Substituent Effects and Charge Delocalization Mode in Chrysenium, Benzo[c]phenanthrenium, and Benzo[g]chrysenium Cations:  A Stable Ion and Electrophilic Substitution Study

2001 ◽  
Vol 66 (3) ◽  
pp. 780-788 ◽  
Author(s):  
Kenneth K. Laali ◽  
Takao Okazaki ◽  
Subodh Kumar ◽  
Sergio E. Galembeck
Keyword(s):  
Electrophilic Substitution ◽  
Substituent Effects ◽  
Charge Delocalization

Electrophilic Substitution Reactions of [1]Benzothieno[3,2-b]furan

1996 ◽  
Vol 61 (6) ◽  
pp. 888-900 ◽  
Author(s):  
Jiří Svoboda ◽  
Pavel Pihera ◽  
Petr Sedmera ◽  
Jaroslav Paleček
Keyword(s):  
Electrophilic Substitution ◽  
Nmr Spectra ◽  
Substituent Effects ◽  
Substitution Reactions ◽  
Nmr Parameters ◽  
Elimination Mechanism ◽  
Electrophilic Substitution Reactions ◽  
C Nmr

In chlorination, bromination, iodination, nitration, sulfonation, formylation, and trifluoroacetylation of [1]benzothieno[3,2-b]furan (1) the substituent enters the 2-position. The said halogenations go by the addition-elimination mechanism. When the substitution is continued, the second substituent enters the 6-position of heterocycle 1. The 1H and 13C NMR spectra have been completely assigned. Substituent effects on NMR parameters are discussed.

Substituent Effects in Benz[a]anthracene Carbocations:  A Stable Ion, Electrophilic Substitution (Nitration, Bromination), and DFT Study†

2007 ◽  
Vol 72 (18) ◽  
pp. 6768-6775 ◽  
Author(s):  
Kenneth K. Laali ◽  
Maria A. Arrica ◽  
Takao Okazaki ◽  
Ronald G. Harvey
Keyword(s):  
Electrophilic Substitution ◽  
Substituent Effects ◽  
Dft Study

Formation and reactivity of 1-pyrrolyl-2,2,2-trifluoroethyl cations

1990 ◽  
Vol 68 (10) ◽  
pp. 1709-1713 ◽  
Author(s):  
Annette D. Allen ◽  
Jean-Marc Kwong-Chip ◽  
Wing Cheung Lin ◽  
Paul Nguyen ◽  
Thomas T. Tidwell
Keyword(s):  
Rate Ratio ◽  
Electrophilic Substitution ◽  
Pyrrole Ring ◽  
Solvent Polarity ◽  
Nucleophilic Attack ◽  
Charge Delocalization ◽  
Polarity Parameter ◽  
High Degree ◽  
Low K

1-(1-Methyl-2-pyrrolyl)-2,2,2-trifluoroethyl p-nitrobenzoate (3) reacts by carbocation formation with an m value for the dependence of rate on the solvent polarity parameter YOTs of 0.56, and a rate 41 times slower than (1-methyl-2-pyrrolyl)methyl p-nitrobenzoate. The products from 3 include significant amounts of material derived from solvent attack at the 5-position of the pyrrole ring. The results indicate a high degree of charge delocalization by the strongly donating pyrrolyl group, resulting in a low k(H)/k(CF3) rate ratio and nucleophilic attack on the ring. 1,1, l-Trifluoro-2-(1-methyl-2-pyrrolyl)propan-2-ol (10) reacted with CF3CO2H via a tertiary carbocation, which led to dimeric products resulting from electrophilic substitution on the pyrrole ring. Keywords: pyrrole, trifluoromethyl substituents, carbocations.

Sign in / Sign up

Export Citation Format

Share Document