Regioselective Nitration of Deactivated Mono-Substituted Benzenes Using Acyl Nitrates Over Reusable Acidic Zeolite Catalysts

Nitration of benzonitrile was investigated using a nitric acid/acid anhydride/zeolite catalyst system under different reaction conditions. Trifluoroacetic and chloroacetic anhydrides were found to be the most active among the anhydrides tried. Also, zeolites Hβ and Fe³⁺β (Si/Al = 12.5) were found to...

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Bibliographic Details
Published in:Catalysis letters 2010-02, Vol.134 (3-4), p.270-278
Main Authors: Smith, Keith, Ajarim, Mansour D, El-Hiti, Gamal A
Format: Article
Language:English
Subjects:
Acidic oxides
Aluminum
Anhydrides
Benzene
Benzonitrile
Catalysis
Catalysts
Chemistry
Chemistry and Materials Science
Deactivation
Dichloromethane
Exact sciences and technology
General and physical chemistry
Industrial Chemistry/Chemical Engineering
Ion-exchange
Isomers
Nitrates
Nitration
Nitric acid
Nitriles
Organometallic Chemistry
Physical Chemistry
Silicon
Substitutes
Surface physical chemistry
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
Zeolites
Zeolites: preparations and properties
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Summary:Nitration of benzonitrile was investigated using a nitric acid/acid anhydride/zeolite catalyst system under different reaction conditions. Trifluoroacetic and chloroacetic anhydrides were found to be the most active among the anhydrides tried. Also, zeolites Hβ and Fe³⁺β (Si/Al = 12.5) were found to be the most active catalysts. For example, nitration of benzonitrile with trifluoroacetyl nitrate under reflux conditions in dichloromethane gave 3- and 4-nitrobenzonitriles in quantitative yield, of which the para-isomer represented 24-28%. The yield of para-isomer was improved to 33% when passivated Hβ was used under similar reaction conditions. This is easily the most para-selective nitration of benzonitrile ever recorded. Also, no ortho-isomer was formed under the conditions tried. The zeolite can be easily recovered, regenerated by heating and reused up to six times to give results similar to those obtained with a fresh sample of the catalyst. The nitration system was applied successfully to a range of deactivated mono-substituted benzenes to give para-isomers in significantly higher proportions than in the corresponding traditional nitration reactions. Graphical Abstract [graphic removed]
ISSN:1011-372X
1572-879X
DOI:10.1007/s10562-009-0258-7