Textbook Question
Name the following alkanes using the IUPAC system of nomenclature. [Each molecule exemplifies one of the nomenclature rules in Tables 3.7 and 3.8.]
(j) rule 5
1075
views
4. Alkanes and Cycloalkanes
IUPAC Naming
3:27 minutesProblem 33a
Textbook Question
a. There are 18 isomeric alkanes of molecular formula C8H18. Draw and name any eight of them.
Verified step by step guidance1
Step 1: Understand the concept of isomerism. Isomers are compounds with the same molecular formula but different structural arrangements. In alkanes, isomerism arises due to different branching patterns.
Step 2: Start with the simplest structure, the straight-chain alkane. For C8H18, this is n-octane. Draw a linear chain of eight carbon atoms, each bonded to sufficient hydrogen atoms to satisfy the tetravalency of carbon.
Step 3: Create branched isomers by rearranging the carbon atoms. Begin by shortening the main chain and adding branches. For example, draw 2-methylheptane by having a seven-carbon chain with a methyl group (CH3) attached to the second carbon.
Step 4: Continue creating isomers by varying the position and number of branches. For instance, draw 3-methylheptane, 2,2-dimethylhexane, and 2,3-dimethylhexane. Ensure each structure has eight carbon atoms and eighteen hydrogen atoms.
Step 5: Name each isomer according to IUPAC nomenclature rules. Identify the longest carbon chain, number the chain to give the lowest numbers to the substituents, and list substituents alphabetically. Verify that each name corresponds to a unique structure.
Verified video answer for a similar problem:This video solution was recommended by our tutors as helpful for the problem above
Video duration:
3mKey Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Isomerism
Isomerism refers to the phenomenon where compounds have the same molecular formula but different structural arrangements. In organic chemistry, structural isomers differ in the connectivity of atoms, leading to variations in physical and chemical properties. Understanding isomerism is crucial for identifying and drawing different isomeric forms of a given compound.
Recommended video:
Guided course
06:47
Monosaccharides - D and L Isomerism
Alkanes
Alkanes are saturated hydrocarbons consisting solely of carbon and hydrogen atoms, connected by single bonds. They follow the general formula CnH2n+2, where n is the number of carbon atoms. Alkanes are characterized by their lack of reactivity due to the stability of C-C and C-H bonds, making them a fundamental class of compounds in organic chemistry.
Recommended video:
Guided course
02:47Functionalizing Alkanes
IUPAC Nomenclature
IUPAC nomenclature is a standardized system for naming chemical compounds, ensuring clarity and consistency in communication. For alkanes, the name is derived from the longest carbon chain, with prefixes indicating the presence and position of branches or substituents. Mastery of IUPAC rules is essential for accurately naming and identifying different isomers.
Recommended video:
Guided course
03:43The different parts of an IUPAC name
Related Videos
Related Practice