溶剂热法制备小粒径无皂MMA/St共聚纳米胶乳粒子

溶剂热法制备小粒径无皂MMA/St共聚纳米胶乳粒子;溶剂热法;无皂乳液聚合;纳米粒子;聚(苯乙烯甲基丙烯酸甲酯)     

高浓度窄分布无皂高分子纳米粒子胶乳的制备

在微波辐照和丙酮存在下,进行了苯乙烯(ST)和甲基丙烯酸甲酯(MMA)的无皂乳液聚合.当丙酮的含量在50％以下时,可以得到稳定的窄分布的纳米粒子胶乳.丙酮的含量由0增加到50％,粒子的平均水化半径由278nm降低到35.4nm.在一定的浓度范围内,固定引发剂过硫酸钾（KPS）的用量,则粒子的平均水化半径与单体的浓度成正比;当单体浓度一定时,随着引发剂浓度的增加,粒子平均水化半径从25nm减少到22nm然后又增大.考虑到引发剂既是粒子表面电荷的来源,又增加了体系的离子强度,在粒子形成过程中,起着稳定和絮凝的双重作用,我们得到了一个简单的公式用以描述粒子的平均水化半径<R     

溶剂热法制备无皂P(St-MMA)纳米胶乳粒子

采用溶剂热法,在密闭容器内,以异丙醇-水为分散介质,过硫酸钾为引发剂引发苯乙烯(St)和甲基丙烯酸甲酯(MMA)共聚,制得了粒径约为60 nm的无皂聚(苯乙烯-甲基丙烯酸甲酯)纳米胶乳粒子[P(St-MMA)]。探讨了异丙醇用量和反应温度对P(St-MMA)粒径的影响,并对异丙醇-水和丙酮-水体系中的聚合速率进行了比较。实验结果表明:随着异丙醇用量的增加,P(St-MMA)粒径逐渐减小;随着反应温度的升高,P(St-MMA)粒径先减小后增大;异丙醇-水体系的聚合速率比丙酮-水体系的聚合速率快。     

小粒径无皂阳离子PMMA胶乳粒子的制备与表征

采用溶剂热法,以AIBA为引发剂制得小粒径无皂阳离子PMMA胶乳纳米粒子。讨论了单体用量、引发剂用量和反应温度对胶乳粒径及乳液的粒径分布的影响;用^1H—NMR、TEM、FTIR、GPC、DTA等对聚合物进行了表征。结果表明：采用溶剂热法制得的无皂阳离子胶乳粒子粒径约为35nm,分散均匀;随着温度的升高,粒径逐渐减小;间同、无规、全同立构的相对含量分别为：55．3％、37．8％、6．9％;乳液的抗电解质稳定性好。     

溶剂热法制备无皂PMMA纳米粒子

用溶剂热法制备无皂聚甲基丙烯酸甲酯(PMMA)纳米粒子,讨论了温度和丙酮含量对粒子粒径和分散度的影响,用DTA,^1HNMR,TEM,GPC等对产物进行了表征。结果表明无皂PMMA纳米粒子的粒径约60衄,分子量分布较好、以间同结构为主;随着反应温度增高,PMMA的玻璃化温度增加,间同结构含量有所增大,纳米粒子的粒径逐渐减小,粒径分布变差;溶剂中丙酮含量增加时,粒径逐渐减小,粒径的分布变差。     

微波辐照下无皂阳离子聚(St-MMA)高分子纳米粒子的制备和表征

讨论了微波辐照下 ,以丙酮 水为分散介质 ,利用阳离子型自由基引发剂偶氮二异丁基脒盐酸盐(AIBA)引发苯乙烯 (St)和甲基丙烯酸甲酯 (MMA)共聚 ,合成出表面带正电荷的P(St MMA)共聚物纳米粒子 ,考察了丙酮用量、单体和引发剂浓度对纳米粒子粒径、粒径分布和乳液稳定性的影响 .结果表明 ,丙酮 水的体积比由 0增加到 1 2 6∶1时 ,粒子的平均水化半径从 12 2 2 1nm降低到 2 4 6 8nm ,粒径分布变宽 ,乳液抗电解质稳定性逐渐增强 ;增加引发剂和共聚单体MMA的浓度 ,粒子的水化半径逐渐减小 ,粒径分散系数增大 .     

微波辐照制备无皂阳离子PMMA胶乳粒子

在微波辐照条件下 ,用偶氮二异丁基脒盐酸盐 (AIBA)引发甲基丙烯酸甲酯的均聚 ,制得窄分散的无皂阳离子胶乳粒子 .讨论了引发剂的浓度、单体的浓度、离子强度等对粒子大小、分散性和乳液稳定性的影响 .对微波辐照和水浴加热进行比较 ,发现微波辐照反应速度快、反应无恒速阶段 ,所得粒子的粒径小 ,粒子数目多 ,这为通过改变反应条件制备适宜的窄分散的胶乳粒子提供了一条途径 .     

微波辐照制备多孔乳胶粒

在微波辐照的条件下，通过间歇无皂种子乳液聚合，制得聚[苯乙烯－甲基丙烯酸甲酯－丙烯酸]复合乳液。将所得复合胶乳进行碱／酸分段处理，得到具有多孔结构的乳胶粒。用透射电镜对胶粒形态进行了表征，研究了不饱和酸用量、碱处理初始pH值及碱处理时间对胶粒成孔的影响。     

溶剂热法制备小粒径无皂均聚物纳米胶乳粒子

采用溶剂热法，用过硫酸钾引发苯乙烯均聚，制备出分散性好、粒径约30nm的无皂聚苯乙烯肢乳纳米粒子。讨论了引发剂的用量、助溶剂丙酮的含量、反应温度对粒子尺寸及其粒径分布的影响。实验结果表明：在一定范围内，温度改变，粒径变化较快；引发剂、丙酮和单体用量改变时，粒径变化较缓慢。     

P(MMA-EA-AA)共聚物组成对无皂乳胶粒碱处理后结构形态的影响——异型结构粒子的形成

采用批量法无皂乳液聚合技术合成了粒径窄分布的甲基丙烯酸甲酯(MMA) - 丙烯酸乙酯(EA)- 丙烯酸(AA)三元共聚物胶乳,并通过碱后处理,制备出了具有异型结构的乳胶粒,探讨了AA用量及MMA /EA质量比对胶粒结构形态的影响.结果表明,当AA含量大于0 .0 4mol时,胶乳中开始出现异型结构粒子,随着AA用量的增加和MMA/EA质量比的减小,异型粒子在胶乳中所占比例增加,胶粒体积先增大后减小.当EA用量较高时,粒子边界模糊,异型结构不明显.     

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.     

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.     

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.     

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.     

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.