Ronald Sinclair Nohr

New biomaterials through surface segregation phenomenon: New quaternary ammonium compounds as antibacterial agents

Five new trisiloxane quaternary ammonium compounds were synthesized from hydrotrisiloxane with allyl glycidyl ether to yield the epoxy function. Various amines were then reacted to yield trisiloxane amines which were further reacted to methyl substitute or oxidize the beta-carbons in order to provide thermal stability. These new compounds were employed as melt additives in a nonwoven polypropylene fiber extrusion process to produce, through surface segregation, a new biomaterial with antibacterial properties.

On the mechanism of boron-subphthalocyanine chloride formation

A mechanistic study of chloroboron subphthalocyanine (SubPc) formation from phthalonitrile and BCl3 in aromatic solvents such as p-xylene or toluene suggests that rearrangement of the initial phthalonitrile-BCl3 adduct produces (1Z)-3-chloro-N-(dichloroboryl)-1H-isoindol-1-imine 3, following rearrangement of the initial phthalonitrile-BCl3 adduct. From three molecules of (1Z)-3-chloro-N-(dichloroboryl)-1H-isoindol-1-imine 3, by successive addition, the dichlorosubstituted macrocycle 7 is formed. Quantum-chemical computation shows that the postulated elementary reaction steps leading up to the formation of the SubPc-precursor macrocycle are indeed exothermic, or at least kinetically allowed. The formation of the SubPc is concluded by the elimination of chlorine which is probably catalyzed by BCl3 in a concerted process which might be represented as: dichlorosubstituted macrocycle 7 + BCl3 → SubPc·Cl+ + BCl4- → SubPc + Cl2 + BCl3. The chlorine formed may be photolytically affected if the reaction is carried out under ordinary laboratory lighting (fluorescent lamps), giving rise to a free-radical chain reaction involving the solvent. Alternatively, molecular chlorine may react with aromatic solvents such as toluene and p-xylene in a Friedel-Crafts-type reaction catalyzed by BCl3. In this way, such solvents which are reactive in both ways can protect the reactant phthalonitrile, the reaction intermediates, and the product SubPc from degradation by chlorination.

The elimination of molecular chlorine catalyzed by BCl3: an aspect of chloroboron subphthalocyanine formation

This study is focused on the final stage of the formation mechanism of chloroboron subphthalocyanine from boron trichloride and phthalonitrile, in the context of recent work on the earlier stages of this reaction. The results of extensive quantum-chemical energetic, structural, and charge-distribution computations show that a catalytic effect of boron trichloride is most probably essential to explain the fact that molecular chlorine is liberated in the formation of chloroboron subphthalocyanine (reaction 2). This process turns out to be closely concerted (reactions 2a and 2b).