Olefins, biogenic

The reaction between olefins and ozone produces light that can be measured and related to the concentration of the reactants. One of the preferred methods for measuring ambient ozone concentrations utilizes the chemiluminescence generated in the ozone-ethylene reaction for detection. Recently, Hills and Zimmerman (16) described the use of this detection principle for determining hydrocarbon concentrations. They utilized the chemiluminescence created when ozone reacts with isoprene for development of a continuous, fast-response isoprene analyzer. This real-time isoprene system is reported to be linear over three orders of magnitude and to have a detection limit of about 1 ppbv. Because the system doesn t include a preseparation of hydrocarbons, interferences from other olefins (ethylene, propylene, and so forth) could occur. Thus far the chemiluminescent detector has been used to monitor isoprene emissions under conditions in which the concentrations of olefins that could interfere are negligible compared to those of the biogenic hydrocarbon. 

Interpretation of the aromatic/olefinic hydrocarbon distribution has recently been developed to help characterize hydrocarbon sources. Olefinic compounds are not. ibundant in petroleum thus their predominance would indicate biogenic input (4,11,20,31). 

For the removal of biogenic olefins from the aromatic fraction of a macrofauna or zooplankton extract, we discarded the GPC fraction that eluted prior to n-dodecane. The later eluting fraction, which would contain any aromatic hydrocarbons present (including any of the alkyl homologues commonly found in petroleum), was collected and analyzed by gas chromatography. A gas chromatogram of the aromatic fraction... 

Measurements in wooded and agricultural areas coupled with emission studies from selected individual trees and agricultural crops have demonstrated the ubiquitous nature of biogenic emissions and the variety of organic compounds that can be emitted. Table 2.12 shows the chemical structures of some of the common biogenic hydrocarbons. Each of the compounds shown in Table 2.12 is characterized by an olefinic double bond that renders the molecule highly reactive in the atmosphere, with the result that the lifetimes of these molecules tend to be quite short. 

With the answer to these important stereochemical questions in hand, Esmond, Fraser-Reid and Jarvis turned their attention to the synthesis of trichoverrin B (71), a possible biogenic precursor of the macrocyclic trichothecenes 42). The successful synthesis, shown in Scheme 24, followed a convergent strategy which first necessitated the construction of the two side chain pieces. The acyl-activated chiral diene (222) was prepared from aldehyde (214), a product of D-glucose (see Scheme 23). As before, a Peterson olefination introduced the second ene unit and produced a mixture... 

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