发酵法黄腐酸磺化产物减水性能的研究

以腐植酸（HA）类新技术产品－发酵法黄腐酸（BFA）的磺化（磺甲基化）产物为研究对象,就其物化特性和泡沫性能以及表面活性、水泥净浆流动度和减水率等一系列减水性能进行了较系统的考察和研究,并与常用减水剂木钙（木质磺酸钙）对比,提出发酵法黄腐酸应用于混凝土减水剂的可能性。文中还对BFA磺化（磺甲基化）产物的减水机理进行了探讨。     

甲基萘磺酸系高效减水剂合成研究

减水剂在建筑混凝土中应用广泛,其中萘系高效减水剂具有减水率高,对混凝土的强度不产生有害影响且成本低的优点,在市场上占80%,其它各种减水剂由于减水率低的缺点在市场上仅占20%。实验以甲基萘油为原料,经过磺化、水解、缩合、中和四步反应,合成减水率高达16.8%的甲基萘磺酸系高效减水剂,并对合成中滴加硫酸温度、磺化温度、水解加水量、甲基萘与甲醛的物质量比等的各种影响因素作了进一步的探讨。     

木质素氧化降解研究进展

木质素是当今世界上含量第二丰富的可再生高聚物.氧化降解是木质素价值增值过程中一种非常有前景的方法,它能提供高度官能化的单体和低聚物产品作为其他价值增值过程的起始原料,为代替化石燃料在化工和制药行业中的应用提供了一种可能.主要对木质素及其模型化合物的氧化改性方法进行了综述,包括生物催化、仿生催化、有机金属催化、电化学催化氧化及其他几种催化氧化法,并简单讨论了氧化降解过程的反应机理,为今后木质素的氧化价值增值研究提供一定的参考.     

聚羧酸系高效减水剂合成工艺的优化研究

以甲基烯丙基聚氧乙烯醚(HPEG)和丙烯酸(AA)为单体,以过氧化氢-抗坏血酸(H2 O2-Vc)为氧化还原引发体系,以巯基丙酸(MPA)为链转移剂,共聚合成了HPEGAA型聚羧酸减水剂.研究了合成温度、酸醚比及引发剂用量对聚羧酸减水剂分散性能的影响.结果表明,聚羧酸减水剂的最佳合成工艺为:n(AA):n(HPEG)=...     

纳米氧化铈在催化氧化木质素制备芳香化合物中的应用研究

木质素是自然界中唯一大规模可再生的含芳环聚合物.通过催化氧化的方法,定向解聚木质素得到芳香类化合物,具有非常重要的价值.近年来,氧化铈作为载体在木质素的多相催化氧化反应中表现较好性能.然而,对于氧化铈直接作为催化剂,并探讨其纳米结构与性能之间的研究未见报道.研究结果表明:纳米氧化铈直接作为催化剂时,对于木质素的催化氧化反应具有较好的性能,顺序为氧化铈纳米八面体纳米四方体纳米球纳米棒.纳米八面体表现出最优的催化性能,以其作为催化剂,对乙醇木质素进行催化氧化,得到了大量芳香酸及其酯类化合物.     

木质素:一种有潜力的生物质基催化剂来源

木质素是自然界中储量丰富的唯一含芳环生物质可再生资源,但复杂的结构使其难以高效利用,目前大部分被废弃.除通过氧化还原等过程可将其转化为石油化工产品的替代品外,木质素结构中丰富的含氧官能团及制浆过程引入的硫元素等均可提供有效位点,为其作为催化剂基质提供了丰富的可行性.本文从木质素资源的来源和结构分析出发,根据不同催化反应...     

辣根过氧化物酶改性木质素磺酸钠的结构特征及吸附分散性能

在室温及水溶液体系中,采用辣根过氧化物酶(HRP)对亚硫酸法制浆造纸废液的副产物木质素磺酸钠(木钠)进行改性,通过凝胶渗透色谱、电位滴定、红外光谱和核磁共振波谱等表征了HRP改性木钠的结构.结果表明,HRP可以有效聚合木钠大分子,调节HRP的用量,得到不同分子量的木钠产品,当HRP浓度为6 g/L时,可使木钠分子量增大155%.HRP可氧化木钠分子上的酚羟基变成苯氧自由基,该自由基可直接交联,也可转移到酚羟基的邻位或对位再发生聚合作用,其聚合方式主要为β-O-4'及β-β'连接.HRP改性还可使木钠磺化度增加27%.采用静电逐层自组装技术研究了HRP改性对木钠吸附特征的影响,结果表明,经HRP改性后,木钠在平板上的吸附量增大;对TiO2浆体的分散稳定性能也得到改善,这主要是因为分子量增大,空间位阻作用增强;磺化度增大,静电排斥作用增强,从而使TiO2颗粒更好地分散在水中.     

质子交换膜用磺化聚芳醚的合成与性能研究

合成了一种用于质子交换膜的新型磺化聚芳醚. 由于特殊单体结构的设计, 在聚合物主链上引入取代基对主链进行保护, 用氯磺酸直接磺化方法在聚芳醚高分子侧基上引入磺酸功能基, 实现了聚合物磺化结构的可控定位合成, 得到了稳定性较好的磺化聚芳醚. 用溶液浇膜法制备了质子交换膜, 考察了质子交换膜的各种性能. 结果表明, 这种膜具有良好的成膜性, 水解性稳定性和优异热稳定性能, 5%的热失重温度为362.3 ℃. 氧化稳定性在80 ℃的Fenton’s试剂(3%的过氧化氢和2 mg/L的FeSO₄)中进行, 膜在69 min时才开始变碎, 表现出良好的氧化稳定性.     

2HN缓凝高效减水剂

<正>中科翔-2HN缓凝高效减水剂具有高效减水、缓凝、保坍和增强等功能。适合于各种混凝土结构施工。产品对水泥适应性强,掺量少,使用方便,特别适合于具有缓凝、保坍和高增强要求的商品混凝土工程。主要性能指标减水率20%～25%。对水泥适应性强,引     

聚羧酸系高效减水剂减水机理研究

重点叙述了聚羧酸高效减水剂的特点、研究和发展的状况,并就聚羧酸减水剂的减水机理、分子结构对减水率的影响、减水剂在水泥中的化学作用等因素进行了较详细的综述,分析了影响减水率的规律和可能的作用机理。     

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.