- High density fuels from oxygenated terpenoids
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A method for the efficient synthesis of useful deoxygenated terpenoids from an abundant renewable source, using catalytic conversion of oxygenated terpenoids. Oxygenated terpenoids such as 1,4-cineole and 1,8-cineole are, for example, major components of turpentine and essential oils. These oxygenated terpenoids can also be produced from sugars via a biosynthetic approach. Catalytic deoxygenation of these substrates can be used to efficiently generate commercially important chemicals and high density fuels for turbine or diesel propulsion.
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Page/Page column 7
(2017/07/06)
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- Thermal degradation of terpenes: Camphene, Δ3-carene, limonene, and α-terpinene
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Emissions from wood dryers have been of some concern for a number of years, and recent policy changes by the Environmental Protection Agency have placed emphasis upon the gaseous emissions that lead to the formation of particulate matter as small as 2.5 μm diameter. In this qualitative study, camphene, Δ3-carene, limonene, and α-terpinene were thermally degraded in the presence of air to determine the number and kind of oxidative degradation products that might be expected under drying conditions used in processing wood products. Various chromatographic methods were used to isolate the products for proof of structure by NMR and/or GC-MS. The degradation products resulted from dehydrogenations, epoxidations, double bond cleavages, allylic oxidations, and rearrangements. A number of compounds not previously associated with the thermal degradation of these terpenes were identified. Emissions from wood dryers have been of some concern for a number of years, and recent policy changes by the Environmental Protection Agency have placed emphasis upon the gaseous emissions that lead to the formation of particulate matter as small as 2.5 μm diameter. In this qualitative study, camphene, Δ3-carene, limonene, and α-terpinene were thermally degraded in the presence of air to determine the number and kind of oxidative degradation products that might be expected under drying conditions used in processing wood products. Various chromatographic methods were used to isolate the products for proof of structure by NMR and/or GC-MS. The degradation products resulted from dehydrogenations, epoxidations, double bond cleavages, allylic oxidations, and rearrangements. A number of compounds not previously associated with the thermal degradation of these terpenes were identified.
- Mcgraw, Gerald W.,Hemingway, Richard W.,Ingram Jr., Leonard L.,Canady, Catherine S.,Mcgraw, William B.
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p. 4029 - 4033
(2007/10/03)
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- 2α,4-Dihydroxy-1,8-cineole. A New Possum Urinary Metabolite
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2α,4-Dihydroxy-1,8-cineole (2a) is present in the urine of brushtail possums fed a diet enhanced with 1,8-cineole (1).Chemical syntheses of this novel metabolite (2a) and its 2β-epimer (19a) are described.The n.m.r. spectra of various 1,8- and 1,4-cineoles are reported, and literature assignments for C1 and C4 in the 1,4-cineole series are corrected.
- Carman, Raymond M.,Rayner, Anthony C.
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p. 2087 - 2098
(2007/10/02)
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- Terpenoid Ether Formation in Superacids
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A number of terpenoid bicyclic ethers have been prepared by cyclisation of suitable precursors in fluorosulphuric acid-sulphur dioxide.The products are formed under a mixture of thermodynamic and kinetic control, and five-, and six-, and seven-membered-ring ethers are obtained.Both primary and secondary alcohols have been cyclised by attack of the hydroxy group on carbocation centres generated by protonation of alkenes or ionisation of tertiary alcohols; tertiary alcohols ionise too readily to provide an etheral oxygen atom.Reaction of the unsaturated secondary alcohol dihydrocarveol (2) with antimony pentafluoride in sulphur dioxide gives the ether by a reaction which may not involve a carbocation, and hence may be suitable for ether formation from substrates which rearrange readily in acids.
- Carr, Graham,Dean, Cristopher,Whittaker, David
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p. 351 - 354
(2007/10/02)
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- Etude des phenomenes physico-chimiques intervenant lors du procede d'hydrodistillation
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During the steam distillation of aromatic plants, some terpenic compounds undergo various chemical reactions (hydrolysis, elimination, cyclisation rearrangement) which depend on the acidity of the water in which the plant is soaked.In order to study the physical and chemical phenomena involved in this process and in particular the formation of artefacts, we have performed steam distillation experiments on lavender flowers in a buffered aqueous medium.The essential oils collected are rich in linalol and linalyl acetate, two monoterpenic compounds known for their propensity to undergo heat induced transformations.At pH 4 or 7, the chromatograms of the essential oils are similar whereas in a more acidic medium (pH = 2), the degradation of linalyl acetate gives rise to a number of terpenic products (α and γ terpinenes; 2,6,6-trimethyl 2-vinyl tetrahydropyran; 1,4-cineol, cis and trans ocimenols, myrcenol, terpin 1-en 4-ol, etc.).A study of the reactions involved during the thermal degradation of linalyl acetate in a model experiment (heating to reflux) as well as the determination of the kinetic parameters, show that some terpenes, present in lavender oil originate in part from the transformations of linalyl acetate during steam distillation.Furthermore, the decomposition of this ester is directly and quantitatively related to the concentration of acid in the medium (pseudo first order rate constant is 0.008 min-1 at pH 7 and 0.0147 min-1 at pH 2).It is therefore necessary to control and maintain the pH of the water during steam distillation to avoid the alteration of the essential oils by formation of artefacts and preserve the integrity of the oil originally present in the plant.The study of the various steam distillation fractions gives informaiton on the kinetics of the steam distillation of the various components which apparently do not depend only on the boiling point but also on their polarity (hydrodiffusion phenomenon).
- Morin, Ph.,Gunther, C.,Peyron, L.,Richard, H.
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p. 921 - 930
(2007/10/02)
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- REARRANGEMENTS OF MONOTERPENES IN FUSED ORGANIC ACID
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Rearrangements of terpenic alcohols are significantly influenced by the nature of the organic acid used as the reaction medium.The formation of neoisothujyl alcohol is a highly favoured process in abietic acid.
- Angelis, Francesco De,Ferretti, Gabriella,Botta, Maurizio,Nicoletti, Rosario
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p. 499 - 500
(2007/10/02)
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