Proposed fluorination mechanism of CB(5)H(6)(-) and CB(9)H(10)(-) with HF. Evidence of kinetic control in the formation of 2-CB(5)H(5)F(-) and 6-CB(9)H(9)F(-)

Two pathways have been considered in the fluorination of CB(5)H(6)(-) and CB(9)H(10)(-) by HF. In the ionic HF fluorination pathway, the monocarborane anion cage is first protonated in a BBB face followed by H(2) elimination and fluoride anion addition. In the covalent HF fluorination pathway, HF is first coordinated through hydrogen to the BBB face. Next, the fluorine can add to either an axial or equatorial boron atom which opens the cage to a nido structure with an endo fluoride substituent. Endo to exo rearrangement occurs with a small activation barrier followed by H(2) elimination. In both pathways, fluorination at the equatorial boron position is predicted to have smaller activation barriers even though substitution at the axial position leads to the more stable products.     

Synthesis of 3-(aminooxoethyl)-6-methyl-1-(thiethan-3-yl)-pyrimidine-2,4-(1H,3H)-diones

A new approach to prepare 2-chloroacetamides has been developed, based on the reaction of chloroacetyl chloride with excess of secondary amines. Alkylation of 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1H,3H)-dione with the synthesized 2-chloroacetamides in the presence of potassium carbonate has afforded N ³-acetamido-substituted 6-methyl-1-(thiethan-3-yl)pyrimidine-2,4(1H,3H)-diones.     

OH(3) (-) and O(2)H(5) (-) double Rydberg anions: predictions and comparisons with NH(4) (-) and N(2)H(7) (-)

A low barrier in the reaction pathway between the double Rydberg isomer of OH(3) (-) and a hydride-water complex indicates that the former species is more difficult to isolate and characterize through anion photoelectron spectroscopy than the well known double Rydberg anion (DRA), tetrahedral NH(4) (-). Electron propagator calculations of vertical electron detachment energies (VEDEs) and isosurface plots of the electron localization function disclose that the transition state's electronic structure more closely resembles that of the DRA than that of the hydride-water complex. Possible stabilization of the OH(3) (-) DRA through hydrogen bonding or ion-dipole interactions is examined through calculations on O(2)H(5) (-) species. Three O(2)H(5) (-) minima with H(-)(H(2)O)(2), hydrogen-bridged, and DRA-molecule structures resemble previously discovered N(2)H(7) (-) species and have well separated VEDEs that may be observable in anion photoelectron spectra.     

Synthesis of (-)-(S)-3-sec-butyl- and (+)-(S)-5-sec-butyl-2(1H)-pyridinone

Optically active (+)-(S)-5-sec-butyl- and (-)-(S)-3-sec-butyl-2(1H)-pyridinone are synthesized and the relationship between optical activity and minimum optical purity of the latter is determined.     

An equilibrium analysis of the aqueous H+-MoO4(2-)-(HP)O(3)2- and H+-MoO4(2-)-(HP)O(3)2--HPO4(2-) systems

The speciation in the phosphitomolybdate system, H+-MoO4(2-)-(HP)O(3)2-, has been determined from combined potentiometric and 31P NMR measurements in 0.600 M Na(Cl) medium at 298(1) K. Potentiometric titration data were collected in the ranges 2.5<-log[H+]<6.2, 40.0相似文献   

Syntheses and Structural Characterization of 1-（4-Phenyl-2-thiazolyl）-3-（4-methylphenyl）-5-（2-furyl）-4,5-dihydro-（1H）-pyrazole and 1-（4-（4-Fluoro）phenyl-2-thiazolyl）-3-（4-methyl-phenyl）-5-（2-furyl）-4,5-dihydro-（1H）-pyrazole

The title compounds were synthesized and characterized by IR,1H-NMR,Mass and elementary analysis and single-crystal X-ray diffraction.In 1a,intermolecular C-H…π interactions produce a three-dimensional network.In 1b,intermolecular C-H…O hydrogen bonds generate an R22(22) ring.The hydrogen bonding is supported by C-H…π interactions.