ARS | Publication request: Complete Proton and Carbon Assignment of Triclosan via One- and Two- Dimensional Nuclear Magnetic Resonance Analysis

Submitted to: The Chemical Educator
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2007
Publication Date: September 10, 2007
Citation: Wilson, K.A., Beck, J.J. 2007. Complete Proton and Carbon Assignment of Triclosan via One- and Two- Dimensional Nuclear Magnetic Resonance Analysis. The Chemical Educator.12(5):338-342

Interpretive Summary: Triclosan, chemical name 5-chloro-2-(2,4-dichlorophenoxy)phenol is a common antimicrobial additive in numerous household hygienic items and has been the subject of various environmental fate investigations. Albeit a simple diaryl ether, triclosan presents a challenge for full structure elucidation due to its nearly symmetrical A and B rings. The spectroscopic challenge for triclosan is confident assignment of the quaternary carbons to the correct positions and proton spin-spin systems. Students from an upper-division undergraduate spectroscopy class analyzed one- and two-dimensional 400 MHz NMR spectroscopic data from triclosan in deuterated chloroform. The laboratory experiment provided herein describes a step-by-step analysis of one- and two-dimensional high-field NMR spectroscopic material of triclosan and is presented as a teaching tool for upper-division undergraduate labs and/or courses.

Technical Abstract: Students from an upper-division undergraduate spectroscopy class analyzed one- and two-dimensional 400 MHz NMR spectroscopic data from triclosan in CDCl3. Guided assignment of all proton and carbon signals was completed via 1D proton and carbon, nuclear Overhauser effect (nOe), distortionless enhancement by polarization transfer (DEPT) 135, 1H-1H correlation spectroscopy (COSY), 1H-13C heteronuclear single quantum coherence (HSQC), and 1H-13C heteronuclear multiple bond coherence (HMBC) NMR experiments. The near-symmetry of this diaryl ether provided a challenging structure elucidation problem for early-semester undergraduate spectroscopy students. Experimental 1H and 13C NMR chemical shifts are compared to estimated chemical shifts from computer software.