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Butyl Derivative (butyl + derivative)
Selected AbstractsHeteropolynuclear Palladium Complexes with Pyrazolate and Its 3- tert -Butyl Derivatives: The Effect of Heterometal Ions on the Rate of IsomerizationCHEMISTRY - A EUROPEAN JOURNAL, Issue 19 2006Keisuke Umakoshi Prof. Dr. Abstract The heteropolynuclear complexes [Pd2M,2(,-pz)6] (M,=Ag (1), Au (2); pzH=pyrazole), HT -[Pd2M,2(,-3- tBupz)6] (M,=Ag (3,a), Au (4,a); 3- tBupzH=3- tert -butylpyrazole), and HH -[Pd2Au2(,-3- tBupz)6] (4,b) have been prepared and some of them were structurally characterized. When 3- tert -butylpyrazolate was employed as a bridging ligand, two linkage isomers (head-to-tail (HT) and head-to-head (HH)) arise from the difference in orientation of the substituent groups on the pyrazolate bridges between the two Pd atoms. 1H NMR spectroscopy has been used to identify and to follow the reversible stereochemical rearrangement of the HH isomer of [Pd2Ag2(,-3- tBupz)6] (3,b) to form the HT isomer 3,a in CDCl3 and the HT isomer of [Pd2Au2(,-3- tBupz)6] (4,a) to form the HH isomer 4,b in C6D6. Kinetic studies of the reaction have established the rate law to be ,d(HH)/dt=d(HT)/dt=k2[HH],k1[HT] for 3,b and ,d(HT)/dt=d(HH)/dt=k1[HT],k2[HH] for 4,a, where k1 and k2 denote the rate of isomerization from the HT to the HH isomer and that from the HH to the HT isomer, respectively. For typical runs at 50,°C in C6D6, k1=13.8×10,5 s,1, k2=18.6×10,5 s,1, and Keq=k2/k1=1.24 for 3,b, and k1=1.26×10,5 s,1, k2=3.52×10,5 s,1, and Keq=k1/k2=0.36 for 4,a. Temperature-dependent rate measurements reveal ,H, and ,S, to be 100(1) kJ,mol,1 and 0(3) J,mol,1,K,1 for 3,b and 112(5) kJ,mol,1 and 20(17) J,mol,1,K,1 for 4,a, respectively. The rate of isomerization is essentially unaffected by the concentration of the complex or by the presence of neutral bridging ligands. These data and observations imply that the isomerization involves an intramolecular exchange process. [source] ChemInform Abstract: Synthesis and Properties of 2-(4-Substituted)butyl Derivatives of Some 2,3-Dihydro-1,3-dioxo-1H-pyrrolo[3,4-c]pyridines.CHEMINFORM, Issue 18 2001H. Sladowska Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] N -Isopropyl enols of carboxylic acid amides,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2003Yi Xiong Lei Abstract Eight N -isopropyl compounds of the formal structure YY,CHCONHPr- i (6), Y,Y,,=,CO2Me, CO2CH2CF3, CN; YY,,=,Meldrum,s acid residue; Y,=,CO2Me, Y,,=,CO2CH2CF3, CN; Y,=,CO2CH2CF3, CO2CH(CF3)2, Y,,=,CN, and the N - t -butyl derivative of Meldrum's acid were prepared and their structures were investigated in the solid state and in solution. The x-ray diffraction data indicate that in the solid state the structure is that of the amide 6, when Y,=,Y,,=,CO2Me, whereas when Y,=,CO2Me, Y,,=,CN or YY,,=,Meldrum,s acid residue the structure is that of the enol (5) YY,C=C(OH)NHPr- i. The solid-state 13C spectra indicate structure 6 when Y,=,CO2Me, Y,,=,CO2R, R,=,Me, CH2CF3 and an enol structure for the other compounds studied. 1H, 13C and when available 19F NMR spectra showed that the enol/amide composition in solution is structure and solvent dependent, in analogy with the previously investigated N -Ph analogs. The percentage of enol (and KEnol) decrease in the order of solvents CCl4,>,CDCl3,>,THF- d8,>,CD3CN,>,DMSO- d6, DMF- d7. For Y,Y, the percentage of enol increases when the number of fluorine atoms in R of the CO2R increases, when CN replaces a CO2R group or for the cyclic Meldrum's acid derivative. Both E - and Z -enols were observed when Y,,,Y,, mostly at low temperature. The ,(OH) values increase with increased polarity of the medium and with increased strength of the hydrogen bonds in which they are involved. In THF- d8 and DMF- d7 the Z -enol/E -enol and the amide/enol ratios increase with increase in temperature. A main conclusion from the work is that the percentage of the enol increases, but not drastically, when the N -substituent is changed from Ph to i -Pr. Copyright © 2003 John Wiley & Sons, Ltd. [source] Pharmacokinetics of 4-aminopyridine derivatives in dogsJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2009N. J. OLBY Blockade of potassium channels with 4-aminopryidine (4-AP) restores conduction to demyelinated axons and improves function. Unfortunately, 4-AP causes adverse effects and its clinical effects are unpredictable and limited. Derivatives of 4-AP have been tested in models of spinal cord injury in guinea pigs; three derivatives (methyl-, ethyl- and t -butyl carbamate derivatives) showed promise. This study investigates the safety and pharmacokinetics of these derivatives in dogs. Each derivative was administered orally to dogs starting at doses below effective doses in guinea pigs, and increasing the dose on sequential days. Routine blood work was performed prior to and 24 h after drug administration, blood samples were collected at intervals over 24 h after drug administration, and dogs were monitored for side effects. Derivative plasma levels were determined using high-pressure liquid chromatography. Cerebrospinal fluid (CSF) samples were taken to determine CSF levels. No adverse effects were seen even when using doses higher than those that improved conduction in spinal cord injured guinea pigs. Peak plasma levels occurred at 36.6 (ethyl), 87 (t -butyl) and 175 (methyl) min and plasma level was related to drug dose. Penetration of the central nervous system (CNS) was good, with CSF levels higher than plasma levels for the t -butyl derivative. [source] Basic forms of supramolecular self-assembly organized by parallel and antiparallel hydrogen bonds in the racemic crystal structures of six disubstituted and trisubstituted cyclopentane derivativesACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2001Alajos Kálmán A selection of stereoisomeric 2-hydroxy-1-cyclopentanecarboxamides, a 4- tert -butyl derivative and three tert -butyl derivatives of the respective carboxylic acid were subjected to X-ray crystallography. The optically active molecules (I),(VI) form racemic crystals. Each racemic structure is basically determined by two intermolecular hydrogen bonds of O,H,O=C,XH and O=C,X,H,OH types (X = O, NH). The partially similar patterns of close packing observed reflect five basic forms of supramolecular self-assembly. In the racemic crystals of chiral molecules, there are homo- and heterochiral chains of molecules formed by the principal (O,H,O=C) hydrogen bonds. These chains assemble either in a parallel or antiparallel mode. The parallel homochiral chains (hop) observed in structure (II), (1R*,2R*)-2-hydroxy-1-cyclopentanecarboxamide, demand the polar space group Pca21, while the parallel heterochiral chains (hep) are organized in antiparallel layers with space group P21/n in structure (VI), (1R*,2S*,5R*-5- tert -butyl-2-hydroxy-1-cyclopentanecarboxylic acid). Heterochiral chains in an antiparallel array (hea) are found in (I), (1R*,2S*)-2-hydroxy-1-cyclopentanecarboxamide, and (V) [(1R*,2S*4S*)-4- tert -butyl-2-hydroxy-1-cyclopentanecarboxylic acid, space group P21/c]. Structures (IV), (1R*,2S*,4R*)-4- tert -butyl-2-hydroxy-1-cyclopentanecarboxylic acid, and (III), (1R*,2R*,4S*)-4- tert -butyl-2-hydroxy-1-cyclopentanecarboxamide, reveal that homochiral chains in an antiparallel array (hoa; cross-linked by heterochiral dimers held together by the second hydrogen bonds) can be formed by either translation (space group P) or a screw axis (space group P21/c). These alternatives are denoted hoa1 and hoa2. Similarly, within each pattern (hea, hep and hop) two slightly different alternatives can be expected. The partial similarities in the identified five patterns of hydrogen bonding are described by graph-set notations. Structures (I), (IV) and (V) can be characterized by a common supramolecular synthon, while the highest degree of similarity is shown by the isostructurality of (I) and (V). [source] Asymmetrical Fluorene[2,3- b]benzo[d]thiophene Derivatives: Synthesis, Solid-State Structures, and Application in Solution-Processable Organic Light-Emitting DiodesCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2009Chunyan Du Abstract A series of novel asymmetrical fused compounds containing the backbone of fluorene[2,3- b]benzo[d]thiophene (FBT) were effectively synthesized and fully characterized. Single-crystal X-ray studies demonstrated that the length of the substituent side chains greatly affects the solid-state packing of the obtained fused compounds. DFT, photophysical, and electrochemical studies all showed that the FBTs have large band gaps, low-lying HOMO energy levels, and therefore good stability toward oxidation. Moreover, the substituents strongly influence the fluorescence properties of the resulting FBT derivatives. The di- n -hexyl compound exhibits intense fluorescence in solution with the highest quantum yield of up to 91,%. Solution-processed green phosphorescent organic light-emitting diodes with the di- n -butyl derivative as the host material exhibited a maximum brightness of 14,185,cd,m,2 and a luminescence efficiency of 12,cd,A,1. [source] Basic forms of supramolecular self-assembly organized by parallel and antiparallel hydrogen bonds in the racemic crystal structures of six disubstituted and trisubstituted cyclopentane derivativesACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2001Alajos Kálmán A selection of stereoisomeric 2-hydroxy-1-cyclopentanecarboxamides, a 4- tert -butyl derivative and three tert -butyl derivatives of the respective carboxylic acid were subjected to X-ray crystallography. The optically active molecules (I),(VI) form racemic crystals. Each racemic structure is basically determined by two intermolecular hydrogen bonds of O,H,O=C,XH and O=C,X,H,OH types (X = O, NH). The partially similar patterns of close packing observed reflect five basic forms of supramolecular self-assembly. In the racemic crystals of chiral molecules, there are homo- and heterochiral chains of molecules formed by the principal (O,H,O=C) hydrogen bonds. These chains assemble either in a parallel or antiparallel mode. The parallel homochiral chains (hop) observed in structure (II), (1R*,2R*)-2-hydroxy-1-cyclopentanecarboxamide, demand the polar space group Pca21, while the parallel heterochiral chains (hep) are organized in antiparallel layers with space group P21/n in structure (VI), (1R*,2S*,5R*-5- tert -butyl-2-hydroxy-1-cyclopentanecarboxylic acid). Heterochiral chains in an antiparallel array (hea) are found in (I), (1R*,2S*)-2-hydroxy-1-cyclopentanecarboxamide, and (V) [(1R*,2S*4S*)-4- tert -butyl-2-hydroxy-1-cyclopentanecarboxylic acid, space group P21/c]. Structures (IV), (1R*,2S*,4R*)-4- tert -butyl-2-hydroxy-1-cyclopentanecarboxylic acid, and (III), (1R*,2R*,4S*)-4- tert -butyl-2-hydroxy-1-cyclopentanecarboxamide, reveal that homochiral chains in an antiparallel array (hoa; cross-linked by heterochiral dimers held together by the second hydrogen bonds) can be formed by either translation (space group P) or a screw axis (space group P21/c). These alternatives are denoted hoa1 and hoa2. Similarly, within each pattern (hea, hep and hop) two slightly different alternatives can be expected. The partial similarities in the identified five patterns of hydrogen bonding are described by graph-set notations. Structures (I), (IV) and (V) can be characterized by a common supramolecular synthon, while the highest degree of similarity is shown by the isostructurality of (I) and (V). [source] | ||||||||||