50. Mechanism of substitution at a saturated carbon atom. Part XXXII. The rôle of steric hindrance. (Section G) magnitude of steric effects, range of occurrence of steric and polar effects, and place of the wagner rearrangement in nucleophilic substitution and elimination

1946 ◽  
Vol 0 (0) ◽  
pp. 173-194 ◽  
Author(s):  
I. Dostrovsky ◽  
E. D. Hughes ◽  
C. K. Ingold
Keyword(s):  
Carbon Atom ◽  
Nucleophilic Substitution ◽  
Steric Hindrance ◽  
Steric Effects ◽  
Saturated Carbon Atom

scholarly journals The role of steric hindrance in the intramolecular oxidative aromatic coupling of pyrrolo[3,2-b]pyrroles

2016 ◽  
Vol 52 (77) ◽  
pp. 11539-11542 ◽  
Author(s):  
Maciej Krzeszewski ◽  
Paweł Świder ◽  
Łukasz Dobrzycki ◽  
Michał K. Cyrański ◽  
Witold Danikiewicz ◽  
...  
Keyword(s):  
Carbon Atom ◽  
Steric Hindrance ◽  
Sterically Hindered

Sterically hindered tetraaryl-pyrrolo[3,2-b]pyrroles undergo oxidative aromatic coupling, forming a fluorene scaffold linked via a spiro carbon atom with a novel π-conjugated scaffold.

Effect of Alkyl Group Structure on Cure Characteristics of N,N-Dialkylthio-Carbamyl-N′,N′-Dialkylsulfenamide Vulcanization Accelerators

1974 ◽  
Vol 47 (4) ◽  
pp. 906-910 ◽  
Author(s):  
R. D. Taylor
Keyword(s):  
Carbon Atom ◽  
Steric Hindrance ◽  
Alkyl Group ◽  
Group Structure ◽  
Substituent Effects ◽  
Steric Effects ◽  
Alkyl Groups ◽  
Inductive Effects ◽  
Cure Rates ◽  
Alpha Carbon

Abstract Wide variations in scorch times and cure rates can be attained with tetraalkylthiocabamylsulfenamides through variation in alkyl groups. Substituent effects are substantial on either the carbamate nitrogen or on the sulfenamide nitrogen. Both inductive effects and steric effects influence the scorch times and cure rates. Positive inductive effects shorten scorch times and increase cure rates. Steric hindrance at the sulfenamide nitrogen increases the scorch time. Branching at the carbon atom beta to the nitrogen has a larger effect on scorch time than branching at the alpha carbon. Thiocarbamylsulfenamides can give appreciably higher cure rates and cure efficiencies than their benzothiazole sulfenamide analogs.

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