Substituent effects in the bis(benzotriazolylmethylation) of aromatic amines

1990 ◽  
Vol 68 (3) ◽  
pp. 446-455 ◽  
Author(s):  
Alan R. Katritzky ◽  
Stanislaw Rachwal ◽  
Jing Wu
Keyword(s):  
Steric Hindrance ◽  
Mannich Reaction ◽  
Aromatic Amines ◽  
Spectral Properties ◽  
Strong Influence ◽  
Substituent Effects ◽  
Equilibrium Mixture ◽  
Partial Separation ◽  
Alkyl Groups ◽  
The Stability

1-(Hydroxymethyl)benzotriazole and aromatic amines react to give an equilibrium mixture of N-mono- and N,N-bis(benzotriazolylmethyl)arylamines. Electron-releasing substituents on the arylamine ring shift the equilibrium towards the N,N-bis(benzotriazolylmethylated) products, and removal of water formed in the reaction leads to these bis derivatives in quantitative yields. These products were isolated as mixtures of three isomers, the benzotriazolyl-1,1′, -1,2′, and -2,2′ derivatives; these mixtures were characterized by full assignment of their 13CNMR spectra and by partial separation and enrichment. Electron-withdrawing substituents on the arylamine ring increase the isomer interconversion energy barriers and make N,N-bis(benzotriazolylmethyl)arylamines more resistant to hydrolysis. A strong influence of ortho alkyl groups on the stability and NMR spectral properties of N,N-bis(benzotriazolylmethyl)arylamines is interpreted on the basis of steric hindrance. Keywords: Mannich reaction, benzotriazole isomerization, substituent effects, anilines, bis(benzotriazolylmethyl)arylamines.

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.

Tyrosine-Selective Bioconjugation with Iminoxyl Radicals

2020 ◽  
Author(s):  
Katsuya Maruyama ◽  
Takashi Ishiyama ◽  
Yohei Seki ◽  
Kounosuke Oisaki ◽  
Motomu Kanai
Keyword(s):  
Reaction Time ◽  
Steric Hindrance ◽  
Room Temperature ◽  
Water Soluble ◽  
Light Irradiation ◽  
Sodium Ascorbate ◽  
Iminoxyl Radical ◽  
Short Reaction Time ◽  
Modified Peptides ◽  
The Stability

A novel Tyr-selective protein bioconjugation using the water-soluble persistent iminoxyl radical is described. The conjugation proceeded with high Tyr-selectivity and short reaction time under biocompatible conditions (room temperature in buffered media under air). The stability of the conjugates was tunable depending on the steric hindrance of iminoxyl. The presence of sodium ascorbate and/or light irradiation promoted traceless deconjugation, restoring the native Tyr structure. The method is applied to the synthesis of a protein-dye conjugate and further derivatization to azobenzene-modified peptides.

Sustainability Of Oaken Landscapes And Dynamics

2020 ◽  
Vol 02 (10) ◽  
pp. 274-278
Author(s):  
Alisher Khodjimatov ◽  
Keyword(s):  
Economic Activity ◽  
Strong Influence ◽  
Human Economic Activity ◽  
The Stability

The article is based on the multifactorial nature of the stability and dynamics of landscapes, especially the strong influence of human economic activity on the stability and dynamics of oasis landscapes.

Addition of Aliphatic and Aromatic Amines to Catechol in Aqueous Solution Under Oxidizing Conditions

1989 ◽  
Vol 42 (3) ◽  
pp. 365 ◽  
Author(s):  
MK Manthey ◽  
SG Pyne ◽  
RJW Truscott
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Aromatic Amines ◽  
Aliphatic Amines ◽  
Substitution Pattern ◽  
Vinylogous Amides ◽  
The Stability

The oxidation of catechol in the presence of two aliphatic and aromatic amines has been investigated. In aqueous solutions of pH 7.0 and 11.7, the substitution pattern of the adduct was dependent on the type of amine used. Aromatic amines produced 4,5-disubstituted o-quinones, whereas aliphatic amines gave either 2,4,5-trisubstituted or 2,4-disubstituted o-quinone adducts. A rationale based upon the stability of vinylogous amides is presented to account for the observed substitution pattern.

The Mannich Reaction Between Aromatic Ketones, Aromatic Aldehydes and Aromatic Amines

Synthesis ◽  
1991 ◽  
Vol 1991 (09) ◽  
pp. 717-718 ◽  
Author(s):  
Yi Lin ◽  
Lei Huangshu ◽  
Zou Junhua ◽  
Xu Xiujuan
Keyword(s):  
Mannich Reaction ◽  
Aromatic Amines ◽  
Aromatic Aldehydes ◽  
Aromatic Ketones ◽  
The Mannich Reaction
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