How will you prepare (i) cis-pent-2-ene and trans-pent-2-ene by starting with ethyne ?

Explanation

To prepare cis-pent-2-ene and trans-pent-2-ene starting from ethyne, we can follow these steps:

### Step 1: Formation of Ethyne
Start with ethyne (C2H2), which is represented as H-C≡C-H.

### Step 2: Deprotonation to Form Dianion
React ethyne with sodium amide (NaNH2). The sodium amide acts as a strong base and removes two protons (H+) from ethyne, resulting in the formation of the ethyne dianion (C2H2^2-).

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