Naming Alkenes

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Mara Lockhart 3J
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Naming Alkenes

Postby Mara Lockhart 3J » Sat Mar 07, 2015 4:32 pm

On number 25 in the yellow Introduction to Organic Chemistry textbook, I am confused on how you name the alkene. I was confused and looked at the answer, but it confused me even more. I know it is Z (or cis) because the two largest molecules are on the same side, and on the bottom of each sidearm methyl's so it's dimethyl, and the longest strange is peptone, but when you name the rest of the molecule, I just do not understand how (Z)-3,4-dimethyl-3-heptene. I guess I'm mostly confused on the numbering. Any help is greatly appreciated!

martha-1I
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Re: Naming Alkenes (cis, trans)

Postby martha-1I » Sat Mar 07, 2015 6:20 pm

This is the numbering for the longest carbon chain. It goes from left to right because we want to give the double bond the lowest possible number. There are two methyls so it's dimethyl and they are on the 3rd and 4th carbon, so it is (Z) 3,4-dimethyl-3-heptene. You are correct about it being cis/(Z),
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Re: Naming Alkenes (cis, trans)

Postby Chem_Mod » Sat Mar 07, 2015 8:38 pm

martha-1I wrote:This is the numbering for the longest carbon chain. It goes from left to right because we want to give the double bond the lowest possible number. There are two methyls so it's dimethyl and they are on the 3rd and 4th carbon, so it is (Z) 3,4-dimethyl-3-heptene. You are correct about it being cis/(Z),


Martha's explanation is correct.


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