Studies on Stable Free Radicals. X. Photolysis of Hindered N-Chloroamines

Abstract

Photolysis of the hindered N-Chloroamines, 1-chloro-2,2,6,6-tetramethyl-4-oxopiperidine (IIa), 1-chloro-2,2,6,6-tetramethylpiperidine (IIb), and 1-chloro-2,2,5,5-tetramethyl-4-oxoimidazolidine (IIc), in benzene solution were carried out in an ESR spectrometer cavity. The ESR spectra of the corresponding amino radicals IIIa, IIIb, and IIIc were observed in evacuated solutions. In solutions containing oxygen, it was found that amino radicals IIIb and IIIc, readily reacted with oxygen to give the corresponding stable nitroxide radicals IVb and IVc, from the shapes of spectra and g-values. Amino radical IIIa did not react with oxygen. Although the amino radicals could not be isolated, their formation was confirmed by the isolation of a coupling product with a benzyl radical generated from dibenzylmercury.

A new disinfectant compound

“…The molar concentration of combined DC at equilibrium was taken to be the difference between the measured molar concentrations of total and free chlorine. The decomposition products for DC in the hydrolysis equilibrium were free chlorine (HOC1) and l-chloro-2,2,5,5-tetramethylimidazolidin-4-one, a compound previously prepared elsewhere (Toda et al, 1972) to be used as a source of amino radicals in an ESR experiment, which could be detected by NMR. Stability measurements for chlorine in DC and free chlorine (Ca(OCl)2) were made as described previously (Worley et al, 1987) using standard iodometric titration (American Public Health Association, 1985) to determine total chlorine concentration.…”

Synthesis ofN,N′-Linked Bisazaheterocycles

“…49c 1,1¢-Bipiperidinyl (95) was obtained from azopiperidene (98) by thermolysis or by boiling in toluene. Reaction proceeds through the piperidinyl free radical intermediate 50 Ogawa and co-workers 52 have studied the conformational stability of bispiperidines by 13 C NMR spectroscopy with the aid of molecular mechanics calculation. They have synthesized meso-1,1¢-bi(cis-2,4-dimethylpiperidine) (105b, R = Me) and meso-1,1¢-bi(cis-4-tert-butyl-2-methylpiperidine) (105c, R = t-Bu) by the silver(I) catalyzed peroxodisulphate oxidation of the corresponding piperidines 104 (Scheme 39).…”

Lack of singlet oxygen formation by photoexcited promazine derivatives in aqueous and ethanolic solutions

“…Their conclusion was that the nitroxide radical originated from the reaction between the amine and the singlet oxygen (102) generated by energy transfer from photoexcited promazines to molecular oxygen. It seems however, that this interpretation must be considered as very doubtful since the nitroxide radical could also result from a reaction between molecular oxygen and the 2,2,6,6-tetramethylpiperidinyl free radical as shown by Toda et al (1972).…”

“…In ethanol, another secondary hindered amine was used: the 2,2,6,6-tetramethyl-4-piperidinone which cannot produce the nitroxide radical by a reaction with molecular oxygen (Toda et al 1972). In aqueous solutions, the specific oxidation of cholesterol to 3fi-hydroxy-5a-cholest-6-ene-5-hydroperoxide was used to monitor the 10 2 production (Foote et al 1980).…”