How is propanone converted into (i) propan - 2 - ol (ii) 2 - methylpropan - 2 - ol

To convert propanone into propan-2-ol and 2-methylpropan-2-ol, we can utilize different chemical reactions. Let’s break down each conversion step by step, highlighting the processes involved.

Conversion of Propanone to Propan-2-ol

Propanone, commonly known as acetone, has the chemical formula CH₃COCH₃. To convert it into propan-2-ol (isopropanol), we can perform a reduction reaction. Here’s how it works:

Reduction Reaction

1. **Choosing the Reducing Agent**: A common reducing agent for this transformation is lithium aluminum hydride (LiAlH₄) or sodium borohydride (NaBH₄). These reagents can effectively reduce ketones to secondary alcohols.

2. **Reaction Process**: When propanone reacts with NaBH₄, the hydride ions (H⁻) from the reducing agent attack the carbonyl carbon of the ketone. This leads to the formation of an alkoxide intermediate.

3. **Protonation**: The alkoxide is then protonated by water or an acid, resulting in the formation of propan-2-ol.

The overall reaction can be summarized as follows:

• CH₃COCH₃ + NaBH₄ → CH₃CHOHCH₃ (propan-2-ol)

Conversion of Propanone to 2-Methylpropan-2-ol

To convert propanone into 2-methylpropan-2-ol (tert-butanol), a different approach is required, typically involving a Grignard reaction followed by protonation.

Grignard Reaction

1. **Formation of Grignard Reagent**: First, we need to prepare a Grignard reagent. This can be done by reacting magnesium with an alkyl halide, such as bromobutane (C₄H₉Br), to form butylmagnesium bromide (C₄H₉MgBr).

2. **Reaction with Propanone**: The Grignard reagent then reacts with propanone. The nucleophilic carbon in the Grignard reagent attacks the electrophilic carbonyl carbon of propanone, forming a tertiary alcohol intermediate.

3. **Protonation**: Finally, the intermediate is protonated using water or an acid, yielding 2-methylpropan-2-ol.

The overall reaction can be summarized as follows:

• C₄H₉MgBr + CH₃COCH₃ → C₄H₉C(OH)(CH₃)₂ (2-methylpropan-2-ol)

Summary of Reactions

In summary, the conversion of propanone to propan-2-ol involves a straightforward reduction process, while the conversion to 2-methylpropan-2-ol requires the formation of a Grignard reagent followed by nucleophilic attack and protonation. Each method showcases the versatility of organic reactions and the importance of choosing the right reagents for specific transformations.