Beziehungen zwischen Trockensubstanz,Refraktion und Dichte von Stärkehydrolysaten

Analytical and Bioanalytical Chemistry -     

Silver compounds in synthetic chemistry : Part 4. 4-Tetrafluoropyridyl silver(I), AgC5F4N in redox transmetallations—possibilities and limitations in reactions with group 15 elements

While reactions of AgC₅F₄N with elemental arsenic, antimony, and bismuth proceed selectively yielding E(C₅F₄N)₃ (E = As, Sb, Bi), those with white and red phosphorus remained obscure giving product mixtures of so far unknown stoichiometry. The phosphorus compound was therefore prepared by an alternative route. P(C₅F₄N)₃ and As(C₅F₄N)₃ crystallize isostructurally in the monoclinic space group P2₁/c (no. 14) with four molecules per unit cell. π-π Offset stacking together with edge-face stacking lead to dimeric units which are connected by a second edge-face stacking of nitrogen onto the opposite side of the same tetrafluoropyridyl ring extending the structure into infinite chains.     

Synthesis and reactivity of bis(cycloamidinium-2-yl)alkane bromide tribromides,brominating agents and tectons for molecular engineering

Bis(cycloamidine-2-yl)alkanes easily form bromide tribromide salts in the reduction-oxidation processes with bromine. Bis(tetrahydroimidazolium-2-yl)ethane and bis(hexahydropyrimidinium-2-yl)-ethane bromide tribromides are such new convenient brominating agents for aromatic amides in chemo- and regioselective electrophilic substitutions and α-bromination reactions. Correspondence: Katarzyna Ostrowska, Department of Organic Chemistry, Jagiellonian University, R. Ingardena 3, PL-30060 Kraków, Poland.     

Stereoselective photooxidation of enecarbamates: reactivity of ozone vs singlet oxygen

[reaction: see text]. Oxazolidinone-functionalized enecarbamates show contrasting behavior upon oxidation by singlet oxygen and by ozone. The observed stereoselectivity difference indicates that the oxidation with ozone is subject to classic steric effects, whereas the very high selectivity in the photooxidation with singlet oxygen is derived from vibrational deactivation.     

Maximum flow in a network with fuzzy arc capacities

Our main concern is the maximum flow in a network in which an excess over the beforehand fixed quota of arc capacity is admissible. The problem is represented as a partially fuzzy linear programming task. A theorem equivalent to the Ford and Fulkerson one concerning the classic task of maximum flow is proved in the paper. An algorithm for searching maximum flow assuming integer values of flows on network arcs is presented.