Question

Write structures of the compounds whose IUPAC names are as follows: (i) 2-Methylbutan-2-ol (ii) 1 -Phenylpropan-2-ol (iii) 3,5 -Dimethylhexane \(-1,3,5\) -triol (iv) \(2,3-\) Diethylphenol (v) 1 - Ethoxypropane (vi) 2-Ethoxy-3-methylpentane vii) Cyclohexylmethanol (viii) 3 -Cyclohexylpentan-3-ol (ix) Cyclopent-3-en-1-ol (x) 4-Chloro-3-ethylbutan-1-ol.

Short answer

Structures for each compound are described with specified substitutions and modifications to the carbon skeletons, matching the IUPAC names.

Step-by-step solution

Identifying the Parent Chain and Functional Group (i)

For 2-Methylbutan-2-ol, the parent chain is butane. The functional group present is an alcohol (-OH) located at the second carbon. Additionally, there is a methyl group attached to the second carbon.

Structure Synthesis (i)

The molecular structure involves a four-carbon chain (butane) with an -OH group and a methyl group both attached to the second carbon. This gives the structure: CH₃-C(CH₃)(OH)-CH₂-CH₃.

Understanding the Structure (ii)

For 1-Phenylpropan-2-ol, the parent chain is propane. The functional group is an alcohol (-OH) at the second carbon, and a phenyl group (C₆H₅) is attached to the first carbon.

Structure Synthesis (ii)

The structure is synthesized by attaching a phenyl group to the first carbon of propane, and -OH to the second carbon: C₆H₅-CH₂-CH(OH)-CH₃.

Analyzing the Chain and Functional Groups (iii)

In 3,5-Dimethylhexane-1,3,5-triol, the parent chain is hexane. There are three hydroxyl groups attached to the first, third, and fifth carbons, and methyl groups at the third and fifth carbons.

Structure Synthesis (iii)

The structure is represented by C₃H₇-CH(CH₃)-C(CH₃)(OH)-CH₂-CH₃ with -OH at positions 1, 3, and 5.

Recognizing Aromatic Group and Substituents (iv)

For 2,3-Diethylphenol, the benzene ring (phenol) is the core structure. It has two ethyl groups at the 2nd and 3rd carbon positions, relative to the -OH group attached to the benzene ring.

Structure Synthesis (iv)

This forms an aromatic compound with the structure: C₆H₄(OH)(C₂H₅)₂, where two ethyl groups are connected to the benzene ring along with -OH.

Determining the Alkyl and Ether Components (v)

In 1-Ethoxypropane, the parent chain is propane, and a functional ether group is represented by 'ethoxy' at the first carbon.

Structure Synthesis (v)

Formation involves joining an ethoxy group (O-C₂H₅) to the first carbon of the propane chain: C₂H₅-O-CH₂-CH₂-CH₃.

Identifying Ether and Alkane Structure (vi)

For 2-Ethoxy-3-methylpentane, note the parent chain is pentane, with an ethoxy group at the second carbon and a methyl group at the third carbon.

Structure Synthesis (vi)

Synthesize the structure with ethoxy and methyl substituents: CH₃-CH(O-C₂H₅)-CH(CH₃)-CH₂-CH₃.

Cyclohexane Substitution Analysis (vii)

Cyclohexylmethanol involves a cyclohexane ring with a methanol group replacing a hydrogen atom on one of the carbons.

Structure Synthesis (vii)

The structure: C₆H₁₁-CH₂OH, where CH₂OH is attached to the cyclohexane ring.

Substituted Pentane with a Ring Group (viii)

In 3-Cyclohexylpentan-3-ol, the parent chain is pentane, and a cyclohexyl and a hydroxyl group are attached to the third carbon of this chain.

Structure Synthesis (viii)

Create the molecular structure: C₅H₁₁-CH(OH)-C₆H₁₁, placing cyclohexyl and -OH on carbon 3.

Naming/Identifying the Cyclic Alcohol (ix)

Cyclopent-3-en-1-ol indicates a cyclopentene ring with an -OH group at the first position.

Structure Synthesis (ix)

The structure is a five-carbon ring with an alkene and hydroxyl group: C₅H₆(OH), with the double bond starting at carbon 3.

Determining the Alkyl Chloride and Alcohol Functionalities (x)

For 4-Chloro-3-ethylbutan-1-ol, the parent chain is butane with a chloro group at the 4th carbon and an ethyl group at the 3rd carbon, plus -OH on the 1st.

Structure Synthesis (x)

Arrange the groups as C₂H₅-CHCl-CH-C(OH)-CH₃ matching the specified positions.

Key concepts

Functional Groups in Organic Chemistry

Functional groups are specific atoms or groups of atoms within molecules that have characteristic chemical behaviors. They play a vital role in determining the chemical properties and reactivity of organic compounds. In the exercise, different functional groups are illustrated, showcasing their diversity and impacting how organic molecules behave.
- **Alcohols** have hydroxyl groups (-OH) that are quite common. They modify hydrocarbons by adding polarity, often increasing solubility in water due to hydrogen bonding. For example, in 1-Phenylpropan-2-ol, the -OH group at the second carbon of the propane chain introduces characteristics typical of alcohols. - **Ethers** like in 1-Ethoxypropane, involve an oxygen atom bonded to two carbon atoms. The presence of the 'ethoxy' group represents an ether, often leading to differences in boiling points and solubility compared to alcohols. - **Chlorides** are another important group as seen in 4-Chloro-3-ethylbutan-1-ol where the chlorine atom substantially alters the reactivity and polarity of the molecule.
Mastering functional groups allows you to predict how a molecule will react under different conditions, forming the basis for understanding organic chemistry.

Molecular Structure Synthesis

Molecular structure synthesis involves constructing the molecular structure of a compound based on IUPAC naming. This is a crucial skill in organic chemistry as it requires understanding and applying the rules of nomenclature to build the correct structure from given names.
In the solutions above, synthesis is accomplished step-by-step:

• First, identify and verify the parent hydrocarbon chain.
• Recognize the position and type of any substituents and functional groups, such as methyl, ethyl, hydroxyl, or phenyl groups.
• Construct the molecular framework connecting all elements as specified in the name using the carbon backbone as a guide.

For example, in 2-Methylbutan-2-ol, a four-carbon butane chain with specific substituents is built such that both a methyl group and an -OH group are attached to the second carbon, illustrating how identified elements in the name translate into molecular structure.
Through practice, recognizing how IUPAC names correlate with molecular structures becomes intuitive and enhances your problem-solving abilities in organic and synthetic chemistry.

Organic Chemistry Problem Solving

Organic chemistry problem solving demands a systematic approach to determine not just the structure but the possible reactivity and interaction of molecules. When approaching problems, students should:

• Develop a methodical approach: Break down the name into recognizable parts and analyze each segment individually.
• Visualize molecules mentally or draw them out on paper. This visualization aids in ensuring accuracy and avoiding simple errors.
• Identify relationships between functional groups and molecular structures. These relationships can predict how molecules will interact in reactions.

For instance, solving for the structure of Cyclopent-3-en-1-ol, involves identifying both an alcohol group and an alkene within the ring. This offers insight into possible reactions, such as hydrogenation or alcohol-related transformations.
With regular practice, students learn to apply these skills efficiently, turning complex organic problems into manageable challenges and leading to a deeper comprehension of organic chemistry principles.

Hydrocarbon Chains

Hydrocarbon chains form the basis of organic molecules, serving as the core backbone to which functional groups attach. They can be classified by the number of carbon atoms and the type of bonding present: single (alkanes), double (alkenes), or triple (alkynes) bonds.
For example, in the exercise, we see:

• **Alkanes** such as butane, hexane, and pentane provide a foundational linear or branched carbon chain essential to the structure's stability.
• **Cycloalkanes and Alkenes** add complexity. Cyclohexane in Cyclohexylmethanol and cyclopentene in Cyclopent-3-en-1-ol each provide varying levels of symmetry and strain along with unique reactive sites.

Identifying the longest continuous carbon chain in a molecule determines the parent compound and sets the stage for aligning functional groups and naming them according to IUPAC standards.
Through understanding hydrocarbon chains, one can predict potential reactivity patterns and stability, a key factor in the broader study of organic chemistry.