Naming Other Substituents - Online Tutor, Practice Problems & Exam Prep

Alkyl Halides Concept 1

So remember that an alkyl halide is just an alkyl group connected to a halogen. Here we're going to say that halogens attached to a carbon chain are named as substituents. Fluorine as a substituent is called Fluoro, Chlorine is called Chloro, Bromine is called Bromo, Iodine is called Iodo. In terms of our naming convention, they're acting as substituents, so we'd have to give their numerical location in terms of our parent chain. They are substituents with these names, and then we have to worry about what is the parent chain. Is it a 6 membered chain? Is it cyclic? Etcetera. So just remember, when it comes to naming organic compounds, these halogens serve as substituents, and as substituents they're given these new names.

Alkyl Halides Example 1

Here it says, determine the systematic name of the following alkane. Our job is first to find the longest carbon chain, which represents our parent chain. We're utilizing steps 1 to 6. Remember, we're utilizing the rules that we learned in terms of naming alkanes with substituents. You have to watch those videos, make sure you go back and take a look at those 6 steps. So here, 1, 2, 3, 4, 5, 6, 7, 8, 9. 9 seems to be the longest chain that we can have in terms of this alkane. So that is our parent chain. We'll highlight it for ourselves.

Now remember, we number from the end closest to a substituent. Here we have a 3 carbon substituent, a 1 carbon substituent, and bromine. 1, 2, 3, 4 to get to this 3 carbon substituent. Or 1, 2, 3 to get to the bromine substituent. We number it from the end closest to a substituent, so we're going to number it from the right side. So, 1, 2, 3, 4, 5, 6, 7, 8, 9. 9 carbons means that our alkane is nonane. Now, about our substituents. A 3 carbon substituent with the bond on the middle, carbon means that this is isopropyl. A one carbon substituent would be methyl, and then bromine is termed bromo.

Remember we basically name, we number these for their location, and we write them alphabetically. B comes before I, I comes before M. So we start out with 3-bromo-6-isopropyl-5-methyl nonane. This would be the name of this particular alkane compound. Here we have the introduction of our halogen bromine group, which is listed as bromo.

Name the following compound.

• A. 3-fluoro-1-ethylpentane
• B. 3-fluoro-1-ethylcyclopentane
• C. 1-ethyl-3-fluorocyclopentane
• D. 1-ethyl-4-fluorocyclopentane

Phenyl Group Concept 2

In this video, we're going to talk about the phenyl group. Now a phenyl group is just basically a benzene ring as a substituent on a parent chain. Now here, the parent chain can be an alkane, an alkene, an alkyne, as long as it's longer than 6 carbons. Remember the formula for benzene is C6H6. But since it's acting as a substituent, we're going to deduct away a hydrogen. So here it becomes C6H5 connected to something else, a longer chain that's an alkane, alkene, or an alkyne. Now, this is its condensed formula, if we wanted to look at its skeletal formula, remember Benzene looks like this, it's a 6 membered ring with alternating double and single bonds. 5 of the carbons have a hydrogen, the 6th one, remember we took away its hydrogen so it can serve as a substituent or branch group, connected to something larger than itself. Because it is a substituent, the naming convention is the location of the Phenyl group, and then the Parent Chain Name. So keep this in mind. Benzene, when it becomes a substituent, we call it Phenyl.

Phenyl Group Example 2

So here we need to determine a systematic name of the following alkane. Here, our carbon chain is this portion here, because it's composed of 1, 2, 3, 4, 5, 6, 7, 8 carbons. Remember, as long as our carbon chain has more than 6 carbons, it becomes the parent chain, and benzene becomes a substituent. And then, besides that benzene, we have these 2 carbon substituents which are methyl groups. Now remember, we number it from the end closest to a substituent. We'd number this end as 1 because on carbon number 1, we immediately have a substituent in the form of Benzene. So 1, 2, 3, 4, 5, 6, 7, 8. And the carbon chain is octane. Benzene as a substituent is phenyl, and then we have methyl groups on carbon number 5. Now, we name substituents alphabetically, M comes before P, so those 2 methyl groups are on 5. So we have to list 5 twice. Because if you just said 5-dimethyl, all I would know is that one of the methyl groups is on carbon number 5, but where is the other one? So we have to say 5,5 to say that both of them are on that carbon number 5. So 5,5, there are 2 identical substituents, so we use the numerical prefix di-methyl 1-phenyl-octane. This will be the name of my alkane compound.

Draw a structure for the following alkane: 3-tert-butyl-1-phenylheptane.

• A.
• B.
• C.
• D.