František Hampl

Amphiphilic quaternary pyridinium ketoximes as functional hydrolytic micellar catalysts — does the nucleophilic function position influence their reactivity?

Hydrolytic efficiency of isomeric amphiphilic quaternary pyridinium ketoximes comicellized with cetyltrimethylammonium bromide (CTAB) was investigated using 4-nitrophenyl diphenyl phosphate (PNPDPP) as a model substrate. Nucleophilicity of the deprotonated hydroxyimino group in these functional surfactants depends on its position relative to micellar surface.

Micellar nickel(II)-2-pyridineketoxime complexes as powerful catalysts of the cleavage of carboxylic acid esters in weakly acidic conditions

Metallomicelles made of Ni(II) complexes of lipophilic 2-pyridineketoximes such as 2 or 3a and CTABr, in water at pH 4, accelerate the cleavage of p-nitrophenyl hexanoate over a half million fold.

Phase-Transfer Catalysis in Oxidations Based on the Covalent Bonding of Hydrogen Peroxide to Amphiphilic Flavinium Salts

The amphiphilic flavin derivatives 1,10‐ethylene‐bridged 3‐alkylalloxazinium salts (alkyl=butyl, octyl, dodecyl and hexadecyl) were shown to catalyse the chemoselective oxidation of sulfides to sulfoxides with hydrogen peroxide in chloroform/water or dichloromethane/water systems. The efficiency of the catalytic oxidation depended substantially on the pH of the aqueous phase to reach maximum values at pH 7. Under such conditions, the complete conversion of aliphatic and aromatic sulfides occurred within a maximum of 24 h, whereas the non‐catalysed reaction gave only traces of products. This new concept of two‐phase oxidation utilises the activation and the increase in the lipophilicity of hydrogen peroxide by its covalent bonding to the alloxazinium catalyst. A practical application in the synthesis of modafinil was demonstrated.

Lipophilic N-[2-hydroxyimino-2-(pyridin-2-yl)ethyl]trialkylammonium salts - new ligands for metal ion extractions into organic solvents

Abstract Several lipophilic N-[2-hydroxyimino-2-(pyridin-2-yl)ethyl]trialkylammonium salts 1 were synthesized from the corresponding oxo compounds and hydroxylamine in the presence of Ni2+ ions which stabilize the oximes by chelation. Salts 1 are surfactants possessing a powerful chelating subunit. Their ability to extract different metal ions from aqueous solutions into organic solvents was tested by metal ion transport through a liquid membrane.

Ultraviolet and electron radiation induced addition of N,N,N′,-N′-tetramethyl-1,ω-alkanediamines to fluorinated alkenes

Abstract The predominant products under the both photochemically and γ- 60 Co induced addition of N,N,N′,N′-tetramethyl-1,ω-di- amines to fluorinated alkenes are 1:1 adducts I and II: It is shown that the minor 1:2 adducts III–VI are the results of intramolecular 1, m (m=5–10) hydrogen transfer in 1:1 adductradical intermediates. Adducts I and II (e.g. XCF 3 , n=6) were converted into the surface active quaternary ammonium salts.