Textbook Question
Which of the following structures represent the same compound? Which ones represent different compounds?
(a)
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4. Alkanes and Cycloalkanes
IUPAC Naming
1:18 minutesProblem 41e,f
Textbook Question
The following names are all incorrect or incomplete, but they represent real structures. Draw each structure and name it correctly.
e. 2-cyclohexylbutane
f. 2,3-diethylcyclopentane
Verified step by step guidance1
Step 1: Understand the naming conventions for cycloalkanes. Cycloalkanes are named by identifying the ring size and then adding substituents as prefixes with their position numbers.
Step 2: For 2-cyclohexylbutane, recognize that the name suggests a cyclohexyl group attached to a butane chain. However, the name is incomplete because it does not specify the position of the cyclohexyl group on the butane chain.
Step 3: Draw the structure for 2-cyclohexylbutane. Start with a butane chain (CH₃-CH₂-CH₂-CH₃) and attach a cyclohexyl group (a six-membered ring) to the second carbon of the butane chain.
Step 4: Correct the name for 2-cyclohexylbutane. The correct name should reflect the position of the cyclohexyl group on the butane chain, ensuring the longest carbon chain is identified and numbered correctly.
Step 5: For 2,3-diethylcyclopentane, recognize that the name suggests two ethyl groups attached to a cyclopentane ring. However, the name is incorrect because it does not follow the proper numbering system for substituents on a cycloalkane ring. Draw the structure with ethyl groups on the second and third carbons of the cyclopentane ring, then rename it using the lowest possible numbers for substituents.
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Video duration:
1mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
IUPAC Nomenclature
IUPAC nomenclature is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry. It provides a standardized way to name chemical compounds, ensuring that each name is unique and descriptive of the compound's structure. Understanding IUPAC rules is essential for correctly naming and interpreting the names of organic molecules.
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Cycloalkane Structure
Cycloalkanes are types of hydrocarbons that contain carbon atoms arranged in a ring structure, with the general formula CnH2n. They are saturated, meaning they have single bonds only. Recognizing the structure of cycloalkanes is crucial for understanding how substituents are attached and how to correctly name compounds with cyclic components.
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Substituent Positioning
In organic chemistry, the position of substituents on a carbon chain or ring is indicated by numbers, which are assigned based on the lowest possible locants rule. This ensures clarity in the structure's description. Correctly identifying and numbering substituents is vital for accurate naming and understanding of molecular structures, especially in complex molecules.
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