CALLING ALL CHEMISTRY MAJORS/GURU
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From: Denton, TX
You are supposed to write the carbons in sequence. Start by finding the longest chain of carbons (in this case, 4). Begin at the end closest to the first functional group. That extra CH3 (the methyl group) is off the SECOND carbon which means you must first write CH3 to account for the first one. Then its CH(CH3), and so on. You'll get it wrong if you don't write it in order.
2-methyl butane
2-methyl butane
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From: Yorba Linda, CA
Originally Posted by Dantheman,Sep 30 2007, 04:22 PM
Not necessarily. The 2- indicates which carbon in the butane chain the methyl group is attached to. If it were off of either the first or last carbon in the chain, it would be superfluous to put 1-methyl butane, but in this case, its not.
The only place a methyl radical can attach to a butane molecule without creating pentane would be at the second or third carbon atom in the chain. But there's no difference between 2-methylbutane and 3-methylbutane: flip the molecule around.
Thus, the only methylbutane is 2-methylbutane; the "2-" is superfluous.
I believe that methylbutane is also known as isopentane.
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From: RSM
Originally Posted by magician,Sep 30 2007, 06:37 PM
Isn't 1-methylbutane properly called pentane?
The only place a methyl radical can attach to a butane molecule without creating pentane would be at the second or third carbon atom in the chain. But there's no difference between 2-methylbutane and 3-methylbutane: flip the molecule around.
Thus, the only methylbutane is 2-methylbutane; the "2-" is superfluous.
I believe that methylbutane is also known as isopentane.
The only place a methyl radical can attach to a butane molecule without creating pentane would be at the second or third carbon atom in the chain. But there's no difference between 2-methylbutane and 3-methylbutane: flip the molecule around.
Thus, the only methylbutane is 2-methylbutane; the "2-" is superfluous.
I believe that methylbutane is also known as isopentane.
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You can't have an alkane coming off the end of an alkane and call it a functional group. It's simply another carbon in the chain.
You name the compound starting with the end closest to the first functional group, so there is no such thing as 3-methylbutane.
You name the compound starting with the end closest to the first functional group, so there is no such thing as 3-methylbutane.
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From: Yorba Linda, CA
Originally Posted by C U AT 9K,Sep 30 2007, 06:54 PM
You can't have an alkane coming off the end of an alkane and call it a functional group. It's simply another carbon in the chain.
You name the compound starting with the end closest to the first functional group, so there is no such thing as 3-methylbutane.
You name the compound starting with the end closest to the first functional group, so there is no such thing as 3-methylbutane.
Originally Posted by Dantheman,Sep 30 2007, 06:42 PM
Its been 2 years since I've taken the class so I'm a bit rusty on the fundamentals
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I'm sorry but how do you have two CH3 molecules binded together and the second one is ALSO binded to another carbon????
Carbon can form 4 bonds. 3 are taken by hydrogens, and the remaining bonds with the second carbon. That second carbon now only has 3 valence electrons left. If those three are taken up by hydrogens, where does the 5th bond come from in order for it to bond to the third carbon?!?
If you wish to write it so those first two CH3's are binded to that one CH, then the CH3's have to come AFTER the CH to show that they are bonded to the CH. But that does not accurately depict the molecule at question.
Carbon can form 4 bonds. 3 are taken by hydrogens, and the remaining bonds with the second carbon. That second carbon now only has 3 valence electrons left. If those three are taken up by hydrogens, where does the 5th bond come from in order for it to bond to the third carbon?!?
If you wish to write it so those first two CH3's are binded to that one CH, then the CH3's have to come AFTER the CH to show that they are bonded to the CH. But that does not accurately depict the molecule at question.
