Textbook Question
Name the following alkanes using the common names for branched substituents.
(c)
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4. Alkanes and Cycloalkanes
Alkyl Groups
4:57 minutesProblem 7a
Textbook Question
Draw the structures of the following groups, and give their more common names.
a. the (1-methylethyl) group
b. the (2-methylpropyl) group
c. the (1-methylpropyl) group
d. the (1,1-dimethylethyl) group
e. the (3-methylbutyl) group, sometimes called the 'isoamyl' group
Verified step by step guidance1
To draw the structure of the (1-methylethyl) group, recognize that it is commonly known as the isopropyl group. It consists of a central carbon atom bonded to two methyl groups (CH₃) and one hydrogen atom. The structure can be represented as: (CH₃)₂CH-.
For the (2-methylpropyl) group, identify it as the isobutyl group. It has a four-carbon chain with a methyl group attached to the second carbon. The structure is: CH₃CH(CH₃)CH₂-.
The (1-methylpropyl) group is known as the sec-butyl group. It consists of a four-carbon chain where the methyl group is attached to the first carbon. The structure is: CH₃CH₂CH(CH₃)-.
The (1,1-dimethylethyl) group is commonly referred to as the tert-butyl group. It features a central carbon atom bonded to three methyl groups. The structure is: (CH₃)₃C-.
For the (3-methylbutyl) group, also known as the isoamyl group, it consists of a five-carbon chain with a methyl group attached to the third carbon. The structure is: CH₃CH₂CH(CH₃)CH₂-.
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4mKey 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 compounds based on their structure, ensuring clear communication among chemists. Understanding IUPAC rules is essential for identifying and naming the structures of organic groups accurately.
Alkyl Groups
Alkyl groups are fragments of alkanes that result when a hydrogen atom is removed from an alkane molecule. They are often used as substituents in larger organic molecules. Recognizing common alkyl groups, such as isopropyl, isobutyl, and tert-butyl, is crucial for drawing and naming organic structures, as these groups frequently appear in organic chemistry.
Structural Isomerism
Structural isomerism occurs when compounds have the same molecular formula but different structural arrangements of atoms. This concept is vital for understanding how different alkyl groups can have distinct structures despite having similar formulas. Identifying isomers, such as the difference between isopropyl and sec-butyl groups, is key to accurately drawing and naming organic compounds.
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