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苯乙烯—丙烯酸丁酯无皂乳液聚合动力学及TEM分析 总被引:2,自引:1,他引:2
讨论了温度对十一烯酸钠存在下的苯乙烯、丙烯酸丁酯无皂乳液聚合体系pH值的影响,描述了聚合反应动力学曲线,求出不同温度下的聚合反应速率常数.利用TEM对几种乳化剂体系的乳液聚合进行比较后发现,在无皂乳液聚合体系中,乳胶粒的均匀性和粘连、形变等都得到了控制.由于体系中不存在游离乳化剂,乳液的稳定性得到提高. 相似文献
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甲基丙烯酸丁酯微波无皂乳液聚合 总被引:6,自引:2,他引:4
以过硫酸钾作为引发剂进行了甲基丙烯酸丁酯的微波无皂化乳液聚合,讨论了单体浓度和引发剂用量对单体转化率,粒子粒径及其分布的影响,并与常规乳液聚合进行了比较。结果表明,通过微波无皂乳液聚合,乳胶粒子的粒径分布没有明显变化,但是聚合速率大为增加。 相似文献
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MMA—St无皂乳液聚合成核机理探讨 总被引:5,自引:0,他引:5
讨论了MMA-St无皂乳液聚合,当[KPS]=2.77×10~(-3)mol/L,[MMA]0.51mol/L,[St]=0.49mol/L,70℃反应5.0小时,能得到较高的聚合转化率,较小的胶乳粒径和较大的粒子浓度,并对不同反应时期聚合物的分子量及其分布进行了测定,认为该无皂乳液聚合体系为均相沉淀成核机理。当转化率大于30.9%时,胶乳粒的凝聚程度大于胶乳粒的生成速度。KPS分解产生的自由基起到了稳定乳液的作用。 相似文献
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研究了少量甲基丙烯酸钠存在下单体极性对甲基丙烯酸甲酯/丙烯酸丁酯无皂乳液共聚合的影响。单体极性降低,使粒径减小,聚合整编提高,乳液表面张力和粘度降低,粒子表面电荷密度增大,聚合物分子量提高。MMA/NaMA无皂乳液聚合物只呈现一个玻璃化温度Tg,BA/NaMA无皂乳液聚合物呈现两个Tg,MMA/BA比为2:1-1:2的MMA/BA/NaMA无皂乳液聚合物呈现四个Tg,这是由于粒子外机相对富含OSO 相似文献
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纯化对三元无皂共聚胶粒性质的影响 总被引:1,自引:0,他引:1
以离子交换和高速离心两方法纯化含不同功能基的三元无皂共聚胶乳,用TEM和电导滴定检测比较了以上两方法的纯化效果,同时考察了这两种纯化方法对三元无皂胶粒形态,大小及表面功能其量的影响。研究发现,只有通过多次离心-倾析-再分散过程才能将胶乳所有杂质除去。离子交换和离心纯化不影响胶粒形态大小,而离心纯化使粒表面功能其量发生显著变化。 相似文献
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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%. 相似文献
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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. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
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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. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
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. 相似文献
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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. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献