Competition between Nucleophilic Substitution of Halogen (SNAr) versus Substitution of Hydrogen (SNArH)—A Mass Spectrometry and Computational Study. Issue 16 (12th March 2015)

• Record Type: Journal Article
• Authors: Błaziak, Kacper; Mąkosza, Mieczysław; Danikiewicz, Witold
• Is Part Of: Chemistry. Volume 21:Issue 16(2015)
• Page Start: 6048
• Page End: 6051
• Publication Date: 2015-03-12
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201406542
• Languages: English
• ISSNs: 0947-6539

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>The mechanism of intramolecular gas‐phase reactions of <italic>N</italic>‐(2‐X‐5‐nitrophenyl)‐<italic>N</italic>‐methylacetamide carbanions (X=H, F, Cl) has been studied using negative ion electrospray mass spectrometry ((−)ESI‐MS) technique and modelled computationally. It was proven that all three anions form cyclic σ^H adducts, which undergo elimination of water. In the case of X=F, formation of the σ^F adduct, leading to S_NAr reaction, was a competing process. This is the first proof that also in the gas phase formation of σ^H adduct proceeds faster than σ^X adduct and only when X=F, rates of these two processes are comparable. The experimental results are in full agreement with quantum chemical calculations.</p> </abstract>