Pr3N—ZSM—5分子筛的合成与表征

硅铝酸盐分子筛的合成一般采用水热晶化法,反应混台物的pH值大于10,并且体系中含有金属离子,分子筛原粉必须通过铵离子交换和焙烧才能转变为氢型催化剂,1986年,Guth等人曾在非碱性介质含氟体系中,在加晶种条件下以三丙胺为模板剂得到ZSM-5分子筛,文献报道的ZMS-5分子筛大单晶的合成均采用四丙基铵离子作模板剂,尚未见到用其它有机分子作为模板剂合成ZMS-5大单晶的报道,我们在非碱性介质含氟体系中以三丙胺直接合成出ZSM-5分子筛,并得到了大单晶。用多种实验技术对三丙胺在ZSM-5分子筛中的存在状态进行了表征。     

模板剂对SAPO-34分子筛晶粒尺寸和性能的影响

分别以三乙胺、四乙基氢氧化铵及二者的混合物为模板剂合成了硅磷酸铝分子筛SAPO- 34. 应用XRD,SEM,DTA和NH3 -TPD等方法考察了合成产品的物化性能.所得结果表明.模板剂的种类对SAPO-34的晶粒大小和酸性质有显著影响.在甲醇转化制低碳稀烃的过程中,以不同模板剂合成的SAPO-34的催化性能也不同,其中,以双模板剂合成的分子筛具有较高的低碳烯烃选择性.     

铝对SAPO—5分子筛的影响

SAPO-5分子筛是一种具有良好骨架结构和热稳定性的微孔晶体。在催化等方面有很好的应用前景。其合成所采用的铝源一般为水铝石,其它铝源活性较差。我们在HF存在下,以H_3PO_4、水铝石和硅溶胶为原料,三丙胺为模板剂合成出SAPO-5分子筛,并得到了大单晶。研究了反应混合物中Al的配位环境对SAPO-5形成的影响。     

低硅SAPO-34分子筛的复合模板剂法合成及其对甲醇制烯烃的催化性能

系统考察了模板剂比例和晶化条件对复合模板剂(三乙胺+四乙基氢氧化铵)法合成低硅SAPO-34分子筛的影响;评价了合成产物对甲醇制烯烃的催化性能.结果表明,190℃晶化时不易合成低硅SAPO-34分子筛,而170℃晶化、模板剂组成为2Et3N+0.3TEAOH时可合成纯相SAPO-34分子筛.较高温度晶化时,延长晶化时间,SAPO-34有向SAPO-5转晶的趋势,而较低温度晶化时则相反.与晶化3 d的分子筛样品相比,170℃晶化5 d后的分子筛样品的比表面积较大、强酸中心较多、弱酸中心较少、对甲醇制烯烃反应的催化寿命较长.     

用TEAOH-C4H9NO复合模板剂合成SAPO-34分子筛的研究Ⅰ.SAPO-34分子筛的合成与表征

 以吗啉(C4H9NO)为主要模板剂,以少量四乙基氢氧化铵(TEAOH)为辅助模板剂合成了SAPO -34分子筛,并采用X射线衍射、扫描电镜、傅里叶变换红外光谱和热重-差热分析等手段对 合成的SAPO-34分子筛进行了表征. 结果表明,TEAOH在导向生成SAPO-34分子筛骨架过程中 表现活跃,占据了较多的平衡骨架负电荷的位置,而吗啉主要起到填充分子筛孔道的作用. 用 TEAOH-C4H9NO复合模板剂合成的SAPO-34分子筛,其晶粒远小于单用吗啉模板剂合成的 分子筛.     

模板剂对SAPO—34分子筛性能的影响

分别以三乙胺、四乙基氢氧化铵以及二者的混合物为模板剂，采用水热法合成了三种ＳＡＰＯ－３４分子筛样品。用化学分析、ＸＲＤ、ＴＰＤ和ＩＲ方法研究了不同模板剂对ＳＡＰＯ－３４分子筛性能的影响。实验结果表明，四乙基氢氧化铵有利于硅进入分子筛骨架；三乙胺有利于生成较多的强酸中心；将三乙胺与四乙基氢氧化铵联用，能有效地调变所合成的ＳＡＰＯ－３４的酸中心分布，使其对甲醇转化制低碳烯烃具有较高的选择性。     

模板剂对SAPO─34分子筛性能的影响

分别以三乙胺、四乙基氢氧化铵以及二者的混合物为模板剂，采用水热法合成了三种ＳＡＰＯ－３４分子筛样品。用化学分析、ＸＲＤ、ＴＰＤ和ＩＲ方法研究了不同模板剂对ＳＡＰＯ－３４分子筛性能的影响。实验结果表明，四乙基氢氧化铵有利于硅进入分子筛骨架；三乙胺有利于生成较多的强酸中心；将三乙胺与四乙基氢氧化铵联用，能有效地调变所合成的ＳＡＰＯ－３４的酸中心分布，使其对甲醇转化制低碳烯烃具有较高的选择性。     

用TEAOH-C4H9NO复合模板剂合成SAPO-34分子筛的研究I．SAPO-34分子筛的合成与表征

以吗啉(C4H9NO)为主要模板剂，以少量四乙基氢氧化铵(TEAOH)为辅助模板剂合成了SAPO-34分子筛，并采用X射线衍射、扫描电镜、傅里叶变换红外光谱和热重-差热分析等手段对合成的SAPO-34分子筛进行了表征．结果表明，TEAOH在导向生成SAPO-34分子筛骨架过程中表现活跃，占据了较多的平衡骨架负电荷的位置，而吗啉主要起到填充分子筛孔道的作用．用TEAOH—C4H9NO复合模板剂合成的SAPO-34分子筛，其晶粒远小于单用吗啉模板剂合成的分子筛．     

模板剂种类、浓度、硅源对SAPO-5分子筛结构性质的影响

研究了模板剂种类、浓度及硅源等因素对ＳＡＰＯ５分子筛结构、性质及酸催化性能的影响．结果表明，在合成ＳＡＰＯ５分子筛时，较合适的模板剂为三乙基胺或四乙基氢氧化铵．模板剂对分子筛结构的影响在于其空间效应，对酸性的影响在于其对硅反应性能和骨架硅含量的改变．不同硅源对分子筛骨架中的硅含量和酸性有较大的影响．得到较强酸性ＳＡＰＯ５分子筛催化剂的条件是：采用三乙胺模板剂和正硅酸乙酯．     

非碱性介质中全硅分子筛的合成与表征

在非碱性介质中,F-离子存在下,采用水热方法研究了全硅分子筛的合成。以三丙胺、胆碱、三亚乙基二胺和哌嗪为模板剂,合成出具有MFI结构(ZSM-5型)的全硅分子筛。全硅Theta-1和ZSM-39的模板剂分别为1,6-已二胺和四甲基溴化铵。~(29)Si MAS NMR研究结果表明,该体系得到的全硅分子筛具有结晶度高和缺陷少的特点。     

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.     

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.     

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.     

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.     

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.     

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.