Issue 9, 2020

Evidence for photochemical synthesis of fluoromethane

Abstract

Photochemical generation of volatile fluoromethane in a dilute acetic acid medium is demonstrated. Radical halogen atom transfer (XAT) from an intermediate Cu–F transition metal fluorocomplex to abundant ˙CH3 generated by UV homolysis of acetic acid, rather than direct formation of free ˙F radicals, is hypothesized as being the synthetic route. The presence of Cu(II) is indispensable for CH3F formation. GC-MS identification of the gaseous products released from a photolysed 2% (v/v) solution of acetic acid containing 60 mg L−1 added Cu(II) as a sensitizer confirms synthesis of CH3F as the volatile fluorinated species, which is not detectable in the absence of Cu(II). Reaction efficiency remains unchanged whether the sample medium is exposed to V-UV radiation (185 nm) or germicidal UV-C radiation (primarily 254 nm and longer wavelengths) from the source. Experimental optimization of generation conditions (pH, irradiation time, UV wavelength, acetic acid concentration, metal ion sensitizer and concentration) was undertaken with a view to elucidation of mechanism as well as maximizing synthetic yield. Although the low yield (<1%) of CH3F currently precludes its efficacious use as a means of enhancing analyte introduction efficiency into atomic spectrochemical sources, this study demonstrates successful application of XAT to encompass PVG of the most difficult of the halogens to process in this manner and may provide insights into further studies to ultimately achieve higher yields.

Graphical abstract: Evidence for photochemical synthesis of fluoromethane

Article information

Article type
Communication
Submitted
18 mar 2020
Accepted
06 maj 2020
First published
07 maj 2020

J. Anal. At. Spectrom., 2020,35, 1720-1726

Evidence for photochemical synthesis of fluoromethane

R. E. Sturgeon and E. Pagliano, J. Anal. At. Spectrom., 2020, 35, 1720 DOI: 10.1039/D0JA00108B

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements