Question

The IUPAC name of the compound \(\mathrm{CH}_{3}-\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2}-\mathrm{CH}=\mathrm{C}\left(\mathrm{CH}_{3}\right)_{2}\) is (a) \(1,1,3,3\) -tetramethyl-but-1-ene (b) \(1,3,3\) -trimethyl-pent-2-ene (c) \(2,2,4\) -trimethylbut- 4 -ene (d) \(2,4,4\) -trimethylpent- 2 -ene

Short answer

The IUPAC name is (d) \(2,4,4\) -trimethylpent- 2 -ene.

Step-by-step solution

Identify the Longest Carbon Chain

First, identify the longest continuous chain of carbon atoms that includes the double bond(s). In this compound, the longest chain including the double bond has 5 carbon atoms. This indicates a 'pent' root name because 'pent' corresponds to a 5-carbon chain.

Number the Carbon Chain

Number the carbon chain starting from the end closest to the double bond to give the smallest possible number to the double bond. Therefore, the chain is numbered from left to right, resulting in the double bond starting at the 2nd carbon atom.

Identify and Name the Substituents

Identify the methyl groups (CH\(_3\)) as substituents. There are 3 methyl groups attached to the main chain: two at carbon 3 and one at carbon 2. This results in a total of three methyl groups.

Assemble the IUPAC Name

Combine the elements of the name by placing the numbers of the carbon atoms where the substituents are attached followed by the substituent names, followed by the root name indicating the length of the longest chain, and finally the position and nature of the double bond. The complete name is thus '2,4,4-trimethylpent-2-ene'.

Key concepts

Organic Chemistry

Organic chemistry is the study of carbon-containing compounds and their properties, reactions, and structures. Carbon's unique ability to form stable covalent bonds with itself and other elements leads to an immense variety of compounds. These compounds can range from simple molecules like methane to complex macromolecules like proteins.
One of the most interesting aspects of organic chemistry is the vast diversity of compounds that carbon can create. Understanding these compounds involves studying their structural formulas and learning principles to identify and name them accurately. Such skills are critical in helping chemists communicate chemical compositions and reactions succinctly and clearly.

Chemical Structure Identification

Identifying chemical structures is a fundamental skill in chemistry that allows chemists to understand and predict the behavior of molecules. It involves interpreting molecular formulas, recognizing functional groups, and determining the spatial arrangement of different atoms.
When we look at a chemical structure, like the one in the exercise, we see a pattern of atoms and bonds. Each carbon atom has a specific number of bonds, typically four, due to its tetravalency. The position of these bonds, particularly in relation to double bonds or functional groups, helps us determine its chemical behavior and how it interacts with other molecules.
Remember, chemical structure identification isn't just about spotting features. It's about understanding how those features dictate the compound's properties and reactivity.

Alkene Naming

Alkenes are hydrocarbons characterized by the presence of one or more carbon-carbon double bonds. This double bond is the defining feature for naming these compounds. The IUPAC system, which stands for the International Union of Pure and Applied Chemistry, provides the naming standards.
In IUPAC nomenclature, alkenes have the suffix "-ene," indicating a double bond. The position of this bond is crucial and should be identified when numbering the carbon chain. Begin numbering from the end nearest to the double bond to assign the lowest possible number to the bond's location. In our exercise, the double bond in the compound begins at carbon 2, leading to the "pent-2-ene" portion of the name.
Correctly naming alkenes ensures clear communication of their structure and potential chemical reactions.

Longest Carbon Chain

Identifying the longest carbon chain in a molecule is essential for determining its root name in IUPAC nomenclature. This chain serves as the backbone of the compound, and the number of carbon atoms it contains dictates the primary identifier.
In the given exercise, the longest chain containing the double bond has five carbon atoms, which corresponds to the root name "pent". This chain must be chosen to include the double bond, providing the main structural characteristic of the molecule.
Remember, accurately identifying the longest chain helps in systematically naming complex organic structures, allowing for an organized and predictable method of chemical classification.

Substituents Naming

In organic chemistry, substituents are atoms or groups of atoms attached to the main carbon chain. Properly naming these substituents is crucial, as they modify the properties and name of the compound.
Methyl groups, indicated by the chemical formula CH extsubscript{3}, are common substituents in organic frameworks. In our exercise, three methyl groups are present, two on carbon 3 and one on carbon 2. This leads to the "2,4,4-trimethyl" segment of the compound's name.
Substituents increase the complexity of the molecule's structure and function, making it imperative to follow IUPAC rules to assign their numbers and names correctly. This ensures the clarity and consistency necessary for chemical communication.