Synthesis of the possible carcinogenic dihydrodiol and diol epoxide of phthalazine

Inverse-Diels-Alder reaction of dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate with benzene cis-diol gave dihydrodiol containing the 1,4-dihydropyridazine ring. Attempts at oxidation of the dihydropyridazine ring with PIFA and MnO₂ resulted in the formation of 5- and 5,6-dihydroxy-phthalazine derivatives. The oxidation of the dihydropyridazine ring was achieved by way of photooxygenation. The phthalazine type dihydrodiol is unstable and easily undergoes aromatization. The Diels-Alder reaction of tetrazine with cyclohexadiene acetonide and epoxy-ketal cyclohexene as a dienophile was investigated. These reactions led to the possible carcinogenic phthalazine type of dihydrodiol and diol epoxide where the hydroxyl groups are protected.     

Evolution of small copper clusters and dissociative chemisorption of hydrogen

The structural evolution of small copper clusters of up to 15 atoms and the dissociative chemisorption of H2 on the minimum energy clusters are studied systematically using density functional theory. The preferred copper sites for chemisorption are identified and the transition state structures and activation barriers for clusters four to nine atoms are determined and found to be inconsistent with the empirical Bronsted-Evans-Polanyi relationship. The physicochemical properties of the clusters are computed and compared with the bulk and surface values. The results indicate that a phase transition must occur in the going from cluster to bulk.     

Photooxygenation of 5-dialkylamino-4-pyrrolin-3-ones. Synthesis of highly functionalized ureas, 2-oxazolidinones, and 2-oxazolinones

5-Dialkylamino-4-pyrrolin-3-ones, available from cyclocondensation of amidines with dimethyl acetylenedicarboxylate (DMAD), undergo rapid singlet oxygenation to give highly functionalized ureas by way of a 1,2-dioxetane cleavage of the initially formed [2 + 2] cycloadducts. These latter compounds undergo cyclization to 2-oxazolidinones in MeOH. Catalytic hydrogenation of the ureas in EtOAc gives 2-oxazolinones. The DBU-DMAD adduct undergoes photooxygenation by an entirely different pathway to give a large ring heterocycle.     

Polarization studies of Lyman-α radiation emitted in atom-H2-molecule collisions

A polarization study of Lyman-α radiation emitted in collisions of H⁺, H, He⁺, and He projectiles with H₂ molecules has been performed at projectile energies ranging from 1–25 keV. In H⁺?H₂ and H?H₂ collisions, the measured linear polarization is negative at low incident velocities, indicating a preferred alignment of the excited electron charge cloud perpendicular to the incident projectile direction. This is taken as significance for a rotational coupling which in these two collision systems predominantly populates the H(2p _±1) substates. In He⁺?H₂ and He?H₂ collisions, the measured linear polarization is about zero and independent of the projectile energy. In these more asymmetric systems,a′?a′ and a′?a″ couplings are now of comparable magnitude.     

Cyclocondensation of amidines with dimethyl acetylenedicarboxylate: A convenient entry into tetramic acids

Amidines undergo cyclocondensations with dimethyl acetylenedicarboxylate (DMAD) to give highly functionalized 5‐dialkylamino‐4‐pyrrolin‐3‐ones. The products are crystalline, highly colored compounds that are uniquely functionalized and represent advanced intermediates in the construction of several other heterocyles, in particular the biologically active tetramic acids. The synthetic transformations of these compounds to tetramic acids are also described.     

Paleoclimatology

The Lamas Basin is an area covering ～4400 km² situated on the eastern Mediterranean coast of Turkey covered with highly karstified limestone and dolomitic limestone from the Miocene and Mesozoic age, respectively. Owing to the area’s low karstification basement, groundwater in the karst aquifer circulates deep from the surface towards the springs along the coast as well as to the submarine springs. This study aims working out the salinization level and recharge characteristics of the Lamas Basin using environmental isotopes techniques. In the study, the data collected previously to discover, in general terms, the groundwater characteristics within the area are reanalyzed to fulfil the purpose of the study. In conclusion, it is found that the down gradient karst springs discharging along the Mediterranean coast mostly contain groundwater contributions from higher altitudes with depleted δ¹⁸O and δ²H compositions. The δ¹⁸O-altitude effect was determined as approximately?0.12 ‰/100 m which may indicate sea-spray intrusion towards inland. As a result, the salinization level of coastal springs changes ranging between 1.2 % and 17.0 %. Owing to the seawater encroachment, Ca–HCO₃ water type changes to Na–HCO₃ or Na-Cl water by the cation exchange during the dry period. As the unique freshwater potential extends along the coastal area, the groundwater production should be exploited in a way that seawater encroachment is kept at minimum.     

Determination of the recharge area and salinization degree of karst springs in the Lamas Basin (Turkey)

The Lamas Basin is an area covering approximately 4,400 km(2) situated on the eastern Mediterranean coast of Turkey covered with highly karstified limestone and dolomitic limestone from the Miocene and Mesozoic age, respectively. Owing to the area's low karstification basement, groundwater in the karst aquifer circulates deep from the surface towards the springs along the coast as well as to the submarine springs. This study aims working out the salinization level and recharge characteristics of the Lamas Basin using environmental isotopes techniques. In the study, the data collected previously to discover, in general terms, the groundwater characteristics within the area are reanalyzed to fulfil the purpose of the study. In conclusion, it is found that the down gradient karst springs discharging along the Mediterranean coast mostly contain groundwater contributions from higher altitudes with depleted delta(18)O and delta(2)H compositions. The delta(18)O-altitude effect was determined as approximately-0.12 per thousand/100 m which may indicate sea-spray intrusion towards inland. As a result, the salinization level of coastal springs changes ranging between 1.2 % and 17.0 %. Owing to the seawater encroachment, Ca-HCO(3) water type changes to Na-HCO(3) or Na-Cl water by the cation exchange during the dry period. As the unique freshwater potential extends along the coastal area, the groundwater production should be exploited in a way that seawater encroachment is kept at minimum.     

Syngas cleaning with nano-structured micro-porous ion exchange polymers in biomass gasification using a novel downdraft gasifier

Sulphonated nano-structured micro-porous ion exchange polymers,known as sulphonated PolyHIPE Polymers(s-PHPs) were used in syngas cleaning to investigate their impact on tar composition,concentration and dew point depression during the gasification of fuel cane bagasse as a model biomass.The results showed that the s-PHPs used as a secondary syngas treatment system,was highly effective at adsorbing and reducing the concentration of all class of tars in syngas by 95%-80%which resulted in tar dew point depression from 90℃to 73℃.It was shown that tars underwent chemical reactions within s-PHPs,indicating that tar diffusion from syngas was driven by chemical potential.It was also observed that s-PHPs also captured ash forming elements from syngas.The use of s-PHPs in gasification as well as in an integrated thermochemical biorefinery technology is discussed since the tar loaded s-PHPs can be used as natural herbicides in the form of soil additives to enhance the biomass growth and crop yield.     

Flavonol Glycosides and Iridoids from Asperula lilaciflora

A new flavonol glycoside, quercetin 3‐O‐[6′′′‐O‐3,5‐dihydroxycinnamoyl‐β‐glucopyranosyl‐(1→2)]‐β‐galactopyranoside (named lilacifloroside; 1 ) and a new iridoid 2 (named asperulogenin), were isolated from the aerial parts of Asperula lilaciflora in addition to eight known secondary metabolites, i.e., quercetin, kaempferol, quercetin 3‐O‐β‐glucopyranosyl‐(1→2)‐β‐galactopyranoside, quercetin 3‐O‐β‐glucopyranosyl‐(1→2)‐arabinopyranoside, asperuloside, deacetylasperulosidic acid, asperulosidic acid methyl ester, and chlorogenic acid. The structures were elucidated on the basis of extensive 1D‐ and 2D‐NMR experiments as well as MS data. Compound 1 contains the rare 3,5‐dihydroxycinnamoyl moiety in its structure. This work constitutes the first phytochemical study of the title plant.