1. Phase-Switching Catalysis
By simply adding or removing carbon dioxide,
chemists in Scotland devised a neat trick for
reversibly shuttling a homogeneous catalyst
between the organic and aqueous phases in a
biphasic solvent system (C&EN, Jan. 26, page 11;
Angew. Chem. Int. Ed. 2009, 48, 1472). The
phase-switchable catalyst designed by Simon L.
Desset and David J. Cole-Hamilton of the
University of St. Andrews adds flexibility to the
often complicated techniques required to isolate
products and recycle catalysts during
homogeneous reactions. The secret to the
switchability is a weakly basic amidine group,
–N=C(CH 3)N(CH 3)2, that the researchers added to
the phenyl rings of triphenylphosphine. The
rhodium catalyst made with the modified
phosphine ligand is soluble in organic solvent. On bubbling CO 2 into an aqueous-organic reaction system containing the catalyst, the CO 2 reacts with water to form carbonic acid (H 2CO 3). The transient acid protonates the amidine groups and renders the catalyst water-soluble. Subsequently bubbling N 2 into the biphasic system drives off CO 2 and shifts the equilibrium of the catalyst-carbonic acid complex, leading the
catalyst to deprotonate and making it water-insoluble again. After a reaction is
completed in either organic solvent or water, the researchers separate the product and catalyst into different phases, remove the product, and then shuttle the catalyst back into the original phase for the next reaction cycle. Building switchability into basic chemicals in this manner could facilitate greener and less-energy-intensive industrial chemical processes.
能够转相的催化反应
通过简单的添加或除去二氧化碳，苏格兰的科学家发明了一种在两相系统中来回转运匀相催化剂的灵巧的把戏。
St. Andrews 大学的Simon L. Desset and David J. Cole-Hamilton 发明的这种可以转相的催化剂使得通常需要复杂的技术来分离产品和重复利
Angew. Chem. Int. Ed. Switchphos Bubbling CO 2 and then N 2 into a reaction tube modifies the rhodium catalyst’s phosphine ligands, switching the catalyst (yellow) from the organic reaction phase to the aqueous phase while the organic product is removed, and then back to a fresh organic phase.
用催化剂的均相反应的灵活性增强了。
催化剂的这种转相的能力的秘密是科学家在三苯基膦中的苯环上加上的弱碱性的脒基团，–N=C(CH3)N(CH3)2。
用这种修改过的配位体配位的催化剂铑可溶于有机溶剂。
当往水-有机含有催化剂的两相反应体系中通入CO2时，二氧化碳就和水反应生成碳酸。
碳酸电离的氢离子与脒基团结合，使得催化剂变成水溶性的。
之后，向两相体系通入氮气，赶走里面的二氧化碳，改变原有的平衡，从而使得催化剂再次变成疏水性的。
通过这样，科学家们就可以在有机相内的反应结束后，把催化剂转移到水中，然后将产物取走，之后，又把催化剂转到有机溶剂中，开始催化新的反应。
通过这种方式在基础化学上建立这种转换能力能够促进更环保和低能耗的化学工业。
W ater On The Moon
This year,
space
scientists were
finally able to
answer one of
the biggest
questions in
lunar science:
Is there water
on the moon?
The answer is
yes. NASA
announced last month that debris kicked up
during the deliberate crash of the Lunar Crater
Observation & Sensing Satellite (LCROSS)
spacecraft did contain a sprinkling of water and
possibly some organic compounds (C&EN, Nov.
23, page 31). LCROSS launched on June 18
together with a long-term mapping spacecraft, the Lunar Reconnaissance Orbiter. On Oct. 9, LCROSS sent a spent booster rocket crashing into a crater near the moon’s south pole and then hurtled itself into the crater in a planned self-destruction. Scientists had suspected water ice might exist in the permanently darkened crater, named Cabeus, and others like it. After several weeks of analysis, the team reported that both infrared and ultraviolet spectrometers had indeed found evidence of water in the plumes of debris created by the impacts—the tons of ejected material contained about 100 kg of water. Possible sources of the water include comets or hydrogen ions from the solar wind interacting with mineral oxides on the lunar surface.
月球上的水
今年，太空科学家终于可以回答月球科学中的大问题：月亮上有水吗？答案是，有。
NASA在上个月声明，精心准备的LCROSS飞行器撞击月球激起的废墟中确实有稀稀落落的水，可能还有一些有机化合物。
LCROSS在六月十八日和一个长期观测航天器，Lunar Reconnaissance Orbiter.（大致是一种绕月飞行的飞行器，我也不知道该叫它什么好了）一起发射升空。
十月九号，LCROSS发射了一个失效的火箭推进器撞向靠近月球南极的一个火山口，然后依照计划好的自毁计划，撞向了同一个火山口。
科学家们猜测在死火山的火山口处或者其他类似的地方存在冰。
这种死火山的火山口，称作Cabeus。
通过数周的分析，研究小组报告说，红外线和紫外线光谱仪都确实在撞击后的废墟喷发出来的烟柱中找到了水存在的证据——喷发出来的数吨物质中大约有100kg的水。
这些水可能的来源包括彗星或者来自太阳风的氢离子与月球表面的矿物中的氧的反应。
姐姐啊，这种文章真的不难，你真该拿本字典好好地自己翻译一下。
都快要读研的人了，这点英语都看不过来，还怎么去搞研究啊。
我翻
译得也不咋地，你自己看着办吧。