Acidic properties of N, N-naphthoquinonylamines

Galina Temtsin; Sofia Gorohovsky; Shmuel Bittner

doi:10.1016/S0040-4020(02)00533-1

Acidic properties of N, N-naphthoquinonylamines

Galina Temtsin, Sofia Gorohovsky, Shmuel Bittner

Department of Chemistry

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

The new system in which two naphthoquinonic moieties are bridged via a NH group shows acidic properties due to its vinylogous-imide nature. In the dichloro derivative (BClNQA) strong mesomeric and inductive effects result in unusually high acidity. Its pK_a value in methanol is equal to 7.51±0.02, which is several orders of magnitude lower than that of normal aliphatic or aromatic imides or even aliphatic carboxylic acids. The new system can form stable salts with various organic bases (e.g. triethylamine). The chromophoric nature of BClNQA and its anion is expressed by a dramatic bathochromic shift of its λ₃ in polar solvents from the orange (441-473nm) to the blue region (608-624nm). This unusual red shift is due to substantial polarization of the quinonic system and delocalization of its anionic form.

Original language	English
Pages (from-to)	5639-5643
Number of pages	5
Journal	Tetrahedron
Volume	58
Issue number	28
DOIs	https://doi.org/10.1016/S0040-4020(02)00533-1
State	Published - 8 Jul 2002

Keywords

Acid-base equilibrium
N, N-naphthoquinonylamines
pK

ASJC Scopus subject areas

Biochemistry
Drug Discovery
Organic Chemistry

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10.1016/S0040-4020(02)00533-1

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title = "Acidic properties of N, N-naphthoquinonylamines",

abstract = "The new system in which two naphthoquinonic moieties are bridged via a NH group shows acidic properties due to its vinylogous-imide nature. In the dichloro derivative (BClNQA) strong mesomeric and inductive effects result in unusually high acidity. Its pKa value in methanol is equal to 7.51±0.02, which is several orders of magnitude lower than that of normal aliphatic or aromatic imides or even aliphatic carboxylic acids. The new system can form stable salts with various organic bases (e.g. triethylamine). The chromophoric nature of BClNQA and its anion is expressed by a dramatic bathochromic shift of its λ3 in polar solvents from the orange (441-473nm) to the blue region (608-624nm). This unusual red shift is due to substantial polarization of the quinonic system and delocalization of its anionic form.",

keywords = "Acid-base equilibrium, N, N-naphthoquinonylamines, pK",

author = "Galina Temtsin and Sofia Gorohovsky and Shmuel Bittner",

note = "Funding Information: This research was supported by the Israel Science Foundation founded by the Academy of Science and Humanities. Authors wish to thank Dr Lev Shapiro for his help in p K a determination and Mrs Ethel Solomon for skillful technical help.",

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doi = "10.1016/S0040-4020(02)00533-1",

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T1 - Acidic properties of N, N-naphthoquinonylamines

AU - Temtsin, Galina

AU - Gorohovsky, Sofia

AU - Bittner, Shmuel

N1 - Funding Information: This research was supported by the Israel Science Foundation founded by the Academy of Science and Humanities. Authors wish to thank Dr Lev Shapiro for his help in p K a determination and Mrs Ethel Solomon for skillful technical help.

PY - 2002/7/8

Y1 - 2002/7/8

N2 - The new system in which two naphthoquinonic moieties are bridged via a NH group shows acidic properties due to its vinylogous-imide nature. In the dichloro derivative (BClNQA) strong mesomeric and inductive effects result in unusually high acidity. Its pKa value in methanol is equal to 7.51±0.02, which is several orders of magnitude lower than that of normal aliphatic or aromatic imides or even aliphatic carboxylic acids. The new system can form stable salts with various organic bases (e.g. triethylamine). The chromophoric nature of BClNQA and its anion is expressed by a dramatic bathochromic shift of its λ3 in polar solvents from the orange (441-473nm) to the blue region (608-624nm). This unusual red shift is due to substantial polarization of the quinonic system and delocalization of its anionic form.

AB - The new system in which two naphthoquinonic moieties are bridged via a NH group shows acidic properties due to its vinylogous-imide nature. In the dichloro derivative (BClNQA) strong mesomeric and inductive effects result in unusually high acidity. Its pKa value in methanol is equal to 7.51±0.02, which is several orders of magnitude lower than that of normal aliphatic or aromatic imides or even aliphatic carboxylic acids. The new system can form stable salts with various organic bases (e.g. triethylamine). The chromophoric nature of BClNQA and its anion is expressed by a dramatic bathochromic shift of its λ3 in polar solvents from the orange (441-473nm) to the blue region (608-624nm). This unusual red shift is due to substantial polarization of the quinonic system and delocalization of its anionic form.

KW - Acid-base equilibrium

KW - N, N-naphthoquinonylamines

KW - pK

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U2 - 10.1016/S0040-4020(02)00533-1

DO - 10.1016/S0040-4020(02)00533-1

M3 - Article

AN - SCOPUS:0037043187

SN - 0040-4020

VL - 58

SP - 5639

EP - 5643

JO - Tetrahedron

JF - Tetrahedron

IS - 28

ER -

Acidic properties of N, N-naphthoquinonylamines

Abstract

Keywords

ASJC Scopus subject areas

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