that of SO2-4-TiO2 and MoO3-TiO2.The results showed that SO2-4-MoO3-TiO2 had better catalytic performance than SO2-4-TiO2 and MoO3-TiO2.There was evident coordination between MoO3 and SO2-4 when they coexisted on TiO2.     

Synthesis of 1-Bromo-3-butyn-2-one and 1,3-Dibromo-3-buten-2-one

Synthetic procedures for the preparation of 1-bromo-3-butyn-2-one and 1,3-dibromo-3-buten-2-one are given. These compounds are prepared from 2-bromomethyl-2-vinyl-1,3-dioxolane, which can readily be prepared from 2-ethyl- 2-methyl-1,3-dioxolane. The synthetic routes are as follows: 2-bromomethyl-2-vinyl-1,3-dioxolane is converted to 2-(1,2-dibromoethyl)-2-bromomethyl-1,3-dioxolane. Double dehydrobromination with ^tBuOK affords 2-ethynyl-2-bromomethyl-1,3-dioxolane. Formolysis with formic acid gives 1-bromo-3-butyn-2-one. Deacetalized 2-bromoethyl-2-vinyl-1,3-dioxolane was treated with Br₂ and Li₂CO₃/12-crown-4 in tetrahydrofuran to give 1,3-dibrom-3-buten-2-one in moderate yield.     

Relative reactivities of cyclic ketene acetals via cationic 1,2-vinyl addition copolymerization1

The relationship between the relative reactivities of ten cyclic ketene acetals and their structures was determined via cationic copolymerizations of eight different monomer pairs. Thus, 2-methylene-1,3-dioxolane (1) was copolymerized with 2-methylene-4-methyl-1,3-dioxolane (2), 2-methylene-4,5-dimethyl-1,3-dioxolane (3), 2-methylene-4,4,5,5-tetramethyl-1,3-dioxolane (4), 2-methylene-4-phenyl-1,3-dioxolane (5), and 2-methylene-4-(t-butyl)-1,3-dioxolane (6). Also 2-methylene-1,3-dioxane (7) was copolymerized with 2-methylene-4-methyl-1,3-dioxane (8), 2-methylene-4,4,6-trimethyl-1,3-dioxane (9), and 2-methylene-4-isopropyl-5,5-dimethyl-1,3-dioxane (10). The relative reactivities of these monomers are: 3 > 5 > 4 > 2 > 1 > 6; and 10 > 9 > 8 > 7. In spite of steric demands, substituents at the 4- or 5-positions in 2-methylene-1,3-dioxolane and substituents at the 4- or 6-positions in 2-methylene-1,3-dioxane serve to increase the copolymerization reactivity. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2841–2852, 1999     

The hydroxyacetylpiperidines and their N-benzyl derivatives. The 2-hydroxymethyl-2-piperidyl- and 2-hydroxymethyl-2-pyridyl-1,3-dioxolanes

The hydroxyacetylpiperidines, their ethylene ketals, and the N-benzyl derivatives of these new piperidines have been synthesized. Methylolation of 2-(2- and 4-pyridyl)-1,3-dioxolanes by heating with paraformaldehyde at 185° led to 2-hydroxymethyl-2-(2- and 4-pyridyl)-i,3-dioxolanes ( 7,8 , respectively). 2-Hydroxymethyl-2-(3-pyridyl)-1,3-dioxolane ( 13 ) was obtained by reaction of 2-bromomethyl-2-(3-pyridyl)-1,3-dioxolane with aqueous sodium hydroxide at 190°. Hydrogenation of these pyridine ketals with rhodium-charcoal catalyst produced the corresponding piperidine ketals (16,17,18). Acid hydrolysis of the piperidine ketals and their N-benzyl derivatives led to the hydroxyacetylpiperidines (1,2,3) and their N-benzyl derivatives (25,26,27). The N-benzylhydroxyacetylpiperidines undergo rapid hydrogenolysis with palladium-charcoal catalyst to produce the hydroxyacetylpiperidines. Further hydrogenation produces the piperidyl-1,2-ethanediols. The hydroxyacetylpiperidines are somewhat unstable, hygroscopic substances which polymerize with dehydration on standing; in solution they are relatively stable. Their N-benzyl, ketal, and hydrochloride salt derivatives, on the other hand, represent stable, synthetically useful intermediates from which the reactive trifunctional hydroxyacetylpiperidines may readily be prepared.     

硫酸镓催化法合成环己酮乙二醇缩酮

以环己酮和乙二醇为原料,硫酸镓为催化剂,在微波辐射和无溶剂条件下,合成了环己酮乙二醇缩酮．探讨了酮醇物质的量比、催化剂用量、微波功率和辐射时间对产品收率的影响．结果表明,环己酮乙二醇缩酮的最佳合成条件为：n（环己酮）：n（乙二醇）=1：3,催化剂用量为反应物总质量的2．0％,微波功率为375W,辐射时间为20min．在此条件下,缩酮收率可达96．3％,说明硫酸镓是一种合成环己酮乙二醇缩酮的优良催化剂．