Asymmetric Synthesis. VII. Double Stereodifferentiation in Allylation of Ketimines Bearing Two Chiral Auxiliaries. Application to Enantioselective Synthesis of α-Allylglycine

A double asymmetric induction has been observed in allylation of the imines derived from (+)-camphor, (+)- and (-)- 2-hydroxypinan-3-ones with (+)- and (-)-menthyl glycinates. After hydrolysis of the allylated intermediates, (R)- and (S)-α-allylglycines are obtained in 3–90% optical yields.     

A Facile O-Alkyl Cleavage of Esters with Sodium Hydrogen Selenide

Sodium hydrogen selenide generated in the dipolar aprotic solvent DMF is shown to be an effectively selective reagent for the dealkylation of esters to give the corresponding carboxylic acids in good yields.     

煤浆电解制氢的动力学研究

研究了煤浆电解过程中电压、温度、H₂SO₄浓度、Fe³⁺浓度等因素的影响,并进行了电解前后煤粉样品的热重测试和电解后溶液的成分分析。结果表明,电压、温度、添加的Fe³⁺浓度、H₂SO₄浓度等参数对电解过程的电流密度有较大影响。其中,温度对电流密度的影响符合阿伦尼乌斯方程,在电解电压1 V条件下煤浆电解活化能为31.87 kJ/mol。TGA和ICP分析表明,电解后煤中的部分金属离子溶入溶液,导致结构和灰分成分发生了较显著的变化。     

New mesogen with thermotropic cubic phase: 3,4,5‐tris‐(11,11,12,12,13,13,14,14,15,15,16,16,16‐tridecafluorohexadecyloxy)benzoic acid

A new mesogen, 3,4,5‐tris(11,11,12,12,13,13,14,14,15,15,16,16,16‐tridecafluoro‐hexadecyloxy)benzoic acid, with a thermotropic cubic phase was synthesized. The phase behaviour of the fluorinated compound and its corresponding non‐fluorinated analogue was investigated by differential scanning calorimetry, polarizing optical microscopy, and synchrotron small‐angle X‐ray diffraction. The fluorinated compound, which contains three partially perfluorinated alkoxy moieties and one carboxylic acid group capable of forming hydrogen bonding, exhibits a very interesting sequence of isotropic, cubic and hexagonal columnar phases, whereas its non‐fluorinated compound does not have a liquid crystalline phase. The cubic phase exists over a wide temperature range (from ～200°C to ～30°C on cooling) and is hence amenable to various physical measurements and potential applications. The ability to self‐assemble molecules into ordered superstructure via both partially perfluorinated chains and hydrogen bonding provides new insight for the development of novel liquid crystalline materials.     

Study on the flow resistance of the dispersion system of deformable preformed particle gel in porous media using LBM-DEM-IMB method

After being injected into the porous media, the dispersion system of preformed particle gel (PPG) tends to enter high permeability regions and block water channeling passages, which forces the subsequent water to turn to the low permeability regions and thus increases sweep efficiency and enhances oil recovery. However, it is still unclear about the influence factors and the mechanisms how PPG increases water flow resistance, which limits the application of PPG in more oilfields. Therefore, the paper combines the lattice Boltzmann method (LBM), the discrete element method (DEM) and the improved immersed moving boundary (IMB) method to simulate the migration of deformable PPG in porous media. On the basis, the paper quantitatively analyzes the variation law of displacement pressure across the porous media and discusses the influence factors such as the PPG diameter, elasticity modulus and the number concentration. Results indicate that, because of the friction and retention of PPG in pore-throat, the displacement pressure across the porous media during PPG flooding is much higher than that during water flooding. In other words, the existence of PPG increases the flow resistance of injected water. Besides, the displacement pressure is always fluctuant resulting from the continuous process of PPG migration, retention, deformation and remigration. Influence factor analysis shows that the incremental value and fluctuation degree of flow resistance increase with the PPG diameter, elasticity modulus and the number concentration. The study not only provides useful reference for future PPG flooding, but also benefits the development of deformable particle flow theory.     

The behavior of technetium in technetium-scrubbing stage of PUREX process

Technetium decontamination factor as a function of the acidity, flow ratio, scrubbing stage number was investigated by counter-current cascade experiments or mixer-settler batch tests. Results showed that the acidity of the scrubbing acid has little influence on the decontamination factor of technetium when the acidity was kept in the range of 4.5–6 M. The most effective method to increase the decontamination factor is to lower the feed-to-acid flow ratio. Keeping other condition same the factor increased to 10.3 from 3.1 when feed-to-acid ratio changed to 4 from 5.6. The loss of uranium and plutonium can be recovered through a re-extraction technology.     

Suitable dose of 60Co γ-ray for mutation in Roegneria seeds

Seeds from six accessions of three species of Roegneria were radiated with ⁶⁰Co γ-ray at different doses (50, 100, 150, 200, 250, 300 and 400 Gy). Following these treatments, germination energy, germination rate, seedling height, plant height, plant survival, and seed set were observed. Plant survival was highly correlated with seedling height (R ² > 0.91, P < 0.01) and seed set (R ² > 0.82, P < 0.01). The semi-lethal dose of each accession, calculated using a ‘Multi-target single-hit’ model, ranged from 60 to 173 Gy. The most suitable absorbed doses for each accession were deduced from these data. The suitable doses for Roegneria kamoji, Roegneria ciliaris and Roegneria japonensis were 65–100 Gy, 63–150 Gy and 80–170 Gy, respectively. According to the range of suitable doses, R. kamoji (Pr87-88-353) was the most sensitive to radiation, and R. japonensis (88-89-267) was the most resistant to radiation. Suitable doses of R. ciliaris were close to that of R. kamoji (ZY1007). This research provides preliminary guidelines for radiation induced mutagenesis in Roegneria.