Polyamine disulfides

A study of the thermal oxidative breakdown of polyethylene under static conditions has revealed that polyamine disulfides are stabilizers, yet to varying degrees (Fig. 1). 

Aliphatic polyamine disulfides—imino-, carbamide-, thiocarbamide-, ethylenediamine------are low-effi-... 

Figure 1 Thermal oxidative breakdown of polyethylene (temperature 200°C P02 = 350 Tor stabilizer concentration 0.5 mass percent). 1-without stabilizer 2-CaO-6 3-polydii-minodiphenylmethane disulfide 4-polydiiminodiphenylsul-fon disulfide 5-polyparaoxydiphenylamine disulfide 6-po-lydimethylaniline disulfide 7-polyaniline disulfide 8-polydiiminodiphenyloxide disulfide 9-polythiosemicarbaz-ide disulfide 10-polyamine disulfide 11-polycarbamide disulfide 12-poly thiocarbamide disulfide 13-polyethylenedi-amine disulfide.

Polythiosemicarbazide disulfide is the most efficient aliphatic polyamine disulfide for inhibiting the thermal oxidative breakdown of polypropylene, while polyimi-noaniline disulfide and polydiiminodiphenyloxide disulfide (Fig. 3) are the most efficient aromatic polyamine disulfides. In contrast to polyethylene, the thermal oxidative breakdown period increases as the concentration increases (Fig. 4), Depending on the concentration, the flow-melt index at 230°C increases at a lower rate than in the case of commercial stabilizer Santanox (Table 2)-... 

Just as in the case of polyethylene, the efficiency of polyamine disulfides can be presented in the series polythiosemicarbazide disulfide, polydiiminodiphenyloxide disulfide, polyiminoaniline disulfide. 

The stabilizing activity of polyamine disulfides is specified by the imine group and the disulfide bridge, which participate simultaneously in the breaking of the chain by suppressing the radicals and in the free radical destruction of peroxides and hydroxides. 

Table 2 Effect of Polyamine Disulfide Concentration on the Polypropylene Flow-Melt Index During Thermal Oxidative Breakdown...

Adrenergic receptors. The development of polyamine disulfides, such as benextramine, an adrenergic blocking agent, allowed the hypothesis of symmetrical properties... 

We suggested that an early release of DNA during or after penetration into the cell, probably promoted by the reduction of a disulfide bridge placed between the polyamine and the lipid, implies a total loss of... 

The trimethylsilyl derivative 109 was chosen because its optical purity can be easily increased by recrystallisation until a virtually enantiopure compound is obtained in 56% yield. Some screening showed that polyamines such as PMDETA in combination with. s-BuLi constitute the optimum conditions in order to minimise undesired functionalisation of the methylene group. Under these conditions, 109 was regioselectively lithiated and the carbanion further elaborated by known methods to afford, after a standard desilylation step, a-hydroxyphosphine sulfide 110 (55% yield, 94% ee) and p-hydroxyphosphine sulfide 111 (50% yield over two steps, 96% ee). The method was also adapted to yield diphosphine sulfides 112 (69% yield, 90% ee) and 113 (46% yield, 99% ee). The latter compound is indeed the disulfide of (5, 5)-t-Bu-MiniPHOS. During its synthesis it was observed that no meso compound was formed. 

The dithiocarbamate-type ligand produced from the reaction of carbon disulfide with silica-polyamine composites represents a viable alternative to the previously reported ethylene-sulfide-modified composites. This material should prove useful for immobilizing mercury that is contained in aqueous waste streams. The resin is not going to be useful for applications requiring the regeneration and reuse of the resin. There are several other polystyrene and silica-based mercury removal resins available on the market, and it remains to be shown how these resins compare with WP-3. 

During the past decade the development of novel protection groups for the directed protection of primary and secondary amines led to a large improvement of the linkers and resins to serve the different needs. The first solid phase syntheses of polyamines were reported by Sergheraert and coworkers [156]. The synthesis of reduced trypanothione disulfide (45) and its oxidized form (46) involved the selective protection of the primary amines of spermidine with a ferf-butyldiphenylsilyl (TBDPS)... 

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