Review of The Illustrated Guide to Home Chemistry Experiments by Robert Thompson. Posted at Kevin Kelly's Cool Tools Blog
Actually a review of two books - the author reminisces about The Golden Book of Chemistry Experiments from 1960, to start off. In singing the praises of this out-of-print and not obsessively safety-concious tome from the last century, the author defines his standards. He then goes on to describe the corresponding good points, common sense and practicality of the featured work. This book is for hobbyists and homeschoolers who need a practical guide to real chemistry while being thrifty regarding amounts, substitutions and equipment. Even disposal after the experiements is covered. This work is truly unique in its quality and scope.
Using FTIR Spectroscopy to Analyze Gemstones. Stephen Lowry. American Laboratory May 2008, Vol. 40, No. 10.
Lowry presents an interesting use of FTIR spectroscopy to evaluate gemstones. IR can't distinguish among colors of rubies and sapphires which are essentially aluminum oxide which depend on ppm levels of metal atoms for their colors. Common stone enhancement techniques, however, tend to use heat which drives off naturally occurring water. FTIR detects naturally occurring water which is not present in synthetic stones or enhanced natural stones. Emeralds are aluminum and beryllium silicates with traces of chromium atoms providing color. Acceptable enhancements involve treatment with natural waxes or oils, while refractive index-matching polymers are considered "too" synthetic. FTIR can distinguish among these common enhancement techniques.
An efficient biomimetic Fe-catalyzed epoxidation of olefins using hydrogen peroxide. Anilkumar, Bitterlich, Gelalcha, Tse and Beller. Chem. Commun. 2007, 289-291.
Efficient biomimetic epoxidation catalysts are sought for industrial use to mimic the selectivity, reactivity and mild conditions found in systems of biochemical origin. These researchers found that ferric chloride (5 mol%) with pyridine-2,6-dicarboxylic acid (10 mol%) and hydrogen peroxide (2 equiv) as the terminal oxidant convert terminal and 1,2-disubstituted olefins to epoxides at room temperature with good selectivity.
An Aqueous Rechargeable Lithium Battery with Good Cycling Performance. Wang, Fu, Zhao, Yang, Wu and Wu. Angew. Chem. Int. Ed. Eng. 2007, 46, 295-297.
A Li-ion battery with an aqueous electrolyte and good cycling characteristics is reported. The cathode is lithium cobalt oxide (LiCoO3) and the anode is lithium vanadate (LiV3O8) and aqueous, saturated lithium nitrate (LiNO3) is the electrolyte. Aqueous electrolytes are attractive is high-rate cells due to their higher conductivity over inorganic electrolytes by two orders of magnitude.
A Designed Receptor for pH-Switchable Ion Binding in Water. Tajc, S.G. and Miller, B.LJ. Am. Chem. Soc. 2006, 128, 2532-2533.
The authors performed conformational studies by molecular mechanics of a trityrosine derivative of a 1,3,5 tricarbinolcyclohexane. The p-hydroxyl group on each tyrosine can hydrogen bond to a neighboring amino-nitrogen. The investigators then synthesized the molecule, as well as a non-hydroxy version as a control, to verify the computational predictions. 1H-1H NOESY studies by NMR and isothermal titration calorimetry confirmed the pH-dependent behavior. Neither the control compound lacking hydroxyls or tyrosine methyl ester showed the pH-dependent NMR results. Zn2+ and Cd2+ ions were bound inside the cavity formed by the closed conformation of the model receptor.
Vitamin E Imaging and Localization in the Neuronal Membrane. Monroe, Jurchen, Lee, Rubakhin and Sweedler. J. Am. Chem. Soc. 2005, 127, 12152-12153.
While a typical view of Vitamin E is as a fat-soluble antioxidant, these authors demonstrate a significant neurological function by using single-cell time-of-flight secondary ion mass spectrometry (ToF-SIMS) and found the highest concentration if Vitamin E in tissues at the soma-neurite junction.
Iodobenzene-Catalyzed a-Acetoxylation of Ketones. In situ Generation of Hypervalent (Diacyloxyiodo)benzenes Using m-Chloroperbenzoic Acid. Ochiai, Taheuchi, Katayama, Sueda and Miyamoto. J. Am. Chem. Soc. 2005, 127, 12244-12245.
Ketones are a-acetoxylated in good (41-83%) yields by catalytic generation of the diacyloxyiodo intermediate by m-chloroperbenzoic acid (2 equiv) and iodobenzene (10 mol%) in the presence of boron trifluoride etherate. Some (5-10 mol%) water is necessary for the reaction to proceed.
Ionic Liquids: The Neglected Issues. Scammells, Scott and Singer. Aust. J. Chem. 2005, 58, 155-169.
Great review of what many authors don't say about ionic liquids as a reaction medium. Addresses purity, stability, biodegradability, toxicity and recyclability. The range of behaviors in each of these categories is great and needs to be kept in mind.
Abnormal Solvent Effects on Hydrogen Atom Abstraction. 2. Resolution of the Curcumin Antioxidant Controversy. The Role of Sequential Proton Loss Electron Transfer. Litwinienko, G.; Ingold, K.U. J. Org. Chem. 2004, 69, 5888-5896.
The authors resolve a controversy about curcumin, a yellow phenolic compound present in tumeric and curry. Its antioxidant properties make it an attractive molecule to study. Jovanovich in 1999, proposed a hydrogen atom transfer mechanism (HAT) to account for the reported high AO activity. Barclay questioned whether the structure or technique were able to support such a conclusion and found curcumin to be a normal phenolic chain-breaking antioxidant.
The present study on curcumin and derivatives showed that a relatively slow HAT occurred only in non-ionizing media, but when the solvent permitted ionization a new mechanism called sequential proton loss electron transfer occurred with much higher rates on radical chain-inhibition. So, the phenoxy radical formed initially, followed by charge migration from phenolic O- to the keto/enol CH2.
Ionic Liquids as a Convenient New Medium for the Catalytic Asymmetric Dihydroxylation of Olefins Using a Recoverable and Reusable Osmium/Ligand. Branco and Afonso. J. Org. Chem. 2004, 69, 4381-4389.
Gives examples of ionic liquids used for the Sharpless asymmetric dihydroxylation of styrene or 1-hexene with yields in the 80-95% range and ee of 80-90%. The facile recovery and recycling of the osmium catalyst overcomes the cost and toxicity objections for a successful industrial process.
Cooperative Effects in the Activation of Molecular Oxygen by Anionic Silver Clusters. Hagen, Bernhardt, et al. J. Am. Chem. Soc. 2004, 126, 3442-3443.
The structure of the intermediates of silver cluster catalysts (useful for ethylene) and molecular oxygen are deduced by experiment and theory. When the number of Ag atoms in the cluster is odd (1, 3, 5) one O2 is weakly bound to the cluster in the rate-determining step, followed by a second, more strongly bound O2. This last oxygen has a lengthened O-O bond indicating activation in preparation for reaction.
Baeyer-Villager Oxidations in Ionic Liquids. A Facile Conversion of Ketones to Esters and Lactones. Yadav et al. Chemistry Letters 2004, 33, 248.
The usefulness of the Baeyer-Villager oxidation of ketones and esters to lactones is due to the ring-expansion and functional group transformation abilities of this reaction. The slow rates observed with m-chlororperbenzoic acid (mCPBA), frequent need for an acid catalyst and aqueous workup detract from its usefulness. This article reports oxidation by mCPBA in ionic liquids [bmim]BF4 (and others) proceed smoothly and quickly without added acids but with high yields, high selectivity, and constant activity when the solvent is recycled. I would expect similar improvements in industrial oxidations in ionic liquids to be just around the corner.
The Sulfur Chemistry of Shiitake Mushrooms. George et al. J. Am. Chem. Soc 2004, 126, 458-459.
The rich sulfur chemistry of shiitake mushrooms was thought to be similar to that of the allium genus (onion, garlic, Chinese chive, etc) in that cell damage leads to enzymatic oxidations generating a highly reactive sulfenic acid, whose subsequent reactions lead to herbivore deterrents (onion lachrymator) and aroma and flavor components prized in food. This paper reports the utility of K-edge X-ray absorption spectroscopy on intact and homogenized samples in identifying the sulfur species present. The compounds do not change significantly on cell disruption or air oxidation and thus do not seem to be candidates for herbivore deterrents.
Evidence for Ozone Formation in Human Atherosclerotic Arteries. Wentworth et al. Science 7 Nov 2003: 1053-1056.
Chemical signatures of ozonolysis of cholesterol suggest ozone is produced in and by tissues. The steroidal oxidation products are implicated in the development of arterial disease.
Catalytic Reduction of Dinitrogen to Ammonia at a Single Molybdenum Center. Yandulov and Schrock. Science 4 Jul 2003: 76-78.
This important reaction is the one behind nitrogen fixation in plants that take molecular nitrogen from the atmosphere and convert it to a reduced form usable by plants.
Efficient Epoxidation of Olefins with >99% Selectivity and Use of Hydrogen Peroxide. Mizuno et al; Science 9 May 2003: 964-966.
Olefins are epoxidized under mild conditions with minimal by-products and high efficiency by hydrogen peroxide by using an easily prepared silicon-tungstate catalyst. The homogeneous catalyst can be easily recovered from the reaction mixture.
Microstructural Optimization of a Zeolite Membrane for Organic Vapor Separation. Tsapatsis et al. Science, 18 Apr 2003: 456-460.
Seeded growth of films provides membranes with structural features such as 5.5Å channels that give superior separations of molecules of similar size and shape, such as xylene isomers.
The Pentacovalent Phosphorus Intermediate of a Phosphoryl Transfer Reaction. Dunaway-Mariano, Allen, et al. Science 28 Mar 2003: 2067-2071.
The pathway of biological phosphorylation is illuminated in an X-ray structure study. An enzyme was crystallized in the presence of co-factors and substrates and the X-ray diffraction results show a 5-cordinate intermediate.
Carbon Nanotube Flow Sensors. Ghosh, Sood and Kumar. Science 14 Feb 2003: 1042-1044.
Liquid flow in carbon nanotube bundles induces in the liquid a voltage with a logarithmic velocity dependence. The magnitude of the voltage depends on the ionic conductivity and polar nature of the liquid. This could be the basis for a microscopic flow meter of the future.
