Now when it comes to the formation of hemiacetals and acetyls, we're going to say that 1 mole of alcohol produces hemiacetals, and 2 moles of alcohol produce acetals. If we take a look here, we have an aldehyde and a ketone. Both of them react, let's say with 1 mole of an alcohol. Doing this will help change those aldehydes and ketones into hemiacetals. Now how does this work? Well, we're going to say here that this carbonyl carbon is the same as this alcohol carbon, just like here and here. We're going to say the alcohol, the OR portion of the alcohol, will provide the OR portion that attaches to my formerly known carbonyl carbon. So the OR portion of this alcohol is what's attaching here to what was the carbonyl carbon. And then we can say here that the oxygen that was the carbonyl carbon gets converted into an OH group. That's the way you have to look at it. So the OR portion of the alcohol attaches to the carbonyl carbon, and then the oxygen that was double bonded becomes an OH group.
Now, if we decide to add another mole of alcohol, so we add a second mole of alcohol to both of these hemiacetals, the same thing would happen again now. Now the OR portion of this alcohol is what's going to attach to what was my carbonyl carbon. Well, remember, carbon can only make up to 4 bonds. It can't go up to 5 bonds. So for it to attach, the OH groups have to go away. And that's what happens. And that's why at the end, we'll have 2 OR groups attached to what was my carbonyl carbon. That's the whole process. We react 1 mole with these aldehydes and ketones and we stop at the hemiacetal. But once we introduce a second mole of alcohol, they continue further to make a full acetal or acetal compound. Alright. So keep that in mind when it comes to their formations.