Trichloropyruvate N-acylimines. Reactions with phosphorus nucleophiles

Reactions of N-aroyltrichloroethaneimines CCl₃C(R)=NCOAr (II, R = COOMe, CN) with phosphorus nucleophiles were studied. The reaction of imines II with o-phenylenediethylamidophosphite proceeded as [4+1]-cycloaddition leading to formation of stable spirocyclic phosphoranes. The structure of one of them was proved by the XRD analysis. The reaction of imine II with acyclic P(III) derivatives [Ph₃P, Ph₂POEt, (PhO)₃P] also includes the formation of labile monocyclic phosphoranes which eliminate phosphine oxide and undergo chlorotropic transfer leading to trichloroazadienes CCl₂=C(R)N=C(Cl)Ar. The reaction of imines II with (EtO)₂POH in the presence of triethylamine leads to the formation of (EtO)₂P(O)Cl and the corresponding dichlorovinylamides CCl₂=C(R)NHCOAr.     

Formation of regular nanoscale undulations on a thin polymer film imprinted by a soft mold

We observed the formation of regular nanoscale undulations on a polystyrene film when imprinted by a soft poly(dimethylsiloxane) mold above the polymer's glass transition temperature. The shape of the wave was reminiscent of a buckling wave frequently observed for a metal film supported on an elastomeric substrate. We derived a simple theoretical model based on an anisotropic buckling of the polymer film rigidly bound to a substrate, which agrees well with the experiment.     

Conversion of 2-aryl-4-dichloromethylen-5(4<Emphasis Type="Italic">H</Emphasis>)oxazolones to 5-acylamino-substituted pyrimidine bases

Available polycentral unsaturated azlactones with 4-dichloromethylene group by successive treating with benzamidine and then with morpholine or its analogs were converted to substituted 5-acylamino-4-hydroxypyrimidines containing the residues of the corresponding nitrogen bases in the position 6. The structure of these cyclization products is consistent with the scheme of their preparation and has been confirmed also by ¹H NMR spectroscopy and XRD analysis.     

Bonding structure analysis of carbon nitride films by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS)

Carbon nitride films were prepared by an opposed-target DC reactive sputtering system and the bonding behaviors were investigated according to the nitrogen content and annealing temperature. Annealing leads to a loss of nitrogen from the films and the CN is totally removed at 600 °C. Due to annealing at 600 °C, the C---C out-of-plane vibrational band intensity at 700 cm⁻¹ becomes very low and also the CN band at 2200 cm⁻¹ disappears completely. The sp² bonding in a CN compound is the most stable phase. Due to carbon's atypical nature in having its p orbital more compact and tightly bound compared to s states, the C=N sp² phase is more stable than the C---C sp³ phase. As the C=N sp² phase dominates the structure, the film is mainly graphite-like with some proportion of C---C, CN and N=N bonds.     

21α‐Fluoro‐7‐norvouacapane‐17β,21α‐lactone

The crystal structure of 21α‐fluoro‐7‐norvouacapane‐17β,21α‐lactone, C₂₀H₂₅FO₃, a new synthetic derivative of the diterpenoid 6α,7β‐di­hydroxy­vouacapan‐17β‐oic acid isolated from Pterodon polygalaeflorus Benth fruits, is described.     

Optical spectra of aqueous solutions of glutamine-tryptophan associates

The optical density and luminescence ability of aqueous solutions of glutamine-tryptophan depend on the degree of oxidation of the initial dry substances of dipeptide. Glutamine-tryptophan has a high associating ability, which increases if stored. The general form of the optical absorption and luminescence spectra of the associates differs little from the spectra of monomers. Among the spectral-optical symptoms of association of a substance in a solution for glutamine-tryptophan, we discovered the hypochromism and narrowing of the absorption spectra and shortening of the fluorescence lifetime. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 436–439, July–August, 2000.     

Preparation and characterization of iodinated poly(vinyl alcohol) microfibril

Iodination of poly(vinyl alcohol) (PVA) microfibril, which was obtained from saponification of poly(vinyl pivalate), was conducted before and after zone drawing at various conditions. The resulting PVA microfibrils were characterized by differential scanning calorimeter and scanning electron microscopy. Surface morphologies of these PVA microfibrils showed some differences between PVA microfibril iodinated after and before drawing. Crude shapes of PVA microfibrils iodinated after drawing indicated that iodine decreased the structural regularity severely. On the other hand, PVA microfibrils iodinated before drawing showed relatively ordered surfaces. This was ascribed to the enhanced molecular ordering of PVA microfibrils due on zone drawing. Iodinated PVA microfibrils showed a decrease in crystal melting temperature of about 100°C compared to the untreated sample. PVA microfibrils drawn after iodination showed relatively higher crystal melting temperature than those of microfibrils iodinated after drawing. These results were considered as the proofs of the changes in crystalline lattice of the PVA microfibrils. Effects, of drawing temperature on sublimation of iodine were also evaluated.