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Volume 3, No. 2, June 2008, Jumada 2 1429 H 

Articles

 

 

Microwave-Assisted Synthesis of 3-Nitro-2H-Chromenes Under
Solvent-less Phase-Transfer Catalytic Conditions

Speedy synthesis of 3-nitro-2-H-chromenes (2a-h) in dry media, under solid-liquid phase-transfer catalytic conditions. The reactions were carried out by simply mixing salicylaldehyde derivatives (1a-h) with excess of 2-nitro ethanol and a catalytic amount of TBAB. The mixtures were adsorbed on dry potassium carbonate, and then irradiated in a small transparent polypropylene beaker in a domestic microwave oven for two minutes.

 

Rafik A.  Koussini* and  Ayed S.  Al-Shihri

JJC, 2008, 3(2), 103-107

Halogen Substituted Bis(arylimino)Pyridine Transition Metal Complexes as Catalysts for the Oligomerization and Polymerization of Ethylene

A series of 15 complexes containing 3d transition metals ranging from titanium to nickel and halogen functionalized bis(arylimino)pyridine ligands was synthesized and characterized. After activation with methylalumoxane (MAO), these catalysts oligomerized ethylene to give a-olefins with 4-40 carbon atoms. Some of the described catalyst precursors showed the potential to isomerize a-olefins and to generate olefins with uneven numbers of carbon atoms.

 

 

Marcus Seitz, Christian Görl, Wolfgang Milius, Helmut G. Alt*

JJC, 2008, 3(2), 109-145

Half-Sandwich Ruthenium Complexes of Heterocyclic-Dithiocarboxylato Ligands

The heterocyclic-dithiocarboxylato complexes CpRu(PPh3)(κ2S,S-S2C-het) [het= 2-C4H3O, 2-C4H3S, 1-C4H8N] are obtained by the reaction CpRu(PPh3)2Cl with het-CS2-.  The X-ray structure of CpRu(PPh3)(κ 2S,S-S2C-1-C4H8N) is determined by single crystal X-ray diffraction.

 

 

Mohammad El-khateeb*, Mousa Al-Noaimi, Mohammad Harb, Helmar Görls, Wolfgang Weigand

JJC, 2008, 3(2), 147-153

G3 Global Minima for CH4BX Structural Isomers X = Li to Br

The energetic and structural relationships of various CH4BX (X = Li to Br) isomers were elucidated at HF/6-311+G**, B3LYP/6-311+G**, and G3 levels of theory. The relative stabilities of bisected, eclipsed, bridged, and cyclic XCH2BH2 species, as well as their global minima, are determined by the electronegativity and the basicity of X. Alternatively, CH3BHX structural isomers are the global minima when X is a methyl group or an element with at least one lone-pair. Eclipsed BX rather than BH CH3BHX conformers are generally preferred, but the energy differences are small.

(a)

(b)

(c)

 

(d)

(e)

 

Orbital interactions in (a) π-bridged, perpendicular (b) π-bridged, tilt (c) bisected (d) eclipsed and (e) cyclic minima of XCH2BH2.

 

 

Mustafa R. Helal*, Akef T. Afaneh, Paul von R. Schleyer

JJC, 2008, 3(2), 155-168

Substituent Effects on the Hydrolysis of m-Substituted Benzonitriles in Sulfuric Acid Solutions at 25.0 ± 0.1 oC

Analysis of the rate constants for the hydrolysis of m-substituted benzonitriles in 18.2 M sulfuric acid showed that electron-withdrawing groups enhanced the hydrolysis,  while the reaction of benzonitriles in 10 M sulfuric acid  speeded by electron-releasing groups. Two mechanisms were suggested.

 

 

Khamis A. Abbas*

JJC, 2008, 3(2), 169-177

Organochlorine Pesticides  in Sheep Liver,
Kidney and Adipose Tissues in Jordan

Levels of fifteen organochlorine pesticides were determined in 30 samples of liver, kidney and adipose tissues from sheep (male and female) gathered from slaughter houses in Amman/Jordan. All samples were extracted, cleaned-up and then analyzed using high resolution gas chromatography with electron capture detector (63Ni). Three groups of the organochlorine pesticides in addition to hexachlorobenzene (HCB) namely: DDT, HCH, and Cyclodiene groups were determined.  The results show that almost all samples are contaminated with HCB, HCH’s heptachlor and aldrin at  relatively  high concentrations and almost all studied organochlorine pesticides were found  in the studied sample.

 

 

Mahmoud A. Alawi*, Jehad S. Al-Hawadi

JJC, 2008, 3(2), 179-187

Applications and Analysis of Palladium Vapor Deposited on Stainless Steel for High Temperature Electrical Contacts

Schematic illustration of ultra high vacuum with two source of electron beam evaporation system.  In this scheme other evaporation techniques can be added for coating using sputtering technology. This system also contains mass spectrometer for detection gases and contaminants like water. The thickness of film can be monitored by ICP plus supplied by Inficon cooperation. To have the system ready two mechanical and turbo molecular pumps where added to it to achieve very low pressure.

 

Shehdeh Jodeh*

JJC, 2008, 3(2), 189-198

Spectroscopic and Conductometric Investigation of the Interaction of Azithromycin with Iron (II) Ion

The interaction of azithromycin with ferrous sulfate and ferrous perchlorate in methanol has been investigated by spectroscopic and conductometric methods under equilibrium conditions. The interaction of azithromycin with both salts has been  found to form one complex with metal to ligand composition of 1:1. The value of log Kf calculated from the absorption spectra for FeSO4-azithromycin complex at 25˚C was 5.16 ± 0.07 (K= 1.4 x 105 M-1). The value of log Kf for Fe(ClO4)2-azithromycin complex calculated from the conductivity measurements at 25˚C was 5.20 ± 0.08 (K= 1.6 x 105 M-1). The enthalpy and entropy of complexation were determined from the temperature dependence of the complexation constants. The ΔHº and ΔSº were 103.8 kJ/mol and 486.9 J/mol.K, respectively.

 

 

Abdul-Wahab El-Rjoob*, Jamil Al-Mustafa, Ziyad Taha, and Moufaq Abous

JJC, 2008, 3(2), 199-209