聚酰亚胺/SiO2杂化膜的制备、表征和气体渗透性能

采用溶胶凝胶法,在以TiO2为过渡层的硅藻土-莫来石陶瓷膜管基底上,制备了组分不同的聚酰亚胺/SiO2杂化膜。聚酰亚胺是利用4,4′-六氟亚异丙基邻苯二甲酸酐、2,4,6-三甲基-1,3-苯二胺和3,5-二氨基苯甲酸在溶液中进行亚胺化完成的。采用FT-IR、TG/DTA、DSC、SEM、BET和气体渗透测定对膜进行了表征和测试。结果表明,聚酰亚胺通过支链上的羧酸基和SiO2相键连织构成了具有规则孔道的空间网状结构,并且随着SiO2含量的增加孔径逐渐减小;杂化膜具有较高的热稳定性和有机无机兼容性;相对于聚酰亚胺膜,杂化膜对H2、CO2和H2O与N2相比较具有较高的分离性,SiO2含量为25(wt)%的杂化膜对H2/N2、CO2/N2和H2O/N2的分离因子分别达到55.9、31.1和42.8。     

Pd修饰的选择分离氢的负载型PI-SiO2杂化膜的制备及应用

 以负载TiO2过渡层的硅藻土-莫来石陶瓷膜管为支撑体,采用溶胶-凝胶法制备了金属钯修饰的负载型聚酰亚胺-二氧化硅杂化膜(Pd-PI-SiO2). 利用红外光谱、扫描电子显微镜和低温N2吸附等手段对膜材料结构、微观形貌及孔径分布等进行了表征,并对CH4, H2O, H2, CO2, CO和N2等气体进行了选择渗透性测试. 结果表明,杂化膜中聚酰亚胺与二氧化硅间形成了键联结构; 钯以还原后的金属态存在且分散均匀,能对聚酰亚胺-二氧化硅膜的孔结构起到修饰作用; 杂化膜孔径为 4 nm 左右; N2在此膜中的渗透通量为0.20×10-7 mol/(m2·Pa·s), H2/N2分离因子达542; 钯能够促使H2在膜渗透过程中按表面扩散机制进行,有助于分离混合气中的氢分子.     

负载型聚酰亚胺-二氧化硅-银杂化膜的制备和表征

采用溶胶凝胶法制备了硅藻莫来石负载的SiO2(SiO2KM)负载的聚酰亚胺二氧化硅银杂化膜,采用IR、TGA、SEM、XRD、氮吸附、气体渗透性能测量等方法对膜的性能进行了表征.银的加入使杂化溶胶的粘度增大,膜孔径增大,孔径分布弥散;二氧化硅在杂化膜中以无定型存在,银以氯化银的形式存在;Ag+和聚酰亚胺中的氮以配位键络合在一起,丙烯通过双键吸附在Ag+上;杂化膜热稳定性随二氧化硅的加入而增加,随银的加入而降低.丙烯丙烷在杂化膜上的分离因子为3.54～4.1,银的加入对丙烯的传输有明显的促进作用.     

RAFT聚合制备PBMA/AA-SiO2杂化纳米材料

以三硫代二[4-(甲氧羰基)苄基]碳酸酯为链转移剂(CTA),甲基丙烯酸丁酯(BMA)为单体,通过可逆加成-断裂链转移自由基聚合(RAFT)法修饰丙烯酸(AA)功能化的纳米二氧化硅(SiO2),制备了PBMA/AA-SiO2有机/无机杂化纳米材料。并通过FT-IR、GPC、TGA、TEM表征和分析了杂化材料的结构、分子量、SiO2纳米粒子在基体中的分散性以及杂化材料的热稳定性。结果表明,PBMA/AA-SiO2杂化微球粒径约为22 nm,分布均匀;TGA分析表明此杂化材料的热稳定性良好,PBMA接枝率为19%。     

二氧化硅负载全氟丁基磺酰亚胺的制备与耐水性研究

酸官能团C4F9SO2NHSO2-通过两步溶胶-凝胶法,链接到SiO2载体上,制备得到一种新型的有机-无机杂化固体酸(PSFSI-MSMA15/SiO2).反应以对苯乙烯磺酰基全氟丁基磺酰亚胺钠(1)为原料,与3-甲基丙烯酰氧基丙基三甲氧基硅烷(MSMA)共聚形成预聚体(2),2与原硅酸四乙酯水解缩合,获得PSFSI-MSMA15/SiO2,负载的酸官能团通过FT-IR,TG/DTG及XPS表征,酸负载量约0.62 mmol/g,热稳定性可达到210℃.实验结果表明,酸组分在水体系中稳定,是一种耐水性强酸.催化性能及可循环性在进一步研究中.     

聚甲基丙烯酸丁酯/(SiO2-TiO2)杂化材料的研究

以γ-甲基丙烯酰氧丙基三甲氧基硅烷(TMSPM)为偶联剂，用溶胶一凝胶法制备了聚甲基丙烯酸丁酯／(SiO2-TiO2)杂化材料，进行了结构表征和性能研究。经电镜观察，杂化体系固化膜两相间结合紧密，无机相是一种粒径介于10～20nm之间的球形颗粒。实验结果表明：杂化体系固化膜均匀性好和热氧化稳定性得到很大提高。由于无机相与有机相通过共价键相连，聚甲基丙烯酸丁酯／(SiO2-TiO2)杂化材料在无机物含量较高时，仍能保持良好的柔韧性。     

碳纳米管/聚氨酯杂化膜的原位聚合构建及气体渗透性能

采用H2SO4/HNO3混酸处理得到不同氧化程度的多壁碳纳米管(MWCNT-COOH),再通过与4,4′-二苯基甲烷二异氰酸酯(MDI)、1,4-丁二醇(BDO)的预聚和扩链反应构建碳纳米管/聚氨酯(MWCNT-COOH/PU)杂化膜。利用傅里叶红外光谱(FTIR)、拉曼光谱(Raman)和透射电子显微镜(TEM)等分析表征多壁碳纳米管结构;探讨了多壁碳纳米管氧化程度和填充量对MWCNTCOOH/PU杂化膜的形貌和CO2、N2渗透性能的影响。结果表明,混酸处理后的多壁碳纳米管带有一定的含氧基团,并随氧化程度的提高,多壁碳纳米管的拉曼光谱G峰和D峰的强度之比(ID/IG)有所增大;氧化程度对多壁碳纳米管在溶剂和杂化膜中的分散性有较大影响,氧化程度越高,分散性越好;杂化膜的CO2、N2渗透性及CO2/N2渗透选择性随多壁碳纳米管氧化程度的增加有所增大,而随多壁碳纳米管填充量的增加表现出先增大后减小的趋势,当氧化程度较高的多壁碳纳米管(H-MWCNT-COOH)填充量为1.0wt%时,H-MWCNT-COOH/PU杂化膜的CO2渗透系数为67.8 Barrer,CO2/N2渗透选择性可达45,表明适量填充MWCNT-COOH能显著提高MWCNT/PU杂化膜的CO2渗透性及CO2/N2的渗透选择性。     

Pickering乳液模板法制备有机/无机杂化微胶囊

以亲水性的二氧化硅(SiO2)纳米粒子稳定的水包油Pickering乳液为模板,利用聚氧化丙烯二醇和二苯基甲烷二异氰酸酯预聚物(PPG-TDI)与二乙烯三胺(DETA)在油水界面的聚合反应制备了聚脲(PU)包裹苯乙酸乙酯(EPA)-异佛尔酮二异氰酸酯(IPDI)有机/无机杂化微胶囊.通过控制不同油水比得到不同粒径大小的微胶囊,粒径分布为20~90μm.热重分析表明EPA-IPDI的装载量达到53 wt%.扫描电子显微镜图片可以看出,微胶囊表面光滑,呈规整球形,厚度均一,约2μm.     

PVA/SiO2-TiO2杂化电纺纤维膜的形态与性能

以正硅酸乙酯(TEOS)、钛酸四丁酯(TBT)和聚乙烯醇(PVA)为原料, 用溶胶凝胶法制备了PVA/(SiO2-TiO2)杂化纺丝液, 将其电纺成纤维膜. 红外光谱结果证实, PVA的羟基与TEOS和TBT水解后的羟基发生了缩合反应, 杂化电纺纤维膜以网络结构形式相结合; X射线衍射分析表明, 杂化电纺纤维膜的结晶度比纯PVA电纺纤维膜小; 扫描电镜表明, 随杂化纤维膜中无机相含量的增加, 纤维的直径不断增加, 纤维出现一定的弯曲和扭曲, 并伴有少量带状结构的纤维; 紫外-可见光谱结果表明, TiO2的引入增加了纤维膜的抗紫外性; TGA热分析结果表明, 杂化纤维膜的耐热性能优于纯PVA电纺纤维膜的; 耐水性和稳定性测试表明, 杂化纤维膜的耐水性和稳定性优于纯PVA和PVA/SiO2电纺纤维膜的.     

溶胶-凝胶法制备硅系有机-无机杂化分离膜

以α-Al₂O₃多孔陶瓷片为载体,用溶胶-凝胶法制备有机-无机杂化分离膜.通过考察前驱物的组成及杂化溶胶的合成条件对制膜工艺过程的影响,得到了制备有机-无机杂化分离膜的各种适宜性参数.红外光谱(FTIR)分析结果表明,杂化溶胶的性能不仅决定分离膜的性能,而且对膜热处理过程中的龟裂有很大影响.膜层的厚度为1～2μm;在膜两侧压差为0.10MPa、n(PTMOS)/n(TEOS)=1.16时,膜对O₂/N₂,CO₂/N₂和CO₂/O₂的分离因子分别为2.30,4.31和1.17,渗透系数为75.81×10^-17,75.28×10^-17和72.78×10^-17m₃(STP)·m/(m₂·s·Pa).     

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%.     

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.     

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.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

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.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

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.