The role of the double bond position in hydroboration using HBBr2·SMe2, HBCl2·SMe2 and H2BBr·SMe2: A detailed kinetic and mechanistic study

Polyhedron ◽  
2009 ◽  
Vol 28 (6) ◽  
pp. 1145-1149 ◽  
Author(s):  
N. Xaba ◽  
D. Jaganyi
Keyword(s):  
Double Bond ◽  
Double Bond Position ◽  
Mechanistic Study

Cholesterol interactions with tetracosenoic acid phospholipids in model cell membranes: role of the double-bond position

Biochemistry ◽  
1990 ◽  
Vol 29 (14) ◽  
pp. 3466-3471 ◽  
Author(s):  
Eser Ayanoglu ◽  
Bich Huong Chiche ◽  
Mark Beatty ◽  
Carl Djerassi ◽  
Nejat Duzgunes
Keyword(s):  
Double Bond ◽  
Cell Membranes ◽  
Double Bond Position ◽  
Model Cell

Porcine glutathione transferase Alpha 2-2 is a human GST A3-3 analogue that catalyses steroid double-bond isomerization

2010 ◽  
Vol 431 (1) ◽  
pp. 159-167 ◽  
Author(s):  
Natalia Fedulova ◽  
Françoise Raffalli-Mathieu ◽  
Bengt Mannervik
Keyword(s):  
Double Bond ◽  
Glutathione Transferase ◽  
Biological Species ◽  
Glutathione Transferases ◽  
Special Role ◽  
Primary Role ◽  
The Novel ◽  
Protective Function ◽  
Isomerase Activity

A primary role of GSTs (glutathione transferases) is detoxication of electrophilic compounds. In addition to this protective function, hGST (human GST) A3-3, a member of the Alpha class of soluble GSTs, has prominent steroid double-bond isomerase activity. The isomerase reaction is an obligatory step in the biosynthesis of steroid hormones, indicating a special role of hGST A3-3 in steroidogenic tissues. An analogous GST with high steroid isomerase activity has so far not been found in any other biological species. In the present study, we characterized a Sus scrofa (pig) enzyme, pGST A2-2, displaying high steroid isomerase activity. High levels of pGST A2-2 expression were found in ovary, testis and liver. In its functional properties, other than steroid isomerization, pGST A2-2 was most similar to hGST A3-3. The properties of the novel porcine enzyme lend support to the notion that particular GSTs play an important role in steroidogenesis.

Structural preferences for the double bond position in some unsaturated 3,3-diphenylpyrrolidines

1970 ◽  
Vol 48 (23) ◽  
pp. 3742-3745 ◽  
Author(s):  
M. M. A. Hassan ◽  
A. F. Casy
Keyword(s):  
Double Bond ◽  
Methyl Iodide ◽  
Quaternary Salt ◽  
Double Bond Position ◽  
Magnesium Bromide ◽  
Free Base ◽  
Spectroscopic Evidence ◽  
Structural Preferences ◽  
Ethyl Magnesium Bromide ◽  
Sole Product

The reaction between 3,3-diphenyl-3-cyano-1-methylpropyl isocyanate and ethyl magnesium bromide leads to 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline rather than the isomeric 2-ethylidenepyrrolidine. The protonated N-methyl analogue (identical with a major metabolite of methadone) retains the 1-pyrroline structure, but the free base is a cis-trans mixture of the corresponding 2-ethylidenepyrrolidines; the cis Me/Ph isomer preponderates and is the sole product (obtained as a quaternary salt) when the mixture is treated with methyl iodide. 5-Methyl-2-methylene-3,3-diphenylpyrrolidine, a lower homologue of the methadone metabolite, isomerizes to a 1-pyrroline derivative when protonated or methylated. All structural conclusions are based on i.r. and p.m.r. spectroscopic evidence.

scholarly journals Interplay of Unsaturated Phospholipids and Cholesterol in Membranes: Effect of the Double-Bond Position

2008 ◽  
Vol 95 (7) ◽  
pp. 3295-3305 ◽  
Author(s):  
Hector Martinez-Seara ◽  
Tomasz Róg ◽  
Marta Pasenkiewicz-Gierula ◽  
Ilpo Vattulainen ◽  
Mikko Karttunen ◽  
...  
Keyword(s):  
Double Bond ◽  
Double Bond Position

Mechanistic Study of the Role of One-Component Resins in Rubber-to-Brass Bonding in Tires

2004 ◽  
Vol 77 (5) ◽  
pp. 891-913 ◽  
Author(s):  
Pankaj Y. Patil ◽  
William J. van Ooij
Keyword(s):  
Reaction Time ◽  
Secondary Ion Mass Spectrometry ◽  
Gel Permeation Chromatography ◽  
Mechanistic Study ◽  
Coated Steel ◽  
Adhesion Promoters ◽  
Steel Cords ◽  
Adhesion Performance ◽  
Secondary Ion

Abstract Adhesion between rubber and brass-coated steel cords is enhanced by using resins as adhesion promoters. Experiments were carried out using a squalene liquid rubber modeling approach to study the effect of resins on the chemistry of the vulcanization reaction. The formation of new intermediates during vulcanization and changes in chemical concentrations with reaction time was studied using Gel Permeation Chromatography (GPC) analysis of the reacted squalene mixtures. Also, the effect of presence of resins on the surface of sulfidized brass cords was studied by analyzing the adhesion layer's elemental composition using the Electron Dispersive X-ray Spectroscopy (EDX) and Secondary Ion Mass Spectrometry (SIMS) characterization techniques. The changes in surface morphology of the adhesion layer with reaction time was noted by taking micrographs using the Scanning Electron Microscopy (SEM) technique. In this paper, a new mechanism is proposed for the role of resins in the improvement of initial and aged adhesion performance between rubber and brass-coated steel tire cords.

Sign in / Sign up

Export Citation Format

Share Document