`R-CH_(2)-C Cl_(2)-R overset(Reag ent)rarrR-C-=C-R`
The reagent used is

Explanation

To solve the problem of transforming R-CH₂-CCl₂-R into R-C≡C-R, we need to identify the reagents used in this reaction. Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Starting Compound
The starting compound is R-CH₂-CCl₂-R, which is a 1,1-dihaloalkane. This compound contains two chlorine atoms attached to a carbon atom that is also connected to two R groups.

**Hint:** Look for the functional groups and the structure of the starting compound to understand what kind of reactions it can undergo.

### Step 2: First Reagent - Alcoholic KOH
The first reagent used is alcoholic KOH. When this reagent is added to the 1,1-dihaloalkane, it initiates a dehydrohalogenation reaction. This means that one of the chlorine atoms will be removed along with a hydrogen atom from the adjacent carbon, leading to the formation of a double bond.

**Hint:** Remember that alcoholic KOH is commonly used for elimination reactions to form alkenes by removing halogens and hydrogens.

### Step 3: Formation of an Alkene
After the reaction with alcoholic KOH, we form R-CH=CR. This is an alkene where one chlorine atom has been eliminated, resulting in a double bond between the two carbon atoms.

**Hint:** Keep track of the changes in the molecular structure after the elimination of the halogen.

### Step 4: Second Reagent - Sodium Amide (NaNH₂)
The next step involves the addition of sodium amide (NaNH₂). This reagent is also a strong base and will further facilitate the elimination of the remaining hydrogen halide (HCl) from the alkene formed in the previous step.

**Hint:** Sodium amide is often used in reactions to generate alkynes from alkenes by removing hydrogen halides.

### Step 5: Formation of Alkyne
The final product after the reaction with NaNH₂ is R-C≡C-R, which is an alkyne. This occurs through the removal of HCl, resulting in the formation of a triple bond between the two carbon atoms.

**Hint:** Recognize that the transformation from an alkene to an alkyne involves the removal of a hydrogen halide, leading to the formation of a triple bond.

### Conclusion
The reagents used in the transformation of R-CH₂-CCl₂-R to R-C≡C-R are:
1. Alcoholic KOH (for the first elimination to form an alkene)
2. Sodium amide (NaNH₂) (for the second elimination to form an alkyne)

**Final Answer:** The reagents used are alcoholic KOH and NaNH₂.