Isoprene

Weitz, H. M.; Löser, E.

doi:10.1002/14356007.a14_627

Cited by 17 publications

(18 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Thus, the emission kinetics of isoprene and monoterpenes may not necessarily be identical. In particular, the saturated partial pressure of monoterpenoids on the order of 0.02–0.6 kPa at 25°C is considerably lower than that of isoprene of 73.6 kPa at 25°C [ Mackay and Shiu , 1981; Howard and Meylan , 1997; Daubert et al , 1998; Weitz and Loser , 1998] (see also R. L. Brown and S. E. Stein, Boiling point data, in NIST Chemistry WebBook, NIST Standard Reference Database Number 69, edited by P. J. Linstrom and W. G. Mallard, National Institute of Standards and Technology, Gaithersburg, Md., available at http://webbook.nist.gov, July, 2001) and monoterpene molecules are also larger and diffuse more slowly than the isoprene molecules. This suggests that depending on the partitioning of diffusion limitations between lipid, liquid, and gas phases, the monoterpenoid emission rates may occasionally be limited by volatility and intraleaf diffusion also in species lacking specialized foliage monoterpene‐storage compartments.…”

Section: Introductionmentioning

confidence: 99%

A model analysis of the effects of nonspecific monoterpenoid storage in leaf tissues on emission kinetics and composition in Mediterranean sclerophyllousQuercusspecies

Niinemets¹,

Reichstein

2002

Global Biogeochemical Cycles

View full text Add to dashboard Cite

[1] Although monoterpenoid-emitting Quercus species lack specific terpene storage structures, they may store monoterpenoids in nonspecific leaf compartments. To determine whether such storage may influence emission responses to diurnal changes in environmental factors, a dynamic emission model including ''fast'' and ''slow'' storage pools in parallel was constructed. Existence of two storage pools was inferred from the circumstance that monoterpene efflux from darkened leaves was poorly described by single-exponential decay relationship, but was well parameterized by double exponentials. Simulations indicated that nonspecific terpenoid storage may significantly alter daily monoterpenoid emission both at leaf and canopy scales. The model also described shifts in fractional monoterpenoid composition after changes in environmental factors that cannot be explained by current algorithms. Time constants for the ''fast'' pool were negatively associated with monoterpenoid equilibrium gas/water partition coefficient (H), suggesting that the ''fast'' pool is in leaf liquid phase. The time constants for the ''slow'' pool were independent of H, but scaled positively with monoterpenoid octanol/water partition coefficient, indicating that this pool is in lipid phase. Based on tentative pool locations and monoterpenoid physico-chemical characteristics, time constants of various pools were computed using a flow/conductance model. Although the time constants were correlated, the theoretical estimates were larger than those derived empirically. Nonhomogeneous monoterpenoid distribution, aggregation within leaf liquid phase, and adsorption to apoplast surfaces that all decrease the area for diffusion and decrease the effective diffusion coefficients likely explain this discrepancy. We conclude that physico-chemical models are needed to parameterize nonspecific storage effects on monoterpene emission dynamics and emission composition.

show abstract

Section: Introductionmentioning

confidence: 99%

A model analysis of the effects of nonspecific monoterpenoid storage in leaf tissues on emission kinetics and composition in Mediterranean sclerophyllousQuercusspecies

Niinemets¹,

Reichstein

2002

Global Biogeochemical Cycles

View full text Add to dashboard Cite

show abstract

“…Auch in der Kooperation von Michelin mit Amyris wird an dem direkten Weg zu Isopren gearbeitet [65]. Hierbei entsteht 2-Methyl-1-Buten, das anschließend dehydriert wird [62]; es werden Ausbeuten von 70 -80 % berichtet [66]. Hierbei entsteht 2-Methyl-1-Buten, das anschließend dehydriert wird [62]; es werden Ausbeuten von 70 -80 % berichtet [66].…”

Section: Butadienunclassified

“…Darüber hinaus gibt es eine ganze Reihe weiterer Wege zu Isopren, unter anderem beispielsweise durch Umsetzung von Ethylen mit Propen in Toluol in Gegenwart von Triethylaluminium. Nach einem Isomerisierungsschritt wird das Intermediat 2-Methyl-2-penten bei über 650°C unter Methan-Abspaltung in das Isopren mit einer Gesamtselektivität von 50 % überführt [62]. Dieses Verfahren wurde nie industriell eingesetzt, im Gegensatz zur Isopren-Herstellung aus Acetylen und Aceton: Hierbei werden die beiden Edukte im ersten Schritt in flüssigem Ammoniak bei 10 -40°C zu 2-Methyl-but-3-in-2-ol in Gegenwart von KOH umgesetzt.…”

Section: Butadienunclassified

Herstellung von Grundchemikalien auf Basis nachwachsender Rohstoffe als Alternative zur Petrochemie?

Wagemann

2014

Chemie Ingenieur Technik

View full text Add to dashboard Cite

Die derzeitige Entwicklung in den USA, geprägt durch billiges Schiefergas, hat starke Auswirkungen auf die Produktion von Basischemikalien. Der Beitrag geht der Frage nach, ob sich vor diesem Hintergrund der Anteil nachwachsender Rohstoffe für die Chemikalienproduktion steigern lässt oder ob sich die Zahl biobasierter Produkte und Verfahren eher verringern wird. Antworten liefert für einige ausgewählte Grundchemikalien der Vergleich von bestehenden Produktionsverfahren auf petrochemischer Basis mit Alternativen auf Basis nachwachsender oder anderer fossiler Rohstoffe (bspw. Methan und niedere Alkane).

show abstract

“…As an ubiquitous and important family of molecules, terpenes, provide flavors, fragrances, medicines, and commercial products. 1 Although terpenes possess a seemingly endless variety of architectural complexities, nature is able to utilize simple five-carbon moieties to build the tens of thousands of different members of the terpene family. 2 The biosynthesis of terpenes often occurs in a unified fashion as a “two-phase” process: 3 (1) in the “cyclase” phase, small linear hydrocarbon phosphate building blocks are coupled together, followed by both enzymatic and nonenzymatic cyclizations and rearrangements; (2) in the “oxidase” phase, the oxidations of alkenes and carbon–hydrogen bonds result in large structural diversity.…”

Section: Introductionmentioning

confidence: 99%

Mechanism, Reactivity, and Selectivity of Nickel-Catalyzed [4 + 4 + 2] Cycloadditions of Dienes and Alkynes

et al. 2014

View full text Add to dashboard Cite

Density functional theory (DFT) calculations with B3LYP and M06 functionals elucidated the reactivities of alkynes and Z/E selectivity of cyclodecatriene products in the Ni-catalyzed [4 + 4 + 2] cycloadditions of dienes and alkynes. The Ni-mediated oxidative cyclization of butadienes determines the Z/E selectivity. Only the oxidative cyclization of one s-cis to one s-trans butadiene is facile and exergonic, leading to the observed 1Z,4Z,8E-cyclodecatriene product. The same step with two s-cis or s-trans butadienes is either kinetically or thermodynamically unfavorable, and the 1Z,4E,8E- and 1Z,4Z,8Z-cyclodecatriene isomers are not observed in experiments. In addition, the competition between the desired cooligomerization and [2 + 2 + 2] cycloadditions of alkynes depends on the coordination of alkynes. With either electron-deficient alkynes or alkynes with free hydroxyl groups, the coordination of alkynes is stronger than that of dienes, and alkyne trimerization prevails. With alkyl-substituted alkynes, the generation of alkyne-coordinated nickel complex is much less favorable, and the [4 + 4 + 2] cycloaddition occurs.

show abstract

Isoprene

Cited by 17 publications

References 59 publications

A model analysis of the effects of nonspecific monoterpenoid storage in leaf tissues on emission kinetics and composition in Mediterranean sclerophyllousQuercusspecies

A model analysis of the effects of nonspecific monoterpenoid storage in leaf tissues on emission kinetics and composition in Mediterranean sclerophyllousQuercusspecies

Herstellung von Grundchemikalien auf Basis nachwachsender Rohstoffe als Alternative zur Petrochemie?

Mechanism, Reactivity, and Selectivity of Nickel-Catalyzed [4 + 4 + 2] Cycloadditions of Dienes and Alkynes

Contact Info

Product

Resources

About