Free radical reactions to generate alkenes and/or ionic reactions to generate hydroximoyl chlorides when β-nitrostyrenes react with triethylaluminium or diethylaluminium chloride

1999 ◽  
pp. 47-52 ◽  
Author(s):  
Cheng-Ming Chu ◽  
Ju-Tsung Liu ◽  
Wen-Wei Lin ◽  
Ching-Fa Yao
Keyword(s):  
Free Radical ◽  
Radical Reactions ◽  
Free Radical Reactions ◽  
Ionic Reactions

Reaction of Chloral with 1,4-Polyisoprene

1963 ◽  
Vol 36 (4) ◽  
pp. 1056-1058
Author(s):  
Christian Pinazzi ◽  
Rene Pautrat ◽  
Roland Cheritat
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Nitrogen Atmosphere ◽  
Radical Reactions ◽  
Molar Ratio ◽  
Free Radical Reactions ◽  
Main Fraction ◽  
Ionic Reactions ◽  
Macromolecular Substance ◽  
Chloroform Methanol

Abstract The cis-1,4-polyisoprenes are composed of 2-methyl-2-butene units, the double bonds of which must be favorable to the addition of strongly electrophylic reagents such as certain aldehydes. Chloral is of this type and its ionic reactions with various simple olefins has been described. We found it worth while to transpose these results to polyisoprenic macromolecules, either natural or synthetic. The ionic reactions generally create less modifications of the chain, such as fission or crosslinking, than would result from free radical reactions. Also, if the formation of free radicals is avoided, the possible fixation of chloral on the halogen carrying carbon (group —CCl2—CHO) becomes very unlikely. Pure anhydrous chloral is used as the reagent. A solution of 2% cis-1,4-polyisoprene (natural) in cyclohexane or decalin (free of peroxides) is heated under a nitrogen atmosphere with the reagent and in presence of a catalyst such as AlCl3 or BF3 at a concentration of 1–3% relative to the polyisoprene. The macromolecular product obtained is then subjected to a fractionation by the chloroform-methanol combination. After purification and desolvation of the main fraction an elemental analysis is made and the level of fixation n calculated based on the chlorine content. Table 1 relates some of the results obtained by using AlCl3 or BF3. In the absence of catalyst (Figure 1, A) the level of fixation is low: n=4 and therefore the nature of the reaction remains uncertain. In the presence of AlCl3 or of BF3, n increases rapidly in function of the temperature and of the relative molar concentration of the reagents, as shown by the curves B and C of Figure 1. The highest level of fixation obtained in these experiments is n=22. Figure 2 demonstrates this limit which is reached beyond the molar ratio of m=4, in the presence of AlCl3 (3%). Table 2 shows the particular action of AlCl3 which among all the catalysts tested proves to be as effective as BF3 without yielding any notable crosslinking of the macromolecular substance.

The initial reaction mechanism and thermal sensitivity of a fluoropolymer-containing energetic molecular system: the coupling effect of interfacial interactions and free radical reactions

CrystEngComm ◽  
2021 ◽  
Vol 23 (16) ◽  
pp. 3006-3014
Author(s):  
Wen Qian
Keyword(s):  
Free Radical ◽  
Coupling Effect ◽  
Molecular System ◽  
Thermal Sensitivity ◽  
Radical Reactions ◽  
Initial Reaction ◽  
Interfacial Interactions ◽  
Free Radical Reactions ◽  
Molecular Systems ◽  
Reactive Molecular Dynamics

A strategy combining classic and reactive molecular dynamics is applied to find the coupling effect of interfacial interactions and free radical reactions during the initial thermal decomposition of fluoropolymer-containing molecular systems.

Further studies on free-radical pathology in the major central nervous system disorders: effect of very high doses of methylprednisolone on the functional outcome, morphology, and chemistry of experimental spinal cord impact injury

1982 ◽  
Vol 60 (11) ◽  
pp. 1415-1424 ◽  
Author(s):  
H. B. Demopoulos ◽  
E. S. Flamm ◽  
M. L. Seligman ◽  
D. D. Pietronigro ◽  
J. Tomasula ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Free Radical ◽  
Tissue Injury ◽  
Functional Restoration ◽  
Radical Reactions ◽  
Free Radical Reactions ◽  
Cord Injury

The hypothesis that pathologic free-radical reactions are initiated and catalyzed in the major central nervous system (CNS) disorders has been further supported by the current acute spinal cord injury work that has demonstrated the appearance of specific, cholesterol free-radical oxidation products. The significance of these products is suggested by the fact that: (i) they increase with time after injury; (ii) their production is curtailed with a steroidal antioxidant; (iii) high antioxidant doses of the steroidal antioxidant which curtail the development of free-radical product prevent tissue degeneration and permit functional restoration. The role of pathologic free-radical reactions is also inferred from the loss of ascorbic acid, a principal CNS antioxidant, and of extractable cholesterol. These losses are also prevented by the steroidal antioxidant. This model system is among others in the CNS which offer distinctive opportunities to study, in vivo, the onset and progression of membrane damaging free-radical reactions within well-defined parameters of time, extent of tissue injury, correlation with changes in membrane enzymes, and correlation with readily measurable in vivo functions.

Solvent Effects on the Oxidative Free Radical Reactions of 2-Amino-1,4-naphthoquinones.

ChemInform ◽  
2005 ◽  
Vol 36 (14) ◽  
Author(s):  
Chao-Ming Tseng ◽  
Yi-Lung Wu ◽  
Che-Ping Chuang
Keyword(s):  
Free Radical ◽  
Solvent Effects ◽  
Radical Reactions ◽  
Free Radical Reactions

Simulation of dioxygen free radical reactions

1993 ◽  
Vol 21 (3) ◽  
pp. 256S-256S ◽  
Author(s):  
PEDRO MONIZ-BARRETO ◽  
DAVID A. FELL
Keyword(s):  
Free Radical ◽  
Radical Reactions ◽  
Free Radical Reactions
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