What is the correct way to name alkanes with multiple branches?

In summary, the first problem is a 4-carbon chain with methyl branches at both C2 and C3, making it 2,3-dimethylbutane. The second problem is a 6-carbon chain with a butyl branch at C2 and an ethyl branch at C3, resulting in 2-butyl-3-ethylbutane. The third problem is an 8-carbon chain with a methyl branch at C3 and methyl and ethyl branches at C4, making it 4-ethyl-4,3-dimethyloctane.
  • #1
Suzyscans
2
0
1. This is my first posting, I am having trouble naming alkanes. I believe my first two problems are correct, but am unsure. The third problem I am having trouble with. I am just not sure what to name the branches coming off the carbon chain.
2.

1. (CH3)2CHCH(CH3)2 2. CH2Ch2CH2CH3
l
CH3CH2CH2CHCH2C--H
l l
CH3CH2 H3.
CH3 H
l l
CH3CH2CH2CH2--C--C--CH2CH3
l l
CH2 CH3
l
CH3

3. Problem 1 :4-carbon chain makes it butane. The branches at both C2 and C3 are methyl, so the name is 2,3-dimethylbutane.

Problem 2: 6-carbon chain makes it hexane. The branch at C2 is butyl. The branch at C3 is ethyl, so the name is 2-butyl-3-ethylbutane.

Problem 3:
8-carbon chain= octane
branch at C3 is methyl
branches at 4C are methyl and ethyl
That is where I get stuck on the name. Is it 4-ethyl-4,3-dimethyloctane??

Thanks very much for your input!
 
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  • #2
I can't get the equations to display properly! I will edit as soon as I figure it out :)
 
  • #3
You have 1) correct.
 

1. What are alkanes?

Alkanes are a type of hydrocarbon compound consisting of only carbon and hydrogen atoms bonded together in a straight chain structure. They are also known as saturated hydrocarbons because they only contain single bonds between the carbon atoms.

2. How do you name alkanes?

Alkanes are named using a systematic nomenclature system called the IUPAC (International Union of Pure and Applied Chemistry) system. This involves identifying the longest carbon chain in the molecule and then using prefixes and suffixes to indicate the number and position of any substituent groups.

3. What is the purpose of naming alkanes?

Naming alkanes allows for a standardized way of identifying and communicating the structure of a molecule. This is important in the fields of chemistry and biology where precise and accurate descriptions of molecules are necessary for research and communication.

4. What is the difference between structural and systematic naming of alkanes?

Structural naming of alkanes involves using common names such as methane, ethane, propane, etc. based on the number of carbon atoms in the molecule. Systematic naming, on the other hand, uses a specific set of rules to name alkanes based on their structure and functional groups present.

5. Are there any exceptions to naming alkanes?

Yes, there are some exceptions to the IUPAC naming system for alkanes. For example, the prefixes "iso-" and "neo-" are sometimes used instead of "methyl-" and "ethyl-" for certain branched alkanes. Additionally, some common names, such as isopentane and neopentane, still persist in use even though they do not follow the systematic naming rules.

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