Probing the Role of Promoters in Zinc Reduction of Nitrobenzene: Continuous Production of Hydroxylaminobenzene [PREPRINT]
Abstract
Production of hydroxylaminobenzene (HAB) via zinc reduction of nitrobenzene (NB) is an established batch process based on aqueous electrolytic reactions involving an electrolyte as the promoter. This experimental study explored continuous production of HAB that is needed as an intermediate in a novel zinc/biocatalyst processing train to obtain aminophenols. Experiments were conducted suing a Zn packed bed to probe the role of promoters under continuous-flow conditions at a temperature of 60 deg. C and promoter/NB molar ratios of 0.75, 1.15 and 1.5. In addition to the conventional NC4Cl, ammonium formate and acetate were used as promoters. The best HAB yield was 95%, as compared to the batch yield of 68%. The formation of oxidized zinc species caused the packed bed to build back pressure, which appeared to enhance the selectivity of HAB/aniline. In situ voltammetric measurements provided evidence of the formation of NB and ammonium/zinc complexes, based on which reaction pathways were proposed. These findings can be used to further improve performance of continuous-flow reactors for HAB production.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 30, 2006
- Accession Number
- ADA459770
Entities
People
- Jim C. Spain
- Lixiong Li
- Lloyd Nadeau
- Theodore V. Marolla
Organizations
- Air Force Research Laboratory