classifying alcohols in organic chemistry we can classify alcohols as primary secondary or tertiary and we're going to look at how to do that so let's start with primary alcohols we have to look at the carbon that the '08 group is attached to if it's got one R group of one alkyl group attached to it it's a primary alcohol so for example ethanol is a primary alcohol because that carbon that the O H groups attached to also has a ch3 group attached to it and two hydrogen's and that's what makes a primary alcohol secondary alcohols have two alkyl groups attached to that carbon so let's have a look at an example remember the R groups show the a general alkyl group it doesn't matter what alkyl group it could be anything be fairly foul Pro pal so there's a carbon we'll put a methyl group there and an e foul group attached to it as well and a hydrogen atom and the two alkyl groups make it a secondary alcohol now notice our longest chain has four carbons and we number them to make the alcohol and have the lowest number possible it's on that second carbon so that would actually be butan too old let's have a look at tertiary alcohols the carbon that has the O H group will have three alkyl groups attached to it or three R groups attached to it that's what makes it a tertiary alcohol and again it doesn't matter what our group to use it could be me file groups if our groups pro power groups they can be as long as you like so in this case we'll put three methyl groups attached about central carbon and there's your age group and what we have here is a chain with three carbons in the O H groups on the middle carbon we've also got a me file groups or it actually be to me file propound to all so let's have a look at some examples of primary secondary and tertiary alcohols and see if we can classify them correctly so for our first molecule we're going to draw a hydrocarbon chain we'll put three carbons in there rope at the O H on the end carbon a methyl group coming off the middle and let's work out of its primary secondary or tertiary at first glance you might be tempted to say it's a tertiary alcohol but remember we look at the carbon to which the Oh H group is attached it's only got one alkyl group even though that group is branched it's got two hydrogen so that actually makes it a primary alcohol so don't get caught out branches don't necessarily make it secondary or tertiary you have to look at the carbon that the o H group is attached to let's have a look at another example now so we've got four carbons in the chain with a methyl group coming off one of them and the no H group coming off the other and again look at that carbon that the O H group is attached to we've got a methyl group there and then we've got another our car group on the other side and one hydrogen so you've got two our car groups in the hydrogen which makes it secondary let's have a look at a final example we've now got four carbons in the chain and off that first carbon we've got to me file groups and our H group so on the carbon that has a yo8 group we've actually got one two three alkyl groups which makes it a tertiary alcohol so the main thing to do is just look at that carbon that the your H group is attached to and check how many alkyl groups are attached to it you can work out with its primary secondary or tertiary just finally a top tip when you're drawing alcohols have a look at an example of a picture of ethanol so we've got two carbons pop the hydrogens in and because it's ethanol that's got an H group that's not a good way to draw it why well it looks like that bond is going to the hydrogen not the oxygen which is bad so let's redraw it properly two carbons pop the hydrogen's in remember the bond goes to the oxygens and make it really clear that that bond is connecting the car the oxygen and then that's a good structure