Complexation of 4-azido-2,2,6,6-tetramethylpiperidine-1-oxyl (R1) and 4- oxybenzenesulfonyl-2,2,6,6-tetramethylpiperidine-1-oxyl (R2) with β-cyclod extrin (β-CD) and [2-O-(2-hydroxypropyl)]-β-cyclodextrin(2-HP-β-CD) in aqueous solution have been studied by electron spin resonance (ESR). The isot ropic nitrogen hyperfine coupling constants aN and the rotational correlation ti me τC of the radicals change regularly after complexing with β-CD and 2-HP- β-CD. The magnitude of change in τC is in order: R1/2-HP-β-CD >R1/β-CD; R1/β-CD >R2/β-CD, R1/2-HP-β-CD >R2/2-HP-β-CD.
Two new kinds of supramolecular inclusion compound of β cyclodextrin(host)and chloro cyclopentadi enyl tricarbonyl molybdenum(tungsten)(guest) have been prepared and characterized by using the chemical elemental analyses, infrared spectroscopy, nuclear magnetic resonance,powder X ray diffractometry and thin layer chromatography(TLC). The results show that β CD formed one to one compounds with guest and the cyclopentadienyl group of guest may be included into the hydrophobic cavity of β CD. Differential thermal analyses reveal that after formation of the supramolecular inclusion compounds, thermal stability of the host and guest molecules increased.
A number of 1,3-disubstituted derivatives are associated with various types of biological activity [1]. Some thioureas are useful as herbicides, insecticides and plant-growth regulators. Treatment of acylisothiocyanates, prepared from aroyl chlorides (0.0431mol) and potassium thiocyanate (33ml ofa 33% KSCN solution) using tetrabutylammonium bromides as a catalyst, were treated with aniline to yield the corresponding thioureas. However, probable hydrolysis of the aroyl chlorides led to decreased yields. The reaction of acid chlorides with different phenylthioureas or N1-acetyl-N3-arylthioureas requires high temperature and long reaction times. None of the other reported methods proved satisfactory. As a continuation of our earlier work on the biological activity of these compounds, [2-5] we now report acid chlorides are quantitatively converted to the acylisothiocyanates under solid-liquid phase-transfer conditions using PEG-400 as the catalyst. Treatment of these isothiocyanates with polymethylenediamines provides compounds 3 in high yields (scheme 1). The results were summarized in table 1.
