Naming Alkanes

As with any functional group there is a list of rules that must be followed for naming alkanes. 

Naming Alkanes

Concept: Rules for Naming Alkanes

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Example: Naming the following alkane compound. 

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Video Transcript

Hey guys! In this new video, we're going to continue with our discussion of naming alkanes. In this first one, we’re asked to name the following alkane compound. What we need to realize here is that here we have a ring. This is a cyclic alkane. Because it's in a ring, we say cyclo. Here it has six carbons because remember every edge, every corner is a carbon. There’s six carbons within this ring. It's going to be called cyclo because it's cyclic. Six carbons is hexane. This is a cyclohexane.
You want to number the carbons in the ring in a way that these groups which are substituents which didn't get numbered get the lowest numbers possible. What does that mean? That means that I want to count either one, two, three or one, two, three. Here it really doesn't matter because it's symmetrical both ways. Let's go with the first way. We're going to stay here that this is one carbon, a CH3, so this is a methyl.
Again, it becomes important that you guys remember what these groups look like. Here this is three carbons connected to something, so this is a propyl. Again, this is a methyl. M before p so alphabetical order for substituents. There are two methyls so that's dimethyl. They're located on carbons 1 and 3. This would be 1,3-dimethyl and notice how the numbers are grouped together and separated by a comma but numbers and words are separated by a hyphen. Then the propyl is on carbon 2 so hyphen, because that propyl is on carbon 2. 2-propyl cyclohexane. That should all be one word, so I'm going to move it closer. That would be the name of our compound. Again, because we're dealing with a ring, we use the word cyclo now.
Now that we've attempted this one, take a look at the next one. Once you figure out what it could possibly be named, click on the next video and see an example of me going over it and see if your answer matches mine.

Example: Naming the following alkane compound. 

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Video Transcript

Alright guys! Let's continue with the naming of alkanes. Here in this next example, we’ve got to name this structure. What we got to do here is look for the longest chain. You can go one, two, three. You can go one, two, three. You can go one, two, three. It doesn't matter which way you count. The longest chain is three carbons. Let's just make it simple on ourselves. We’ll say that this is the longest chain, which means these two things here are substituents. That's a methyl here and a methyl here. We want to count from the end, one of the end. We can say 1, 2, 3 or 1, 2, 3 the other way. We count from the end closest to the substituents. Either way it gets me there on carbon 2.
Here's the thing. There's two methyl so that's dimethyl. I know they’re both on the same carbon but you can't say 2 dimethyl because to dimethyl means this. 2-dimethyl just means, okay there are two methyl groups and I know the location of one of them. One of them is on carbon 2 but I don't know what the location of the other one is. You have to actually say 2,2-dimethyl. You have this state 2 twice because each one is its own separate thing located on carbon 2. We use di to pull them together because they have similar names. But each one is it's an individual substituent. We have 2,2-dimethyl and a three-carbon chain is propane. That's what we’ll name this structure.
Keep practicing. Keep going all over all the different examples that we’re going through. Attempt to do the next one. Click on the next video and see how I answer it. Check to see if your answer matches mine.

Example: Naming the following alkane compound. 

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Example: Determine the structure for the following alkane compound.

3, 4, 5-trimethyldecane 

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Example: Determine the structure for the following alkane compound.

4-tert-butyloctane

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Example: Determine the structure for the following alkane compound. 

1-bromo-2,3-dichlorocycloheptane

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Naming Alkanes Additional Practice Problems

Write the IUPAC name for the compound below. Be sure to use correct punctuation. 

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Each of the following names is wrong. Draw structures based on them, and correct the names:

(a) 3,3-dimethylbutane

(b) 1.1,1-trimethylheptane

(c) 1,4-diethylcyclopentane

(d) 1-propylcyclohexane

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Each of the following names is wrong. Draw structures based on them, and correct the names:

(a) 4-methylhexane

(b) 2-ethylpentane

(c) 2-methylcyclohexane

(d) 3,3-methyl-4-ethyloctane

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Draw the structure or give the name of each compound:

(c) 1,2-diethylcyclopentane

(d) 2,4,5‒trimethylnonane

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Draw the structure or give the name of each compound:

(a) 2,3-dimethyloctane

(b) l-ethyl-3-methylcyclohexane

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What is the IUPAC name of CH 3CH2CH2CH3?

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CH3CH2CH(CH3)CH(CH3)CH2CH3

Name the Alkane and express the answer in IUPAC name.

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Which of the following is one possible form of pentane?

A) CH3CH2CH2CH2CH3

B) CH3CH2CH2CH2CH2CH3

C) CH3CH = CHCH2CH3

D) CH3CH2-O-CH2CH2CH3

E) CH3CH2CH2CH2CH2NH2

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Name the following alkanes. 

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Name the following cycloalkanes. 

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Name the following cycloalkanes. 

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 Determine the structure for each of the following compounds.

a) 4-tert-butyloctane

 

 

b) 3,5-dichloro-4-ethylnonane

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Name the following alkanes.  

 

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NAMING ALKANES

When naming any alkane compound there is a set of rules you should follow to get the correct answer.

  1. Find the longest carbon chain and assign a root name accordingly.
  2. If there is a tie between longest chains, choose the chain that gives _____________ substituents.
  3. Number the chain from the end closest to a substituent.
  4. Substituents will be named alphabetically and a number will accompany the location of their attachment.
  5. If more than one of a similar alkyl group is present then we must use numerical prefixes to describe the number of them.

__________ – 2                __________ – 3                __________ – 4                __________ – 5

 

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Alkane Prefixes: Alkanes are fully saturated hydrocarbons with the molecular formula CnH2n+2 that end with –ane. The name of alkanes is based on the number of carbons in the compound. These alkane “prefixes” must be memorized in order to name more complex structures.  

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The organic compound CH3CH2CH3 is called

1. butane.

2. methane.

3. ethane.

4. pentane.

5. propane

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Alkanes are compounds that contain only carbons and hydrogens single bonded to one another. They are sometimes referred to simply as “saturated” hydrocarbons. State the names of the first 10 alkanes.

 

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Alkanes are fully saturated hydrocarbons that end with the suffix –ane. Based on the number of carbons present there is also a set of alkane prefixes that must be used. In the chart below fill in the alkane prefix name based on the number of carbons stated.

 

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Name the following organic molecule.

 

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Name the following organic molecule.

 

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Name the following alkane.

 

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Name the following alkane.

 

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