Ch.23 - Organic and Biological Chemistry
Chapter 23, Problem 69
Benzyne, C6H4, is a highly energetic and reactive molecule. The carbon atoms are connected in a six-membered ring. Provide a line drawing for benzyne. What functional group is present?

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Step 1: Begin by drawing a hexagonal ring to represent the six carbon atoms in benzyne, similar to the structure of benzene.
Step 2: Add alternating double bonds around the hexagonal ring to depict the aromatic nature of the molecule, as seen in benzene.
Step 3: Identify the unique feature of benzyne: a triple bond between two adjacent carbon atoms in the ring, replacing one of the double bonds.
Step 4: Add hydrogen atoms to each carbon atom to ensure each carbon has four bonds in total. In benzyne, two carbon atoms will each have one hydrogen due to the triple bond.
Step 5: Recognize that the functional group present in benzyne is an alkyne, characterized by the carbon-carbon triple bond within the ring.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Aromatic Compounds
Aromatic compounds are cyclic structures that follow Huckel's rule, which states that they must have a planar ring of p-orbitals containing a total of 4n + 2 π electrons, where n is a non-negative integer. Benzyne, as a derivative of benzene, retains the aromatic character but has a unique structure due to the presence of a triple bond between two carbon atoms, making it highly reactive.
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Functional Groups
Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. In the case of benzyne, the functional group is the alkyne (due to the presence of a triple bond), which significantly influences its reactivity compared to other aromatic compounds.
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Line Drawings in Organic Chemistry
Line drawings, or skeletal structures, are a shorthand way of representing organic molecules. In these drawings, carbon atoms are represented by the ends and intersections of lines, while hydrogen atoms are often omitted for simplicity. Understanding how to interpret and create line drawings is essential for visualizing molecular structures like benzyne.
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Related Practice