Textbook Question
Draw skeletal structures for the following:
b. 1,3-dimethylcyclohexane
4. Alkanes and Cycloalkanes
Naming Cycloalkanes
4:38 minutesProblem 37c,d
Textbook Question
Each of the following descriptions applies to more than one alkane. In each case, draw and name two structures that match the description.
c. a cis-diethylcyclohexane
d. a trans-dihalocyclopentane
Verified step by step guidance1
Understand the problem: You are tasked with drawing and naming two structures for each description. The descriptions involve specific stereochemical configurations (cis and trans) and substituents on cycloalkanes. Let's break this down step by step.
Step for part (c): 'cis-diethylcyclohexane':
1. Recall that 'cis' means both substituents are on the same side of the cyclohexane ring (either both axial or both equatorial).
2. Draw the cyclohexane ring in its chair conformation. Place one ethyl group on a carbon atom in the ring. Then, place the second ethyl group on a different carbon atom such that both groups are on the same side of the ring (either both pointing up or both pointing down).
3. Repeat the process to create a second structure by placing the ethyl groups on different carbons of the ring, ensuring the 'cis' configuration is maintained.
4. Name the structures according to IUPAC nomenclature, ensuring the positions of the ethyl groups are correctly numbered to give the lowest possible locants.
Step for part (d): 'trans-dihalocyclopentane':
1. Recall that 'trans' means the two halogen substituents are on opposite sides of the cyclopentane ring (one pointing up and the other pointing down).
2. Draw the cyclopentane ring. Place one halogen atom (e.g., chlorine or bromine) on a carbon atom in the ring. Then, place the second halogen atom on a different carbon atom such that the two halogens are on opposite sides of the ring.
3. Repeat the process to create a second structure by placing the halogen atoms on different carbons of the ring, ensuring the 'trans' configuration is maintained.
4. Name the structures according to IUPAC nomenclature, specifying the positions of the halogen atoms and their identities (e.g., 1,2-dibromocyclopentane).
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Video duration:
4mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Cis-Trans Isomerism
Cis-trans isomerism, also known as geometric isomerism, occurs in compounds with restricted rotation around a bond, typically in cyclic structures or alkenes. In cis isomers, substituents are on the same side of the double bond or ring, while in trans isomers, they are on opposite sides. Understanding this concept is crucial for drawing and naming structures like cis-diethylcyclohexane and trans-dihalocyclopentane.
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Cycloalkanes
Cycloalkanes are saturated hydrocarbons that contain carbon atoms arranged in a ring structure. They can exhibit different conformations and isomeric forms based on the arrangement of substituents around the ring. Recognizing the properties and naming conventions of cycloalkanes is essential for accurately representing structures like diethylcyclohexane and dihalocyclopentane.
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Substituent Naming and Positioning
In organic chemistry, substituents are groups attached to the main carbon chain or ring. Proper naming involves identifying the type and position of these substituents, which is critical for distinguishing between isomers. For example, in diethylcyclohexane, the positions of the ethyl groups must be specified to differentiate between cis and trans forms, as well as in dihalocyclopentane where the halogen substituents' positions affect the compound's name and properties.
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