Are acetic acid derivatives really negative to the iodoform test?

Daiki Nagata,Nagatoshi Nishiwaki

doi:10.1007/s42452-021-04777-0

Abstract

Acetic acid derivatives such as ethyl acetate have been considered to be negative to the iodoform test because of the predominant hydrolysis leading to acetic acid. We clarified the immiscible property of the ester was the actual reason for the negative result. When THF or 1-propanol was used as a solvent, even alkyl acetate underwent the iodoform reaction; however, it cannot be used as qualitative test because of high solubility of iodoform into these solvents. This problem was overcome by conducting the test in methanol. Indeed, not only alkyl acetates but also N,N-dimethylacetamide showed positive to the iodoform test producing a yellow precipitates.

Highlights

In last decades, natural science has developed remarkably, which has accompanied the change of content of education in high schools and universities drastically
The iodoform test is one of the important qualitative analyses to know the presence of acetyl group in the substrate, which is commonly taught in high school or introductory chemistry
Two plausible reasons were considered for the negative results; (1) iodoform reaction did not proceed, (2) even though iodoform was formed, it could not be detected as yellow precipitates because of high solubility in THF

Summary

Introduction

Natural science has developed remarkably, which has accompanied the change of content of education in high schools and universities drastically. When a substrate possessing an acetyl group is reacted with iodine under alkaline conditions, iodoform is observed as yellow precipitates [1], 2]. When ethyl acetate is used as a substrate, yellow precipitates may occur, which is explained as being caused by ethanol produced by hydrolysis.

Results

Conclusion