Kinetic Study of the Catalyzed Substitution Reaction of Benzal Chloride and Sodium Iodide in Acetone

The substitution reaction of benzal chloride (PhCHCl₂) and sodium iodide in acetone needs a metal-ion catalyst. Without considering the effects of solubility and the dissociation of salt, salts of Cr(III), Mn(II), Fe(II, III), Co(II), Ni(II), Cu(II)m Zn(II), Cd(II), Hg(I, II), and Sb(III) ions are used to study their catalytic reactivities. It is found that the Fe(II) ion exhibits acceptable catalytic effect. The overall Fe(II)-catalyzed PhCHCl₂-NaI reaction can be described by the following competitive consecutive scheme: PhCHCl₂ → PhCHCII → PhCHI₂. Under suitable conditions, coupling products such as PhCH=CHPh and PhCHClCHClPh are also found. The rate of the first-stage substitution of the PhCHCl₂-NaI reaction increases linearly with the PhCHCl₂ concentration. It increases asymptotically with the FeCl₂ concentration. However, there is an optimum concentration for Nal. The apparent activation energies are 104 ± 4 kJ/mol and 133 ± 4 kJ/mol for the Fe(II)-catalyzed PhCHCl₂-NaI and PhCHCH-NaI reactions, respectively.     

含硫Schiff碱配合物的研究(Ⅶ)——钴与邻氯苯甲醛和亚苄基丙酮Schiff碱的配合物

合成了从S-苄基二硫代肼基甲酸衍生的Schiff碱的配合物,进行了组成分析、红外、电子光谱和磁性的测定。结果表明,邻氯苯甲醛Schiff碱(以HL_1表示)形成反磁性的八面体配合物,其中配体为单价双齿阴离子。亚苄基丙酮Schiff碱(以HL_2表示)形成钴的双聚结构的配合物[Co_2(HL_2)2(L_2)_2X_2],其中X=Ac~-或Cl~-,并作为桥配体,Co(Ⅱ)有八面体配位环境。配合物具有异常低的磁矩,表明2个Co(Ⅱ)离子之间存在着磁交换相互作用,显反铁磁性。抑菌活性试验表明配体HL_1及其配合物存在活性。     

Formation of epoxides and N-arylaziridines via a simple Mg-Barbier reaction in DMF

The Mg-activation of benzal bromide 2b in DMF in the presence of carbonyl compounds 1 or imines 4 leads to epoxides 3 and N-arylaziridines 5, respectively, with acceptable isolated yields. It was found that DMF is likely involved in this process to form a nucleophilic intermediate by reaction with a first generated electrophilic carbene. Results obtained in this chemical approach are compared to those obtained using electrochemical activation, also in DMF.     

Synthesis and Characterization of Benzylidene Bis-Dithiobenzoate

Benzal chloride reacts with sodium sulfide in alcoholic solution to yield three main products: benzyl disulfide, benzyl dithiobenzoate, and a new interesting compound 5 , C ₂₁ H ₁₆ S ₄ , which was isolated and characterized as benzylidene bis-dithiobenzoate. The intermediates obtained from the autoxidation-reduction of the unisolable thiobenzaldehyde are implied in subsequent nucleophilic addition and substitution processes. NMR spectra and X-Ray structure analysis of 5 are discussed.     

Polymers from intermediates obtained from hydrogen cyanide

The recent demonstration of an easy synthesis of diiminosuccinonitrile (DISN) from hydrogen cyanide and cyanogen, the reduction of DISN to diaminomaleonitrile (DAMN), and the use of these compounds to form difunctional heterocycles has made several new polyamide intermediates accessible. The 1- and 2-methyl-1,2,3-triazole-4,5-dicarbonyl chlorides have been polymerized interfacially to form high-melting polyamides of good heat stability. Interfacial polymerization of 1-methylimidazole-4,5-dicarbonyl chloride and trans-2,5-dimethylpiperazine has given a polyamide that is water-soluble. The 2,6- and 2,3-pyrazinedicarbonyl chlorides have been similarly converted to high-melting polyamides. 2,6-Dicyano-3,5-dipiperazinylpyrazine has been prepared from tetracyanopyrazine and piperazine and reacted with toluene diisocyanate to form a strong, stiff polyurea. Polyamides were also made from 2,3-diaminoquinoxaline, 1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, and DAMN.     

Stereocomplex Formation from Enantiomeric Polyamides Derived from Tartaric Acid

Summary: The formation of stereocomplexes from the pair of enantiomorphs of the chiral polyamide poly(hexamethylene di‐O‐methyl tartaramide) was investigated for a variety of experimental conditions. DSC and X‐ray diffraction data evidenced that efficiency in enantiomeric association is highly sensitive to the procedure used for preparing the complex. A comparative isothermal crystallization study revealed that the stereocomplex crystallized from the melt at a rate lower than the enantiomerically pure components. The radial growth of individual spherulites was also delayed in the crystallization of the complex. No evidence of stereocoupling was detected for other poly(alkylene di‐O‐methyl tartaramide)s with the alkylene unit length different from six. It was concluded that molecular interlocking of hydrogen bonds in the enantiomeric pair is highly selective in this family of polymers.

Spherulitic growth at 200 °C from the melt.     

Cytotoxic diterpenoids from Podocarpus madagascariensis from the Madagascar rainforest

Bioassay-directed fractionation of an extract of the root and bark of Podocarpus madagascariensis resulted in the isolation of a new totarol diterpenoid (1) in addition to the three known cytotoxic diterpenoids 19-hydroxytotarol (2), totaradiol (3), and 4beta-carboxy-19-nor-totarol (4). The structure of the new compound 1 was established as methyl-13-hydroxy-14-isopropyl-9(11),12,14(8)-podocarpatriene-19-oate on the basis of 1D and 2D NMR spectroscopic interpretation and methylation of 4. All the compounds exhibited cytotoxic activity against the A2780 ovarian cancer cell line.     

Synthesis of isoxazolines from nitrile N-oxides generated from nitroalkenes

In this review, information on the production of isoxazolines and condensed isoxazoline systems by the intramolecular 1,3-bipolar cycloaddition of unsaturated nitrile N-oxides generated in situ from nonconjugated nitroalkenes is generalized and systematized. The isoxazoline derivatives formed as the result of these reactions are promising synthons in the synthesis of various natural compounds and their analogues.Krakow Polytechnic Institute, Poland. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 291–305, May–August, 1992.     

Engineers are from PDMS-land, Biologists are from Polystyrenia

As the integration of microfluidics into cell biology research proceeds at an ever-increasing pace, a critical question for those working at the interface of both disciplines is which device material to use for a given application. While PDMS and soft lithography methods offer the engineer rapid prototyping capabilities, PDMS as a material has characteristics that have known adverse effects on cell-based experiments. In contrast, while polystyrene (PS), the most commonly used thermoplastic for laboratory cultureware, has provided decades of grounded and validated research conclusions in cell behavior and function, PS as a material has posed significant challenges in microfabrication. These competing issues have forced microfluidics engineers and biologists to make compromises in how they approach specific research questions, and furthermore, have attenuated the impact of microfluidics on biological research. In this review, we provide a comparison of the attributes of PDMS and PS, and discuss reasons for their popularity in their respective fields. We provide a critical evaluation of the strengths and limitations of PDMS and PS in relation to the advancement and future impact on microfluidic cell-based studies and applications. We believe that engineers have a responsibility to overcome any challenges associated with microfabrication, whether with PS or other materials, and that engineers should provide options and solutions that assist biologists in their experimental design. Our goal is not to advocate for any specific material, but provide guidelines for researchers who desire to choose the most suitable material for their application, and suggest important research directions for engineers working at the interface between microfabrication technology and biological application.     

Alkaloids from the Tunicate Polycarpa aurata from Chuuk Atoll

Two new alkaloids, polycarpine (1) and N,N-didesmethylgrossularine-1 (4), have been isolated from extracts of the ascidian Polycarpa aurata collected in Chuuk, Federated States of Micronesia. Three degradation products of 1 were also isolated. The structures of 1, 2, and 4 were determined by X-ray crystallography. The dimeric disulfide 1 inhibited the enzyme inosine monophosphate dehydrogenase, but the inhibition could be reversed by addition of excess dithiothreitol suggesting that 1 reacts with sulfhydryl groups on the enzyme.     

Fish attractants from marine invertebrates: Arcamine from Arca Zebra and strombine from Strombus Gigas

The isolation and characterisation of two fish attractants, a new dipeptide (Arcamine, hypotauryl-2-carboxyglycine),1 and Strombine (C-methyl-imino diacetic acid),2 are described.     

Evaporation from microemulsions

The composition of W/O microemulsions during slow evaporation at room temperature and at 90°C was determined by chemical analysis. One series of microemulsions was stabilized by pentanol combined with sodium dodecyl sulfate, the other one was combined with hexadecyltrimethylammonium bromide.The hydrocarbon was styrene and the evaporation in the microemulsion was compared to that of the corresponding styrene/pentanol solutions.The results showed significant influence on the evaporation by the microemulsion structure; especially for water contents close to the minimum for stability     

Structurally diverse diterpenoids from Isodon ternifolius collected from three regions

Phytochemical investigation of the aerial parts of Isodon ternifolius from three regions in Yunnan Province afforded 9 new diterpenoids, ternifoliusins A–I (1–9), together with 26 known diterpenoids. Among them, ternifoliusins A–D possess rare 6,7:8,15-diseco-7,20-olide-6,8-cyclo-ent-kaurane diterpenoid scaffold. The structures of all compounds were determined by comprehensive spectroscopic analysis, as well as quantum chemical calculation methods. Moreover, the molecular constitutions and configurations of ternifoliusins A, E, and F (1, 5, 6) were confirmed by single-crystal X-ray diffraction analysis. Ten compounds were assayed for their cytotoxic activity against the HL-60, SMMC-7721, A-549, MCF-7, and SW-480 human tumor cell lines, and compounds 13, 17, 19, 20, 31 and 34 were demonstrated to be active against all of the five human tumor cell lines.     

Diazapentacenes from Quinacridones

Bis(silylethynylated) 5,7- and 5,12-diazapentacenes were synthesized from cis- and trans-quinacridone using protection, alkynylation and deoxygenation. The solid-state packing of the targets is determined by choice and position of the silylethynyl substituents. The position of the substituents and nitrogen atoms influence the optical properties of the targets.     

Scattering from Ferrogels

Summary: This paper introduces a simple mean‐field theory for gels with magnetic properties. The main emphasis in this paper is the discussion of the scattering properties. Therefore, a simple model is introduced, such that the chains carry magnetic moments along their main axis. Naturally these magnetic moments interact sensitively to theory orientation with each other. Thus a distinguished interplay between chain and dipole orientation induces strong coupling between the macroscopic deformation and magnetic properties. These effects can be experimentally demonstrated with scattering methods. Here some mean‐field expressions for the structure factors are predicted and discussed in some detail.

The configurations adopted by polymers possessing a magnetic moment and undergoing dipole‐dipole interactions.     

Polyastriazines from Oxalamidrazone

High molecular weight soluble poly-as-triazines were prepared by solution cyclopolycondiensation of oxalamidrazone with various bisglyoxals and bisbenzils Solutions of the phenyl-substituted poly-as-triazines at solids content of -20%_c are metastable increasing in viscosity and, in some cases, selling, The gelling phenomenon can be alleviated without any appreciable detrimental effect upon the polymer by upsetting the stoichiometry of the reactants Relatively high molecular weight polymer (e g η_inh=1 76) can be obtained when the stoichiometry is upset by 1%_c in favor of either reactar t Polyphenyl-as-triazines films exhibited room temperature (RT) tensiie strength as high as 18,400 psi (tensiie modulus of 400 000 psi and ultimate elongation of 5%_c) Titanium and stainless steel tensile shear specimens provided RT strength of 2850 and 3400 psi, respectively Polyphenyl-as-triazines exhibit good thermal oxidative stability after aging for 1000 hr at 500°F (260°C) in circulating air.     

Nanoparticles from Chitosan

Novel biodegradable nanoparticles were synthesized by chemical modification of the chitosan linear chain. A natural dicarboxylic acid (malic acid) was used as a crosslinking agent for intramolecular covalent condensation reaction to obtain hydrophilic nanoparticles based on chitosan. A variety of methods including, solubility studies, laser light scattering (DLS), transmission electron microscopy (TEM) and nuclear magnetic resonance (NMR) was used to characterize the crosslinked macromolecules. The prepared biodegradable chitosan nanoparticles, soluble in aqueous media, might be useful for various biomedical applications, like injectable drug- or gene-delivery systems.     

“无中生有”的化学

Chemistry contributes a lot to the rapid development of science and technology. Herein, applying the concept of "chemistry from nothing", we explained the principles in cutting-edge chemical achievements for undergraduates. Reading this article, they are supposed to understand the theoretical knowledge further and show more interested in the frontiers of chemistry.     

Micromotors from Microfluidics

Inspired by the motions of natural objects, attention and efforts have been paid and devoted to fabricate micromotors of spherical, tubular, helical or other shapes for applications in emerging fields including delivery, remediation, and other biomedical applications. Among the proposed methods, the microfluidic technology offers an opportunity to fabricate micromotors with different microstructures. This review presents research progress on micromotors, especially those from microfluidics. The morphologies of the micromotors were firstly outlined. Then, the microfluidic technology used to fabricate different micromotors was discussed. Finally, the applications of these micromotors were briefly introduced, followed by their challenges and future developments.     

Ceratoluteolin: A new flavonoid from Salvia ceratophylla from Jordan

Ceratoluteolin 1, a new luteolin derivative was isolated from Salvia Ceratophylla growing wild in Jordan along with other 14 known compounds including two sterols, two triterpenes, four flavonoids and six phenolic compounds, one of which is reported for the first time from Lamiaceae family. The isolated compounds were genkwanin-4′-methyl ether 2, β-sitosterol 3, oleanolic acid 4, ursolic acid 5, apigenin 6, β-sitosteryl glucoside 7, p-hydroxyphenyl caffeate 8, caffeic acid 9, shimobashiric acid B 10, methyl rosmarinate 11, butyl rosmarinate 12, luteolin 13, luteolin-7-O-glucoside 14 and rosmarinic acid 15. Complete structural verification of the isolated compounds was achieved by careful inspection of their spectral data including NMR (1D & 2D) and HREIMS.