What would be the correct names for each of the following molecules?

Question

a. O

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H₃C—O—C—CH₃

b. H₃C—CH₂–C≡C—CH₂—CH₃

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Answer 1

A. The molecule is an ester due to its COO group with carbons extending the chain at both ends (R₁-COO-R₂). Esters are named with the suffix -anoate. The carbon within the COO group defines the start of the main chain and it extends with 1 more carbon for a total of 2, ethanoate. The secondary chain extending from the oxygen contains 1 carbon, methyl. Full name: methyl ethanoate.

B. The triple bond defines this molecule to be an alkyne. They are named by the longest carbon chain that contains the triple bond and the suffix -yne. This is a simple example as there only is one chain that contains 6 carbons: hexyne. One more thing to clarify...the name needs to specify the position of the triple bond in the chain. Count the carbons from both ends until you reach the triple bond and use the lowest number. In this example, it is the 3rd carbon from both ends that has the triple bond. Full name: 3-hexyne.

Extra alkyne example:

H3C-CH2-C=C-CH3

2-pentyne (not 3-pentyne, use the lowest count from either end)