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Summary Optically pure (+)-beta-eudesmol is a possible starting material for the synthesis of several termite defense compounds. A
two step procedure for the isolation of gram quantities of (+)-beta-eudesmol from commercially availableAmyris balsamifera oil (syn. West Indian sandalwood oil), containing 8% beta-eudesmol, was developed. Step one consisted of an efficient vacuum
distillation of the total oil. Step two was a medium pressure LC separation with an AgNO3 impregnated silica gel stationary phase. Several other separation procedures failed due to the presence of many closely related
sesquiterpene alcohols (75% of the oil). 相似文献
3.
Abdurashitov JN Gavrin VN Girin SV Gorbachev VV Ibragimova TV Kalikhov AV Khairnasov NG Knodel TV Kornoukhov VN Mirmov IN Shikhin AA Veretenkin EP Vermul VM Yants VE Zatsepin GT Bowles TJ Nico JS Teasdale WA Wark DL Cherry ML Karaulov VN Levitin VL Maev VI Nazarenko PI Shkol'nik VS Skorikov NV Cleveland BT Daily T Davis R Lande K Lee CK Wildenhain PW Khomyakov YS Zvonarev AV Elliott SR Wilkerson JF 《Physical review letters》1996,77(23):4708-4711
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Abazov AI Anosov OL Faizov EL Gavrin VN Kalikhov AV Knodel TV Knyshenko II Kornoukhov VN Mezentseva SA Mirmov IN Ostrinsky AV Pshukov AM Revzin NE Shikhin AA Timofeyev PV Veretenkin EP Vermul VM Zatsepin GT Bowles TJ Cleveland BT Elliott SR O'Brien HA Wark DL Wilkerson JF Davis R Lande K Cherry ML Kouzes RT 《Physical review letters》1991,67(24):3332-3335
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Interferences affecting the determination of butyltin species by sodium tetraethylborate (STEB) derivatisation followed by purge-trap preconcentration were systematically studied using synthetic solutions, natural water samples and sediment extracts. Substances that did not cause interferences included most common cations (apart from those metal ions listed below), anions, metalloids and polar organic compounds. Natural organic matter (NOM) specifically interfered with tributyltin (TBT) due to a mechanism involving partitioning of the butyltin to the hydrophobic portions of the NOM. The metal ions Ag(I) (≥2 μM), Cd(II) (≥2 μM), Cu(II) (≥0.5 μM) interfered predominantly with the determination of monobutyltin (MBT) due to catalytic degradation of the STEB reagent. Pb(II) (≥14 μM) interfered with butyltin determination by an unknown mechanism. Other interferences to the purge-trap method were shown to occur in the presence of chelating agents (e.g. EDTA) or hydrophobic liquids such as diesel fuel. A mixture comprising methanol (MeOH), EDTA and Mn(II) was used to partially mask the effect of interfering NOM and metals. Spike recoveries (mean±S.D. of n=7 different samples) of MBT, dibutyltin (DBT) and TBT in contaminated natural water samples were improved from 70±36,90±11 and 91±24 to 102±10,98±3 and 98±4%, respectively. Spike recoveries (mean±S.D. of n=5 different samples) of MBT, DBT and TBT in aliquots of sediment extracts were improved from 86±17,79±18 and 59±32 to 97±6.2,103±3.6 and 103±5.0%, respectively. The ability to analyse larger aliquots of sediment extracts in the presence of the masking mixture improved the detection limit four-fold if MBT and DBT determination was required and 10-fold if only TBT determination was required. 相似文献
8.
A new synthetic route to stable spin-delocalized radicals, annelated nitronyl nitroxides, has been developed on the basis of the condensation of benzofuroxan with aryl nitrones. The electronic structure of the resulting radicals was investigated through absorption spectroscopy, EPR, electrochemistry, and computation (DFT-UB3LYP). The annelated radicals exhibit electronic transitions in the near IR (850-900 nm) and are excellent electron acceptors (E(red) approximately 0.0 vs SCE) ideal for the development of multifunctional magnetic materials. 相似文献
9.
Benkoski JJ Bowles SE Korth BD Jones RL Douglas JF Karim A Pyun J 《Journal of the American Chemical Society》2007,129(19):6291-6297
The assembly and direct imaging of ferromagnetic nanoparticles into one-dimensional mesostructures (1-D) are reported. Polymer-coated ferromagnetic colloids (19 nm, 24 nm) were assembled at a crosslinkable oil-water interface under both magnetic field induced and zero-field conditions and permanently fixed into 1-D mesoscopic polymer chains (1-9 mum) in a process referred to as Fossilized Liquid Assembly (FLA). In the FLA process, nanoparticle chains were fixed at the oil interface through photopolymerization, enabling direct visualization of organized mesostructures using atomic force microscopy. Using the FLA methodology, we systematically investigated different conditions and demonstrated that dispersed ferromagnetic colloids possess sufficient dipolar interactions to organize into mesoscopic assemblies. Application of an external magnetic field during assembly enabled the formation of micron-sized chains which were aligned in the direction of the applied field. This universal methodology is an attractive alternative technique to cryogenic transmission electron microscopy (cryo-TEM) for the visualization of nanoparticle assembly in dispersed organic media. 相似文献
10.
Air oxidation of N-cyclopropylanilines was shown to occur under either ambient conditions or accelerated conditions (warming or shining light) in an open container. A subsequent fragmentation resulted in formation of the corresponding acetamide. While potential mechanisms have been previously proposed, simple aerobic oxidation to β-hydroxy-propionamides in the absence of a radical promoter has not been previously reported. 相似文献