Derivatization Technique To Identify Specifically Carbonyl Groups by Infrared Spectroscopy: Characterization of Photooxidative Aging Products in Terpenes and Terpeneous Resins

Zumbühl, Stefan; Brändle, Andreas; Hochuli, Andreas; Scherrer, Nadim; Caseri, Walter (2017). Derivatization Technique To Identify Specifically Carbonyl Groups by Infrared Spectroscopy: Characterization of Photooxidative Aging Products in Terpenes and Terpeneous Resins Analytical Chemistry, 89(3), pp. 1742-1748. American Chemical Society 10.1021/acs.analchem.6b04008

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Analysis of bioorganic materials by infrared spectroscopy (FT-IR) is frequently limited due to overlapping of diagnostic bands from the various components, which poses a fundamental problem to this analytical technique. The distinction of oxidized di- and triterpenes, for example, is hindered by the superposition of similar absorption bands of carbonyl functional groups summing up to a broad, nondistinctive signal. This study presents a technique for selective fluorination of various carboxylic acids by exposure to gaseous sulfur tetrafluoride. The derivatization treatment leads to characteristic band shifts, allowing the separation of otherwise overlapping bands. Accordingly, the IR bands of primary acids, α,β-unsaturated acids, tertiary acids, peroxy acids, esters, ketones, and α,β-unsaturated ketones are split into distinct absorption bands. The capability of this method is demonstrated on the example of natural resins and their ingredients, which are commonly known to be susceptible to oxidation at ambient conditions. The derivatization method enables one to identify various carbonyl containing functional groups by infrared spectroscopy, even in complex mixtures of terpenes. It unveils previously hidden degradation reactions running in terpenes and natural resins exposed to artificial aging by irradiation with light. New insight is presented on the individual reaction pathways of the terpenes hydroxydammarenone and abietic acid as well as of natural resin varnishes made from dammar and colophony.

Item Type:	Journal Article (Original Article)
Division/Institute:	Bern Academy of the Arts Bern Academy of the Arts > Institute Materiality in Art and Culture Bern Academy of the Arts > HKB Teaching Bern Academy of the Arts > Institute Materiality in Art and Culture > Material analyses
Name:	Zumbühl, Stefan0000-0002-8896-2938; Brändle, Andreas; Hochuli, Andreas; Scherrer, Nadim0000-0002-6576-885X and Caseri, Walter
Subjects:	N Fine Arts > ND Painting
ISSN:	0003-2700
Publisher:	American Chemical Society
Language:	English
Submitter:	Nadim Scherrer
Date Deposited:	12 Dec 2019 14:22
Last Modified:	18 Dec 2020 13:28
Publisher DOI:	10.1021/acs.analchem.6b04008
Related URLs:	Publisher
Additional Information:	Date: 2017
ARBOR DOI:	10.24451/arbor.8050
URI:	https://arbor.bfh.ch/id/eprint/8050