Predict the products of the following reactions.
(a) cyclopentyl methyl ketone + excess Cl₂ + excess NaOH
(b) 1-cyclopentylethanol + excess I₂ + excess NaOH
(c) propiophenone + excess Br₂ + excess NaOH

Verified step by step guidance

1. <b>Step 1:</b> Identify the type of reaction for each scenario. These reactions involve halogenation in the presence of a base, which suggests the possibility of haloform reactions.
2. <b>Step 2:</b> For reaction (a), cyclopentyl methyl ketone with excess Cl₂ and NaOH, recognize that this is a haloform reaction. The methyl ketone will undergo multiple halogenations at the alpha position, followed by cleavage to form a carboxylate and chloroform (CHCl₃).
3. <b>Step 3:</b> For reaction (b), 1-cyclopentylethanol with excess I₂ and NaOH, note that the alcohol can be oxidized to a ketone under these conditions, and then the ketone can undergo a haloform reaction. The final products will include a carboxylate and iodoform (CHI₃).
4. <b>Step 4:</b> For reaction (c), propiophenone with excess Br₂ and NaOH, identify that the methyl group adjacent to the carbonyl will be brominated multiple times, leading to the formation of a carboxylate and bromoform (CHBr₃).
5. <b>Step 5:</b> Summarize the products for each reaction: (a) a carboxylate and chloroform, (b) a carboxylate and iodoform, (c) a carboxylate and bromoform.

Key Concepts

Halogenation of Ketones

Halogenation of ketones involves the reaction of ketones with halogens in the presence of a base, leading to the formation of α-halo ketones. The base facilitates the deprotonation of the ketone, allowing the halogen to add to the α-carbon. This reaction is important for predicting products in the presence of excess halogen and base, as seen in the reactions provided.

Haloform Reaction

The haloform reaction occurs when a methyl ketone reacts with halogens in the presence of a base, resulting in the formation of a haloform (like chloroform) and a carboxylate ion. This reaction is significant in predicting the products of reactions involving ketones and halogens, especially when excess halogen and base are present, as they drive the reaction to completion.

Oxidation of Alcohols

The oxidation of alcohols involves converting alcohols into carbonyl compounds or carboxylic acids, depending on the conditions. In the presence of iodine and a base, secondary alcohols can undergo oxidation to form ketones, while primary alcohols can be oxidized to aldehydes or carboxylic acids. Understanding this concept is crucial for predicting the products of reactions involving alcohols and halogens.