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Category: Synthesis
Posted on: March 5, 2007 7:55 PM, by Molecule of the Day
For quantum mechanical reasons; triply bonded carbon tend strongly to be linear. Benzene-like compounds derive their special stability by virtue, in part, of being in a planar ring. Surprisingly, certain substituted benzenes can form "benzynes," which have an additional degree of unsaturation. Less surprisingly, they're very reactive species; these tend to be something observed by virtue of what products they produce. It's not something you get in a bottle.
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Comments
Trypticene is a great undergrad prep, anthracene plus xs. benzyne, and clean up with maleic anhydride then alkali. It would be great fun to oxidatively couple C-H to H-C or more likely start with 9,9-bianthryl. Now that is a snuggle and kiss! Undoubtedly cute proton NMR, too.
10,10'-Dibromo-9,9'-bianthryl as substrate is way too much fun! Reductively dehalogenate the ditrypticene to a very respectable rigid rod polymer.
Posted by: Uncle Al | March 5, 2007 9:19 PM
What's the going rate for 100cc of benzyne, in solution ?
Posted by: _Arthur | March 5, 2007 9:57 PM
dear blogger: I found your blog while I was researching molecule structure of food coloring. really enjoy your blog! I learned so much as a no-science-brain artist:) Thank you Thank you!!
Posted by: yaya | March 5, 2007 11:21 PM
aromatic chemistry... not my favourite but definitely one of the easier sectoins of organic chem!!! for arthur... this is a transition state of benzene derivative during a reaction. the drawing represents the ring being electron rich and the ring would tend toward being a stanard benzene ring (hence it can't be bought in a bottle as it would spontaneously react to give a benzene ring). what would one do with 100cc of this stuff anyway? :)
Posted by: Lee | March 6, 2007 5:34 AM
The major self-rxn products of benzyne are biphenylene (23-40% typical; 83% from oxidation of 1-aminobenzotriazole) and triphenylene via 1,2-cycloaddition; cracking to acetylene, linear oligomers. Real fast kinetics, fellas. From HyperChem,
barrelene: 26.7169 kcal/mole, 1.51656 A aliphatic C-C
bibarrelene: 61.223 kcal.mole, 1.52692 connecting C-C
trypticene: 7.7117 kcal.mole, 1.40851 A Ar-C
bitrypticene: 34.8994 kcal.mole, 1.555172 A connecting C-C
The big snuggle looks entirely doable from bianthryl. Nice undegrad lab (especially with a proton NMR). Will the linear polymer selectively adsorb molecular hydrogen and empower the H*Y*D*R*O*G*E*N car?
http://www.mazepath.com/uncleal/bitrypt.png
stereogram
Posted by: Uncle Al | March 6, 2007 6:11 PM