用制备的纳米氧化铜直接合成三乙氧基硅烷的研究

合成了纳米氧化铜催化剂并进行了表征，对催化剂在溶剂中以硅粉与气态乙醇反应合成三乙氧基硅烷进行了研究，讨论了反应温度、催化剂用量、硅粉粒度、不同溶剂对反应的影响．并与CuCl催化剂进行了比较。     

γ—（乙二胺基）丙基三乙氧基硅烷的合成

γ-(乙二胺基)丙基三乙氧基硅烷是一种新型的偶联剂和交联剂。其合成方法可首先通过γ-氯丙基三氯硅烷与无水乙醇发生醇解反     

直接法制备三乙氧基硅烷催化剂的研究进展

综述了直接法合成三乙氧基硅烷的研究进展,着重对直接法的反应机理和催化剂组分的筛选进行了分析讨论.同时介绍了以三乙氧基硅烷为原料,合成烯丙基三乙氧基硅烷、γ-(2,3-环氧丙氧)丙基三乙氧基硅烷、苯乙基三乙氧基硅烷、五乙氧基二硅烷等衍生物的工艺,提出了催化剂制备过程中存在的问题及研究方向.     

直接合成三烷氧基硅烷铜系催化剂的研究现状

三烷氧基硅烷(HSi(OR)3)既含有可水解的Si-OR键,又具有活泼的Si-H键.其中,Si-OR键通过水解缩合可转化成聚硅氧烷,与格氏试剂反应可生成烷氧基硅烷;Si-H键在铂系催化剂作用下,可与一系列含不饱和基的化合物发生氢硅化加成反应,得到各种碳官能硅烷、硅氧烷及硅基改性有机聚合物[1     

乙炔和三乙氧基硅烷的硅氢加成反应研究

制备了氯铂酸-异丙醇、氯铂酸-聚甲基乙烯基硅氧烷和氯铂酸-三苯基膦三种催化剂,评价了它们在乙炔与三乙氧基硅烷的硅氢加成反应中的催化活性及选择性;并考察了反应温度、乙炔流量、氯铂酸-聚甲基乙烯基硅氧烷与三乙氧基硅烷摩尔比、PPh3/H2PtCl6摩尔比等因素对产物收率的影响.结果表明,氯铂酸-聚甲基乙烯基硅氧烷对该反应表现出较高的催化活性,在催化剂与三乙氧基硅烷摩尔比为1.2×10-4∶1,T=80℃,乙炔流量=120 mL/min的条件下反应,产物乙烯基三乙氧基硅烷的选择性为100%,收率可达97.5%.     

恒电流库仑分析法测定乙烯基三乙氧基硅烷

建立了恒电流库仑分析法测定乙烯基三乙氧基硅烷(VTES)含量的方法. 探讨了电解液、反应时间、极化电位、溶剂等因素对测定的影响. 结果表明, 选用V(甲酸)∶V(KBr (2 mol/L))∶V(乙醇)＝6∶1∶3为电解液, 极化电位为200 mV, VTES与溴的四氯化碳溶液反应30 min, 甲醇为VTES的溶剂时测定结果最佳. 该方法用于样品VTES的测定, 加标回收率为98.4%～102.7%, 相对标准偏差为1.7%.     

γ-脲丙基三乙氧基硅烷的制备及表征

采用γ-氨丙基三乙氧基硅烷与尿素进行亲核取代反应,合成了γ-脲基丙基三乙氧基硅烷;通过对工艺条件的优化制备得到了纯度高达99%以上的产品并采用红外光谱及核磁进行了表征。     

乙烯基硅烷-丙烯酸酯乳液共聚动力学研究

以乙烯基三乙氧基硅烷(VTES)、丙烯酸酯为单体,乙氧基醇磺基琥珀酸二钠(A—102)为乳化剂,合成了有机硅改性丙烯酸酯共聚乳液。研究了乳化剂、引发剂、VTES、反应温度以及功能性单体甲基丙烯酸羟乙酯(HEMA)对乳液共聚反应速率的影响。结果表明:聚合速率随乳化剂浓度、引发剂浓度、HEMA浓度的增大及反应温度的升高而增大,但随VTES浓度增大而逐渐减小。由实验得出恒速阶段聚合反应速率R_p与乳化剂浓度C_E、引发剂浓度C_1及有机硅单体浓度C_(VTES)的关系为R_p∝C_E~(0.35)C_I~(0.48)C_(VTES)~(-0.64),表观活化能E_a为81.1kJ·mol~(-1)。     

盐酸法测定γ-氨丙基三乙氧基硅烷及其修饰的纳米二氧化硅表面氨基

建立了用盐酸乙醇标准溶液非水滴定γ-氨丙基三乙氧基硅烷(APS)偶联剂及其修饰的二氧化硅纳米颗粒表面氨基的方法,探讨了滴定溶剂、指示剂对滴定结果的影响,并用电位滴定法对指示剂的终点进行了确定。实验表明:以乙醇作溶剂、百里酚兰作指示剂时,其准确度较高、精密度较好,对APS偶联剂工业样品(A)的回收率为99.40%~100.8%,RSD为0.1%;对APS修饰的二氧化硅纳米颗粒(B),其回收率为99.45%~102.2%,RSD为0.66%。该方法简便、快速,可作为APS含量及其二氧化硅纳米颗粒表面修饰的氨基含量测定的基本方法和企业生产控制与质量检测的方法,具有良好的应用前景。     

添加三甲基乙氧基硅烷制备耐高温硅/铝复合气凝胶

以仲丁醇铝(ASB)和三甲基乙氧基硅烷(TMEO)为前驱体,采用溶胶-凝胶法,经乙醇超临界干燥制备了耐温高、成型性好的硅/铝复合气凝胶。用透射电子显微镜、N₂吸附分析仪、红外光谱仪、X射线衍射仪、hot disk热分析仪等仪器表征了气凝胶的形貌、孔结构、表面基团、晶相、热学等性能。在溶胶-凝胶过程中,通过添加TMEO在氧化铝纳米颗粒表面引入了-Si-(CH₃)₃基团,该基团经高温热处理后会在Al₂O₃表面形成SiO₂纳米颗粒,有效地抑制了Al₂O₃纳米颗粒在高温下的晶体生长,使得该复合气凝胶具有优异的耐温性能。在1 200 ℃高温处理后,线性收缩低至16%,比表面积可达141 m²·g^-1,这将进一步促进气凝胶材料在高温保温隔热、吸附、催化等领域的广泛应用。     

The Direct Synthesis of Arylxenon Trifluoromethanesulfonates via electrophilic substitution

The reaction of xenonbis(trifluoroacetate) and trifluoromethanesulfonic acid (triflic acid) gave the new, highly reactive unsymmetrical xenon-oxo species CF₃COOXeOSO₂CF₃. Benzene derivates, containing electron withdrawing substituents such as -F, -CF₃, -Cl or -NO₂ were electrophilic attacked by this intermediate to yield arylxenon trifluoromethanesulfonates. Via this one-pot synthesis trifluoromethanesulfonates with the cations [Xe(2,4,6-F₃C₆H₂)]⁺, [Xe(2-F-5-NO₂C₆H₃)]⁺, [Xe(2-F-5-CF₃C₆H₃)]⁺ and [Xe(3,5-(CF₃)₂C₆H₃)]⁺ were prepared. All compounds were characterized by their NMR, mass, and vibrational spectra. Additionally, several new arylxenon trifluoromethanesulfonates were detected by ¹²⁹Xe-NMR spectroscopy as products of the reaction of 1,3-F₂C₆H₄ and further deactivated benzenes with xenontrifluoroacetate trifluoromethane sulfonate. Fluoro substituents in ortho position to xenon significantly increase the thermal stability of the arylxenon trifluoromethanesulfonates obtained. The molecular structure of [Xe(2,6-F₂C₆H₃)][OSO₂CF₃] was determined by single crystal diffraction methods. The arylxenon unit is weakly coordinated by one oxygen atom of the CF₃SO₃ anion. The salt crystallizes in the triclinic space group P1 , a = 880.9(3) pm, b = 1093.9(5) pm, c = 1209.8(5) pm, α = 89.04(4)°, β = 74.23(3)°, γ = 86.03(3)°, Z = 4.     

Synthesis of C-Homoaporphines via Microwave-Assisted Direct Arylation

Representatives of the C-homoaporphine class of alkaloids have shown interesting biological activities. To date the synthesis of these molecules has never been attempted via a direct-arylation strategy. We report herein the first Pd-mediated intramolecular direct arylation in the synthesis of C-homoaporphines via the use of microwaves. Use of tricyclohexylphosphine tetrafluoroborate as ligand gave good percentage conversions and suppressed competing debromination with the substrates evaluated. This arylation strategy should be broadly useful in the synthesis of C-homoaporphine alkaloids as demonstrated herein in the synthesis of (±)-homonantenine.     

Synthesis of acenes via coupling of 1,4-dilithiobutadienes with diiodoarenes in the presence of CuCl

Dilithiobutadienes prepared from diiodobutadienes reacted with diiodobenzene or diiodonaphthalene to afford substituted naphthalene, anthracene, dihydronaphthacene, and dihydropentacene derivatives in the presence of CuCl and DMPU. Dihydronaphthacene and dihydropentacene derivatives were converted into the corresponding naphthacene and pentacene derivatives.     

熔融聚合法直接合成生物降解材料PLEG

以乳酸(LA)和分子量1000的聚乙二醇(PEG)为原料(mLA／mPEG=9),以氯化亚锡为催化剂(mc／mLA=0．005),165℃、70Pa下熔融聚合10h,合成生物降解材料聚乳酸-聚乙二醇(PLEG)。其[η]最高可达0．3398dL／g。直接熔融聚合法有利于降低其成本。     

羟基新戊醛直接电氧化合成羟基新戊酸的研究

在硫酸水溶液中,以质子交换膜为隔膜,以羟基新戊醛为原料,在PbO₂电极上直接电氧化制取羟基新戊酸.研究了羟基新戊醛浓度、pH、温度及氧化电位对目标产物选择性和电流效率的影响.结果发现,pH对产物选择性和电流效率的影响最大.选择性最高可达92.6%,电流效率最高可达61.4%.用高效液相色谱分析反应过程中原料和产物的浓度变化.通过熔点、红外光谱和元素分析对分离提纯后的产物进行了表征.     

Synthesis of POSS‐Functionalized Polyisobutylene via Direct Initiation

POSS‐functionalized polyisobutylenes (PIBs) were synthesized by carbocationic polymerization using an epoxy‐POSS/TiCl₄ initiating system in hexane/methyl chloride (60:40 v/v) solvent mixture at −80 °C. ¹H NMR spectroscopy verified the incorporation of one epoxy‐POSS per polymer chain. Light scattering and TEM analysis demonstrated the formation of 50–100 nm sized aggregates and micron‐sized clusters.

     

Synthesis of Conformationally Restricted Cyclic Hexadepsipeptides via Direct Amide Cyclization

Ring closure by direct amide cyclization was used in the synthesis of 19‐membered cyclic depsipeptides 27 (Schemes 1 and 3). The linear hexapeptide precursors 4 , containing the β‐hydroxy acid 3‐hydroxy‐2‐phenylpropanoic acid (Tro), and five α‐amino acids of the type Aib, Gly, and Pro, were prepared according to Scheme 2. The α,α‐disubstituted α‐amino acid Aib was incorporated into the peptide chain via the azirine/oxazolone method, and Gly and Pro were introduced by using the TBTU/HOBt coupling method. The cyclic depsipeptides 27a – 27f were obtained in reasonable‐to‐excellent yields (Scheme 3 and Table 1).     

Synthesis of Cyclic Depsipeptides and Peptides via Direct Amide Cyclization

The 2,2-disubstituted 2H-azirin-3-amines 7 (2,2-disubstituted 3-amino-2H-azirines) were used as amino-acid synthons in the preparation of medium-sized cyclic depsipeptides and peptides derived from salicylic acids 6 and anthranilic acid 19 , respectively (Schemes 2--4 and 5, resp.). The combination of the ‘azirine/oxazolone method’ for the synthesis of linear peptides containing α,α-disubstituted α-amino acids and the acid-catalyzed amide cyclization in DMF at 60° proved to be an excellent preparative route to ten-membered cyclic depsipeptides and peptides. In the case of the anthranilic-acid derivative, a transannular ring-closure reaction was observed ( 24 → 25 ). Larger rings proved to be extremely sensitive to hydrolysis.