The kinetics, stereochemistry, and deuterium isotope effects in the α-pinene pyrolysis. Evidence for incursion of multiple conformations of a diradical

Gajewski, Joseph J.; Kuchuk, I. D.; Hawkins, Christopher M.; Stine, Robert A.

doi:10.1016/s0040-4020(02)00676-2

Cited by 25 publications

(54 citation statements)

References 16 publications

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“…Figure 1 reveals that 1 a and 1 b differ from each other with respect to the selectivity of the products formed. As described later, almost all compounds (4)(5)(6)(7)(8) were identified. Multiple assignments in the case of 4 and 5 refer to different diastereomers formed during the reaction and will be discussed later in this section.…”

Section: Resultsmentioning

confidence: 80%

“…In contrast to a-pinene, no racemization occurred. [5,8] The configuration of the optically active acyclic reaction products (À)-2 and (+)-3 is determined by the absolute configuration of the starting material (Table 2). [5] Both almost optically pure diastereomers (+)-1 a and (À)-1 b used herein were S-configured at C 2 and the same configurations are found for the chiral centers of the formed products ((À)-2, (+)-3) with nearly identical ee ( Table 2, Scheme 2).…”

Section: Resultsmentioning

confidence: 99%

“…[4][5][6][7] The rearrangement of a-pinene leads to the formation of limonene and alloocimene. [4,8] Linalool, an important building block in the synthesis of vitamin E and flavor compounds, is formed by thermal isomerization of 2-pinanol. [9] All of these isomerization reactions of bicyclic pinane-type compounds yield at least one acyclic Abstract: Catalyzed and uncatalyzed rearrangement reactions of terpenoids play a major role in laboratory and industrial-scale synthesis of fine chemicals.…”

Section: Introductionmentioning

confidence: 99%

“…limonene from a-or b-pinene). [4,5,[8][9][10][11] The use of compounds without p-bonds in the reactive part of the bicyclic molecule (carbon atoms C 1 , C 2 of 1; Scheme 1) [12] leads to the formation of acyclic products only (e.g. 2 from 1 or linalool from 2-pinanol) by opening of the cyclobutane ring.…”

Section: Introductionmentioning

confidence: 99%

“…[5] Based on this knowledge, there seems to be an apparent oversight in not finding 3 in the product mixtures of most undertaken studies, despite its low but significant concentration. Additionally, as shown in Scheme 1, there is also a minor reaction pathway (path III) that yields monocyclic terpenes of the pmenthane-type (6)(7)(8). [4,19] Furthermore, consecutive reactions of 2 and 3 lead to the formation of substituted cyclopentanes 4 and 5, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Thermal Isomerization of (+)‐cis‐ and (−)‐trans‐Pinane Leading to (−)‐β‐Citronellene and (+)‐Isocitronellene

Stolle

Ondruschka

Bonrath

et al. 2008

Chemistry A European J

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Catalyzed and uncatalyzed rearrangement reactions of terpenoids play a major role in laboratory and industrial-scale synthesis of fine chemicals. Herein, we present our results on the thermally induced isomerization of pinane (1). Investigation of the thermal behavior of (+)-cis- (1 a) and (-)-trans-pinane (1 b) in a flow-type reactor reveals significant differences in both reactivity and selectivity concerning the formation of (-)-beta-citronellene (2) and (+)-isocitronellene (3) as main products. Possible explanations for these results are discussed on the basis of reaction mechanism and ground-state geometries for 1 a and 1 b. To identify side reactions caused from ene cyclizations of 2 and 3, additional pyrolysis experiments were conducted that enabled the identification of almost all compounds in the network of C(10)H(18)-hydrocarbon products formed from 1.

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Thermal Isomerization of (+)‐cis‐ and (−)‐trans‐Pinane Leading to (−)‐β‐Citronellene and (+)‐Isocitronellene

Stolle

Ondruschka

Bonrath

et al. 2008

Chemistry A European J

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Comprehensive Kinetic and Mechanistic Considerations for the Gas‐Phase Behaviour of Pinane‐Type Compounds

Stolle

Ondruschka

Bonrath³

2007

Eur J Org Chem

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The thermal behaviour of selected pinane‐type compounds, α‐pinene (1), β‐pinene (2), pinane (3) and nopinone (4), has been investigated. The conversion of the bicyclic starting materials to their acyclic and monocyclic isomers as well as the consecutive reactions of the acyclic main isomerisation products are discussed. The conversion of 1–4 in a reaction network is presented and the experimental evidence for the formation of pyrolysis products by a biradical pathway is discussed. In addition to these results a kinetic model describing the isomerisation of the bicyclic compounds to their acyclic and monocyclic isomers is presented. A good correlation between kinetic simulations and experimental data is revealed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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Thermal transformations of some monoterpene compounds in supercritical lower alcohols

Anikeev¹

2010

Flavour & Fragrance J

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This review systematizes the results of basic studies on thermal transformations of phytogenic terpene compounds (a-and b-pinenes, turpentine, cis-verbenol) performed in supercritical lower alcohols. The main result is the demonstration of a considerable increase in the rate of thermal isomerization of monoterpene compounds in supercritical lower alcohols, with the retained selectivity toward target products of the reaction as compared to the rate of similar reactions conducted in the gas or liquid phase. The kinetic studies provided a deep insight into the isomerization mechanism of these compounds and elucidated the role of supercritical solvent in a manifold increase of the reaction rate compared to isomerization of the same compounds in the gas or liquid phase. The pressure of a supercritical solvent was shown to strongly facilitate the acceleration of the reactions under study. Chemical transformations of the considered terpene compounds in supercritical fluid solvents can be used as a basis of modern highly efficient technologies for the production of a wide range of practically important organic compounds, medicinal and perfume substances.

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The kinetics, stereochemistry, and deuterium isotope effects in the α-pinene pyrolysis. Evidence for incursion of multiple conformations of a diradical

Cited by 25 publications

References 16 publications

Thermal Isomerization of (+)‐cis‐ and (−)‐trans‐Pinane Leading to (−)‐β‐Citronellene and (+)‐Isocitronellene

Thermal Isomerization of (+)‐cis‐ and (−)‐trans‐Pinane Leading to (−)‐β‐Citronellene and (+)‐Isocitronellene

Comprehensive Kinetic and Mechanistic Considerations for the Gas‐Phase Behaviour of Pinane‐Type Compounds

Thermal transformations of some monoterpene compounds in supercritical lower alcohols

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