A Novel Synthetic Route to New 1,2,4-Triazolo-1,3,5-triazin-4-ones Derivatives

The reaction of ethyl chloroformate with iminoesters derived from 3-aminotriazole, followed by amine or phenyl hydrazine condensation, leads to a variety of 1,2,4-triazolo-1,3,5-triazin-4-ones in a 60–85% overall yield.     

STUDY OF THE EFFECT OF TWO BPO/AMINE INITIATION SYSTEMS ON THE FREE-RADICAL POLYMERIZATION OF MMA USED IN DENTAL RESINS AND BONE CEMENTS

ABSTRACT

The kinetics of the free radical bulk polymerization of methyl methacrylate (MMA) was studied by DSC, using the benzoyl peroxide (BPO)/amine initiation system. N,N dimethyl-4-aminophenethyl alcohol (DMPOH), which is a newly synthesized and used amine in the preparation of acrylic dental resins and bone cements was examined, and the results compared to the most commonly used in these applications amine, the N,N dimethyl-p-toluidine (DMT). For both amines, the effect of the molar ratio of BPO/amine and of the reaction temperature, on the polymerization kinetics was investigated. The prepared polymers were characterized by determination of the average molecular weights (M¯ _n and M¯ _w ) and molecular weights distribution (M¯ _w /M¯ _n ) using Gel Permeation Chromatography. DMPOH was found to lead in slightly higher polymerization rates, lower gel times and lower molecular weights than DMT. The values of these parameters for both amines were influenced by the molar ratio of BPO to amine, when the product of the concentrations of these was kept constant. The highest polymerization rate occurred in the lowest gel time, resulting in polymers with the lowest molecular weight, and was observed when a molar ratio of about 1.5 BPO/amine was used. However, the final monomer conversion was found to be independent of the molar ratio and amine used. The activation energy of polymerization was found to be 51.8 kJ/mol K for BPO/DMPOH and 47.1 kJ/mol K for BPO/DMT.     

Water mediated synthesis of various [1,3]oxazine compounds using alum as a catalyst

Abstract

A simple, efficient, and practical procedure for the synthesis of various substituted 2,3-dihydro-2-phenyl-1H-naphtho[1,2-e][1,3]oxazines and 3,4-dihydro-3-phenyl-2H-naphtho[2,1-e][1,3]oxazines using KAl(SO₄)₂ 12H₂O (alum) as a non-toxic, reusable, inexpensive, and easily available catalyst is described using water as a solvent. These improved reaction conditions allow the preparation of a wide variety of substituted [1,3]oxazines in high yields and purity under mild reaction conditions.     

Tandem reaction of heterocyclic ketene aminals with diazoesters: Synthesis of pyrimidopyrrolidone derivatives

A tandem reaction of heterocyclic ketene aminals (HKAs) with diazoesters in the presence of a Cu catalyst is demonstrated for the efficient synthesis of pyrimidopyrrolidone derivatives. The reaction shows a broad substrate scope and excellent functional group tolerance. Our method provides rapid access to diverse pyrimidopyrrolidones in moderate to excellent yields under mild reaction conditions.     

含非典型性生色团的发光聚合物

发光聚合物一般是由具有大p电子系统的共轭基元作为发光单元, 通过共价键连接而成的高分子. 近年来, 研究者发现: 另一类仅含有脂肪胺、羰基、酯基、酰胺等传统意义上的助色团的聚合物在适当条件下也能发射强的荧光. 树枝状聚酰胺胺(PAMAM)和超支化聚酰胺胺(hb-PAMAM)是最早和最广泛被研究的含非典型性荧光生色团的聚合物. 最近, 这类聚合物被扩展到含有叔胺基元的聚氨酯、聚醚酰胺、聚脲体系. 这些体系的生色团被认定为其结构中的叔胺基元, 叔胺的氧化是荧光产生的根源. 同时, 也有文献报道马来酸酐与醋酸乙烯酯交替共聚物、异丁烯与顺丁烯二酸酐共聚物、聚多糖动态高分子、聚酰腙以及通过RAFT试剂制备的含聚三硫碳酸酯的多嵌段共聚物等也可以发射荧光. 这些聚合物的一个共同特点是结构中不含叔胺基元, 而仅含羰基和酯基, 其发光机理通常用多个羰基聚集效应或羰基和苯环之间的相互作用来解释.     

An Efficient One‐Pot Four‐Component Synthesis of Functionalized Imidazo[1,2‐a]pyridines

An efficient one‐pot four‐component protocol for the synthesis of imidazo[1,2‐a]pyridines was developed by condensing ethane‐1,2‐diamine ( 2 ), 1,1‐bis(methylthio)‐2‐nitroethene ( 1 ), aldehydes 3 , and activated methylene compounds in EtOH under reflux conditions (Tables 1–3). The features of this procedure are operational simplicity, good yields of products, in situ preparation of heterocyclic ketene aminals (HKA), and catalyst‐free conditions.     

Synthesis of Functionalized Pyrroles by Reaction of 3,4‐Diacetylhexane‐2,5‐dione with Primary Amines in Water

3,4‐Diacetylhexane‐2,5‐dione (tetra‐acetylethane) undergoes a complex reaction with primary amines in boiling water to produce N‐alkyl‐3‐acetyl‐2,5‐dimethylpyrroles, together with small quantities of N‐alkyl‐3,4‐diacetyl‐2,5‐dimethylpyrroles and 2,5‐dimethyl‐1H‐pyrrol‐3‐yl‐vinyl‐acetamides. When the reaction was carried out in methanol at room temperature, the yields of the latter products increased.     

Solid-Liquid Phase Transfer Catalytic Method for the Preparation of Acyclic and Cylic and Cyclic Ketene Acetals

Solid-liquid phase transfer catalytic elimination reaction for the preparation of acyclic and cyclic ketene acetals has been developed.     

Spectroscopic characterization and preparation of low molecular,water‐soluble chitosan with free‐amine group by novel method

Low molecular, water‐soluble chitosan (LMWSC) with a free amine group was prepared by the novel salts‐removal method described in this study. A weight‐average molecular weight and degree of deacetylation (DDA) of LMWSC were determined by viscometry and Kina titration, resulting in 18,579 Da and 93% DDA, respectively. In the Fourier transform infrared spectroscopic, ¹H NMR, and ¹³C NMR spectra the absorption band by the carboxyl group derived from lactic acid and the impurities formed in the enzymatic process disappeared or were significantly lower than that of the control chitosan. Also, from the ¹H NMR and ¹³C NMR spectra the empirical value for the area ratio of the proton and carbon corresponds nearly to its theoretical values. The matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrum identified the difference in the two adjacent peaks as 161. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3796–3803, 2002     

葡萄糖与杂环化合物在甲酰胺中的焓相互作用参数

由于糖具有特殊的生物和生理性质 ,在工业生产中已有广泛应用 ,故其溶液热力学性质已成为人们感兴趣的研究课题之一 .糖在水溶液中的热力学性质已见文献报道 [1] ,但在非水体系中的有关数据则较少报道 .研究表明 ,溶剂介质的变化对溶质的溶剂化状态和溶质间相互作用的影响较大 ,选用酰胺为溶剂可以获得模拟蛋白质环境条件下的溶质 -溶剂、溶质 -溶质间相互作用的信息 [2～ 4] .本文利用微量量热法测得了葡萄糖在杂环化合物与甲酰胺的混合溶剂中的溶解焓 .如果把杂环化合物作为 x,葡萄糖作为 y,按照 Mc Millan- Mayer[5 ] 理论 ,1 mol葡萄…