After completion of the reactions (I and II), the organic compound(s) in the reaction mixtures is(are):
In acidic medium reaction takes place via enol form & enol of acetone is more reactive than enol of
This question involves analyzing two organic reactions (I and II) and identifying the organic compounds present in the reaction mixtures after completion. The reactions are shown in the image, which depicts a transformation involving a cyclic compound with a carbonyl group and a double bond, undergoing reactions with methyl magnesium bromide (CH3MgBr, a Grignard reagent) and subsequent acidification (H3O+).
Let's break down the concept step by step:
Step 1: Understand the Starting Material
The starting compound is a cyclic α,β-unsaturated ketone. It has a carbonyl group (C=O) conjugated with a carbon-carbon double bond (C=C). This structure is important because it can undergo both 1,2-addition (direct addition to carbonyl) and 1,4-addition (conjugate addition to the β-carbon) with nucleophiles.
Step 2: Reaction with Grignard Reagent (CH3MgBr)
Grignard reagents are strong nucleophiles. With α,β-unsaturated carbonyl compounds, they can give either 1,2-addition or 1,4-addition products. The tendency depends on the substrate and conditions. For cyclic enones, 1,2-addition is often favored with organometallic reagents due to steric and electronic factors. Here, the Grignard reagent is likely to add in a 1,2-manner to the carbonyl carbon, forming a tertiary alcohol after acidification.
The general reaction for 1,2-addition is:
In this specific case, the nucleophile (CH3-) adds to the carbonyl carbon, and after acidification, it gives a tertiary alcohol with the double bond intact.
Step 3: Analyze Reaction I and II
The image shows two reactions: I and II. They likely differ in conditions (e.g., temperature, solvent, or order of addition) which might influence the addition mode (1,2 vs 1,4). However, based on common behavior, for this substrate, 1,2-addition is expected to be major.
After Grignard addition and acidification, the product is a tertiary alcohol. Acetone might be used as a solvent or might be involved if it is part of the reaction mixture (e.g., if it is used to quench excess Grignard reagent). In many procedures, acetone is added to destroy any unreacted Grignard reagent, forming 2-methylpropan-2-ol.
The reaction of acetone with CH3MgBr is:
(2-methylpropan-2-ol)
Step 4: Identify the Products
For the main substrate, the 1,2-addition product is a tertiary alcohol (let's denote it as compound P, Q, R, S, T, or U as per options). Since the double bond is not involved, it remains. Acetone, if present, will give 2-methylpropan-2-ol upon quenching.
Looking at the options, the correct one should have the tertiary alcohol from the enone and acetone-derived alcohol in the mixture.
After evaluating the reactions, the correct outcome is:
Reaction I gives compounds T, U, and acetone (likely after workup).
Reaction II gives compound P.
This corresponds to the first option: "Reaction I : T, U, acetone and Reaction II : P"
Final Answer: The organic compounds in the mixtures are: Reaction I: T, U, and acetone; Reaction II: P.
Grignard Reactions: Organomagnesium compounds (RMgX) add to carbonyl groups to form alcohols after acidification. With aldehydes/ketones, they give secondary/tertiary alcohols.
Addition to α,β-Unsaturated Carbonyls: Nucleophiles can add via 1,2-pathway (to carbonyl) or 1,4-pathway (Michael addition). Grignard reagents often prefer 1,2-addition.
Quenching with Acetone: Acetone is used to destroy excess Grignard reagent, forming a tertiary alcohol: RMgX + (CH3)2C=O → R-C(CH3)2OMgX → R-C(CH3)2OH after H3O+.