Synthesis and antimalarial effects of 2-(3,4-dichloroanilino)-7-[[[(dialkylamino)alkyl]amino]]-5-methyl-s-triazolo[1,5-a]pyrimidines

3,4-Dichlorophenylisothioeyanate ( 10 ) was allowed to react with 2-methy1-2-thiopseudourea to give methyl 4-(3,4-dichlorophenyl)(dithioaltophanimidate ( 11 ) (41%), which upon treatment with hydrazine afforded 3-amino-5-(3,4-dichloroanilino)-s-triazole ( 12 ) (54-91%). Ring-closure with ethyl acetoacetale in acetic acid afforded 2-(3,4-dichloroanilino)-5-methyl-s-triazolo[ 1,5-α ]-pyrimidin-7-ol ( 13 ) (81%). Chlorination with phosphorus oxychloride gave 7-chloro-2-(3,4-dichloroanilino)-5-methyl-s-triazolo[1,5-α ]pyrimidine ( 14 ) (98%), which was condensed with various amines to yield the desired 2-(3,4-diehloroanilino)-7-¶[(dialkylamino)alkyl]arnino¶-5-methyl-s-triazolo[ 1,5-α]pyrimidines ( 6 a-d). The structures of the s-triazolo[ 1,5-α ]pyrimidines were based on nmr spectroscopy and ring stability considerations. Several of the amino-s-triazolo[ 1,5-α ]pyrimidines possessed antimalarial activity against P. berghei in mice.     

Formation of hydroxyl radical from the photolysis of frozen hydrogen peroxide

Hydrogen peroxide (HOOH) in ice and snow is an important chemical tracer for the oxidative capacities of past atmospheres. However, photolysis in ice and snow will destroy HOOH and form the hydroxyl radical (*OH), which can react with snowpack trace species. Reactions of *OH in snow and ice will affect the composition of both the overlying atmosphere (e.g., by the release of volatile species such as formaldehyde to the boundary layer) and the snow and ice (e.g., by the *OH-mediated destruction of trace organics). To help understand these impacts, we have measured the quantum yield of *OH from the photolysis of HOOH on ice. Our measured quantum yields (Phi(HOOH --> *OH)) are independent of ionic strength, pH, and wavelength, but are dependent upon temperature. This temperature dependence for both solution and ice data is best described by the relationship ln(Phi(HOOH --> *OH)) = -(684 +/- 17)(1/T) + (2.27 +/- 0.064) (where errors represent 1 standard error). The corresponding activation energy (Ea) for HOOH (5.7 kJ mol(-1)) is much smaller than that for nitrate photolysis, indicating that the photochemistry of HOOH is less affected by changes in temperature. Using our measured quantum yields, we calculate that the photolytic lifetimes of HOOH in surface snow grains under midday, summer solstice sunlight are approximately 140 h at representative sites on the Greenland and Antarctic ice sheets. In addition, our calculations reveal that the majority of *OH radicals formed on polar snow grains are from HOOH photolysis, while nitrate photolysis is only a minor contributor. Similarly, HOOH appears to be much more important than nitrate as a photochemical source of *OH on cirrus ice clouds, where reactions of the photochemically formed hydroxyl radical could lead to the release of oxygenated volatile organic compounds to the upper troposphere.     

Isolation of a carbon nanohoop with M(o)bius topology

Carbon nanohoop,a class of constrained molecular architecture consisting of linked arene units,has attracted considerable interest from both experimental and th...     

Effects of Different Extraction Methods on Vanilla Aroma

To establish the analytic conditions for examining the aroma quality of vanilla pods, we compared different extraction methods and identified a suitable option. We utilized headspace solid-phase microextraction (HS-SPME), steam distillation (SD), simultaneous steam distillation (SDE) and alcoholic extraction combined with gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS) to identify volatile components of vanilla pods. A total of 84 volatile compounds were identified in this experiment, of which SDE could identify the most volatile compounds, with a total of 51 species, followed by HS-SPME, with a total of 28 species. Ten volatile compounds were identified by extraction with a minimum of 35% alcohol. HS-SPME extraction provided the highest total aroma peak areas, and the peak areas of aldehydes, furans, alcohols, monoterpenes and phenols compounds were several times higher than those of the other extraction methods. The results showed that the two technologies, SDE and HS-SPME, could be used together to facilitate analysis of vanilla pod aroma.     

1,4-bis[2-(4-pyridyl)ethenyl]-benzene衍生物热致变色研究

本文制备了三种在1,4-bis[2-(4-pyridyl)ethenyl]-benzene(bp-eb)上接枝不同烷基链长度的热致变色材料DC8、DC12、DC16. 在365 nm激发光下,随着温度升高,它们呈现出荧光颜色的改变,这种改变来自于晶体态与无定形态之间的转变. 此外,DC16也呈现出光致变色的性质. 通过差示扫描量热法测试得到的相转变温度高于实验过程中荧光颜色改变时的温度. 因此,这种变色行为来自于光与热共同作用的结果. 乙醇可以使粉末变回起始的晶体状态,从而使荧光颜色恢复,实现热致变色行为的可逆. 本研究对理解热致变色分子的结构-性质关系,指导热致变色分子设计具有重要意义.     

Propagation of phase-locked partially coherent flattened beam array in turbulent atmosphere

Analytical formulae for phase-locked partially coherent flattened beam array propagating in a turbulent atmosphere are derived based on the extended Huygens–Fresnel principle. Beam propagation factor (BPF) is introduced to evaluate the beam quality at the receiving plane. The influence of beam order, transverse coherence width length and the intensity of turbulence is discussed in detail.     

Comparison between relay propagation and direct propagation of Gaussian-Schell-model beam in turbulent atmosphere along a slant path

The relay propagation of Gaussian-Schell-model in turbulent atmosphere along a slant path is studied in this paper. Based on the extended Huygens-Fresnel principle and a quadratic approximation, an analytical formula of average intensity for Gaussian-Schell-model beams in turbulent atmosphere along a slant path is derived, and some special cases are discussed. From the study and the comparison with the direct propagation, we can see that the relay propagation has an advantage over the direct propagation. When the altitude of the target is low, the peak intensity of relay propagation is much larger than that of direct propagation. However, because of the limitation of the relay system aperture for relay propagation and the variation of coherence length for direct propagation, the difference in peak intensity between the two propagations decreases with the increase of the target altitude.     

Organic Reactions in Ionic Liquids: Ionic Liquid Ethylammonium Nitrate–Promoted Knoevenagel Condensation of Meldrum's Acid With Aromatic Aldehydes

The Knoevenagel condensation of Meldrum's acid with aromatic aldehydes proceeded efficiently in a reusable ionic liquid, ethylammonium nitrate, at room temperature in the absence of any catalyst with high yields.