环己烯制备实验中氯化钙脱除环己醇的研究

环己烯的制备是一个经典的有机化学实验项目，实验中用无水氯化钙脱除有机相中微量的环己醇。然而没有文献证实氯化钙具有良好的脱除环己醇的能力，需要通过实验进行验证。另外，还比较了氯化钙吸附异戊醇和乙醇的性能，以分析其对醇类物质的脱除能力。测试结果表明氯化钙脱除乙醇的效率较好，而吸附环己醇和异戊醇的能力弱，吸附时间长。可以作为教学实验的补充材料，供实验者参考。     

Calcium Hydride Cation [CaH]+ Stabilized by an NNNN‐type Macrocyclic Ligand: A Selective Catalyst for Olefin Hydrogenation

Reaction of dibenzyl calcium complex [Ca(Me₄TACD)(CH₂Ph)₂], containing the neutral NNNN‐type macrocyclic ligand Me₄TACD (Me₄TACD=1,4,7,10‐tetramethyl‐1,4,7,10‐tetraazacyclododecane), with triphenylsilane gave the cationic dinuclear calcium hydride [Ca₂H₂(Me₄TACD)₂](PhCHSiPh₃)₂ which was characterized by NMR spectroscopy and single‐crystal X‐ray diffraction. The cation can be regarded as the ligand‐stabilized dimeric form of hypothetical [CaH]⁺. Hydrogenolysis of benzyl calcium cation [Ca(Me₄TACD)(CH₂Ph)(thf)]⁺ gave dicationic calcium hydrides [Ca₂H₂(Me₄TACD)₂][BAr₄]₂ (Ar=C₆H₄‐4‐^tBu; C₆H₃‐3,5‐Me₂) containing weakly coordinating anions. In THF, they catalyzed the isotope exchange of H₂ and D₂ to give HD and the hydrogenation of unactivated 1‐alkenes.     

Use of some Inorganic and Organic Compounds as Decontaminants for Cobalt-60 and Caesium-134 by Clover Plant Grown on Inshas Sandy Soil

Outdoor lysimeter experiments were carried out to elucidate the effect of 4 inorganic and 3 organic salts on ⁶⁰Co and ¹³⁴Cs uptake and dry matter yield of three cuts of clover in the soils of Inshas. A new concept was proposed for assessing the difference in capacity of soil to supply radionuclides to plants as affected by applied inorganic or organic compounds. A relation of plant tissue radionuclide content with time can be expressed in an exponential equation with corresponding regression coefficients. When the same plant species is grown on the same soil differing only in the applied compounds (e.g. Fe-EDDHA, Fe-DTPA, Fe-OAC, Fe(COO)₂, Al(OH)₃, Ca(H₂PO₄)₂, Fe₂O₃) the derived equation will change. Differences of either Co or Cs accumulation with time between control and any other treatment were evaluated. The data also show that Fe-DTPA is preferred for ⁶⁰Co as enhancing compound for plant uptake (for decontamination use), compared with other applied salts, on the other hand, any tested salts did not significantly effect ¹³⁴Cs taken by clover. It was also found that more than 70% of the total cobalt uptake was accumulated in the roots which indicate that Co is less mobile in plants than Cs.     

Hydrido Complexes of Calcium: A New Family of Molecular Alkaline‐Earth‐Metal Compounds

The application of solid calcium hydride CaH₂ has been mostly confined to its use as a desiccant, although its catalytic activity has long been known. Since the first isolation of a well‐defined molecular calcium hydride in 2006, the past decade has witnessed a gradual emergence of this new family of compounds. Although the detrimental Schlenk equilibrium has kept the number of examples low, the novelty of their reactivity, especially in small‐molecule activation, holds great promise. This Minireview gives an overview of the molecular calcium hydrides reported to date, highlighting their synthesis, structure, and reactivity.     

Calcium‐Catalyzed Formal [2+2+2] Cycloaddition

A formal intermolecular [2+2+2] cycloaddition reaction of enynes to aldehydes is presented, which can be realized in the presence of a simple and benign calcium catalyst. The reaction proceeds with excellent chemo, regio‐ and diastereoselectivity and leads to a one‐step assembly of highly interesting bicyclic building blocks containing up to three stereocenters from simple precursors via a new type of skeletal rearrangement of enynes. The observed diastereoselectivity is accounted for by two different mechanistic proposals. The first one engages mechanistic prospects arising from a gold catalyzed reaction in the absence of the stabilizing gold substituent. The second proposal involves an unprecedented cyclization–carbonyl allene ene reaction–hydroalkoxylation cascade.     

Effect of counter-ions on the solution conformation and adsorption behaviors of comb-like polycarboxylates on calcium carbonate

Three kinds of polycarboxylate ether (PCE) polymers with the same length of side chains but different backbone length were synthesized by aqueous free radical polymerization. Adding counter-ions (i.e., Na⁺, Ca²⁺) to dilute PCE solutions was found to induce a more complicated conformational change, since the screening of the electrostatic intramolecular repulsion and the different complexation behaviors of Ca²⁺ with carboxylic groups. Further characterization on the adsorption indicated that the differences of the adsorption ability resulted from the difference in the solution conformation of PCE molecule. PCE of a medium backbone length studied herein possesses a more extended polymer backbone due to the intermolecular steric hindrance, which result in more carboxylic groups could be accessible for adsorption. Obviously, the solution conformation of PCE strongly impacts the accessible carboxylic group contribution to adsorption. In this way it may provide a new insight to design the polymer structures of PCE with superior adsorption ability.