Kinetics and mechanism of trichloroisocyanuric acid/NaNO2-triggered nitration of aromatic compounds under acid-free and Vilsmeier-Haack conditions

Kinetics and mechanism of nitration of aromatic compounds using trichloroisocyanuric acid (TCCA)/NaNO₂, TCCA-N,N-dimethyl formamide (TCCA-DMF)/NaNO₂, and TCCA-N,N-dimethyl acetamide (TCCA-DMA)/NaNO₂ under acid-free and Vilsmeier-Haack conditions. Reactions followed second-order kinetics with a first-order dependence on [Phenol] and [Nitrating agent] ([TCCA], [(TCCA-DMF)], or [(TCCA-DMA)] >> [NaNO₂]). Reaction rates accelerated with the introduction of electron-donating groups and retarded with electron-withdrawing groups, but did not fit well into the Hammett's theory of linear free energy relationship or its modified forms like Brown-Okamoto or Yukawa-Tsuno equations. Rate data were analyzed by Charton's multiple linear regression analysis. Isokinetic temperature (β) values, obtained from Exner's theory for different protocols, are 403.7 K (TCCA-NaNO₂), 365.8 K (TCCA-DMF)/NaNO₂, and 358 K (TCCA-DMA)/NaNO₂. These values are far above the experimental temperature range (303-323 K), indicating that the enthalpy factors are probably more important in controlling the reaction.     

Light‐Switchable Polymer from Cationic to Zwitterionic Form: Synthesis,Characterization, and Interactions with DNA and Bacterial Cells

A novel cationic polymer poly(N,N‐dimethyl‐N‐[3‐(methacroylamino) propyl]‐N‐[2‐[(2‐nitrophenyl)methoxy]‐2‐oxo‐ethyl]ammonium chloride) is synthesized by free‐radical polymerization of N‐[3‐(dimethylamino)propyl] methacrylamide and subsequent quaternization with o‐nitrobenzyl 2‐chloroacetate. The photolabile o‐nitrobenzyl carboxymethyl pendant moiety is transformed to the zwitterionic carboxybetaine form upon the irradiation at 365 nm. This feature is used to condense and, upon the light irradiation, to release double‐strand DNA tested by gel electrophoresis and surface plasmon resonance experiments as well as to switch the antibacterial activity to non‐toxic character demonstrated for Escherichia coli bacterial cells in solution and at the surface using the self‐assembled monolayers.

     

Synthesis and characteristics of the poly(carboxybetaine)s and the corresponding cationic polymers

Two types of carboxybetaines and their corresponding cationic monomers and polymers are synthesized in this study. Comparing the chemical shifts of the methylene groups in the cationic monomers and carboxybetaines in both ¹H- and ¹³C-NMR spectra reveal that the respective methylene groups are clearly distinguished from their chemical shifts in ¹H- and ¹³C-NMR spectra. The solubilities, moisture regain properties, and solution properties of the poly(carboxybetaine)s and cationic polymers are investigated in relation to their molecular structures. Because the cationic polymers were ionized in an aqueous solution, the cationic polymers were more soluble than the poly(carboxybetaine). For the various functional groups of poly(carboxybetaine)s and cationic polymers, the order of tendency for moisture regain is  COO >  CONH . Results obtained from the reduced viscosity for cationic poly(TMMPAMS) are reversed from that for zwitterionic poly(DMAEAPL). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3527–3536, 1997     

硝酸对N,N-二甲基羟胺γ-辐解及液态辐解产物的影响

N,N-二甲基羟胺(DMHA)是用于动力堆乏燃料后处理U与Pu和Np分离的新型无盐还原剂, 本文研究了硝酸对DMHA γ-辐解及液态辐解产物的影响. 研究结果表明: 在U、Pu分离循环和Pu纯化循环的辐照剂量下, 在0.3-1.0 mol·L^-1的硝酸溶液中, 0.1 和0.5 mol·L^-1 DMHA具有较好的辐照稳定性. 当吸收剂量为5-25kGy时, DMHA硝酸溶液的液态辐解产物主要有单甲基羟胺、甲醛、甲酸和亚硝酸. 有机物的浓度远远高于亚硝酸浓度, 且随着剂量和硝酸浓度的增加而增大. 对于相同的硝酸浓度和剂量, 0.1 mol·L^-1 DMHA辐解产生的一甲基羟胺的浓度高于0.5 mol·L^-1 DMHA, 但前者辐解产生的甲醛浓度低于后者; 当硝酸浓度较高时, 0.1 mol·L^-1 DMHA辐解产生的甲酸浓度高于0.5 mol·L^-1 DMHA. 亚硝酸浓度与硝酸浓度及剂量的关系取决于起始DMHA和硝酸浓度.     

Determination of penicillin V potassium in pharmaceuticals and spiked human urine by chemiluminescence

A simple and selective method for penicillin V potassium (PVK) determination by chemiluminescence (CL) was developed. Oxidation of PVK by alkaline hydrogen peroxide produces CL, which is greatly enhanced by N, N-dimethyl formamide (DMF) and N-cetyl-N,N,N-trimethylammonium bromide (CTMAB). Optimum conditions were established using luminometry. There is a linear relationship between the chemiluminescent peak height and the amount of PVK within the range 0.5–129.5 mg L⁻¹, with a detection limit of 0.2 mg L⁻¹. The coefficient of variation was 1.2% for 40 mg L⁻¹ PVK solution (n = 7). The method is very simple, has high sensitivity and good selectivity, and is usable for process control. It was successfully utilized for the determination of PVK in pharmaceuticals and spiked human urine.      

Regioselective synthesis and biological evaluation of novel dispiropyrrolidine derivatives via one-pot four-component reaction

Abstract

A new series of regioselective dispiropyrrolidine analogs via efficient one-pot four-component tandem reaction has been discovered. The reaction was carried out in the presence of four common reactants and magnesium silicate nanoparticles (NPs) in ethanol under microwave irradiation. The reaction proceeds rapidly and can be completed within 60–90?min. This methodology offers several significant advantages such as high yield, mild catalyst, and easy to perform. The synthesized compound was further screened for antibacterial and antiproliferative activities. The results showed that compound 5c and 5a were potent antibacterials against Gram-positive and Gram-negative bacteria. Further, 5a showed best antiproliferative activity against tested cell lines.     

Solubility of sulphur dioxide in polar organic solvents

The solubility of sulphur dioxide in N,N-dimethylformamide, dimethyl sulphoxide, N,N-dimethyl acetamide, sulpholane, tributyl phosphate and diethanolamine has been determined. A solubility model is proposed and the solubilities calculated by the model show good agreement with experimental data.     

Investigations of molecular interactions in propionic acid–N,N-dimethyl formamide binary system—FTIR study

FTIR spectra of propionic acid (PA), N,N-dimethyl formamide (DMF) and its binary mixtures with varying molefractions of the PA were recorded in the region 500–3500 cm⁻¹, to investigate the formation of hydrogen bonded complexes in a mixed system. The observed features in ν(CO), δ(OC–N) and ν_as(CN) of DMF, ν(CO) and ν(CO) of PA have been explained in terms of the hydrogen bonding interactions between DMF and PA and dipole–dipole interaction. The intrinsic bandwidth for the vibrational modes ν_as(CN) and ν(CO) has been elucidated using Bondarev and Mardaeva model.     

N,N-二甲基苄胺催化合成丙烯酸间苯二酚环氧酯的机理

Ｎ，Ｎ－二甲基苄胺催化合成丙烯酸间苯二酚环氧酯的机理高俊刚，王洪芳，袁翠红（河北大学化学系，保定０７１００２）关键词丙烯酸间苯二酚环氧酯，Ｎ，Ｎ－二甲基苄胺，催化反应机理不饱和酸环氧酯是由不饱和核酸与环氧化合物进行环氧化反应形成的一种化合物，它在涂料...