Question

The IUP\LambdaC name of the compound is (1) 2 -methyl pent- 1 -en- \(\mathbf{4}\) -yne (2) 4 -methyl pent-4-en-1-yne (3) 2 -methyl pent-2-en-4-yne (4) 4 -methyl pent- 3 -en- 1 -yne

Short answer

Option (3): 2-methyl pent-2-en-4-yne

Step-by-step solution

- Identify the Longest Carbon Chain

Determine the longest carbon chain that includes both the double bond (ene) and triple bond (yne). In all options, the longest chain consists of 5 carbon atoms, making it a 'pent' structure.

- Number the Chain Correctly

Number the chain from the end nearest to the first point of unsaturation (double or triple bond). This ensures that double and triple bonds get the lowest possible numbers.

- Identify the Positions of Substituents

Look at the positions of any methyl groups and ensure they are accurately placed based on the numbering from Step 2. This helps in confirming the exact IUPAC name.

- Assemble the Full Name

Combine the information: positions of double and triple bonds and the substituents. Make sure to order the substituents and functional groups correctly.

- Compare with Given Options

Compare the correct IUPAC name derived from the previous steps with the given options to find the matching one.

Key concepts

organic chemistry

Organic chemistry is the study of carbon-containing compounds and their properties. It's centered on understanding how carbon atoms bond with other elements, particularly hydrogen, oxygen, and nitrogen. One of the key reasons carbon is so special is its ability to form four covalent bonds, leading to a vast variety of molecular shapes and sizes.

In organic chemistry, compounds are often categorized based on their functional groups—specific groups of atoms that confer particular chemical properties. For instance, alkanes are saturated hydrocarbons containing only single bonds, while alkenes and alkynes contain double and triple bonds, respectively. Understanding these differences is crucial for mastering this field.

Another important concept in organic chemistry is isomerism. Isomers are compounds with the same chemical formula but different structures. These structural differences can result in vastly different chemical and physical properties. This is why clear naming conventions, like the IUPAC nomenclature, are so important in organic chemistry.

chemical nomenclature

Chemical nomenclature is the system for naming chemical compounds. The International Union of Pure and Applied Chemistry (IUPAC) has set the rules that standardize these names, making it easier for scientists around the world to communicate. For organic compounds, the IUPAC system names start with identifying the longest carbon chain in the molecule and then numbering it.

This longest chain must include the highest-priority functional groups, such as double (ene) or triple (yne) bonds. After identifying the main chain, number the chain in a way that gives the lowest possible numbers to the double and triple bonds.

Next, any additional side chains or substituent groups such as methyl groups are identified and numbered according to their position. The final name is assembled by listing the substituents in alphabetical order, followed by the base name of the longest chain, and ending with the position and type of double and triple bonds. Doing this correctly ensures that each compound has a unique and unambiguous name, essential for accurate scientific communication.

alkenes and alkynes

Alkenes and alkynes are types of hydrocarbons, distinguished by their double and triple bonds, respectively. They are classified as unsaturated hydrocarbons because they have fewer hydrogen atoms per carbon compared to alkanes.

Alkenes contain at least one carbon-carbon double bond (C=C). These double bonds create geometric isomers because the bond restricts rotation, leading to 'cis' and 'trans' configurations. For example, 2-butene can exist as either cis-2-butene or trans-2-butene, depending on the relative positions of the substituent groups around the double bond.

Alkynes, on the other hand, have at least one carbon-carbon triple bond (C≡C). These triple bonds are linear and do not have cis-trans isomerism. Common examples include ethyne (also known as acetylene) and propyne. The naming of alkenes and alkynes requires careful attention to the position of these multiple bonds within the carbon chain. Numbering the chain from the end nearest to these bonds ensures that they receive the lowest possible numbers, which is crucial for correctly applying the IUPAC nomenclature rules.