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.

Heavy Water as a Probe of the Free Radical Nature and Electrical Conductivity of Melanin

2015 ◽  
Vol 119 (48) ◽  
pp. 14994-15000 ◽  
Author(s):  
Shermiyah B. Rienecker ◽  
A. Bernardus Mostert ◽  
Gerhard Schenk ◽  
Graeme R. Hanson ◽  
Paul Meredith
Keyword(s):  
Electrical Conductivity ◽  
Free Radical ◽  
Heavy Water ◽  
Radical Nature

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

scholarly journals Shedding Light on the Free Radical Nature of Sulfonated Melanins

2020 ◽  
Vol 124 (46) ◽  
pp. 10365-10373
Author(s):  
J. V. Paulin ◽  
A. Batagin-Neto ◽  
P. Meredith ◽  
C. F. O. Graeff ◽  
A. B. Mostert
Keyword(s):  
Free Radical ◽  
Radical Nature

Free Radical Nature of Compound I

1982 ◽  
pp. 285-291 ◽  
Author(s):  
Rick Rutter ◽  
Lowell P. Hager ◽  
Peter Debrunner
Keyword(s):  
Free Radical ◽  
Compound I ◽  
Radical Nature
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