Which carbon?

[seancassell]

Hi everyone;

I'm in grade 12 chemistry, and am trying to teach myself more advanced chemistry (frankly, I find the subject matter we're looking at in class too boring and too easy). I've started reading about organic chemistry, and it quite intrigues me.

I can't seem to figure out how, in a chemical reaction, it can be predicted which carbon will be affected. I mean, let's say you have ribose (a 5 cabron sugar) and you want to make it into deoxyribose (derived from ribose by the repacement of the hydroxyl group at the 2 position with hydrogen, leading to the net loss of an oxygen). How do you know that carbon-2 will be affected and not, say, carbon-3 or carbon-1?


Thanks!