[macman104]

So, my biochemistry professor refers to the different oxidation states of carbon.  For example, an ester is in the same oxidation state as an amide (both +3).  Or, an isocyanate has the same oxidation state as carbon dioxide (+4).  I could not understand what he was going on about, and he admitted when I asked him about it, that being a biologist and not an organic chemist, he wasn't sure the best way to explain it.  And me being an organic chemist wanted answers, since I had never heard of this numbering convention.  Finally after talking for a while, I understood he was talking about a "bookkeeping" count of the environment the carbon is in.  I had never heard of this before.

http://en.wikipedia.org/wiki/Organic_oxidation

Anyway, just wondering if this is common and I've just never encountered it.  I've never heard organic chemists speak in terms of saying an ketone is in an oxidation state of +2, or methane is a -4 oxidation state, have you?

[omegasynthesis999]

I think this website is also helpful:

http://www.usm.maine.edu/~newton/Chy251_253/Lectures/OxidationLevels/OxidationLevelsFS.html

9 stable oxidation states! Wow! But yeah, I think your right in that I haven't heard organic chemists talk about oxidation states like this either. I believe that the numbering system is more accurate and orgo people sort of assume people know what is going on (ie. I learned how to calculate oxidations in my basic chem course). For example, despite the oxidation state, a Carbon is typically reduced when H is added. These descriptions may not be precise if applied to all of chemistry but for orgo they are pretty good generalizations so perhaps traditional bookkeeping is ignored.

[tamim83]

I learned the "relative"  oxidation of carbon in various compounds (ie- I know that a carboxyilic acid carbon has a higher oxidation state than a ketone carbon.  Later (like in my graduate studies) I was taught how to do it.  Basically any atom more elctronegative than carbon contributes +1 for each bond to the carbon.  Hydrogen contributes -1 and bonds to other carbons contribute nothing.  So basically the more electronegative atoms get the electrons. 

[movies]

Organic chemists tend to just use the "relative" descriptors of alkane, alcohol, ketone, acid, and CO₂ to describe oxidation states of carbon.  You can tell which one you have by just imagining adding water to whatever you have and see which kind of compound you would end up with.

The numerical representation is more like the inorganic chemists way of thinking about oxidation states, and that is what you would encounter if you were doing organometallic chemistry or something.