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Ch.21 - Organic Chemistry
Chapter 21, Problem 55a,b

Draw the correct structure for each compound. a. 4-octyne b. 3-nonene

Verified step by step guidance
1
Identify the base structure for each compound: For 4-octyne, the base is an 8-carbon chain (octane), and for 3-nonene, the base is a 9-carbon chain (nonane).
Determine the type of bond and its position: For 4-octyne, there is a triple bond starting at the 4th carbon. For 3-nonene, there is a double bond starting at the 3rd carbon.
Draw the carbon chain for each compound: For 4-octyne, draw a straight chain of 8 carbon atoms. For 3-nonene, draw a straight chain of 9 carbon atoms.
Incorporate the multiple bonds: For 4-octyne, replace the single bond between the 4th and 5th carbon with a triple bond. For 3-nonene, replace the single bond between the 3rd and 4th carbon with a double bond.
Add hydrogen atoms to satisfy the tetravalency of carbon: Ensure each carbon atom forms four bonds in total by adding the appropriate number of hydrogen atoms to each carbon in both structures.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Alkynes

Alkynes are hydrocarbons that contain at least one carbon-carbon triple bond. They follow the general formula CnH2n-2, where 'n' is the number of carbon atoms. The presence of the triple bond gives alkynes unique properties, including increased reactivity compared to alkenes and alkanes. In the case of 4-octyne, the triple bond is located between the fourth and fifth carbon atoms in an eight-carbon chain.
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Alkenes

Alkenes are unsaturated hydrocarbons characterized by at least one carbon-carbon double bond. They follow the general formula CnH2n, indicating that they have fewer hydrogen atoms than alkanes due to the presence of the double bond. The position of the double bond is crucial for naming and drawing the structure, as seen in 3-nonene, where the double bond is located between the third and fourth carbon atoms in a nine-carbon chain.
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Structural Representation

Structural representation in organic chemistry involves depicting the arrangement of atoms within a molecule. This can be done using various methods, such as Lewis structures, condensed formulas, or skeletal structures. Understanding how to accurately represent the structure of compounds like 4-octyne and 3-nonene is essential for visualizing their molecular geometry and predicting their chemical behavior.
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