The influence of a substituent with free radical character (reverse effect) on some nucleophilic substitutions involving benzylic systems

1983 ◽  
pp. 982-983 ◽  
Author(s):  
Manuel Ballester ◽  
Jaime Veciana ◽  
Juan Riera ◽  
Juan Castañer ◽  
Olga Armet ◽  
...  
Keyword(s):  
Free Radical ◽  
Reverse Effect ◽  
Nucleophilic Substitutions ◽  
Radical Character

The chemistry of pyrrolic compounds. III. The free radical nature of the oxyporphyrins

1966 ◽  
Vol 19 (8) ◽  
pp. 1481 ◽  
Author(s):  
PS Clezy ◽  
FD Looney ◽  
AW Nichol ◽  
GA Smythe
Keyword(s):  
Free Radical ◽  
Structure Of Molecules ◽  
Radical Nature ◽  
Radical Character

The preparation of a-meso-oxy-1,2,3,4,5,8-hexamethyl-6,7-bis-(2?- ethoxycarbonylethyl)porphin (Ib), a new member of the oxyporphyrin series, is described. The structure of molecules of this type, which have now been shown to exhibit radical character, is further discussed.

Investigation of Radical and Polar Mechanisms in Vulcanization Reactions

1960 ◽  
Vol 33 (2) ◽  
pp. 342-356 ◽  
Author(s):  
J. Reid Shelton ◽  
E. T. McDonel
Keyword(s):  
Free Radical ◽  
Curing Temperature ◽  
Zinc Salt ◽  
Crosslinking Reaction ◽  
Zinc Salts ◽  
Single Complex ◽  
Radical Traps ◽  
Radical Character ◽  
Polar Mechanism ◽  
Curing Systems

Abstract The results obtained with free radical traps in a variety of curing systems for SBR rubber give evidence for both polar and free radical mechanisms. There is apparently no one mechanism even for sulfur vulcanization and the relative free radical or polar character of the crosslinking reaction varies over a broad range including situations in which both types occur in the same formulation. This may be due to competing reactions which function independently, or it may be the result of a combination of polar and free radical reactions in a single complex mechanism. For example, certain accelerators may initiate the reaction by dissociation to free radicals which attack the S8 molecule and form polysulfides which then decompose by a polar mechanism to initiate the propagation stage of the reaction. Based on the information obtained in this study and other supporting evidences, it is possible to group the familiar curing systems according to the apparent polar or free radical character of the reaction as observed in SBR. It is interesting to note that the accelerated sulfur curing systems which most closely approximate a polar mechanism either involve an amine (DPG) or a compound which is either present as a zinc salt (dithiocarbamate) or can easily form zinc salts at the curing temperature (thiuram disulfide and mercaptobenzothiazole systems). All curing systems studied which include free sulfur appear to involve a polar mechanism.

Electrochemical and EPR studies of two substituted bis-cadmium tris-phthalocyanine complexes: elucidation of unexpectedly different free-radical character

2009 ◽  
pp. 1136-1144 ◽  
Author(s):  
Michael J. Cook ◽  
Isabelle Chambrier ◽  
Gaye F. White ◽  
Eleanor Fourie ◽  
Jannie C. Swarts
Keyword(s):  
Free Radical ◽  
Radical Character

Influence of a free radical substituent on reactivity (reverse effect). Results involving benzylic systems

1982 ◽  
Vol 23 (48) ◽  
pp. 5075-5078 ◽  
Author(s):  
M. Ballester ◽  
J. Veciana ◽  
J. Riera ◽  
J. Castañer ◽  
C. Rovira ◽  
...  
Keyword(s):  
Free Radical ◽  
Reverse Effect

Potentiation of bromotrichloromethane hepatotoxicity in male rats exposed to 10 ppm dietary chlordecone: Electron Microscopic and biochemical study

1990 ◽  
Vol 48 (3) ◽  
pp. 284-285
Author(s):  
O. M. Faroon ◽  
R. W. Henry ◽  
M. G. Soni ◽  
H. M. Mehendale
Keyword(s):  
Free Radical ◽  
Biochemical Study ◽  
Prior Exposure ◽  
Male Rats ◽  
Cellular Injury ◽  
Low Doses ◽  
Mixed Function Oxidase ◽  
Electron Microscopic ◽  
Potent Inducer ◽  
Cellular Energy

Previous work has shown that mirex undergoes photolytic dechlorination to chlordecone (CD) (KeponeR) in the environment. Much work has shown that prior exposure to nontoxic levels of CD causes potentiation of hepatotoxicity and lethality of CCl4, BrCCl3 and other halomethane compounds. Potentiation of bromotrichloromethane hepatotoxicity has been associated with compounds that stimulate the activity of hepatic mixed-function oxidase (MFO). An increase in the metabolism of halomethane by the MFO to a free radical initiates peroxidative decomposition of membranal lipids ending in massive cellular injury. However, not all MFO inducers potentiate BrCCl3 hepatotoxicity. Potentiation by much larger doses of phenobarbital is minimal and th at by a more potent inducer of MFO, mirex, is negligible at low doses. We suggest that the CD and bromotrichloromethane interaction results in a depletion of cellular energy and thereby reducing the cellular ability to undergo mitosis.

Deaminative carbonylative thioesterification of activated alkylamines with thiophenols under transition-metal-free conditions

2021 ◽  
Author(s):  
Fengqian Zhao ◽  
Xiao-Feng Wu
Keyword(s):  
Free Radical ◽  
Transition Metal ◽  
Metal Free

A transition-metal-free radical carbonylation of activated alkylamines with thiophenols has been successfully developed. Various thioesters were selectively produced with moderate to good yields.

1120: Citrate and Vitamin E Blunt the SWL-Induced Free Radical Surge in an In-Vitro MDCK Cell Culture Model

2004 ◽  
Vol 171 (4S) ◽  
pp. 295-295
Author(s):  
Fernando C. Delvecchio ◽  
Ricardo M. Brizuela ◽  
Karen J. Byer ◽  
W. Patrick Springhart ◽  
Saeed R. Khan ◽  
...  
Keyword(s):  
Cell Culture ◽  
Free Radical ◽  
Vitamin E ◽  
Mdck Cell ◽  
Cell Culture Model ◽  
Culture Model
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