Help with naming O-Chem using IUPAC?
2017-07-24 11:04 am
I got 3-ethyl-1-pentyne. However the answer sheet says that it's 3-methyl-1-pentyne. I don't understand why since the substituent attached has 2C's & 5H's. Please help me understand! Thanks.
回答 (2)
2017-07-24 11:44 am
Refer to the diagram showing the structure of the compound.
The parent chain, indicated by a red line, has 5 carbon, i.e. "pent(a)-". In numbering an alkyne, we have to make the number of alkyne (C≡C triple bond) the smallest, i.e. the C≡C triple bond is between C₁ and C₂, and numbered as "1-". Hence, the parent chain is named as 1-pentyne.
Besides, there is a methyl group (-CH₃) at C₃, i.e. "3-methyl-". Hence, the compound is named as 3-methyl-1-pentyne.
The parent chain, indicated by a red line, has 5 carbon, i.e. "pent(a)-". In numbering an alkyne, we have to make the number of alkyne (C≡C triple bond) the smallest, i.e. the C≡C triple bond is between C₁ and C₂, and numbered as "1-". Hence, the parent chain is named as 1-pentyne.
Besides, there is a methyl group (-CH₃) at C₃, i.e. "3-methyl-". Hence, the compound is named as 3-methyl-1-pentyne.
2017-07-24 11:09 am
Ok, your answer of 3-ethyl-1-pentyne has 7 total Carbons, whereas your diagram only contains 6. The diagram consists of a 5 Carbon chain plus a methyl side group at the 3 position, making a total of 6 carbons.
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