含氟光引发剂的合成及其性能研究

以2-羟基-4'-(2-羟乙氧基)-2-甲基苯丙酮(Irgacure 2959)和全氟辛酰氯(PFOC)为原料合成了光引发剂全氟辛酸-2-[4-(2-羟基-2-甲基丙酰)苯氧基]乙酯(2959-F),利用红外光谱(FT-IR)和核磁共振(¹⁹F NMR)对2959-F进行了结构表征;通过紫外吸收光谱测定了2959-F的紫外吸收谱;通过实时红外光谱(RT-IR)对合成的含氟光引发剂进行了光聚合反应动力学研究,考察了光强和引发剂浓度对单体的双键转化率和聚合速率影响,并研究了光引发剂2959-F的抗氧阻聚性能.结果表明:随着光强的增大,单体的双键转化率和聚合速率增加;在一定范围内,引发剂的浓度越高,双键转化率越高,聚合速率越快.2959-F具有较高的双键转化率和较快的聚合速率,并且具有较好的抗氧阻聚性.     

4,4'-二甲氧基二苯基氮氧自由基调控甲基丙烯酸甲酯聚合动力学研究

合成了4,4'-二甲氧基二苯基氮氧自由基(DMDPN)和相应的烷氧基胺引发剂,用于甲基丙烯酸甲酯(MMA)的氮氧自由基调控聚合,研究了聚合过程中的动力学机理.通过电子自旋共振(ESR)表征,测定了DMDPN型烷氧基胺引发剂在100~120?C范围内的解离速率常数kd0,结果表明kd0符合阿伦尼乌斯公式(k=Ae-Ea/RT),其活化能Ea为135.2 k J·mol-1,指前因子A为3×1014.测定了末端官能团化聚合物PMMA-DMDPN的解离速率常数kd,由于DMDPN中胺氧基团周围的空间位阻较小,受到前末端效应的影响较弱,kd仅为kd0的6倍.采用间接法测定了110?C时增长自由基和DMDPN的结合速率常数kc,并绘制了该温度下MMA/DMDPN聚合体系的Fischer相图,结果表明该聚合体系对应的kd和kc值处于相图的可控/"活性"区域内.     

反应型受阻胺-4-丙烯酰胺基-2,2,6,6-四甲基哌啶(AATP)熔融本体光聚合反应动力学研究

合成了反应型受阻胺4-丙烯酰胺基-2,2,6,6-四甲基哌啶(AATP),用FTIR、¹H-NMR和元素分析对其结构和组成进行了综合表征.以AATP为聚合单体,利用光-DSC技术研究了AATP熔融本体光聚合反应动力学.结果表明:AATP光聚合的诱导时间随引发剂浓度和辐照光强增加而缩短,光聚合速率随温度的升高而减小;在聚合初期,AATP光聚合速率分别与引发剂浓度和辐照光强的平方根呈较好的线性增长关系.并用稳态和非稳态相结合的光-DSC方法测定了AATP光聚合过程的动力学参数:链增长速率常数k_p=2.22-7.96×10²L/mol·s、链终止速率常数k_t=0.08-2.67×10⁴L/mol·s、表观活化能为E_p-E_t/2=-7.70-13.36kJ/mol、指前因子A_p/A_t^0.5=0.076-0.333(L/mol·s)0.5,k_p和k_t在聚合初期均随单体转化率的提高而增大,但kt增加的幅度远大于k_p.     

大分子量二苯甲酮光引发剂的合成及动力学研究

以4-羟基二苯甲酮(HBP)、甲苯-2,4-二异氰酸酯(TDI)、4,4′-二羟基二苯甲酮(DHBP)为原料,通过两步反应,合成了一种大分子量二苯甲酮光引发剂:HBP-TDI-DHBP-TDI-HBP(HTDTH).通过实时红外研究了HTDTH的光聚合动力学.结果表明,HTDTH是一种有效的光引发剂.采用HTDTH/胺光引发体系引发二缩三丙二醇二丙烯酸酯(TPGDA)聚合时,随着胺和引发剂浓度的增大,反应速率(R_p)和单体最终转化率(P)同时增大.     

Reactive-HALS III: ATMP光聚合动力学研究

以受阻胺哌啶醇衍生物4-(丙烯酰氧基)-2,2,6,6-四甲基哌啶醇酯(ATMP)作为聚合单体,利用光差动热分析法(DPC)系统地研究了ATMP的光聚合反应活性和反应动力学规律.结果表明:反应体系的组成和聚合条件对ATMP光聚合动力学有显著的影响;在聚合初期,ATMP光聚合速率同引发剂浓度和辐照光强的平方根呈线性关系;利用DPC测定了ATMP光聚合过程的动力学参数(kp和kt),链终止速率常数kt远大于链增长速率常数kp, kt/kp= 100.01～394.78;kt和kp均随着转化率的增大而减小,但kt的减小幅度大于kp;电子顺磁共振谱(EPR)定量结果表明:原位生成的微量[(2～6)×10-7mol/L]稳定氮氧自由基对ATMP的溶液光聚合过程的阻聚效应不明显.     

季戊四醇四苯甲酰甲酸酯的合成及光引发性能

大分子光引发剂可以解决小分子光引发剂残留碎片带来的毒性对其在食品和医用材料领域应用的限制,为此,本文以苯甲酰甲酸(BF)和季戊四醇(PET)为原料,通过酰氯法在季戊四醇主链上引入了4个苯甲酰甲酸酯基团,制备了多官能度的季戊四醇四苯甲酰甲酸酯(PTF)大分子光引发剂。 PTF在225 ℃时失重15%,热稳定性优于2-羟基-2-甲基-1-苯基-1-丙酮(1173)光引发剂,与1173光引发剂相比,用PTF作光引发剂所制备的光固化涂料,在起始分解温度以及失去相同比例质量所需温度均提高了100 ℃以上。 PTF引发三羟甲基丙烷三丙烯酸酯(TMPTA)聚合时最大反应速率为0.037 s^-1,最终双键转化率为39.5%,PTF光引发活性大于1173光引发剂。 在同等实验条件下,PTF的相对小分子残留量仅为1173光引发剂的5%。     

含2,2′,4-三(2-氯苯基)-5-(3,4-二甲氧基苯基)-4′,5′-二苯基-1,1′-双咪唑光引发体系的光聚合动力学研究

2,2′,4-三(2-氯苯基)-5-(3,4-二甲氧基苯基)-4′,5′-二苯基-1,1′-二咪唑(CZ-HABI)是一种高效的光引发剂,其结构通过傅里叶红外光谱仪、核磁共振仪、紫外吸收光谱进行表征.复合引发体系(PI)由光引发剂CZ-HABI、增感剂4,4′-双(二乙氨基)苯甲酮(EMK)、供氢体N-苯基甘氨酸(NPG)组成,利用实时红外(RT-IR)对该复合光引发体系进行了光聚合反应动力学研究,结果表明:在没有供氢体条件下,基本上没有引发效果,增加供氢体后,引发效率大幅增加;增加复合光引发体系用量能提高光聚合反应的双键转化率,且最大聚合速率与[PI]1/2成正比;随着光强的增强,单体的双键转化率与最大反应速率均增大;复合光引发体系引发双丙烯酸酯类单体的最终双键转化率比三丙烯酸酯类单体要高.复合光引发体系的引发效率比ITX/EDAB光引发体系的引发效率高,与1-羟基环己基苯基甲酮(184)、2-羟基-2-甲基-1-苯基-1-丙酮(1173)的引发效果相近.     

可聚合二苯甲酮类光引发剂的合成及其光聚合性能研究

以4-(2,3-环氧丙氧基)二苯甲酮(EBP)和丙烯酸为原料,通过开环反应合成了含有不饱和双键的可聚合光引发剂4-(丙烯酸-2-羟基丙酯-3-氧基)二苯甲酮(AEBP).采用红外光谱(FT-IR)、核磁共振氢谱(¹HNMR)对其结构进行表征,利用紫外吸收光谱对AEBP的紫外吸收波长进行表征,通过实时红外(RT-IR)研究了AEBP引发丙烯酸酯单体的光聚合动力学.采用萃取法对比了BP与AEBP引发固化体系后的迁移性.结果表明,随AEBP浓度增加,单体最终转化率增加;当助引发剂N,N-二甲氨基苯甲酸-乙酯(EDAB)浓度为1.2%时,单体最终双键转化率最高;AEBP对双官能度单体的引发效率较之三官能度单体的好;聚合速率随光照强度的增强而变快;固化后AEBP的迁移性比传统的BP大大降低.     

甲基丙烯酸甲酯的可控/“活性”细乳液光聚合

在室温下, 以2,2,6,6-四甲基-4-羟基哌啶-1-氧自由基(HTEMPO)为调控介质, 1-羟基-环己基-苯基甲酮(Irgacure 184)为引发剂, 采用光化学方法研究了甲基丙烯酸甲酯(MMA)/十二烷基硫酸钠(SDS)/十六醇(CA)/水细乳液体系的光聚合反应控制动力学. 结果表明, 该细乳液体系非常稳定, 在整个聚合过程中即没有絮凝物产生, 也没有沉淀析出, 获得了良好的ln([M0]/[M])与时间、数均分子量与转化率之间的线性动力学关系, 并且在整个聚合反应过程中MMA均聚物的分子量分布比较窄, 其多分散性指数较低(PDI=1.27~1.36), 具有明显的活性聚合特征.     

纳米SiO_2锚固光敏基团引发MMA光接枝聚合研究

对纳米SiO2进行了锚固光引发剂的表面修饰,进而引发甲基丙烯酸甲脂(MMA)光接枝聚合制备有机/无机复合粒子.纳米SiO2粒子首先用氯化亚砜进行表面氯化,再与光引发剂2-羟基-4-(2-羟基乙氧基)-2-甲基苯丙酮(Irgacure2959)反应从而锚固上光引发剂.通过紫外光引发MMA在经过修饰过的纳米SiO2表面上进行表面光接枝聚合.采用IR、TGA和TEM等方法表征了接枝前后纳米粒子的变化,证明了表面接枝物的存在,并研究了不同反应条件对单体转化率、接枝率和接枝效率的影响.研究结果表明,搅拌对接枝过程的影响比较显著.TGA结果显示未搅拌聚合时接枝率只能达到比较小的程度,而在搅拌条件下180min内MMA的接枝率可达到110%.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

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.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.