密胺树脂/硼酸锌双层包覆微胶囊化红磷的制备及其在阻燃聚烯烃中的应用

描述了采用密胺树脂和硼酸锌连续双层包覆微胶囊化红磷(MRP)的最新制备方法。采用红外光谱、电子能谱和透射电镜等分析手段对其进行了表征，并证实红磷已被完全包覆。实验数据表明：经包覆的MRP的热稳定性获得了明显改善，吸水率和磷化氢的发生量均大大减少。MRP作为阻燃助剂应用于聚烯烃阻燃材料表现出了良好的阻燃效果。实时红外和热失重测量以及扫描电镜观察表明：其阻燃机制是红磷受热时与树脂反应促进了含磷膨胀炭层的形成，从而提高了材料的热稳定性，碳层起到了隔氧、隔热作用，而且主要在凝聚相中发挥其阻燃作用。     

PVA改性脲醛树脂对聚α-烯烃的包覆研究

以脲素和甲醛为原料、PVA为改性剂,合成了脲醛预聚体,并通过原位聚合法对聚α-烯烃颗粒进行微胶囊包覆;考察了反应温度、反应时间、PVA改性剂以及脲素和甲醛的摩尔比对脲醛预聚体制备及最终包覆效果的影响。结果表明:PVA的加入改善了脲醛预聚体的合成,当脲素与甲醛的摩尔比为2:3、PVA含量占脲素甲醛溶液质量的3.30%、反应温度为70℃、反应时间为120min时,制备的预聚体性质稳定,并且在丁醇-水介质中,对聚α-烯烃颗粒有较好的包覆效果,包覆率达15.3%。     

微胶囊无卤阻燃剂的研究进展

介绍了作为微胶囊芯材的无卤阻燃剂——无机阻燃剂、膨胀阻燃剂、氮磷系阻燃剂的分类及优缺点。以微胶囊阻燃剂的包覆壳材料为重点,综述了阻燃剂的无机包覆、有机包覆、双层或多层包覆和反应生成阻燃剂型包覆的最新研究进展,最后介绍了界面聚合法、原位聚合法、溶胶-凝胶法和超临界法等四种制备微胶囊阻燃剂的方法,并展望了微胶囊阻燃剂的未来发展方向。     

微胶囊化超细红磷的制备及其安定性研究

研究了用硝酸铝溶胶凝胶法制备微胶囊化超细红磷的工艺，通过着火点测试研究了包覆材料和包覆工艺以及影响包覆效果的因素，发现以5%氢氧化铝溶胶凝胶制备微胶囊化红磷在150 ℃左右真空干燥得到的样品安定性较好，XPS表明有95.3%的红磷被包覆，透射电镜显示形成一层均匀的包覆层，超细红磷的安定性得到了较大的提高。     

一种致密的相变储能微胶囊的制备与表征

制备了以聚脲为第一壁材、苯乙烯-二乙烯苯为第二壁材,以相变点在16℃左右的石蜡为芯材的相变储能微胶囊。采用红外光谱、差示扫描量热分析、热重分析测试技术表征了制备的相变储能微胶囊的结构组成以及热性能;采用溶剂淋洗法研究了影响包覆率的因素。结果表明,相变储热微胶囊是复合相变材料,微胶囊的热稳定性好,致密性优良;通过对水油比、乳化剂及苯乙烯-二乙烯苯用量等各因素对微胶囊包覆率影响的讨论,得出在水与油质量比3.2,乳化剂相对于水的质量分数为2%时,加入苯乙烯与二乙烯苯质量比为10∶1混合液的质量分数为6.0%时,其包覆率达81.14%;制备的微胶囊能耐较高温度,在150℃以下无质量损失,且微胶囊储热能力高达80J/g。同时发现,储热能力与芯壁比有关,比值越大储热潜能越高。     

原位聚合法制备聚磷酸铵微胶囊及其应用的研究进展

以聚磷酸铵微胶囊阻燃剂的包覆壳材料为重点,综述了聚磷酸铵微胶囊阻燃剂的无机材料包覆、有机材料包覆、双层或多层包覆以及纳米材料包覆,总结了国内外关于原位聚合法制备聚磷酸铵微胶囊的最新研究进展。介绍了聚磷酸铵微胶囊形成过程中,包覆壳材料与聚磷酸铵的原位聚合方法及机理。并且提出了聚磷酸铵阻燃剂在材料燃烧过程中存在的协同效应。最后,结合聚磷酸铵微胶囊阻燃剂在阻燃过程中存在的问题,展望了原位聚合在微胶囊阻燃领域中的未来发展方向。     

用溶剂蒸发法研制维生素C微胶囊

本文用溶剂蒸发法研制了以乙基纤维素、羟两基甲基纤维素苯二甲酸酯等聚合物为包覆材料的维生素C微胶囊,探讨了微胶囊化的条件和包覆效果,并测定了微胶囊的载药量及其溶解释放性能。     

阻燃剂9,10-二氢-9-氧杂-10-膦杂菲-10-氧化物合成中酯化反应和酰基化反应的优化

有机磷杂环化合物9,10-二氢-9-氧杂-10-膦杂菲-10-氧化物(DOPO)因性能优异而作为无卤阻燃剂得到广泛应用。为了提升和改进DOPO的合成,不少文献对合成中的4个反应,即酯化反应、酰基化反应、水解反应和关环反应进行了大量研究,但是由于缺少合适的分析方法和仪器,对酯化反应和酰基化反应仍没有得出明确的结论。本文则采用了核磁共振磷谱以及测量反应产物HCl吸收碱液的温度变化两种方法,精确地得到了酯化反应和酰基化反应的优化条件。首先采用核磁共振磷谱,讨论了酯化反应温度、原料配比和加料方式对酯化反应产物组成的影响,得出了邻苯基苯氧基二氯化磷(CC)含量高的工艺条件:反应温度80℃,PCl3过量25%~50%,采用邻苯基苯酚(OPP)加入PCl3的反滴法;并得出酯化反应产物的组成直接决定了6-氯-(6氢)-二苯并-(c,e)-氧磷杂己环(CDOP)在酰基化反应产物中的含量。另通过测量HCl吸收碱液的温度变化,间接表征酰基化反应的反应速度,由此得出合适的酰基化反应温度和催化剂用量。结果为:当催化剂固定为0.2 g时,酰基化反应在150℃几乎不反应,随温度升高,反应变快,180℃下4 h完全,190℃下1.5 h即可完成;温度180℃下,1~1.5 g/1 mol OPP的催化剂较为合适,酰基化反应在3~4 h结束。     

甲胺基阿维菌素苯甲酸盐微胶囊的制备与表征

以三聚氰胺-甲醛树脂为壁材,采用原位聚合法制备了甲胺基阿维菌素苯甲酸盐微胶囊,研究了三聚氰胺与甲醛的质量比、芯壁比、乳化剂、搅拌速度与时间、pH值、温度等因素对微胶囊形成的影响,对制备的微胶囊进行了表征,测定了甲维盐微胶囊化前后的光解率。结果表明,三聚氰胺与甲醛质量比为1∶2、芯材与壁材质量比为3∶2、以质量分数1%羟乙基纤维素(HEC)为乳化剂、在1000r/min搅拌速度下、pH=5.0和50℃保温2h可制备出形貌较好、平均粒径4.4μm的甲维盐微胶囊。红外光谱分析证明,甲维盐已完全被包覆在微胶囊中。紫外分光光度法测定其缓释性能良好。光解实验表明,微胶囊化可有效降低甲维盐原药的光解。     

微胶囊碳酸氢钠合成工艺及热分解特性的研究

利用环氧树脂(EP)对碳酸氢钠(SB)进行包覆合成微胶囊碳酸氢钠,通过红外光谱仪(FTIR)、扫描电子显微镜(SEM)、差示扫描量热计(DSC)和热重分析仪(TG)等表征手段,分析了合成反应温度、环氧树脂与碳酸氢钠的质量比对微胶囊碳酸氢钠的结构、表面形貌特征以及热分解特性的影响.结果表明:当反应温度为70℃,环氧树脂与...     

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.