Isomerismo cis-trans: de Werner aos nossos dias

In coordination chemistry the study of geometrical isomerization and reactivity of specific isomers is a topic of major importance. The preparation of specific isomers often requires considerable complexity, and it is important to acquire a sense of what is involved in studying isomerism in laboratory. If it is difficult sometimes to prepare pure isomers, it is not easier to understand the mechanisms of isomerization reactions since studies on this subject have shown conflicting results and diferent interpretations on the same system have been reported in the literature. Although cis-trans isomerism in octahedral metal complexes is a common occurrence, there are relatively few studies reporting how these isomerizations occur. This paper gives an overview on cis-trans isomerization processes and identification of these species.

Investigação espectroscópica dos carbonilos heterobimetálicos cis-[Fe(CO)4(HgX)2], X = Cl, Br,I

The series of compounds cis-[Fe(CO)4(HgX)2], X=Cl,Br,I shows an octahedral geometry around the iron atom with the two HgX groups cis to each other. In this paper the assignment for the carbonyl stretching modes and the calculation of their force constants were performed on the basis of the Cotton-Krainhanzel model. Taking into account all the data from the IR, 199Hg NMR and UV-vis spectra it is possible to verify the influence of X on the electronic densities at the metallic centers.

Polimerização 1,4-cis de butadieno com sistemas catalíticos Ziegler-Natta à base de neodímio

Nowadays the catalyst systems based on neodymium are the ones most used in the high cis polybutadiene production. These systems contain a neodymium compound (catalyst), an alkylaluminium compound (cocatalyst) and a halogen compound (halogenating agent). The microstructure, molecular weight characteristics and the reaction activity are influenced by the nature and concentration of catalyst system components. Those characteristics are also affected by the polymerization conditions. This paper presents a brief review on 1,4-cis-butadiene polymerization on neodymium catalysts.

Explosion-proof requirements for Electrical Machines in Chemical, Oil and Gas Industry in Russia and CIS Countries

One of the main industries which form the basis of Russian Economical structure is oil and gas. This industry is also playing a significant role for CIS countries. Oil and gas industry is developing intensively attracting foreign investments. This situation is providing sustainable development of machinery production for hazardous areas. Operating in oil and gas areas is always related with occurrence of explosion gas atmospheres. Machines for hazardous areas must be furnished with additional protection of different types. Explosion protection is regulated with standards according to which equipment must be manufactured. In Russia and CIS countries explosion-proof equipment must be constructed in compliance with GOST standards. To confirm that equipment is manufactured according to standards’ requirements and is safe and reliable it must undergo the approval procedure. Certification in Russia is governed by Federal Laws and legislation. Each CIS country has its own approval certificates and permissions for operating in hazardous areas.

Reações de oxidação de derivados de cis-octalinas promovidas por trinitrato de tálio (TTN)

The reaction of ten cis-octalins and cis-octalones with thallium trinitrate (TTN) leads to different products, depending mainly on the substitution pattern of the substrate. Functionalized cis-hydrindanes were obtained from the reaction of 1,2,3,4,4a,5,8,8a-octahydro-4a-methylnaphthalene and of 1,2,3,4,4a,5,8,8a-octahydro-4a,7-dimethylnaphthalene with TTN in acetonitrile, whereas a cyclic ether was formed treating 1,2,3,4,4a,5,8,8a-octahydro-6,8a-dimethylnaphthalen-1-ol with TTN in trimethylorthoformate (TMOF).

Optimization of a HPLC procedure for simultaneous determination of cisplatin and the complex cis,cis,trans-diamminedichlorodihydroxoplatinum(IV) in aqueous solutions

A RP-HPLC procedure for the simultaneous determination of cisplatin and the complex cis,cis,trans-diamminedichlorodihydroxo-platinum(IV), was development. The developed procedure was validated in terms of linearity, accuracy, precision, limits of detection (LOD), limits of quantification (LOQ) and specificity. The limits of detection (LOD) were 0.47 x 10-4 and 0.53 x 10-4 mol L-1 and the limits of quantification (LOQ) were 1.57 x 10-4 and 1.75 x 10-4 mol L-1, for cisplatin and cis,cis,trans-diamminedichlorodihydroxopla-tinum(IV), respectively. The average recoveries of cisplatin and cis,cis,trans-diamminedichlorodihydroxoplatinum(IV) was 100.6% ± 1.4 and 101.2% ± 1.1, respectively. Intermediate (inter-day) precision, repeatability and specificity of the procedure for hydrolysis products of cisplatin were studied. The results of the study showed that the proposed RP-HPLC procedure is simple, rapid, precise, accurate and specific.

Descriptores globales y locales de la reactividad para el diseño de nuevos fármacos anticancerosos basados en cis-platino(II)

Density functional theory was used to investigate the global and local reactivity of some cis-platinum(II) complexes including anticancer drugs, such as cisplatin and carboplatin. Calculated equilibrium geometries at mPW1PW/LANL2DZ* are in close agreement with their available X-ray data. We develop three new local reactivity descriptors: atomic descriptor of philicity, atomic descriptor group and atomic descriptor of philicity group for determining chemical reactivity and selectivity of the studied complexes. This contribution on chemical reactivity allow us to establish qualitative trends, which enable our descriptors for use in rational platinum based anticancer drug design.

Exploración estocástica de las superficies de energía potencial de dímeros cis-trans y trans-trans del ácido fórmico

Potential energy surface (PES) of cis-trans and trans-trans formic acid dimers were sampled using a stochastic method, and the geometries, energies, and vibrational frequencies were computed at B3LYP/6-311++G(3df,2p) level of theory. The results show that molar free energy of dimerization deviated up to 108.4% when basis set superposition error (BSSE) and zero-point energy (ZPE) were not considered. For cis-trans dimers, C=O and O - H bond weakened, whereas C - O bonds strengthened due to dimerization. Also, trans-trans FA dimers did not show a trend regarding strengthening or weakening of the C=O, O - H and C - O bonds.

Integrum - Databases from Russia and CIS - New possibilities for economists

Integrum-aineistokoulutuksen 28.9. - 29.9.2011 materiaali

Integrum - Databases from Russia and CIS - New possibilities for economists

Integrum-aineistokoulutuksen 28.9. - 29.9.2011 koulutusmateriaali

Integrum - Databases from Russia and CIS - New possibilities for political and social studies

Integrum-aineistokoulutuksen 28.9. - 29.9.2011 koulutusmateriaalia

Integrum - Databases from Russia and CIS - New Possibilities for Public Libraries

Integrum-aineistokoulutuksen 28.9. - 29.9.2011 koulutusmateriaalia

alpha-Tocopherol enhances tumour growth inhibition by cis-dichlorodiammine platinum (II)

Present studies indicate that alpha-tocopherol enhances the efficacy of cisplatin as demonstrated by inoculation of Dalton's lymphoma cells incubated with either cisplatin (5 or 10 µg/ml) alone or cisplatin + alpha-tocopherol (25 or 50 µg/ml) into C3H/He mice. Tumour cells (3 x 10(6) cells/mouse) incubated with cisplatin grow slowly in syngeneic mice as indicated by the late appearance of tumour. However, mice failed to develop tumour when inoculated with tumour cells incubated with cisplatin + alpha-tocopherol. When the animals were challenged with tumour cells (3 x 10(6) cells/mouse) on the 15th day after the initial inoculation, 30-50% survived more than 60 days, with 10% tumour-free survivors being observed in some groups. Antitumour activity was higher in mice receiving lymphoma cells (3 x 10(6) cells/mouse) preincubated with cisplatin + alpha-tocopherol compared to cisplatin alone. Tumour-bearing mice receiving cisplatin in combination with different concentrations of alpha-tocopherol exhibited significantly higher (P<0.001) intratumour platinum content (123-306%) but without any change in the kidney platinum content as compared to those receiving cisplatin (5 or 10 µg/ml) alone. Enhancement of cisplatin-induced tumour growth inhibition is probably due to the modulation of tumour cell membrane permeability by alpha-tocopherol. alpha-Tocopherol might increase the influx of cisplatin into tumour cells, causing the DNA repair machinery to be less efficient due to increased efficiency of adduct formation in the DNA molecule. This effect of alpha-tocopherol can render cisplatin more effective as an antitumour agent.

Alterações estruturais in vivo dos isômeros todo-trans, 9-cis e 13-cis do beta-caroteno

Com o objetivo de verificar alterações estruturais nos isômeros todo-trans, 9- e 13-cis do beta-caroteno foi realizado um ensaio biológico baseado no modelo de esgotamento das reservas hepáticas de carotenóides em ratos. Animais depletados desses carotenóides receberam, durante quinze dias, os isômeros puros todo-trans, 9-cis e 13-cis do beta-caroteno. Ao final deste período, verificou-se a ocorrência de re-isomerização in vivo desses isômeros, a partir da quantificação dos mesmos depositados no fígado dos animais. Foi observada re-isomerização do 9-cis em todo-trans, do todo-trans em 9-cis, do 13-cis em 9-cis e todo-trans. O 13-cis foi mais susceptível à isomerização que o 9-cis, pois este último passou a todo-trans e nunca a 13-cis. Já o 13-cis, tanto pode se transformar em 9-cis quanto em todo-trans.

Efecto de la mezcla de ácido linoleico conjugado,cis-9, trans-11 y trans-10, cis-12, en la respuesta a la insulina en un modelo experimental diabetizado con dieta hipercalórica.

Tesis (Maestría en Ciencias en Nutrición) UANL, 2012.