Conformationally flexible hexakis-urea 1 was synthesized efficiently by condensing hexakis(aminomethyl)benzene with 4-nitrophenyl-(3,5-di-tert-butylphenyl)carbamate. The hexakis-urea 1 is unexpectedly soluble in organic solvents of low polarity duet oi ntramolecular hydrogen bonding. The hexakis-urea 1 recognizes chloride, bromide, and acetate in a1 :2 host-guest ratio and in a positive allosteric manner in CDCl 3 .T he ability of 1 to recognize dihydrogen phosphate is au nique outcome, and the structure of the associated complex, which contains four dihydrogen phosphate ions, was clarified by singlecrystal X-ray structurala nalysis. However,i ns olution, a complex with three dihydrogen phosphate ions was identified. The dihydrogen phosphate association in CDCl 3 proceeds in an amphoteric allostericm anner;i napositive allosteric manner (K 1 < K 2 )i nt he first step andanegative allosteric manner (K 2 > K 3 )i nt he subsequent step.
SynopsisGlow discharge polymerizations of tetramethoxysilane (TMOS), tetramethylsilane/oxygen mixture (% molar ratio) (TMS/02), hexamethyldisiloxane (HMDSO), and tetramethyldisiloxane (TMDSO) were carried out for the preparation of thin, polymeric films with siloxane structures. The chemical composition of the formed polymers was examined by elemental analysis, infrared spectroscopy, and electron spectroscopy for chemical analysis (ESCA) in connection with polymerization conditions, especially, a level of the radiofrequency (rf) input power per mass of the monomers (W/FM value). The polymers prepared from HMDSO at fairly low W/FM values resembled in chemical composition the conventionally polymerized polydimethylsiloxane. The surface properties of the formed polymers also were evaluated by the measurement of surface energy.
Forward slip during the rolling process is adopted as a measure in evaluating rolling stability. Forward slip during cold rolling of aluminum has a serious effect on the productivity as well as the quality of rolled sheets. The forward slip must remain within a specified range depending on the thickness of sheet if the rolling is to stay stable. Rolling speed, rolling tension, rolling oil viscosity, additives, rolling surface roughness, and roll diameter constitute an important factor for controlling forward slip during rolling. The present paper examines the effects of these factors on forward slip using both production-type and experimental rolling mills.
Hexakis(aminomethyl)benzene, which is a key precursor for various hexa‐substituted functional molecules, was synthesized by Gabriel synthesis. Nucleophilic substitution of hexakis(bromomethyl)benzene with potassium phthalimide gave hexakis(phthalimidemethyl)benzene in excellent yield. Hydrazinolysis of the phthalimide moieties of hexakis(phthalimidemethyl)benzene afforded a mixture of hexakis(aminomethyl)benzene and 2,3‐dihydrophthalazine‐1,4‐dione. Pure hexakis(aminomethyl)benzene was isolated as its hexahydrochloride upon treating the mixture with HCl. Hexakis‐amides and hexakis‐tosylamide were prepared from hexahydrochloride of hexakis(aminomethyl)benzene in good to high yields. Alkyl‐substituted hexakis‐amide shows extremely high solubility in non‐polar organic solvents like chloroform and n‐hexane. Density functional theory calculation of the structure of hexakis‐amide show that all substituents were oriented to the same side (aaaaaa conformation) via intramolecular hydrogen bonding.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.