Question

Draw the structures of the following compounds. (i) 3 -Methylbutanal (ii) \(p\) -Nitropropiophenone (iii) \(p\) -Methylbenzaldehyde (iv) 4 -Methylpent-3-en-2-one (v) 4-Chloropentan-2-one (vi) 3 -Bromo-4-phenylpentanoic acid (vii) \(p, p^{\prime}-\) Dihydroxybenzophenone (viii) Hex-2-en-4-ynoic acid

Short answer

Draw each compound based on the IUPAC name, ensuring correct placement of functional groups.

Step-by-step solution

Structure of 3-Methylbutanal

Identify the root as "butanal" indicating a 4-carbon aldehyde chain with the aldehyde group (CHO) at one end of the chain. Then add a "methyl" group at the third carbon to complete the structure as follows: 1. Start with a linear 4-carbon chain (butanal). 2. Add CHO to carbon 1 to create the aldehyde group. 3. Place a methyl group (CH3) on carbon 3. The structure is CH3-CH(CH3)-CH2-CHO.

Structure of p-Nitropropiophenone

The root is "propiophenone," which indicates a phenyl group attached to a 3-carbon ketone chain, which is the propanone part. Add a nitro group at the para position relative to the carbonyl group on the benzene ring. 1. Draw a benzene ring attached to a 3-carbon chain ending with a ketone (C=O) group. 2. Place the nitro group (NO2) at the para position of the benzene ring. The structure is C6H5-C(=O)-CH2-CH3 with a NO2 group at the para position.

Structure of p-Methylbenzaldehyde

"Benzaldehyde" refers to a benzene ring with an aldehyde group (CHO) directly attached. The "p-methyl" indicates a methyl group at the para position. 1. Draw a benzene ring. 2. Attach an aldehyde group (CHO) directly to the ring. 3. Place a methyl group (CH3) at the para position (opposite the CHO group) on the benzene ring. The structure is CH3-C6H4-CHO.

Structure of 4-Methylpent-3-en-2-one

The "pent-3-en-2-one" indicates a 5-carbon chain with a double bond at the third carbon and a carbonyl group (C=O) at the second carbon. "4-Methyl" signifies a methyl group on carbon 4. 1. Draw a 5-carbon chain. 2. Insert a carbonyl (C=O) group at carbon 2. 3. Add a double bond between carbons 3 and 4. 4. Attach a methyl group (CH3) to carbon 4. The structure is CH3-CO-CH=CH-CH(CH3)2.

Structure of 4-Chloropentan-2-one

"Pentan-2-one" indicates a ketone with the carbonyl group at the second carbon of a 5-carbon chain. "4-Chloro" indicates a chlorine atom on carbon 4. 1. Draw a 5-carbon chain (pentane). 2. Place a carbonyl group (C=O) on the second carbon. 3. Attach a chlorine atom (Cl) to the fourth carbon. The structure is CH3-C(=O)-CH2-CH(Cl)-CH3.

Structure of 3-Bromo-4-phenylpentanoic acid

"Pentanoic acid" indicates a 5-carbon carboxylic acid. The "3-bromo" indicates a bromine atom on carbon 3, and "4-phenyl" indicates a phenyl group on carbon 4. 1. Draw a 5-carbon chain with a carboxylic acid group (COOH) at the end. 2. Attach a bromine atom (Br) to carbon 3. 3. Attach a phenyl group (C6H5) to carbon 4. The structure is Br-CH2-CH(C6H5)-CH2-COOH.

Structure of p, p'-Dihydroxybenzophenone

"Benzophenone" consists of two phenyl groups (benzene rings) attached to a central ketone group. "p, p'-Dihydroxy" specifies hydroxy groups at the para position of each phenyl ring. 1. Create a structure with a central carbonyl group (C=O) flanked by two benzene rings. 2. Add hydroxy groups (OH) to the para positions of each benzene ring. The structure is HO-C6H4-CO-C6H4-OH.

Structure of Hex-2-en-4-ynoic acid

"Hex-2-en-4-ynoic acid" describes a 6-carbon chain with a carboxylic acid group, a double bond at the second carbon, and a triple bond at the fourth carbon. 1. Draw a 6-carbon chain. 2. Place a carboxylic acid group (COOH) at one end. 3. Create a double bond between carbons 2 and 3. 4. Create a triple bond between carbons 4 and 5. The structure is HOOC-CH=CH-C≡C-CH2-CH3.

Key concepts

Structural Drawing

In organic chemistry, structural drawing is a foundational skill. It helps in visualizing the arrangement of atoms within a molecule. Structures show the connectivity between atoms and the overall shape of the molecule. Understanding this makes it easier to predict reactivity and properties.

To draw a structure, follow these steps:

• Identify the longest carbon chain, as it forms the backbone.
• Determine the functional groups and position them correctly.
• Add any branching groups like methyl or ethyl groups.

By following these steps, you're well-prepared to understand complex molecules.

IUPAC Nomenclature

The International Union of Pure and Applied Chemistry (IUPAC) has established a systematic method for naming organic compounds. This is known as IUPAC nomenclature.

The main steps in IUPAC nomenclature are:

• Identify the longest carbon chain as the base. It determines the main part of the name.
• Name the functional groups and determine their priority.
• Assign numbers to the carbon atoms to indicate the position of groups and identify any substituents.

Understanding IUPAC nomenclature is crucial for efficiently communicating complex structures.

Functional Groups

Functional groups are specific groupings of atoms within molecules. They are responsible for the characteristic chemical reactions of those molecules.

Common functional groups include:

• Aldehydes (CHO): A carbon doubly bonded to an oxygen and singly bonded to hydrogen.
• Ketones (C=O): A carbon doubly bonded to an oxygen.
• Carboxylic Acids (COOH): Contains a carbonyl and an alcohol group.

Recognizing these groups allows predicting how molecules will interact in chemical reactions.

Organic Compounds

Organic compounds are primarily made of carbon atoms. They often include hydrogen and may also incorporate other elements like nitrogen, oxygen, sulfur, or halogens. These compounds are the basis of life and are incredibly diverse.

Categories of organic compounds include:

• Alkanes: Composed only of carbon and hydrogen in single bonds.
• Alkenes: Contain at least one carbon-carbon double bond.
• Alkynes: Have one or more carbon-carbon triple bonds.
• Aromatics: Include benzene rings and other similar structures.

Learning about organic compounds reveals the vast possibilities within organic chemistry.