Further studies on palytoxin. I.

The structures of two degradation products of N-(p-bromobenzoyl) palytoxin were elucidated, and then the sequences of those fragments were determined.     

Effect of surface swelling on diffusion on polymers. II. Delamination

Swelling in chloroform resulted in delamination of surface-hydroxylated styrene-butadiene-styrene block copolymers, with the formation of three fractions: crosslinked gel, reacted sol, and unreacted chloroform-soluble material. From the relative weights of these fractions, the depth of penetration of the reaction and the shape of the reaction front were determined. The weight of the gel fraction gave directly an estimate of the depth of penetration, λ_x which decreased with increasing film thickness. This was attributed to the increased amount of reacted polymer being noncrosslinked material (sol) in the interior compared to the 100% crosslinked nature of the surface region and to a reduction in the penetration of the reaction front resulting from the effect of stress transfer in lowering the permeation rate of peracetic acid. Comparison of the depth of penetration estimates λ_x and λ_s determined from the weight of the unreacted polymer demonstrated that, for the conditions used, the reaction front is quite broad. (For example, at 40°C, in 71% acetic acid for 80 min, the fully crosslinked portion is 15 μm thick and the partially reacted region extends for another 8.5 μm.) The combined influences of the increase in penetration of the reactants in the polymer and the relief of stress secondary to this increase in penetration were reflected in the time dependence of the depths of penetration λ_x and λ_s.     

Research on benzimidazole.

2-Amino derivatives of benzimidazole are formed in good yields by the action of amines with various structures on benzimidazole-2-sulfonic acid.     

Comments on the paper by Dr. C.A. McAuliffe

The first cyclopentadienylplutonium(IV) compounds, (η⁵-C₅H₅)₃PuCl and (η⁵-C₅H₅)₃Pu(NCS) have been prepared, the former by reaction of Cs₂PuCl₆ with TlC₅H₅ in CH₃CN and the latter by treating the chloride with KNCS in tetrahydrofuran. Both compounds are isostructural with ther U^IV and Np^IV analogues. The IR and UV/visible spectra of the new compounds are reported.     

Acetylene chemistry. Part 23 . N-vinylation on acridinones

The vinylation of 9(10H)-acridinones 1a-1d with propiolic acid ethylester resulting in acridinonyl-N-acrylic esters is reported.