Catalytic Reduction of Nitrobenzene and o-NitrotoIuene with Hydrogen in Sulfuric Acid-Methanoi Solution

Takaaki Sone, Masami Karikura, Seiji Shinkai, Osamu Manabe

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The catalytic reduction (5% platinum on carbon carrier and under l atm of H2) of nitrobenzene [1 a] and o-nitrotoluene [1b] with hydrogen was carried out in sulfuric acid-methanol solution at a room temperature. The products were aniline [2a], o-toluidine [2b], and o-as well as p-methoxyanilines. o-and p-Methoxyanilines were considered to form in terms of the Bamberger-type-rearrangement of phenylhydroxylamines [9] which are the intermediates formed in the catalytic reduction of nitrobenzenes to anilines. In the reduction of [lb] more 4-methoxy-2-methylaniline [4b] was obtained than 6-methoxy-2-methylaniline [3b] as s re arrangement product. The maximum yield of [4b] was 56% under the typical reaction con ditions, while that of [3b] was in every case lower than 1%. The yield of [4b] increased to 70% by the addition of a small amount of dimethyl self o xide to a reaction medium. In the reduction of [1a], the total yield of rearrangement products (o-and p-anisidine ([3a], [4a])) was 13% or below, and olp ratio varied significantly from 0.2 to 12 with an amount of sulfuric acid. Although in the rearrangement of phenylhydroxylamine [9a] in sulfuric acid-methanol solution, almost constant o/p ratio ([3a]/[4a] ratio, O.20~0.22) was observed, this ratio increased to 0.31~0.48 in the presence of Pt-C catalyst. The result indicates that when [9] are adsorbed onto a catalyst surface, the rearrangement to o-position becomes energetically more favorable than that to p-position.

Original languageEnglish
Pages (from-to)245-249
Number of pages5
JournalNIPPON KAGAKU KAISHI
Volume1980
Issue number2
DOIs
Publication statusPublished - Jan 1 1980

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2-toluidine
Nitrobenzene
Sulfuric acid
Hydrogen
Aniline
Methanol
Nitrobenzenes
Aniline Compounds
Catalysts
Platinum
Carbon
sulfuric acid
nitrobenzene

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)

Cite this

Catalytic Reduction of Nitrobenzene and o-NitrotoIuene with Hydrogen in Sulfuric Acid-Methanoi Solution. / Sone, Takaaki; Karikura, Masami; Shinkai, Seiji; Manabe, Osamu.

In: NIPPON KAGAKU KAISHI, Vol. 1980, No. 2, 01.01.1980, p. 245-249.

Research output: Contribution to journalArticle

Sone, Takaaki ; Karikura, Masami ; Shinkai, Seiji ; Manabe, Osamu. / Catalytic Reduction of Nitrobenzene and o-NitrotoIuene with Hydrogen in Sulfuric Acid-Methanoi Solution. In: NIPPON KAGAKU KAISHI. 1980 ; Vol. 1980, No. 2. pp. 245-249.
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abstract = "The catalytic reduction (5{\%} platinum on carbon carrier and under l atm of H2) of nitrobenzene [1 a] and o-nitrotoluene [1b] with hydrogen was carried out in sulfuric acid-methanol solution at a room temperature. The products were aniline [2a], o-toluidine [2b], and o-as well as p-methoxyanilines. o-and p-Methoxyanilines were considered to form in terms of the Bamberger-type-rearrangement of phenylhydroxylamines [9] which are the intermediates formed in the catalytic reduction of nitrobenzenes to anilines. In the reduction of [lb] more 4-methoxy-2-methylaniline [4b] was obtained than 6-methoxy-2-methylaniline [3b] as s re arrangement product. The maximum yield of [4b] was 56{\%} under the typical reaction con ditions, while that of [3b] was in every case lower than 1{\%}. The yield of [4b] increased to 70{\%} by the addition of a small amount of dimethyl self o xide to a reaction medium. In the reduction of [1a], the total yield of rearrangement products (o-and p-anisidine ([3a], [4a])) was 13{\%} or below, and olp ratio varied significantly from 0.2 to 12 with an amount of sulfuric acid. Although in the rearrangement of phenylhydroxylamine [9a] in sulfuric acid-methanol solution, almost constant o/p ratio ([3a]/[4a] ratio, O.20~0.22) was observed, this ratio increased to 0.31~0.48 in the presence of Pt-C catalyst. The result indicates that when [9] are adsorbed onto a catalyst surface, the rearrangement to o-position becomes energetically more favorable than that to p-position.",
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AB - The catalytic reduction (5% platinum on carbon carrier and under l atm of H2) of nitrobenzene [1 a] and o-nitrotoluene [1b] with hydrogen was carried out in sulfuric acid-methanol solution at a room temperature. The products were aniline [2a], o-toluidine [2b], and o-as well as p-methoxyanilines. o-and p-Methoxyanilines were considered to form in terms of the Bamberger-type-rearrangement of phenylhydroxylamines [9] which are the intermediates formed in the catalytic reduction of nitrobenzenes to anilines. In the reduction of [lb] more 4-methoxy-2-methylaniline [4b] was obtained than 6-methoxy-2-methylaniline [3b] as s re arrangement product. The maximum yield of [4b] was 56% under the typical reaction con ditions, while that of [3b] was in every case lower than 1%. The yield of [4b] increased to 70% by the addition of a small amount of dimethyl self o xide to a reaction medium. In the reduction of [1a], the total yield of rearrangement products (o-and p-anisidine ([3a], [4a])) was 13% or below, and olp ratio varied significantly from 0.2 to 12 with an amount of sulfuric acid. Although in the rearrangement of phenylhydroxylamine [9a] in sulfuric acid-methanol solution, almost constant o/p ratio ([3a]/[4a] ratio, O.20~0.22) was observed, this ratio increased to 0.31~0.48 in the presence of Pt-C catalyst. The result indicates that when [9] are adsorbed onto a catalyst surface, the rearrangement to o-position becomes energetically more favorable than that to p-position.

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