An efficient multicomponent protocol for the stereoselective synthesis of oxazinobenzothiazole derivatives

An easy and efficient protocol for the stereoselective one-pot synthesis of oxazinobenzothiazole derivatives is described.     

Hydrogen‐bonded thermotropic liquid‐crystalline polyester–amides from bis(hydroxy alkamido)aranes: Synthesis and properties

Hydrogen‐bonded aromatic–aliphatic polyester–amides (PEAs) were prepared by solution/melt polycondensation of aromatic–aliphatic amidodiols 1,4‐bis(4‐hydroxybutyramide)benzene (BHBB), 1,4‐bis(5‐hydroxy pentamide)benzene, 1,4‐bis(6‐hydroxyhexamide)benzene, 1,4‐bis(4‐hydroxybutyramidexylene), 1,4‐bis(5‐hydroxypentamidexylene, 1,4‐bis(4‐hydroxybutyramide)benzene, and 1,4‐bis(6‐hydroxyhexamidexylene) with terephthaloyl chloride/dimethyl terephthalate. Aromatic–aliphatic amido diols were prepared by the aminolysis of γ‐butyrolactone, δ‐valerolactone, and ?‐caprolactone with aromatic diamines such as paraphenylene diamine and paraxylene diamine. The monomers and polymers were characterized by chemical analysis (hydroxyl value and elemental analysis), Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR. The thermal‐ and phase‐transition behaviors of the polymers were investigated by differential scanning calorimetry in combination with hot‐stage optical microscopy. Crystallinity of polymers was examined with wide‐angle X‐ray diffraction. The polymers exhibited liquid crystallinity with layered structures formed by self‐organization of the hetero intermolecular hydrogen‐bonded networks indicating smectic phases except for PEAs prepared from BHBB. The hydrogen atom of the phenyl‐substituent group forces the neighboring carbonyl groups out of plane of the rings preventing formation of layered structures in the case of BHBB. The PEAs retained intermolecular hydrogen bonding even in the mesomorphic state, and variations in the hydrogen‐bonded lamellae/micelles might be responsible for the variations from one smectic to another texture. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 335–346, 2003     

Application of Pschorr reaction to N-(o-aminobenzoyl)-benzyl and phenethyl amines and to N-(o-aminophenylacetyl) anilines

Decomposition of the diazonium chloride from N-(o-aminobenzoyl)-N-methylbenzylamine led to the formation of 3-benzyl-3, 4-dihydrobenzo-triazin-4-one (8), N-benzoylbenzylamine (11), N-benzylphthalimidine (13) ando-diphenic acid N-methyl amide (14), the last one presumably through the intermediary, the expected dibenzazepinone 16. From the analogue, N-(o-aminobenzoyl)-4-methoxybenzyl amine (4), triazinone 10 and N-benzoyl-4-methoxybenzyl amine (12) were obtained. Application of Pschorr reaction to N-(o-aminobenzoyl)-N-methyl-β-(4-methoxyphenyl) ethyl amine (23) afforded 2-methoxy-7-methyl-5, 6, 7, 8- tetrahydrodibenzo (c, e) azocin-8-one (26), with an interesting conformation. From N-(o-aminophenylacetyl)-p-methoxyaniline were obtained under these conditions, indazole-3-carboxylic acidp-anisidide (35) and N-[2-(4-methoxyphenyl carbamoylmethyl) phenyl]-1-(p-methoxyphenyl) isatin-β-hydrazone (37). The structure of 37 was deduced from spectral data and hydrolysis to the acid 42. Diazotisation of N-(o-aminophenylacetyl)-1, 2, 3, 4-tetrahydroquinoline (47) led to the formation of tetrahydroquinoline (49) ando-hydroxyphenyl acetic acid (50) presumably through the salicylamide 48. A similar reaction on N-(o-aminophenylacetyl) tetrahydroisoquinoline (52) gave the benzofurandione hydrazone 55, besides tetrahydroisoquinoline. Oxindole 45 and benzofuranone 56 were likely precursors for 37 and 55 respectively. Salicylamides 5, 7, 24 and 34 were byproducts in the Pschorr reaction.     

Effect of chlorine concentration on the spectral characteristics of electroluminescence in ZnS: Cu: Cl phosphor

ZnS: Cu: Cl phosphor prepared under a vacuum firing process is found to give blue electroluminescence with emission peak at 460 nm which remains unaltered with the frequency of the excitation voltage. Addition of excess chlorine in the phosphor gives blue, green and red emission at 460, 520 and 640 nm. The intensity of the blue band decreases and it finally disappears as chlorine concentration is increased. A scheme involving three energy levels attributed to Cu²⁺, Cu⁺ and Cl^- centres in ZnS explains the experimental results completely.     

A study of the crystallization of γ-irradiated polyethylene terephthalate using differential scanning calorimetry

Summary The crystallization ofγ-irradiated polyethylene terephthalate, crystallized over a wide range of temperatures, has been studied by differential scanning calorimetry. It was found that the difference between theAvrami exponents for the low temperature and pre-melt crystallization processes was not as pronounced as it was for the unirradiated polymer. The superposability of the low temperature crystallization isotherms along the log time axis and the inability of the pre-melt isotherms to do this suggest that the crystallization mechanisms are different. The rates of crystallization and the crystallinity are affected by irradiation, the former being first retarded and then speeded-up with dosage increase, whilst the latter is a minimum at 2 mrad. The differing rates and crystallinities are discussed with respect to chain scission and crosslinking. The relationship between the crystalline melting points and the crystallization temperatures for the premelt process is as predicted by theory. The melting points of the low temperature crystallization process are higher than those predicted by theory, annealing or further recrystallization being thought to have occurred.

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Zusammenfassung Die Kristallisation vonγ-bestrahlten Poly?thylen-Terephthalaten die in einem gro?en Temperaturbereich kristallisiert wurden, ist mit Hilfe der Differential-Kalorimetrie untersucht worden. Es wurde festgestellt, da? der Unterschied zwischen demAvrami-Exponenten der Tieftemperatur-Kristallisation und der von vorgeschmolzenen Proben ausgehenden Kristallisation nicht so ausgepr?gt war wie bei dem unbestrahlten Polymer. Die Deckungsgleichheit der Tieftemperatur-Kristallisations-Isothermen entlang der log-Zeit-Achse und das Unverm?gen der Vorschmelz-Isothermen, dasselbe zu tun, weisen jedoch darauf hin, da? die Kristallisations-Mechanismen verschieden sind. Die Kristallisations-Geschwindigkeit und die Kristallinit?t werden mit der Bestrahlung ver?ndert, und zwar wird das ersterw?hnte mit zunehmender Strahlungsdosis anfangs verz?gert und dann beschleunigt, w?hrend das letztere ein Minimum bei 2 mrad hat. Die unterschiedlichen Geschwindigkeiten und Kristallinit?ten werden diskutiert mit Rücksicht auf Kettenspaltung und Vernetzung. Das Verh?ltnis zwischen dem Kristall-Schmelzpunkt und der Kristallisations-Temperatur für den Vorschmelz-Proze? ist wie in der Theorie vorhergesagt. Die Schmelzpunkte beim Tieftemperatur-Kristallisations-Proze? sind h?her als theoretisch, vermutlich durch Tempern oder weitere Rekristallisation.

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Contribution No. 462.     

A new approach to the furan degradation problem involving ozonolysis of the trans-enedione and its use in a cost-effective synthesis of eplerenone

[reaction: see text] Whereas ozonization of furan 3a affords little or no carboxylic acid 5, ozonization of the corresponding trans-enedione 6 afforded carboxylic acid 5 in 82.4% yield (cryst., overall from furan, 100 g scale; after workup with dimethyl sulfide, followed by mildly basic hydrogen peroxide). This new approach to furan degradation is showcased in a cost-effective synthesis of eplerenone, an important new medicine for cardiovascular indications.     

Lithium ion induced stabilization of the liquid crystalline DNA

A comparative study of the effects of alkali metal ions Li(+), Na(+), K(+), Rb(+), and Cs(+) on the liquid crystalline organization of high-molecular-weight calf thymus DNA using polarized light microscopy was performed. Major differences in the behavior of Li(+) as compared to the other ions were found. Critical DNA concentration expected to exhibit anisotropic behavior was found to be the same for all the monovalent ions, except for Li(+). DNA initially showed cholesteric textures, which later changed to higher ordered columnar phase for all ions, with the cholesteric-columnar transition facilitated upon increasing the size of the counterion. For Li(+) ion, a nematic schlieren-like texture was formed initially, which after a few days changed to a highly stable (for more than 2 months) biphasic cholesteric-columnar arrangement. The observed differences between Li(+) and other alkali metal ions could be rationalized on the basis of the higher number of hydration water molecules of Li(+) and its complexation behavior. Highly stable DNA mesophases may find applications in the field of nanoelectronics, in designing biosensing units, and in DNA chips.     

Distribution of uranium in drinking/ground waters in Narsipatnam Revenue Division of Visakhapatnam District of Andhra Pradesh,India and consequent ingestion dose

Journal of Radioanalytical and Nuclear Chemistry - Uranium is a naturally occurring radioactive element. The higher concentrations of U in waters can cause chemical as well as radiological...