Question

Which of the following is / are incorrect IUPAC names? (A) 2-Ethyl-3-methyl pentane (B) 1 -amino butane-1-one (C) 2-Methyl-3-ethyl pentane (D) \(4-(1,1\)-dimethyl ethyl)-2-methyl pentane

Short answer

Options (B) and (D) are incorrect IUPAC names. The correct names should be "1-amino butan-1-one" and "2-methyl-4-isopropyl pentane," respectively.

Step-by-step solution

Evaluate Option (A)

For the compound 2-Ethyl-3-methyl pentane, we first identify the parent hydrocarbon chain. The parent chain is called "pentane," which means it has five carbon atoms (C5H12). Next, we have two substituents: "ethyl" with two carbon atoms (C2H5) attached to carbon 2, and "methyl" with one carbon atom(CH3) attached to carbon 3. Since the substituents are numbered based on their position on the chain and follow alphabetical order, the name seems to be correctly written.

Evaluate Option (B)

For the compound 1-amino butane-1-one, we first identify the parent hydrocarbon chain. The parent chain is called "butane," which means it has four carbon atoms (C4H10). There is a mistake right away; the main functional group of this compound should be "butanone" (a ketone) instead of "butane." The correct parent chain should be named "butanone," as it has 4 carbons and a ketone functional group (C4H8O). The substituent "1-amino" indicates there is an amino group (NH2) is attached to carbon 1. The correct IUPAC name should be "1-amino butan-1-one." Therefore, option (B) is incorrect.

Evaluate Option (C)

For the compound 2-Methyl-3-ethyl pentane, we first identify the parent hydrocarbon chain. The parent chain is called "pentane," which means it has five carbon atoms (C5H12). Next, we have two substituents: "methyl" with one carbon atom (CH3) attached to carbon 2, and "ethyl" with two carbon atoms (C2H5) attached to carbon 3. Since the substituents are numbered based on their location on the main chain and follow alphabetical order, the name seems to be correctly written.

Evaluate Option (D)

For the compound 4-(1,1-dimethyl ethyl)-2-methyl pentane, we first identify the parent hydrocarbon chain. The parent chain is called "pentane," which means it has five carbon atoms (C5H12). Next, we have a substituent called "1,1-dimethyl ethyl," which should instead be named "isopropyl" (CH(CH3)2), attached to carbon 4. There is also a "methyl" substituent with one carbon atom (CH3) attached to carbon 2. The correct IUPAC name should be "2-methyl-4-isopropyl pentane." Therefore, option (D) is incorrect. In conclusion, options (B) and (D) are incorrect IUPAC names.

Key concepts

Organic Chemistry

Organic chemistry is the branch of chemistry that studies the structure, properties, composition, reactions, and preparation of carbon-containing compounds. These compounds may contain hydrogen, nitrogen, oxygen, and other elements. One core aspect of organic chemistry is identifying how carbon atoms can form chains and rings to build a nearly endless variety of complex molecules.

Carbon's ability to form stable covalent bonds with many different elements, including itself, leads to a vast diversity of carbon compounds. This foundational concept is essential for understanding the behavior and transformation of organic molecules.

To better understand organic chemistry, you'll often deal with IUPAC nomenclature, a systematic method for naming organic compounds. This ensures that each compound has a unique and universally accepted name, aiding in effective communication among scientists worldwide.

Functional Groups Identification

Understanding and identifying functional groups is crucial in organic chemistry. Functional groups are specific groupings of atoms within molecules that have characteristic properties and dictate the molecule's chemical behavior. They are the reactive parts of molecules that participate in reactions.

Here are some common functional groups:

• Alcohols: –OH group
• Carboxylic Acids: –COOH group
• Amines: –NH2 group
• Ketones: carbonyl group C=O within the chain

Identifying these groups helps in predicting how a molecule will react in given conditions. For example, when dealing with IUPAC nomenclature, the main functional group often dictates the suffix of the compound name.

In the solved exercise, the amine group and a ketone were identified in one of the options, which was crucial for the correct naming of the compound as butan-1-one.

Hydrocarbon Chain Identification

Another key step in understanding organic compounds is correctly identifying the hydrocarbon chain. The hydrocarbon chain is the backbone of organic molecules, consisting entirely of carbon and hydrogen. These chains can be straight, branched, or even form rings.

In IUPAC nomenclature, the longest continuous chain of carbon atoms in a molecule is identified as the parent chain. Its length determines the root name, such as methane (1 carbon), ethane (2 carbons), propane (3 carbons), etc.

Once the parent hydrocarbon chain is identified, it helps in organizing and naming the compound properly. For example, in the provided exercise, "pentane" was identified as the parent chain, indicating five carbon atoms. Correct identification of this chain is crucial when determining the position of functional groups or substituents.

• Identify the longest chain to determine the base name.
• Locate and number substituents on the chain.
• Use prefixes to indicate multiple substituents and their positions.

Proper identification ensures that the compound is named following standard conventions, preventing confusion and errors in chemical communication.