To synthesize 2-butanone (also known as methyl ethyl ketone) from ethyne (acetylene), you can follow these steps:
Step 1: Preparation of Propyne
First, convert ethyne (C₂H₂) into propyne (CH₃CCH) through a partial hydrogenation reaction. Use a catalyst like Lindlar's catalyst to add two hydrogen atoms to each molecule of ethyne. This will yield propyne.
C₂H₂ + 2H₂ → CH₃CCH
Step 2: Hydration of Propyne
Now, perform a hydration reaction on propyne to introduce a hydroxyl group (OH) onto the terminal carbon atom. Use an acidic catalyst, typically sulfuric acid (H₂SO₄) or phosphoric acid (H₃PO₄), to carry out the hydration.
CH₃CCH + H₂O → CH₃COH
Step 3: Oxidation of Propionaldehyde
Oxidize the propionaldehyde (CH₃CHO) formed in the previous step into 2-butanone (CH₃COCH₂CH₃) using a mild oxidizing agent like potassium dichromate (K₂Cr₂O₇) in the presence of sulfuric acid (H₂SO₄).
CH₃CHO + [O] → CH₃COCH₂CH₃
Step 4: Purification and Isolation
After the reaction is complete, purify and isolate the 2-butanone using techniques such as distillation or solvent extraction to obtain the final product.
This synthetic route transforms ethyne into 2-butanone by first converting it to propyne, then hydrating it to propionaldehyde, and finally oxidizing the propionaldehyde to produce 2-butanone. It's important to carry out these reactions under controlled conditions and ensure proper safety precautions when working with chemicals.