12AX7 - 5-8-2005 at 04:10
What kind of chemical reactivity do ketones and aldehydes have?
Also, just how stable is a C6 ring? What does it take to break it? Form it?
Tim
sparkgap - 5-8-2005 at 06:06
In a nutshell:
1.) The electrophilic carbonyl carbon (the C in >C=O) of aldehydes and ketones is decently reactive; as matter of fact, it is not so much of a
generalization to say that most life processes depend on carbonyl chemistry! 
2) C6 rings... well a saturated C6 ring is decently stable because all the carbons can assume their natural 109.5° tetrahedral angle. Pretty easy to
make.
More stable, however, is the benzene ring because of the high energy needed to break a benzene ring apart (resonance stabilization).. it's the pi
electrons... 
If you take a good look at the sheer number of existing organic compounds, you'd tend to see more of the stuff with six-membered ring than any
other.
That's about it... yeah.
sparky (~_~)
12AX7 - 5-8-2005 at 08:36
Ok, so what kind of reactions to aldehydes and ketones undergo? Does the =O tend to stay put, does one bond get split (freeing one on the C and O,
such that hydrogenation of -CHO + H2 would = -CH2OH) or what? On an aldehyde, does the H react preferrentially to the O (condensation products for
instance, analagous to esterification of -COOH)?
How hard is it to saturate a benzene ring to cyclohex-? Can you go backwards?
Tim
Madandcrazy - 7-8-2005 at 07:02
interesting,
analagous esterification of a -COOH with C6 rings, good for a oxidation.
(-CH=)-COOH + (-CH=)-COOH
-->
(-CH=)-O-(-CH=)
[benzofuran]
Easy , but how prepared the flourene ?