Atmospheric Chemistry of Titan |
Atmospheric Chemistry of Titan |
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 ![]() |
Here is a "Benzene-O-Vision" graphic showing the amount of benzene and phenyl radicals at high altitudes on Titan. This is based on detections of benzene and phenyl radical (which recombined in the sample chamber to make benzene) using the INMS instrument during closest approach. The numbers are normalized to constant pressure altitude, roughly 1000 km.
The data was taken from Table 1 in: Vuitton et al, Journal of Geophysical Research 113 (2008) E05007. "Formation and distribution of benzene on Titan". doi: 10.1029/2007JE002997 [EDIT 5/24/10: Article freely available here] and overlaid on a map of Titan. The authors mentioned that the errors in these measurements are 20%. These detections are well above the detached haze layer. Most are at the same sun azimuth angle. (T23 observation had the lowest angle.) Assuming that the temporal difference is minimal (each dot is from a different flyby), there doesn't appear to be an obvious correlation with latitude. This graphic does show that benzene is present even waaaay up in the thermosphere and ionosphere. -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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![]() Senior Member ![]() ![]() ![]() ![]() Group: Moderator Posts: 2785 Joined: 10-November 06 From: Pasadena, CA Member No.: 1345 ![]() |
Cute.
To be really, really anal, a radical should show a dot to signify an unpaired electron. So .CH3 or (neutral radical) or .+CH3 for the radical cation. Differently trisubstituted carbon radicals .CR1R2R3 could be in sp3 orbitals. So technically, they could be chiral (have handedness / are not superimposable on their mirror-image) if the three groups are different. The resulting radicals could be chiral (all sp3 hybridization, or may be achiral and planar (unpaired in p, bonding in sp2 orbitals) and react differentially from the two faces to create chiral products. A trisubstituted carbenium ion +CR3 will rehybridize to placing the unoccupied orbital in a p atomic orbital, and the remaining (bonding) orbitals in sp2 orbitals. This is a planar configuration, and is thus achiral. As Professor Barry Sharpless once said while teaching us organic chemistry: "Once you lose your chirality, it is gone forever." ![]() Here is a neat basic intro to radical chemistry: http://www2.fiu.edu/~herriott/ch10%20-%20r...20reactions.pdf -------------------- Some higher resolution images available at my photostream: http://www.flickr.com/photos/31678681@N07/
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