离子液体中锰卟啉催化双氧水氧化烯烃的研究

研究了离子液体中Mn(TFPP)Cl(meso-tatrakis(pentafluoropheyl)porphinato)manganese(Ⅲ)cloride锰卟啉催化烯烃的氧化反应.在离子液体-CH2C12混合溶剂中,以价廉、环境友好的H2O2为氧源,考察了离子液体结构、反应条件等对环氧化反应的影响.当氧化剂/环己烯/催化剂/咪唑=450∶150∶1∶75(摩尔比)时,室温下,在MMISM-CH2Cl2的混合溶剂中,环己烯的转化率和环氧环己烷的选择性可分别达到94.8%和95.5%,远高于在纯CH2Cl2中的实验结果.并在最优反应条件下考察了该催化剂体系对烯烃底物的适用性.此外,反应结束后,产物可以由正己烷萃取出来,考察了混合溶剂中Mn(TFPP)Cl催化剂的重复使用情况.     

离子液体中V2O5催化环己烯选择氧化合成 2-环己烯酮

研究了以V2O5为催化剂,H2O2为氧化剂,在室温离子液体中环己烯氧化制备2-环己烯酮的反应.考察了离子液体种类、反应温度、催化剂用量和氧化剂用量等因素对2-环己烯酮产率的影响.结果表明,在H2O2用量为110 mmol,V2O5/环己烯摩尔比为2%,反应温度为313 K的条件下,在[bmim]BF4离子液体中反应10 h后,环己烯的转化率和2-环己烯酮选择性分别为88.7%和91.1%.对含离子液体的催化体系的重复使用性能进行了考察.结果发现,随着使用次数的增加,环己烯的转化率以及2-环己烯酮的选择性有所下降.     

磷酸镍纳米管的合成及其催化环己烯环氧化反应性能

 在不添加有机模板剂的情况下, 通过尿素缓慢分解调节局部 pH 值, 水热法合成了具有均一孔道直径的磷酸镍纳米管材料 (NiPO-NTs). 采用 N2 吸附-脱附、吡啶吸附红外光谱和氨程序升温脱附对材料进行了表征, 并将其用于催化 H2O2 氧化的环己烯反应中, 考察了反应条件对环氧化反应性能的影响. 结果表明, NiPO-NTs 具有狭窄的孔径分布, 比表面积为 96.6 m2/g, 其表面酸中心以弱 Lewis 酸为主. 该反应中以乙腈为溶剂较为适宜, 高温和高 H2O2/环己烯摩尔比有利于提高环己烯转化率; 而低温和高 H2O2/环己烯摩尔比有利于提高环氧环己烷选择性. 在 60 oC, H2O2/环己烯摩尔比为 3, 反应 6 h 时, 环己烯转化率可达 50.6%, 环氧环己烷选择性为 72.1%.     

Schiff碱铁配合物催化环己烯环氧化

合成了一种吡啶甲醛类Schiff碱铁配合物[Fe(PA2OPd)C12]Cl,并考察了配合物对环己烯绿色环氧化反应的催化活性及反应条件,结果表明:吡啶甲醛类Schiff碱铁配合物对环己烯的环氧化反应有比较高的催化活性及选择性.以过氧化氢为氧源、[Fe(PA2OPd)C12]Cl为催化剂、在pH=5.0左右的乙酸乙酯溶液中25℃反应6.0 h,环己烯转化率可达90.5%,环氧环己烷选择性可达97.2%.     

五氧化二钒催化环己烯烯丙位氧化

 研究了以五氧化二钒为催化剂,以过氧化氢水溶液为氧源氧化环己烯. 考察了溶剂种类、溶剂用量、催化剂用量和反应温度等因素对催化剂性能的影响. 结果表明,常温下环己烯在此催化体系中主要发生烯丙位氧化反应生成环己烯酮. 溶剂的种类对催化活性和烯丙位酮式氧化的选择性具有较大的影响,丙酮是该反应的合适溶剂. 在丙酮与环己烯的体积比为4, 五氧化二钒与环己烯的质量比为1∶40, 过氧化氢与环己烯的摩尔比为3和反应温度为20 ℃的条件下,反应24 h后的环己烯转化率可达60%以上,环己烯酮选择性可达85%. 催化反应过程中丙酮可能与过氧化氢作用生成过氧化酮,从而进行氧转移,催化剂则经过V5+/V4+物种的循环使环己烯氧化成为环己烯酮等产物.     

缺位Dawson型K10Na2H2P2W16O60在环己烯氧化中的催化作用

合成了二缺位杂多化合物K10Na2H2P2W16O60·18H2O,用IR、UV-vis、XRD及TG表征了其结构,考察了该化合物在过氧化氢氧化环己烯反应中的催化作用.研究结果表明,溶剂种类和反应温度对二缺位杂多化合物的催化性能有显著的影响,在叔丁醇中主要生成环己烯酮,在丙酮中主要生成环己二醇.在乙腈中主要生成环氧环己烷,其选择性随着反应温度升高和催化剂用量增加而降低,环己烯酮的选择性则逐步升高.催化剂与产物可通过温控固-液相分离,可以重复使用.     

8-羟基喹啉对V2O5催化氧化环己烯的调变作用

研究了8-羟基喹啉对丙酮中V2O5催化氧化环己烯合成环己烯酮的调变作用,考察了8-羟基喹啉的用量、反应温度、反应时间、溶剂和催化剂用量对环己烯氧化反应的影响,发现在该催化体系中生成的环己烯醇和环氧环己烷可转化成环己烯酮,在适当的反应条件下可抑制环己烯醇和环氧环己烷的生成.结果表明,当五氧化二钒的用量为1%,五氧化二钒与8-羟基喹啉之比为1∶2,在20℃以下反应时,过氧化氢几乎定向地将环己烯氧化成环己烯酮.认为是8-羟基喹啉与钒的配位作用促进了环己烯酮的生成.     

环己烯可控选择性催化氧化的最新进展（英文）

环己烯是一种价格低廉易得的大宗化工原料,通常由苯选择性加氢来合成.该化合物虽然分子结构简单,但却有两个不同的反应位点.随着反应所发生的位点与反应深度的不同,环己烯的氧化反应可生成一系列不同氧化程度与官能团的产物的混合物.环己烯双键的氧化反应,可生成环氧环己烷,而环氧环己烷进一步水解,则生成1,2-环己二醇,其中,随着使用不同催化剂导致的反应机理差异,产物可分别为顺式或反式结构.在强氧化剂作用下,环己烯双键充分氧化,可生成己二酸.环己烯烯丙基C-H键氧化,则可随着反应深度的不同分别生成2-环己烯醇与2-环己烯酮.上述环己烯氧化产物都是重要的有机化工中间体.其中,环氧环己烷是农药杀螨剂的主要原料,也用作合成表面活性剂、橡胶助剂等有用产品;1,2-环己二醇可用于合成化工中间体邻苯二酚;环己烯醇与环己烯酮是生产除草剂、香水、药物的原料;己二酸则是合成重要产品尼龙-6,6的原料.因此,随着市场需求的变化,对环己烯氧化反应进行选择性控制,提高其中某种产物的选择性,是重要的化工合成技术,有着巨大的应用潜力;从而控制反应历程与深度是有机化工合成工艺研究中最具有挑战性的研究课题之一,有很好的科学意义.目前,人们对环己烯的选择性控制氧化反应已进行了广泛的研究.该反应可使用金属催化剂,包括铁、钴、镍、锰、铬、钒、钨、铜、钛、金、银、铋、锇、钼、镉等;也可以使用无金属催化剂如磺酸、2,2,2-三氟苯乙酮、类石墨相碳化氮(g-C3N4)等.反应可使用化学氧化剂,如间氯过氧苯甲酸、醋酸碘苯、过氧叔丁醇等,也可使用更加清洁的过氧化氢、分子氧.研究表明,催化剂的种类、用量,以及反应溶剂、温度、氧化剂等一系列外在条件,可以影响环己烯氧化反应的选择性.本文以反应所使用的氧化剂归类,总结了该课题的最新研究进展,以期对从事环己烯可控选择性氧化的学术与工业研究人员有所帮助.     

三缺位Keggin型磷钨杂多酸盐高选择性催化氧化环己烯

利用三缺位Keggin型杂多酸[A-α-PW9O34]9-和[(FeШ(OH2)2)3(A-α-PW9O34)2]9-的四丁基铵盐做为催化剂,H2O2做为氧化剂催化环己烯氧化反应. 考察了反应时间、H2O2与环己烯的摩尔比,催化剂的用量等因素对反应结果的影响. 结果表明：在1, 2-二氯乙烷为10 mL,H2O2 (30 %)与环己烯的摩尔比为2,反应温度为35 oC,反应时间为6 h,[(C4H9)4N]9[A-α-PW9O34]为催化剂的条件下,环己烯氧化反应的转化率为55 %,主要产物是环氧环己烷,其选择性 ≥ 99 %;而以[(C4H9)4N]9[(FeШ(OH2)2)3(A-α-PW9O34)2]为催化剂时环己烯氧化反应的转化率17 %,主要产物是2-环己烯-1-酮,选择性 ≥ 99 %.     

过渡金属卟啉催化分子氧氧化环己烯性能研究

研究了meso-四(对羟基苯基)卟啉过渡金属配合物(THPPM,M=CoⅡ,MnⅡ)催化分子氧氧化环己烯的反应。结果表明,在反应温度为70℃时,THPPCoⅡ催化分子氧氧化环己烯的转化率达到90%,产物主要是2-环己烯-1-酮(70%)和2-环己烯-1-醇(26%),并考察了反应温度、时间及加入吡啶对环己烯转化率和产物选择性的影响,探讨了THPPCoⅡ催化分子氧氧化反应机理。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.