The aromatisation of terpenes and steroids by dehydrogenation

Hanson, James R.

doi:10.3184/174751915x14246963094093

Cited by 11 publications

(3 citation statements)

References 94 publications

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“…Previous studies on the vulcanization of limonene show compelling evidence for the formation of volatile by-products especially at high temperatures >140 °C, 15,45 namely cyclic monosulfides (Fig. 3, (4)–(7)) and hydrocarbons ( e.g.…”

Section: Resultsmentioning

confidence: 87%

Investigation of low molecular weight sulfur–limonene polysulfide electrodes in Li–S cells

et al. 2022

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Section: Resultsmentioning

confidence: 87%

Investigation of low molecular weight sulfur–limonene polysulfide electrodes in Li–S cells

et al. 2022

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“…The formation of perylene is usually associated with the transformation of terrigenous and/or marine OM during microbial processes in reducing environments, or the release of water fungi products during the destruction of wood [105][106][107]. Previous studies have shown that phenanthrene structures may be associated with diterpene transformation [108] or may form by the dehydrogenation of sterols [109]. The ratio of diterpenoid diagenetic products, methylphenanthrenes (MPI1; Table 2; [110]), is based on different thermodynamic stability and bioavailability of the main four isomers (3MP, 2MP, 9/4MP, 1MP).…”

Section: Polycyclic Aromatic Hydrocarbonsmentioning

confidence: 99%

Molecular Indicators of Sources and Biodegradation of Organic Matter in Sediments of Fluid Discharge Zones of Lake Baikal

et al. 2022

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This paper performs a detailed study of a wide set of organic-geochemical proxies in 15 sediment cores collected from the main basins of Lake Baikal (the northern, the central and the southern) where processes of focused fluid discharge were detected. A variety of studied zones includes sites with gas and hydrothermal seepage, mud volcanoes with or without gas-oil fluid discharge, gas hydrates and authigenic carbonates. The composition of the dispersed organic matter and individual hydrocarbon molecular markers (n-alkanes, dimethyl alkanes, isoprenoids, steranes, terpanes and polycyclic aromatic hydrocarbons) testify to the input from predominantly allochthonous terrestrial and autochthonous microbial and algal sources. The studied sources, maturity and biodegradation parameters of organic matter vary significantly for areas with different fluid discharge. The composition of specific biomarkers including isoprenoids and immature hopanoids reflects the lateral and vertical changes of microbial activity in sediments associated with various environmental conditions. The identified types of terpanes distribution (mature, mixed and immature) correlate well with types of fluid discharge and attest to the development of various methanogenic and methanotrophic microbial communities in sediments. Moreover, the revealed specificity of microbial molecular markers distribution allowed us to suggest the fluid discharge processes in zones where they were not previously detected.

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“…As shown in Figure 1, pimaranes are slightly different in basic structure and stereochemistry if compared to abietanes and most importantly, lacking of conjugated C=C bonds, they do not contribute significantly to oxidation reactions. Conversely, degradation of colophony and Venice turpentine is predominantly the result of the oxidation and dehydrogenation of conjugated dienes of the abietane moiety [31]. Highly oxidized DABA compounds resulting from dehydrogenation of ABA were found in old painting varnishes [32][33] [34] and Stradivari's instruments [4].…”

Section: Colophonymentioning

confidence: 99%

Detecting molecular changes in UV laser-ablated oil/diterpenoid resin coatings using micro-Raman spectroscopy and Laser Induced Fluorescence

Ciofini

Oujja

Cañamares

et al. 2018

Microchemical Journal

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Naturally occurring diterpenoid resins were extensively applied, mainly as oily mixtures, through the ages as protective and decorative coatings on paintings, metals and wood artifacts. When these coatings age, tend to generate tougher films than triterpenoid resins, completely insoluble, increasingly subject to darkening, and then very hard to remove using conventional methods. In this regards, laser sub-micrometric ablative techniques are being increasingly used in the cultural heritage field also for the treatment of synthetic and natural polymer coatings. Here, in the wake of the positive outcomes achieved on triterpenoid resin films, the present approach has been applied and extended to diterpenoid resin coatings, which have never been thoroughly studied yet. In detail, colophony, sandarac and Manila copal resin films, prepared as solvent and linseed oil formulations, were subject to light-ageing and then systematically irradiated at various exposure conditions using the 4 th (266 nm) and 5 th (213 nm) harmonics of a Q-Switched Nd:YAG laser. UV-Vis absorption spectroscopy was used as preliminary characterization of the films optical properties. The assessment of physico-chemical modifications induced by artificial light-ageing and ns UV laser irradiation were assessed non-invasively by µ-Raman spectroscopy, Laser Induced Fluorescence (LIF) and microscopic examination. The results underlined that, due to the presence of a polymer network, sandarac and copal resin coatings showed higher F th than those composed of colophony. Morphologically, all the coatings were subject to bubbling upon 266 nm irradiation, while damage-free at 213 nm. At molecular level, irradiation at 266 nm produced minor changes to ν(CH 3 )/ν(CH 2 ), ν(C=O) and ν(C=C) modes, thus confirming an ablation mechanism mainly driven by photo-thermal bond-breaking through the ejection of gaseous by-products. Raman background fluctuations along with shifting and broadening of LIF maxima were supportive in the assessment of laser-induced surface modifications. Finally, the work performed indicates that the 213 nm wavelength is the most indicated for the treatment of aged solvent and oil diterpenoid-based coatings, as no side effects occurred. This outcome, corroborated by the previous results obtained in triterpenoid resin films, may have important implications in the field of cultural heritage conservation, as it extends the application range of solid-state Nd:YAG lasers to all types of protective and decorative terpenoid coatings.

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The aromatisation of terpenes and steroids by dehydrogenation

Abstract: The formation of aromatic compounds by the dehydrogenation of terpenes and steroids and some of the current uses of the products are reviewed.

Cited by 11 publications

References 94 publications

Investigation of low molecular weight sulfur–limonene polysulfide electrodes in Li–S cells

Investigation of low molecular weight sulfur–limonene polysulfide electrodes in Li–S cells

Molecular Indicators of Sources and Biodegradation of Organic Matter in Sediments of Fluid Discharge Zones of Lake Baikal

Detecting molecular changes in UV laser-ablated oil/diterpenoid resin coatings using micro-Raman spectroscopy and Laser Induced Fluorescence

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