Yoelit Migron

Polarity and hydrogen-bonding ability of some binary aqueous–organic mixtures

The solvatochromic parameters π* for the polarity/polarizability, β for the hydrogen-bond accepting (electron-pair-donating) ability, and α for the hydrogen-bond-donating ability of binary aqueous tetrahydrofuran, N,N-dimethylformamide, pyridine, dimethyl sulphoxide, formamide and formic acid have been determined spectrophotometrically at 25 °C as functions of the composition of the mixtures. They were compared with the local composition of the environment of each kind of molecules in the mixtures, obtained from theoretical models. These parameters were also determined for several water-saturated alkanols and tri-n-butyl phosphate, that are of significance in liquid–liquid distribution studies of organic solutes.

Water sorption, binding and solubility of polyols

The sorption of water by polyhydroxyalkanes and polyalkylene glycols has been studied at 35 °C and 75% relative humidity. The solubilities in water of these compounds were taken from the literature or measured by us, and found to be predictable from Yalkowskis expression and to correlate with the water sorption ability, with some notable exceptions, rationalized with reference to the configurations of the compounds in question. In very concentrated aqueous solutions all the water is bound to the polyols; in dilute solutions two or four molecules of water are bound per oxygen atom of the polyhydroxyalkanes and polyethylene glycols, respectively.

Visualization of sebaceous fingerprints on fired cartridge cases: a laboratory study.

The visualization and endurance of fingerprints on cartridge cases after the firing process have been examined. Cartridges of M16, AK-47 (Kalashnikov) and Parabellum have been tested. Despite difficulties in visualizing these fingerprints, it was found that in some cartridge cases under laboratory conditions--for instance, on M16 brass cartridges--substantial parts of the fingerprints remain intact after shooting. The careful use of illumination after metal vapor deposition enabled visualization. Different possible mechanisms responsible for the partial destruction of the fingerprints are discussed.

Development of Latent Fingerprints on Unfired Cartridges by Palladium Deposition: A Surface Study

Visualized fingerprints on unfired brass cartridge cases developed by a novel method of palladium deposition were examined by Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and electron probe microscopy (EPMA). In spite of the strong contrast of colors between the ridges and the valleys of the developed images, which suggests a selective coating of palladium on the valleys, palladium was found to deposit onto both valleys and ridges. Lumps of organic material were scattered mostly along the ridges. The study suggests a model for the deposition of metals on brass cartridges on which sebaceous fingerprints were impressed.

Syntheses of cis-dichlorodiammineplatinum analogs having steroidal hormones bound to the metal atom via malonato bridges

In search for neutral, chemically stable, antitumor agents with target specificity, twenty-seven steroidal platinum(II) malonate conjugates have been prepared. Estrone, 17β-estradiol, testosterone, epitestosterone, pregnenolone, progesterone, 11α-hydroxyprogesterone, 21-desoxycortisone, prednisolone, litocholic, desoxycholic and etienic acid residues were attached either directly or through stable bridges to malonic esters. Hydrolysis of the modified diesters 1–14 with barium hydroxide followed by treatment of the barium salts 15–28, so formed, with cis-di- ammine-, cis-[bis(cyclobutylamine)]-, (1,2-ethane- diamine)-, or (1,2-cyclohexanediamine)diiodoplatinum in the presence of aqueous silver salts, afforded the desired steroidal cis-platinum complexes.

Hydrogen Bond Donation Properties of Organic Solvents and Their Aqueous Mixtures from13C NMR Data of Pyridine-N-Oxide

Measurements of the 13C nmr chemical shifts <5 of pyridine-N-oxide as a probe in 18 solvents, with literature values for others, established that the differences d2i and d34 of the of carbons 2 and 3 with respect to that of carbon 4 depend solely on the hydrogen bond donation ability of the solvents, as measured by the Taft-Kamlet parameter. This substance and method can, therefore, be used as an effective probe for a, without the need to invoke other solvent properties, such as their polarities/polarizabilities, measured by *, required by other probes. The probe was applied also to aqueous mixtures of acetone, acetonitrile, and methanol (values of * and ß for acetone, besides those of a, being reported here too) with similar results. The two aqueous aprotic solvent mixtures exhibit microheterogeneity, as previously established for aqueous acetonitrile from other results.

Transfer hydrogenylysis of trichloromethyl compounds by alcohols and polystyrene-anchored Rh, Ru and Ir complexes

Abstract Polystyrene-anchored RhCl[P(C 6 H 5 ) 3 ] 3 , RuCl 2 [P(C 6 H 5 ) 3 ] 3 and IrCl-(CO)[P(C 6 H 5 ) 3 ] 2 were shown to catalyze selective transfer hydrogenolysis of various trichloromethyl compounds between 140 and 160 °C in the presence of 2-propanol. 2,2,2-Trichloro-1-phenylethanol, 2,2,2-trichloro-acetophenone and 2-propyl trichloroacetate were converted into 2,2-dichloro-1-phenylethanol, 2,2-dichloroacetophenone and 2-propyl dichloro-acetate, respectively. 1,3,3,3-Tetrachloropropylbenzene gave a 1:1 mixture of 1,3,3- and 3,3,3-trichloropropylbenzene. Under the reaction conditions the catalysts proved to be resistant to leaching. Owing to saturation of the active sites with HCl, the catalytic power dropped after several runs, but it could be restored by extrusion of part of the metal-coordinated chlorine with the aid of air or oxygen.

Studies in the chemistry of erythrina alkaloide derivatives—I : Preparation of erythrinane and erythrinane-homologue derivatives

Abstract The compounds 15-fluoro-, 16-fluoro- and 16,17-benzoerythrinane, their thienyl analogue, 1,2,3,4,4a,5,8,9-octahydro-6 H -thieno[2′,3′-4,3]pyrido[2,1-indol, the erythrinane homologue, 1,2,3,4,4a,5,6,7,9,10-decahydroisoquino[2,1-j]quinoline and its 18-fluoro and 16,17-dimethoxy derivatives were prepared. Their chemical structures and their stereochemistry were investigated. All are of the structure cis A/B, cis B/C.

A facile synthesis of α,α,ω,ω-tetrahalo-α,ω-dicarboxylic esters

Abstract The synthesis of some α,α,ω,ω-tetrachloro and tetrabromo-derivatives of the hypolipidemic 3,3,14,14-tetramethylhexadecanedioic acid from α,ω-dihalo-esters, carbon tetrahalides and lithium diisopropyl amide has been described. Interaction of α,ω-dichloro esters with CBr4 was shown to give the expected α,ω-dibromo-α,ω-dichloro compounds, but treatment of bis(l-methylethyl) 2,15-dibromo-3,3,14,14-tetramethylhexa-decanedioatewith CCl4 was found to result in halogen exchange yielding the tetrachloro-diester as the major product.

Studies in the chemistry of erythrina alkaloide derivatives—II : Synthesis and stereochemistry of decahydro-3-methyl-6H-pyrido]2,1-i]indole

Abstract 1,2,3,4,7,7a,8,9,10,11-Decahydro-3-methyl-6 H -pyrido[2,1-i]indole was prepared as an example of an erythrinane derivative lacking the aromatic moiety. The stereochemical structure of this compound and its 6-oxo derivative were found to be predominantly cis A/B, trans B/C, axial CH3 and cis A/B, axial CH3, respectively.