Synthesis of “capped porphyrins”

The synthesis of “capped porphyrins” ($\text{10}$), ($\text{18}$), and ($\text{28}$), and their (chloro)iron(III), iron(II), cobalt (II), and zinc(II) complexes is reported. These complexes serve as models for the active site of the oxygen binding haemoproteins. In addition to reversible binding of dioxygen by each of the iron (II) porphyrin complexes, the 1-methyl-imidazole-(“C₃-capped porphyrin”) iron (II) complex ($\text{23}$) reacts reversibly with carbon monoxide, in solution at 25°C.     

The complete closed coexistence curves for 2H,3H,6H,7H,8H-5,8-(Dimethylmethano)-5(R)-methylquinoxaline with water and with deuterium oxide

The complete closed solubility curves for 2H, 3H, 6H, 7H, 8H-5,8-(dimethylmethano)-5(R)-methylquinoxaline with water and with deuterium oxide have been determined. With water the lower critical solution temperature (LCST) was found to be 51.4°C and the critical solution temperature (CST) was found to be 215.0°C. With deuterium oxide the values were 40.4°C for the LSCT and 221.7°C for the CST. The deuterium oxide curve completely encompassed the water curve. Solution compositions at the critical temperatures were also determined.     

Oligomerization of ethylene to branched alkenes using neutral phosphinosulfonamide nickel(II) complexes

A series of neutral phosphinosulfonamide complexes of nickel(II) were synthesized that catalyzed the oligomerization of ethylene to branched oligomers with average degrees of polymerization between 10 and 35. Branching numbers varied from 17 to 80 branches per 1000 carbons, depending on the catalyst structure and reaction conditions. The catalysts were active in a variety of solvents, including toluene, CH₂Cl₂, tetrahydrofuran, ethyl acetate, and methanol, but showed decreasing activity at temperatures higher than 40 °C. Electron‐rich phosphinosulfonamides produced the highest catalyst activities in a series of structure–reactivity studies. The mechanism of oligomer formation was investigated with ¹H NMR spectroscopy, which indicated that branching arose from the isomerization of the nickel alkyl species during propagation rather than the reincorporation of α‐olefin products. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4627–4640, 2000     

Aggregation and interfacial properties of an isomerically pure alkylaryl sulfonate

Sodium dodecylorthoxylene sulfonate (SDOXS) was studied as an isomerically pure compound in micellar and microemulsion solutions. The particular isomer of SDOXS used in this work is one in which the sulfonate group is located ortho to the alkyl chain on the xylene ring. Aggregation of SDOXS in deuterated water was followed by specific conductivity and ²³Na NMR measurements at several temperatures. The aggregate size distribution at low concentrations agrees with the picture expected for ideal cooperative micellization but the data show deviations from this behavior at higher concentrations. This suggests either an increase in the average aggregation number with increasing concentration or an enhanced counterion binding at higher concentrations. ¹³C NMR spectra indicate that the benzene-ring motion slows down and the head-group solvation changes at high SDOXS concentrations or with the addition of electrolyte. A similar result was found for a microemulsion solution of SDOXS, n-octane, and NaCl brine. We discuss our results in view of the positional substitution pattern of the SDOXS aromatic ring.     

Veränderung des dielektrischen Relaxationsspektrums von Hochpolymeren mit der Verstreckung

Ohne Zusammenfassung     

The Bartle-Dunford-Schwartz theorem and projection operators in certain banach lattices

The projection map used successfully by Kakutani in his classical characterization of abstract L-spaces is used to establish a variant for certain Banach lattices of a theorem of Bartle, Dunford and Schwartz which dealth with absolute continuity in spaces of measures. Entrata in Redazione il 27 settembre 1999.     

Laser Mass Spectrometry of Organophosphorus Pesticides and Related Compounds

Abstract

Laser mass spectra obtained for 20 organophosphorus (OP) compounds were systematically evaluated for groups containing analogous structural features. Variations in fragmentation can be understood based on simple organic reactions. While detailed mechanistic interpretations of the laser mass spectra (LMS) were not possible, the qualitative features in the LMS obtained from five compounds, not in the original set, could be predicted based on the characteristics of the other OP compounds studied. The success of the prediction lends credence to the qualitative models developed for rationalizing the LMS. A specific feature in the LMS of aromatic thionophosphates is a thiono-thiolo rearrangement. Detailed investigation into the phenomena involved comparison of LMS obtained from aromatic thionophosphates with spectra from electron impact, chemical ionization, field desorption, and secondary ion mass spectrometry. These results led to the conclusion that the rearrangement in laser mass spectrometry must occur during volatilization while the molecule/ion is in the “cloud” present immediately above the laser impact area.     

Polymerization (Polycondensation) of Alkanes over Fluosulfonic Acid and Antimony Pentafluoride

Several low molecular weight alkanes have been polymerized (polycondensed) over HSO₃ F-SbF₅ to yield a highly branched oily oligomer with a molecular weight range from the molecular weight of the monomer to around 700. The order of reactivity for butane and lower molecular alkanes is isobutane > n-butane > propane > ethane > methane. The reactivity is explained by the ease of attack of an acid proton derived from the acid on the alkane sigma bonds as well as the relative stability of the resulting cation formed. A cationic mechanism for this reaction is proposed.