Reactions with Aminobenzoic Acids via Diazonium Salts Open New Routes to Bio-Derived Aromatics

Anthony Farlow,Jens Olaf Krömer

doi:10.4236/ijoc.2016.62010

Anthony Farlow, Jens Olaf Krömer

Open Access

https://doi.org/10.4236/ijoc.2016.62010

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Abstract

Aromatics have a broad application in our everyday life ranging from plastics, coatings and fibres, to food and pharmaceuticals. To date the bulk of these aromatics is derived from naphtha-based pet-rochemistry. However, recent progress in the fermentative production of metabolites using renew-able resources and engineered microbes has enabled the production of bio-precursors, such as 4-amino benzoic acid (pABA) and 2-amino benzoic acid (oABA). In this work we explored the feasibility of Sandmeyer reactions for the conversion of pABA to terephthalic and oABA salicylic acid, providing two very important platform chemicals for the chemical and pharmaceutical industries. We could demonstrate that both acids can be obtained from the amino benzoic acids derived from the shikimate pathway in microbes and plants. Good conversions could be achieved using Sandmeyer reactions at mild conditions with biodegradable reagents and without organic solvents.

Highlights

In nature, 4-aminobenzoic acid and anthranilic acid (2-aminobenzoic acid, oABA) are aromatic inter-How to cite this paper: Farlow, A. and Krömer, J.O. (2016) Reactions with Aminobenzoic Acids via Diazonium Salts Open New Routes to Bio-Derived Aromatics
Krömer mediates that are derived from chorismic acid, an intermediate of the aromatic amino acid biosynthesis. pABA is a precursor in folate synthesis in bacteria, yeast and some plants and a precursor of Coenzyme Q [1] [2], while its isomer oABA is a precursor of the aromatic amino acid tryptophan
The corresponding diazonium salts formed by the reaction of acid pABA with sodium nitrite was uncharacteristically sensitive to nucleophilic attack by water and, under alkaline conditions, excess nitrite

Summary

Introduction

4-aminobenzoic acid (pABA) and anthranilic acid (2-aminobenzoic acid, oABA) are aromatic inter-How to cite this paper: Farlow, A. and Krömer, J.O. (2016) Reactions with Aminobenzoic Acids via Diazonium Salts Open New Routes to Bio-Derived Aromatics. 4-aminobenzoic acid (pABA) and anthranilic acid (2-aminobenzoic acid, oABA) are aromatic inter-. How to cite this paper: Farlow, A. and Krömer, J.O. (2016) Reactions with Aminobenzoic Acids via Diazonium Salts Open New Routes to Bio-Derived Aromatics. O. Krömer mediates that are derived from chorismic acid, an intermediate of the aromatic amino acid biosynthesis. PABA is a precursor in folate synthesis in bacteria, yeast and some plants and a precursor of Coenzyme Q [1] [2], while its isomer oABA is a precursor of the aromatic amino acid tryptophan. Synthesized pABA currently finds application as a sun-blocker, functional food, in diagnostic tests [3] [4], dyes, drug design, and as crosslinking agent for polyurethane resins [5]

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