2-Butyl-2-tert-butyl-5,5-diethylpyrrolidine-1-oxyls: Synthesis and Properties

Nitroxides are broadly used as molecular probes and labels in biophysics, structural biology, and biomedical research. Resistance of a nitroxide group bearing an unpaired electron to chemical reduction with low-molecular-weight antioxidants and enzymatic systems is of critical importance for these applications. The redox properties of nitroxides are known to depend on the ring size (for cyclic nitroxides) and electronic and steric effects of the substituents. Here, two highly strained nitroxides, 5-(tert-butyl)-5-butyl-2,2-diethyl-3-hydroxypyrrolidin-1-oxyl (4) and 2-(tert-butyl)-2-butyl-5,5-diethyl-3,4-bis(hydroxymethyl)pyrrolidin-1-oxyl (5), were prepared via a reaction of the corresponding 2-tert-butyl-1-pyrroline 1-oxides with butyllithium. Thermal stability and kinetics of reduction of the new nitroxides by ascorbic acid were studied. Nitroxide 5 showed the highest resistance to reduction.

Download Full-text

Protamine Neutralization of the Release of Tissue Factor Pathway Inhibitor Activity by Heparins

Thrombosis and Haemostasis ◽

10.1055/s-0038-1649704 ◽

1993 ◽

Vol 70 (06) ◽

pp. 0942-0945 ◽

Cited By ~ 18

Author(s):

Job Harenberg ◽

Marietta Siegele ◽

Carl-Erik Dempfle ◽

Gerd Stehle ◽

Dieter L Heene

Keyword(s):

Tissue Factor ◽

Binding Sites ◽

Tissue Factor Pathway Inhibitor ◽

Factor Xa ◽

Protamine Sulfate ◽

Low Molecular Weight ◽

Factor X ◽

Rebound Phenomenon ◽

Tissue Factor Pathway ◽

Kinetics Of

SummaryThe present study was designed to investigate the action of protamine on the release of tissue factor pathway inhibitor (TFPI) activity by unfractionated (UF) and low molecular weight (LMW) heparin in healthy individuals. 5000 IU UF-heparin or 5000 IU LMW-heparin were given intravenously followed by saline, 5000 U protamine chloride or 5000 U protamine sulfate intravenously after the 10 min blood sample. Then serial blood samples for the measurement of TFPI activity and anti-factor Xa- activity were taken, in order to detect a possible relation between the remaining anti-factor X a activity after neutralization of LMW-heparin with protamine and TFPI activity and to establish whether or not a rebound phenomenon of plasmatic TFPI occurs.There was no difference in the release and in the kinetics of TFPI by UF- and LMW-heparin with subsequent administration of saline. After administration of protamine TFPI activity decreased immediately and irreversibly to pretreatment values. There were no differences between protamine chloride and protamine sulfate on the effect of TFPI induced by UF- or LMW-heparin. No rebound phenomenon of TFPI activity occurred. In contrast anti-factor Xa- activity, as measured by the chromogenic S2222-assay, issued the known differences between UF- and LMW-heparin. The half-life of the aXa-effect of LMW-heparin was twice as long as of UF-heparin. Protamine antagonized UF-heparin completely and about 60% of the anti-factor Xa activity of LMW-heparin, using chromogenic S2222-method. No differences could be detected for protamine chloride and sulfate form of protamineIt is assumed that protamine displaces heparins from the binding sites of TFPI. There were no differences between UF- and LMW-heparin. The data indicate that the sustained antifactor Xa activity after antagonization of LMW-heparins as well as heparin rebound phenomena are not mediated by TFPI activity.

Download Full-text

Kinetics of Reduction of Copper Oxide

International Journal for Research in Applied Science and Engineering Technology ◽

10.22214/ijraset.2018.4645 ◽

2018 ◽

Vol 6 (4) ◽

pp. 3928-3932

Author(s):

Divya Tyagi

Keyword(s):

Copper Oxide ◽

Kinetics Of ◽

Kinetics Of Reduction

Download Full-text

Kinetics of reduction of nickel(II) oxide with deuterium

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19771278 ◽

1977 ◽

Vol 42 (4) ◽

pp. 1278-1284 ◽

Cited By ~ 2

Author(s):

M. Pospíšil

Keyword(s):

Kinetics Of ◽

Kinetics Of Reduction

Download Full-text

The effect of origin and physico-chemical properties on the kinetics of reduction of mixed NiO-Fe2O3 oxides with hydrogen

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19862098 ◽

1986 ◽

Vol 51 (10) ◽

pp. 2098-2108 ◽

Cited By ~ 2

Author(s):

Milan Pospíšil ◽

Jan Topinka

Keyword(s):

Mixed Oxides ◽

Mutual Influence ◽

Spinel Phase ◽

Chemical Properties ◽

Inhibitory Effect ◽

Chemical Parameters ◽

Physico Chemical ◽

Preliminary Annealing ◽

Kinetics Of ◽

Kinetics Of Reduction

We investigated the effect of origin and some physico-chemical parameters on the kinetics of reduction with hydrogen of two series of mixed NiO-Fe2O3 oxides differing by their composition, the character of their precursors (mixed crystalline nitrates and coprecipitated hydroxides) and their decomposition temperature.This effect manifested itself by different magnitudes of specific surfaces of the mixed oxides and coherent regions of present phases as well as by different oxidizing abilities of the surface and differences in morphology and phase composition of corresponding samples in both series investigated. Nonlinear or nonmonotonous composition dependences of physico-chemical parameters investigated point to a mutual influence of individual components, which is also a function of the system origin and which modifies its reactivity during its reduction with hydrogen. The kinetics of the reduction was studied thermogravimetrically at 320-410 °C. The reduction of oxides of the hydroxide origin is catalytically accelerated by primarily reduced nickel, whereas in corresponding samples of the nitrate series, the total NiO is bound to the spinel phase and the reduction is delayed. Experimental IR spectra, the effect of preliminary annealing and DTA of the mixed oxides point to an inhibitory effect of water, which is constitutionally bound in trace admixtures of the goethite phase, on the kinetics of reduction of samples in the hydroxide series.

Download Full-text

Thermodynamic and Kinetic Investigation of the Solvent Effect on the Oxidation of [Co(en)2SCH2COO]+ with S2O82- In Water-Methanol and Water-tert-Butyl Alcohol Mixtures

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19931001 ◽

1993 ◽

Vol 58 (5) ◽

pp. 1001-1006 ◽

Cited By ~ 1

Author(s):

Oľga Vollárová ◽

Ján Benko

Keyword(s):

Transfer Functions ◽

Activation Parameters ◽

Butyl Alcohol ◽

Oxidation Of Co ◽

Kinetics Of Oxidation ◽

Tert Butyl ◽

Tert Butyl Alcohol ◽

Alcohol Mixtures ◽

Kinetics Of

The kinetics of oxidation of [Co(en)2SCH2COO]+ with S2O82- was studied in water-methanol and water-tert-butyl alcohol mixtures. Changes in the reaction activation parameters ∆H≠ and ∆S≠ with varying concentration of the co-solvent depend on the kind of the latter, which points to a significant role of salvation effects. The solvation effect on the reaction is discussed based on a comparison of the transfer functions ∆Ht0, ∆St0 and ∆Gt0 for the initial and transition states with the changes in the activation parameters accompanying changes in the CO-solvent concentration. The transfer enthalpies of the reactant were obtained from calorimetric measurements.

Download Full-text