N-芳基氮氧方酸与HMPA的反应

Ｎ－芳基氮氧方酸与ＨＭＰＡ的反应＊陈益钊李聚才（四川大学化学系成都６１００６４）黄锋（中国人民解放军防化研究院北京１０２２０５）陈凌勇（泸州医学院泸州６４６０００）关键词Ｎ－芳基氮氧方酸六甲基磷酰胺酰胺的酸解环丁烯二酮方酸化学中图分类号Ｏ６２４．４２...

方酸1,2-取代衍生物的合成及反应

对近年来以方酸和方酸简单衍生物（如方酰氯、方酸酯等）为原料制备１，２－取代方酸衍生物的反应。

氮氧方酸酯的合成研究

氧方酸在醇中回流制得氧方酸二酯后,低温下氨解,成功地合成了一系列伯醇和仲醇的氮氧方酸酯。空间阻碍较大的仲醇,可得到氮氧方酸酯和氮氧方酸混合物。相同条件下,叔丁醇不与氧方酸反应。

芳基异方酰胺与HMPA及一些羧酰胺的反应

研究了1,3-双芳基异方酰胺与六甲基磷酰三胺(HMPA)及其它羧酰胺的反应制得了15个既含芳胺基又含脂肪基的不对称方酰胺。该反应提供了制备既含芳胺基又含二甲胺基、甲胺基和乙胺基的不对称方酰胺的较为有效的方法。对反应机理作了初步讨论。

新型异方酰化氨基醇手性配体的合成与表征

将手性氨基醇与对称异方酰胺进行部分(50%)酰胺交换反应,合成了尚未见文献报道的新型异方酰化氨基醇手性配体。其组成和结构已由元素分析、IR、MS和1HNMR所表征。

2-[(1’S,2’R)-(2’-羟基-1’,2’-二苯基乙基)氨基]-3,4-二酮环丁烯硫醇钠的表征与应用

针对2-[(1’S,2’R)-(2’-羟基-1’,2’-二苯基乙基)氨基]-3,4-二酮环丁烯硫醇钠的结构,通过元素分析,红外光谱及核磁共振进行了表征,并考察了它与常见金属离子的作用。实验表明,该化合物是一个优良的手性配体。

新型显色剂2-吗啉基-3,4-二酮环丁烯硫醇钾的合成及显色性能

本文报道了新型显色剂2-吗啉基-3，4-二酮环丁烯硫醇钾的合成，经元素分析，红外光谱及核磁共振表征，确定了它的结构．初步试验了它对常见金属离子的显色性能．

A Novel Efficient Method for Synthesis of β-Organoseleno Substituted Allyl Sulfoxides

Hydroselenation of 1, 2-allenyl sulfoxides give 2-organoseleno substituted allyl sulfoxides in high yields and the reaction is absolute regioselective.

Effect of sodium pyrophosphate on the flotation separation of chalcopyrite from galena

The effect of sodium pyrophosphate （SPH） on the separation of chalcopyrite from galena was examined through flotation, adsorption, electrokinetic studies and infrared spectral analysis. Differential flotation tests indicate that satisfactory separation can be achieved within the pH range from 2.5 to 6 using SPH to depress the galena, but not the chalcopyrite when O-isopropyl-N-ethyl thionocarbamate （IPETC） is used as the collector. The electrophoretic mohilities of both the minerals dramatically become negatively charged following SPH adsorption in the pH range from 2.5 to 12, The infrared spectral analysis suggests that chemical adsorption occurs on galena surface treated by SPH, indicating that a chelate complex has formed. At weakly acidic pH values, the adsorption density of IPETC onto galena is significantly reduced in the presence of SPH. However, the amount of IPETC adsorbed onto chalcopyrite almost remains at the same level. Since the observed adsorption density of IEPTC onto chalcopyrite is quite high compared to galena, the observed flotation results are explained. A possible mechanism for the interaction between the two sulphide minerals and SPH is discussed.

Preparation of spherical cobalt carbonate powder with high tap density

Spherical cobalt carbonate with high tap density, good crystallization and uniform particle size was prepared by controlled chemical crystal method using cobalt chloride and ammonium bicarbonate as cobalt source and precipitator. The effects of pH value and reaction time on crystallization and physical properties of cobalt carbonate were studied. The results show that the key factors influencing the preparation process of spherical cobalt carbonate with high tap density and good crystallization are how to control pH value (7.25±0.05) and keep some reaction time (about 10 h). Co4O3 was prepared by sintering spherical morphology CoCO3 samples at varied temperatures. The results show that as the decomposition temperature increases, the as-obtained Co4O3 products with porous structure transform into polyhedral structure with glazed surface, and simultaneously the cobalt content and tap density increase. However, the specific surface area shows a trend of decrease.

Basic formation mechanisms of Lake Doroninskoye soda water, East Siberia, Russia

The primary scientific goal of studying salt lakes is to better understand the formation of small continental- type hydrogeochemical systems. Many scientists have attributed the metamorphism of the chemical composition of salt lakes to the evaporative concentration of water. How- ever, the formation of soda water is inconsistent with this hypothesis. Thus, analyzing intrabasinal biochemical pro- cesses and water--rocks interactions during the evaporative concentration of water allows us to understand the major mechanisms of the formation and evolution of water com- positions. Therefore, the aim of this paper is to identify the key processes involved in the formation of the chemical composition of the water in Lake Doroninskoye. An analysis of the distribution of major components shows that Na＋, HCO3-, CO32-, and C1- are dominant in this water. High concentrations of these elements are the result of evaporative water concentration. Calcium, magnesium, and potassium are not accumulated because the water is saturated in min- erals containing these elements. The main barrier to the growth of the sulfate content of water is sulfate reduction. This process also contributes to the additional reproduction of carbon dioxide, which reacts with the products of the hydrolysis of aluminosilicates OH- to form HCO3- and CO32-, thus further contributing to the natural processes of soda formation.

Efficient Separation of Butyric Acid by an Aqueous Two-phase System with Calcium Chloride

One of the bottlenecks for bioproduction of butyric acid as bulk chemical is the difficulty in separating butyric acid from the fermentation broth,compared with the petroleum-based chemical synthesis method.In the present work,a novel separation methodology was developed based on an aqueous two-phase system with inor-ganic salts.Calcium chloride was screened out for effective separation of butyric acid from butyric acid-water-salt systems.Within appropriate concentration range of butyric acid and salt,butyric acid was enriched in the upper phase and most of calcium ions remained in the lower phase.This"salting out"effect is very efficient to separate butyric acid from the simulated butyrate fermentation broth,which consists of butyric acid and acetic acid with concentration ratio of 4︰1,so that the final ratio of butyric acid/acetic acid in the upper phase is improved to 9.87. The aqueous two-phase system was used to separate butyric acid from the actual fermentation broth with satisfac-tory result.

Simultaneous Determination of Six UV-Filters in Cosmetics by HPLC

A reversed-phase high performance liquid chromatographic method with diode-array detector was established to simultaneously determine the six UV-filters, isopentyl-4-methoxycinnamate, ethylhexyl methoxycinnamate, ethylhexyl salicylate, homosalate, butyloctyl salicylate and ethylhexyl triazone. They were separated on a Kromasil C18 column, with gradient elution by methanol and water, and detected by HPLC-DAD.All results demonstrated good linear relationship in proper mass concentration range. The limits of quantitation(LOQ) were between 0.5 and 1.25 mg/L. The recoveries of the six compounds ranged from 98.3% to 101.0% at two inrements with the relative standard deviation(RSD) no more than 1.5%.

Biosynthesis of 4-hydroxyphenylpyruvic acid from L-tyrosine using recombinant Escherichia coli cells expressing membrane bound L-amino acid deaminase

4-Hydroxyphenylpyruvic acid （4-HPPA）, a kind of α-keto acid, is an intermediate in the metabolism of tyrosine and has a wide range of application in food, pharmaceutical and chemical industry. Using amino acids as raw material to prod uce the corresponding α-keto acid is thought to be both economic and efficient. Among the enzymes that convert amino acid to α-keto acid, membrane bound L-amino acid deaminase （mL-AAD）, which is anchored to the outer side of the cytomembrane, becomes an ideal enzyme to prepare α-keto acid since there is no cofactors needed and H2O2 production during the reaction. In this study, the mL-AAD from Proteus vulgaris was used to prepare whole-cell catalysts to produce 4-HPPA from L-tyrosine. The secretory efficiency of mL-AAD conducted by its own twin-arginine signal peptide （twin-arginine translocation pathway, Tat） and integrated pelB （the general secretory pathway, Sec）-Tat signal peptide was determined and compared firstly, using two pET systems （pET28a and pET20b）. It was found that the Tat pathway （pET28a-mlaad） resulted in higher cell-associated mL-AAD activity and cell biomass, and was more beneficial to prepare biocatalyst. In addition, expression hosts BI21 （DE3） and 0.05 mmol. L- 1 IPTG were found to be suitable for mL-AAD expression. The reaction conditions for mL-AAD were optimized and 72.72 mmol,L 1 4-HPPA was obtained from 100 mmol.L 1 tyrosine in 10 h under the optimized conditions. This bioprocess, which is more eco-friendly and economical than the traditional chemical synthesis ways, has great potential for industrial application.

Investigation of Geographical Origin and Production Method of L（＋）-Tartaric Acid by Isotopic Analyses with Chemometrics

The determination of the geographical origin as well as the adulteration of natural products is a technical problem due to similar chemical composition between an adulterant and the original. It is assumed that tartaric acid comes from natural sources, however there is no specific regulation for this claim. This paper describes the use of isotope mass spectrometry associated with chemometrics to classify different samples of tartaric acid. The results showed that the variables δ^13C, δ^18O and δ^2H allowed the discrimination of tartaric acid samples by geographical origin and production method. By using a combination of chemometfic analysis it was possible to confirm a notoriousseparation of the samples. Thus, this is a promising method to be applied in the quality control and authenticity of tartaric acid.

Corrosion behaviour of 6061 Al-15vol. Pct. SiC composite and its base alloy in sulphuric acid medium

In this paper the corrosion characteristics of Silicon carbide particulate-reinforced 6061 aluminum composite （ 6061 AI/SiCp composite ） and the base alloy are experimentally assessed. The corrosion tests are carried out at different temperatures in the concentration range of 0.01N to 1N sulphuric acid as corrosion media using Tafel extrapolation technique and Electrochemical Impedance Spectroscopy （EIS）. The results obtained from Tafel extrapolation technique and Electrochemical Impedance Spectroscopy are in good agreement. The results show an increase in the corrosion rate with increase in temperature as well as with increase in the concentration of the corrosion media. The thermodynamic parameters like energy of activation are calculated using Arrhenius theory equation and, enthalpy of activation and entropy of activation are calculated using transition state theory equation.

Phosphatic microspherules and their geobiological implications from the Frasnian-Famennian transition at the Yangdi section, Guilin, South China

Abundant perfectly-preserved phosphatic microspherules have been discovered across the Frasnian-Famennian （F-F） transition from the Yangdi section in Guilin, Guangxi, South China. They are mostly spherical or elliptical in shape and about 150 gin in diameter with smooth exterior surfaces. Each microspherule consistently possesses a small dimple on the surface. The internal texture of microspherules consists of concentric light-colored apatite and dark-colored organic matter bands alternating around a central core. Conodonts have also been found preserved together with phosphatic microspherules in the same horizon, and the abundance of the former is obviously higher than that of the latter. Laser Raman spectral studies show close similarities in spectral patterns between the outer shells of phosphatic microspherules and the blade of the conodont genus Palmatolepis sp., as well as between the microspherule nucleus and the platform of the same conodont genus. Furthermore, the statistical results and geochemical data demonstrate that the elevated abundance of phosphatic microspherules roughly coincides with the blooms of bacteria and algae, but is later than the sharp increase of oceanic nutrients. The phosphatic microspherules are inter- preted here to be the ＇otoliths＇ secreted by conodont animals based on the compositional similarities between phosphatic mi- crospherules and conodonts and their interrelated abundances. In addition, an analogous study reveals morphological and tex- tural similarities between fish otoliths and phosphatic microspherules. The formation of phosphatic microspherules is probably related to seawater eutrophication. We speculate that the explosive growth of bacteria and algae is probably caused by the en- richment of nutrients that is most likely associated with the increase of terrestrial inputs, submarine hydrothermal activities or the upwelling anoxic bottom waters in the late Devonian, which would stimulate the conodont animals to secrete phosphatic microspherules--the ＇otoliths＇ of conodont animals. This study reveals the coupling relationship between organisms and envi- ronments from the perspective of phosphatic microspherules and provides new evidence for the cause of faunal crisis during the Late Devonian F-F transition.

Generation of Cenozoic intraplate basalts in the big mantle wedge under eastern Asia

The roles of subduction of the Pacific plate and the big mantle wedge(BMW) in the evolution of east Asian continental margin have attracted lots of attention in past years. This paper reviews recent progresses regarding the composition and chemical heterogeneity of the BMW beneath eastern Asia and geochemistry of Cenozoic basalts in the region, with attempts to put forward a general model accounting for the generation of intraplate magma in a BMW system. Some key points of this review are summarized in the following.(1) Cenozoic basalts from eastern China are interpreted as a mixture of high-Si melts and low-Si melts. Wherever they are from, northeast, north or south China, Cenozoic basalts share a common low-Si basalt endmember, which is characterized by high alkali, Fe_2O_3~T and TiO_2 contents, HIMU-like trace element composition and relatively low ^(206)Pb/^(204)Pb compared to classic HIMU basalts. Their Nd-Hf isotopic compositions resemble that of Pacific Mantle domain and their source is composed of carbonated eclogites and peridotites. The high-Si basalt endmember is characterized by low alkali, Fe_2O_3~T and TiO_2 contents, Indian Mantle-type Pb-Nd-Hf isotopic compositions, and a predominant garnet pyroxenitic source. High-Si basalts show isotopic provinciality, with those from North China and South China displaying EM1-type and EM2-type components, respectively, while basalts from Northeast China containing both EM1-and EM2-type components.(2) The source of Cenozoic basalts from eastern China contains abundant recycled materials, including oceanic crust and lithospheric mantle components as well as carbonate sediments and water. According to their spatial distribution and deep seismic tomography, it is inferred that the recycled components are mostly from stagnant slabs in the mantle transition zone,whereas EM1 and EM2 components are from the shallow mantle.(3) Comparison of solidi of garnet pyroxenite, carbonated eclogite and peridotite with regional geotherm constrains the initial melting depth of high-Si and low-Si basalts at <100 km and^300 km, respectively. It is suggested that the BMW under eastern Asia is vertically heterogeneous, with the upper part containing EM1 and EM2 components and isotopically resembling the Indian mantle domain, whereas the lower part containing components derived from the Pacific mantle domain. Contents of H_2O and CO_2 decrease gradually from bottom to top of the BMW.(4) Melting of the BMW to generate Cenozoic intraplate basalts is triggered by decarbonization and dehydration of the slabs stagnated in the mantle transition zone.