What are the Basics of Alcohols?

Alcohols are organic compounds that have the hydroxyl group attached to carbon atoms.

So, methyl alcohol is the simplest of the alcohols, this is also known as methanol. And then the next higher alcohol is ethyl alcohol, which we can also call ethanol. Now an alcohol is produced by replacing one hydrogen from an alkane with a hydroxyl group. So we’re replacing this hydrogen with a hydroxyl group. So say we have methane, which has one carbon atom and four hydrogen atoms.

We replace one hydrogen by the hydroxyl group, which is one oxygen atom and one hydrogen atom, so now we have this. So here we still have the same number of carbon atoms that we started with because we’re not doing anything to the carbon. We’re just adjusting, or we’re really just adding this oxygen atom. Because we’re taking one hydrogen out, but we’re adding it right back in, so the total number of hydrogens doesn’t change because we have 4 here, and we have 3 plus 1 is 4, so the only thing that’s changing is this oxygen atom in terms of counting the atoms. So this was called methane, but not we call it methyl alcohol or we can call it methanol. Now another example is ethane, which has 2 carbon atoms and 6 hydrogen atoms.

Again, we’re going to replace 1 hydrogen atom by the hydroxyl group, which is 1 oxygen atom and 1 hydrogen atom. And so now we’re going to get 2 carbon atoms, 5 hydrogen atoms attached to 1 oxygen and 1 hydrogen atom. So the number of hydrogen atoms is staying the same because we started out with a subscript of 6, we have 5 hydrogen atoms here and 1 here so that’s 6 total. And then of course we have carbon which has 2, we have 2 carbons and then we have 2 carbons right here so that’s staying the same in terms of just counting them.

But notice we do have a different structure here as far as the hydrogens go. We have the same number, but here the subscript’s changing so we have different chemicals or chemical compounds, or molecules really that we’re working with here. Now we are adding an oxygen atom here, and so that’s where in terms of counting the atoms that changes. So I hope you’re tracking with me. What I’m trying to differentiate between just counting atoms and then actually looking at molecular structure.

So the molecular structure is definitely changing here, but as far as the number of atoms go, we’re staying the same with carbon and hydrogen, but we’re just adding an oxygen atom. And so, it originally was called ethane, so now we call it ethyl alcohol, or we can call it ethanol. And so if you’re not tracking with the naming system, realize that in the IUPAC naming system, the names of alcohols are derived from the replacement of the e at the end of the word. And so it’s replaced with “ol.” So say we have propane, we would change it to propanol. Or with ethane, we change the e here to ol to get ethanol. Or with methane, we changed the e to ol to get methanol.

So that’s a look at the basics of alcohols.