Now, when it comes to the reduction of aldehydes and ketones, recall that reduction uses a reducing agent to add as many carbon-hydrogen bonds as possible without breaking any carbon-carbon bonds. So that's the whole idea of reduction. If we take a look here, we're only paying attention to what's within this shaded box. That's what's really the most important. But stuff lies outside that box, so let's take a look. So if we're starting here over here on the right, we can say that the most oxidized form of carbon exists as carbon dioxide. Carbon is making its maximum 4 bonds, all of them being to oxygen. Once I start the reduction process, we're going to reduce it some, and we're going to start to add as many carbon-hydrogen bonds as possible. Carbon can only go up to 4 bonds. So to do that, we have to break one of these carbon-oxygen bonds. So that's where this H comes in. Carbon needs to keep making 4 bonds, so that's where this H comes in. Oxygen also needs to make its ideal number of bonds, which is 2. So we add a hydrogen to it as well. If we keep going, we enter the shaded region here. So here we keep adding carbon-hydrogen bonds, so we have to get rid of this bond here, and that's how we wind up with this aldehyde. This aldehyde can undergo further reduction, so we're going to add more carbon-hydrogen bonds to it. Meaning we have to break this carbon-oxygen bond here. So here goes the H that I've added to the carbon, oxygen still wants to keep making 2 bonds, so here it would have its hydrogen added to it as well. So we can see here that reducing an aldehyde has created an alcohol. If we wanted, we could continue further with strong reduction to help create an alkane at the end. The alkane being the last stop in terms of reduction process. But what we need to take from this is that we can reduce an aldehyde into an alcohol. And even if we had a ketone, we could do the same. Because if we reduced that, we want to add as many carbon-hydrogen bonds as we want. So we'd again remove one of these carbon-oxygen bonds. So we'd have our carbon with its 2 carbons, 1 on each side, its newly gained hydrogen, and then the oxygen would also gain a hydrogen. So we can see here that we can reduce both aldehydes and ketones to produce alcohols. Okay. So that's the whole basis when it comes to reducing aldehydes and ketones. Doing so changes them both into alcohols.
15. Aldehydes and Ketones
Reduction of Aldehydes and Ketones
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