REACTION OF BIS-[DIALKOXYPHOSPHORYL]- AND BIS-[DIALKOXYTHIOPHOSPHORYL]- DISULFIDES WITH TRIALKYLSILYLCYANIDES NEW ROUTE TO DIALKYLPHOSPHORO- AND DIALKYLTHIOPHOSPHORO THIOCYANIDATES AND O,O,O,O-TETRAALKYLPYROPHOS- PHOROTRITHIOATES

Abstract

The reaction of organophosphorus disulfides with trialkylsilylcyanide has been investigated. It provided direct evidence for the intermediacy of thiocyanidate >P(X)SCN, X=O, S in this type of reaction. The disulfides studied involved phosphoryl, phosphonyl and/or phosphinyl disulfides. They have been shown to follow the common mechanism. The studied reaction of thiophosphoryl disulfides with trimethylsilylcyanide represents a new and highly efficient route to tetraalkylpyrophosphoro-trithioates.     

Synthesis and Tuberculostatic Activity of Some 2-Piperazinmethylene Derivatives 1,2,4-Triazole-3-Thiones

Abstract

The Mannich reaction's products of 1,2,4-triazole-3-thiones, substituted in position 4 (with ethyl, allyl, phenyl, Ph-4-Br) or 5 (with phenyl, Ph-4-OH, Ph-3,4,5-(OMe)₃, 2-phenyl) were obtained. Their amino-components were 1-phenylpiperazine, 1-(4-fluorophenyl)-piperazine, 1-benzylpiperazine, 1-(2-pyridyl)-piperazine and 1-piperonyl-piperazine. Tuberculostatic activity of the compounds obtained was tested and their MIC values within 25–100 mcg/mL.     

Reduction of Oxoalkylphosphonates by Microorganisms

Abstract

Synthesis of enantiopure compounds is an importaut task because of the increasing interest in understanding the role which chirality plays in nature and of the increasing demand for such molecules in pharmaceutical and agrochemical industry. Microorganisms has been widely used for this purpose and particular their use in stereospecific reduction of aldehydes and ketones is well documented. Baker's yeast seems to be the most popular biocatalyst for the asymmebic reduction of carbonyl compounds. Its incredible ability to respond to new substrrtes gives the opportunity to uncover novel exploitable synthetic capacities. Thus, we studied the utility of this microorgnnisn in enmtioselectivc reductions of oxodkylphosphonates.     

NOTE: Polymerization of Cyclic Esters Using Aminoacid Initiators

The low-molecular weight poly(? -caprolactone) and polylactide were obtained by the polymerization of cyclic esters in the presence of amino acid initiators. The polymer structures were elucidated by means of MALDI TOF, NMR and IR studies. Effects of temperature, reaction time and initiator dosage on the polymerization process were examined.     

Rearrangement of azoxybenzocrowns into chromophoric hydroxyazobenzocrowns and the use of hydroxyazobenzocrowns for the synthesis of ionophoric biscrown compounds

The Wallach rearrangement was used as a method for preparing p-hydroxyazobenzocrown ethers starting from different azoxybenzocrowns as substrates. Synthesis of a series of p-hydroxyazobenzocrowns under modified conditions and characterization of the obtained products are presented. o-Hydroxyazobenzocrowns were identified among the products of the photochemical rearrangement of azoxybenzocrowns. Novel biscrowns were synthesized from p-hydroxyazobenzocrown ethers. The synthesized host molecules, differing in the size of the macrocycles and in the substituents in the aromatic rings, have the same dioxymethylene linkers. They were used as potential sodium or potassium ionophores in classic and miniature (screen-printed) ion-selective electrodes. The properties (tautomerism, acid–base equilibrium) of newly prepared o-hydroxyazobenzocrown ethers and their p-substituted analogs were studied using spectroscopic methods and compared.     

Addition of Dialkyl and Diaryl Phosphites to N-(ortho-Substituted Phenyl) Terephthalic Schiff Bases: The Stereochemical Behavior

The synthesis of bis-aminophosphonates via the phosphite addition to N-aryl terephthalic Schiff bases is reported here. The influence of methoxy and methyl groups in the ortho position on the stereoselectivity of this reaction is also discussed.     

INTITIATION OF 1,3,5-TRITHIAN3 POLYltlERIZATION BY W-IRRADIATION

Abstract

It is well lrnown that l,3,5-trithiane is polymerized to give polythiomethylene by using cationic catalysts or ionizing radiation. It has been suggested that such cyclic monomers polymerize in the solid state by an ionic addition mechanism and therefore cannot be polymerized by the ultraviolet light.     

Effect of time on the metal-support (Fe-MgO) interaction in CVD synthesis of single-walled carbon nanotubes

A study on the effect of the metal-support interaction by employing iron particles supported on magnesium oxide (MgO) nanopowder in an alcohol-CVD process for single-walled carbon nanotubes growth is presented. Upon the prolongation of the process time, three main observations were detected: (i) decrease of the mean nanotubes diameter, (ii) reduction of the diameter distribution by the factor of two, (iii) increase of relative purity of the samples.