Question

Name all the organic products formed in a solution containing benzaldehyde, acetophenone, and dilute sodium hydroxide.

Short answer

The organic products formed in the solution containing benzaldehyde, acetophenone, and dilute sodium hydroxide are dibenzalacetone (\(C_6H_5CH=CHC_6H_5\)) and chalcone (\(C_6H_5CH=CHCOCH_3\)).

Step-by-step solution

Write the molecular structures of the given compounds

We start by writing the molecular structures of benzaldehyde, acetophenone, and sodium hydroxide. Here are their structures: Benzaldehyde: \[ C_6H_5CHO \] Acetophenone: \[ C_6H_5COCH_3 \] Sodium hydroxide (NaOH) is a strong base that will catalyze the aldol condensation reaction between the aldehyde and ketone.

Reaction of benzaldehyde with itself

First, we consider the aldol condensation reaction of benzaldehyde with itself. Benzaldehyde has an aldehyde group, which can undergo aldol condensation: Benzaldehyde + Benzaldehyde → Dibenzalacetone (major product) Dibenzalacetone: \[ C_6H_5CH=CHC_6H_5 \]

Reaction of benzaldehyde with acetophenone

Next, we consider the aldol condensation reaction of benzaldehyde with acetophenone. The aldehyde group of benzaldehyde reacts with the ketone group of acetophenone: Benzaldehyde + Acetophenone → Chalcone (major product) Chalcone: \[ C_6H_5CH=CHCOCH_3 \]

Reaction of acetophenone with itself

Finally, we will consider the reaction of acetophenone with itself. However, the ketone group in acetophenone is not very reactive in an aldol condensation reaction, and there will be no significant product formed in this case.

List the organic products

Based on the aldol condensation reactions, the following organic products are formed: 1. Dibenzalacetone 2. Chalcone No significant product is formed between two acetophenone molecules. Therefore, the final list of organic products in the solution containing benzaldehyde, acetophenone, and dilute sodium hydroxide are dibenzalacetone and chalcone.

Key concepts

Benzaldehyde

Benzaldehyde is a simple aromatic aldehyde with the chemical formula \( C_6H_5CHO \). It's easily identified by its distinctive almond-like smell and is widely used in the synthesis of various organic compounds. In organic chemistry reactions, particularly in the presence of a base like sodium hydroxide, benzaldehyde can participate in aldol condensation reactions.

This is due to the presence of a hydrogen atom adjacent to the aldehyde group, which becomes acidic in nature when a base is present. As a result, benzaldehyde can react with itself or other carbonyl-containing compounds such as ketones to form more complex molecules, such as dibenzalacetone in the case of a reaction with another molecule of benzaldehyde.

Acetophenone

Acetophenone is an aromatic ketone, with the formula \( C_6H_5COCH_3 \). It is characterized by the carbonyl group (C=O) bonded to two hydrocarbon groups, one being a phenyl and the other a methyl group. While less reactive than aldehydes, ketones like acetophenone can still engage in certain organic chemistry reactions, including aldol condensation, under the right conditions.

Despite this potential, acetophenone is less likely to react with itself in the presence of a base due to the steric and electronic effects of the bulky phenyl and methyl groups attached to the carbonyl carbon. This makes it less active compared to benzaldehyde in a typical aldol condensation scenario.

Dibenzalacetone

Dibenzalacetone represents a classic product of an aldol condensation reaction, where two molecules of benzaldehyde couple with one another in the presence of a base. Its chemical structure is denoted as \( C_6H_5CH=CHC_6H_5 \), featuring a central double bond flanked by two phenyl rings.

It is a type of chalcone, compounds that consist of two aromatic rings linked by a three-carbon α,β-unsaturated carbonyl system. Dibenzalacetone is particularly interesting due to its applications in various fields, such as organic semiconductors and as a UV blocker in sunscreen lotions. Its synthesis through the aldol condensation of benzaldehyde is an important organic chemistry reaction and serves as a cornerstone example for teaching concepts of carbonyl chemistry.

Chalcone

Chalcones are a subfamily of the flavonoids, typically formed by an aldol condensation between an aldehyde and a ketone. Specifically, a chalcone is an organic compound with the formula \( C_6H_5CH=CHCOCH_3 \), which can be synthesized from a reaction between benzaldehyde and acetophenone. In this reaction, the aldehyde carbon of benzaldehyde reacts with the alpha carbon of acetophenone to form a carbon-carbon double bond, with the elimination of water as a byproduct.

The significance of chalcones in organic synthesis is not just limited to their interesting chemical properties, but also extends to their biological activities. Chalcones have been studied for their potential anti-inflammatory, antimalarial, and anticancer properties, making them an active area of research in both organic chemistry and pharmacology.

Organic Chemistry Reactions

Organic chemistry reactions, such as the aldol condensation, are fundamental processes that enable the construction of complex molecules from simpler ones. The essence of aldol condensation involves the creation of a carbon-carbon bond through the reaction of a carbonyl compound with an enolate ion or another carbonyl compound in the presence of a base.

This type of reaction not only showcases the reactivity of carbonyl compounds like aldehydes and ketones but also their utility in building diverse molecular architectures. The ability to predict the outcome of such reactions and the products formed, such as the formation of dibenzalacetone and chalcone from benzaldehyde and acetophenone, are critical skills for students studying organic chemistry. The synthesis of these compounds highlights the interconnectedness of organic molecular structures and the elegance of chemical transformations.