A Review on Selective Synthesis and Yield Enhancement of Ortho-Nitrophenol in the Presence of Phase-Transfer Catalysts | [Pakistan Journal of Scientific and Industrial Research (Series A: Physical Sciences) • 2022]

Author(s):

1. Muhammad Ameen Ahmad: Department of Chemistry, Lahore Garrison University,DHA Phase-VI, Lahore,Pakistan

2. Shabbir Hussain: Institute of Chemistry, Khwaja Fareed University of Engineering and Information Technology,Rahim Yar Khan ,Pakistan

3. Muhammad Ahmad: Department of Chemistry, Division of Science and Technology, University of Education,Lahore ,Pakistan

4. Muhammad Waqas: Department of Chemistry, Lahore Garrison University,DHA Phase-VI, Lahore,Pakistan

5. Muhammad Ibrar: Department of Chemistry, Lahore Garrison University,DHA Phase-VI, Lahore,Pakistan

6. Gull Yasmeen: Department of Chemistry, Lahore Garrison University,DHA Phase-VI, Lahore,Pakistan

Abstract:

Current studies were performed to review the synthesis and yield enhancement of orthonitrophenol in the presence of phase-transfer catalysts. Selective synthesis and yield enhancement of orthonitrophenol can be varied in the presence of phase-transfer catalysts under different synthetic mechanisms. The phenols and substituted phenols can be selectively nitrated at their ortho/para positions by direct or indirect nitration and by varying the reaction parameters such as dilution of acid, substrate and the strength of the catalyst. High selectivity can be achieved by indirect nitration with diluted nitric acid in the presence of tetra-butyl ammonium bromide (TBAB) and acetyl trimethylammonium bromide (CTAB). TBAB has been reported to be the most effective catalyst for the conversion of phenolic compounds into o-nitrophenol. However, this regio-selectivity will be reversed to para-position by using sodium bromide as a surfactant. The use of nitronium tetra fluoroborate suspended in acetonitrile process gives highest regio-selective nitration with a 95% yield of ortho product. Performing the nitration under sonication conditions lowers the reaction time and increases the ortho/para regio-selectivity. Under sonication conditions, maximum conversion into ortho derivative (95%) is achieved by using TBAB as catalyst in 20 min but maximum para-selectivity is achieved by using CTAB and NaBr catalysts. The use of PdCl2, Pd(PPh3)2Cl2 and Pd(OAc)2, H-beta zeolite, catalysts for selective nitration has also been reported. Greater than 85% yield of o-nitrophenol was observed by using microwaves system technology.

Page(s): 302-308

DOI: DOI not available

Published: Journal: Pakistan Journal of Scientific and Industrial Research (Series A: Physical Sciences), Volume: 65, Issue: 3, Year: 2022

Keywords:

TBAB , NaBr , phasetransfer catalysts , onitrophenol , regioselectivity

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