Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics

Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook

Bruice 8th Edition

Ch. 5 - Alkenes: Structure, Nomenclature, and an Introduction to Reactivity • Thermodynamics and Kinetics

Problem 55d,e,f

Chapter 6, Problem 55d,e,f

How many of the following names are correct? Correct the incorrect names.
d. 1-ethyl-1-pentene
e. 5-ethylcyclohexene
f. 5-chloro-3-hexene

Verified step by step guidance

Step 1: Analyze the name '1-ethyl-1-pentene'. The name suggests a pentene chain with an ethyl group attached at position 1 and a double bond at position 1. However, this violates IUPAC nomenclature rules because the double bond should be given the lowest possible number, and substituents should not be placed on the same carbon as the double bond. Correct the name by renaming the compound with proper numbering and placement of the substituent.

Step 2: Examine the name '5-ethylcyclohexene'. The name suggests a cyclohexene ring with an ethyl group attached at position 5. However, in cyclic compounds, numbering starts from the double bond and proceeds to give substituents the lowest possible numbers. Correct the name by renumbering the positions of the substituent relative to the double bond.

Step 3: Evaluate the name '5-chloro-3-hexene'. The name suggests a hexene chain with a chlorine substituent at position 5 and a double bond at position 3. According to IUPAC rules, the double bond should be given the lowest possible number. Correct the name by renumbering the chain to prioritize the double bond.

Step 4: Apply IUPAC nomenclature rules to each name to ensure proper numbering of the main chain, placement of substituents, and prioritization of the double bond. This includes identifying the longest continuous chain containing the double bond and ensuring substituents are named and numbered correctly.

Step 5: Rewrite the corrected names for each compound based on the analysis above, ensuring compliance with IUPAC rules. Verify that the corrected names are unambiguous and accurately describe the structure of each compound.

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Key Concepts

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

IUPAC Nomenclature

IUPAC nomenclature is a systematic method for naming organic chemical compounds. It provides rules for naming based on the structure of the molecule, including the longest carbon chain, functional groups, and substituents. Understanding these rules is essential for determining the correctness of compound names and making necessary corrections.

Alkenes and Their Naming

Alkenes are hydrocarbons that contain at least one carbon-carbon double bond. When naming alkenes, the position of the double bond must be indicated by the lowest possible number, and substituents must be named and numbered according to their position on the carbon chain. This is crucial for accurately identifying and correcting names of alkenes.

Cycloalkenes

Cycloalkenes are cyclic hydrocarbons that contain one or more double bonds. When naming cycloalkenes, the position of the double bond is indicated, and substituents are numbered starting from the carbon of the double bond. Understanding the unique rules for cycloalkenes is important for evaluating the correctness of names involving cyclic structures.

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