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Functional Groups 16,516 views

Teacher/Instructor Kendal Orenstein
Kendal Orenstein

Rutger's University
M.Ed., Columbia Teachers College

Kendal founded an academic coaching company in Washington D.C. and teaches in local area schools. In her spare time she loves to explore new places.

Functional groups are groups of atoms in hydrocarbons which are responsible for their chemical properties. The types of functional groups include halocarbons, alcohols, ethers, aminoss, aldehydes, ketones, carboxyllic acids and esters. These functional groups are bound to a hydrocarbon structure denoted R.

When dealing with organic chemistry and hydrocarbons and naming, you're actually going to deal with the functional groups and functional groups are groups that are actually differentiate between, within hydrocarbons and actually give hydrocarbons unique properties.

They are things beside hydrogen and carbon that are, that you actually might add within a chain of hydrocarbon. It can make [IB] organic Chemistry a lot larger. So there's several of them and there's are the ones you're probably going to see most often, the first one being a halocarbon. Halo reminding us that [IB] halogens. So we're dealing with halogens in this. And we're ta- whenever I write r, that means am dealing with a backbone of carbon and some in some sense. So if we have like our parent group of r bonded to a halogen, that is the typical general formula for it. Here's an example. Notice that we have the halogens up here and then we're going to name this 1 bromo 3 chloro 2 flourobutane, butane being four carbons in its backbone. And notice this they're in alphabetical order, b, c and f even though the numbers are not the right way. Make sure your alphabetical order is always first. And another [IB] a practically used might be for halocarbon is teflan. Teflan is a halocarbon. Stuff that you use to make your, the non-stick pants or something along these lines of teflan is actually quite used,used quite often.

Alcohol is another functional group that you'll see. Alcohol is a parent group line it to an OH. It can be anywhere. Doesn't have to be the end of the chain. It could be anywhere within that chain. Here's an example of what an alcohol would look like. This is ethanol and the way you name alcohol is that you put an ol as the suffix. So you are going to call it ethanol. Showing that there's an alcohol there. And different types and ethanol is actually used for drinking. Drinking alcohol is actually, we drink ethanol in alcoholic beverages. Methanol is the alcohol we use to swab our wounds. So methanol having one carbon CH2OH is used for is like a cleanser for cuts and things.

Ethers, ethers have an oxygen in the center. So no hydrogen on it just oxygen. There's one, there's a parent group on one side, parent group on the other and there's oxygen kind of in the middle. Here is one example of an ester, sorry, ether. And so this you now notice there's a [IB] parent. There's a carbon chain on one side, carbon chain on the other and oxygen in the center and though I didn't say that it's an ether is you name, you name the parent chain on either side ending with ether. So you get this will be propyl ethyl ether, saying that one side's a propyl group and the other side's an ethyl group and then it's an ether meaning oxygen in the center of these two. And this is actually used as an anaesthetic. Back in the day, actually not so much anymore, but back in the day it was used a lot for anaesthesia, to actually help numb the pain for surgery.

Amienes are another functional group you'll see and that's NH2 attached to our carbon group. This is a cyclocal hexene, a cycle attached to its amiene group and so an easy way to name this, is it's a cyclohexyl group and there are amiene is our functional group in this, our parent group in this case. So we are going to make sure we have that in there. Cyclohexyl amiene. This shows that this is the functional group and this is the actual parent [IB] the amiene. This is actually used as a pesticide ammonia is actually not, is a poisonous material for most animals and bugs so this will be used as a typical pesticide.

[IB] we have our aldehydes. You might be familiar with aldehydes. Aldehydes have a parent group in the CO C carbon double bonded to an oxygen at the very end of the chain. This will always occur at the very end of the chain. We have only one side that has the parent group. Here's an example right here of an aldehyde. This is ethanal, this is called ethanal. Because there's two carbons meaning that's eth and al, the a-l is indicating that's aldehyde. So that's our suffix. We're dealing with aldehyde al so this ethanal from aldehyde is actually methanal. One has just one carbon attached to it. So that's another thing and this is actually used in glues. Glues use ethanal.

Another one you might come across is ketone. Ketone is when you have, actually it's not, if something is an aldehyde because aldehydes are [IB] end, that makes it unique. Ketone are C double bonds with O in like the middle of the chain. So you have one chain, chain on one side, a chain on the other and carbon double bonded with oxygen somewhere along in the middle. Here is an example of a ketone. [IB] two functional, two parent chains and they got five of the carbon in the middle bonded to an oxygen. And we're showing up where that bond, double bonded oxygen is located and our number. So it's going to be two propanone. So two is telling us that the double bonded oxygen is in the second carbon and there are three carbons making it prop and one is a suffix we're going to use when dealing with ketones. This is actually used in nail polish remover.

My last one is carboxyllic acid. Carboxyllic acid is one of our only acidic group [IB] that we have an H will readily fall off and it will act as an acid. So it's a functional group with COOH bonded at the very end. It will always be found at the very end of the functional group of the sorry. With the parent carbon chain in the front and here's an example of a carboxyllic acid. Notice this is what makes the carboxyllic acid, this is the hydrogen that will fall off and make it an acid. this is ethanoic acid. Eth meaning two carbon and noic acid is the suffix for carboxyllic acid, anoic acid. And this is actually used in vinegar. Another common name for it is acidic acid. You might know if it's acidic acid when you're dealing with acid base unit.

And the last one we're going to talk about today are esters. Esters is when you have like a [IB] group but in the middle. So carboxyllic acid's on the very end but an ester group is actually in the middle. So we have our parent chains of carbon on either side and then carbon bond, double bonded with oxygen and single bonded to another oxygen in the middle. Or it doesn't have to be in the middle but not on the end of the chain. Here's an example of this. We're going to na- this is called ethyl butanoate. The oate indicates that it is an ester. And then the way you name it is, you have a whatever is after the oxygen comes first. This is the ethyl group and butanoate is because there's four carbons before that. But being the prefix four, so this would be ethyl butanoate. And this actually, esters are really scented. They are used in you know, making artificial flavouring and so this is actually the scent of pineapple, ethyl butanoate is actually a pineapple scent.

So these are the main functions which you'll probably see and have [IB] be forced to name actually when you're doing chemistry, organic chemistry. Unfortunately you are going to have to, there's really a hard way to, there's no really good way to actually give you a trick to remembering them. It's a lot of our memorization which is unfortunate but hopefully this will help you understand and help you disect functional groups.