Which reagent will be able to distinguish between 1-butyne and 2-butyne?

Question

Answer

You can also use Cu2Cl2 and NH4OH. 1-Butyne will give a red PPT and 2-Butyne wont

Answer

Silver mirror test that is tollens test

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You may also use AgNO3(NH3) as butyne1 have acidic H it will react with the base whereas butyne 2 won't you may consider these reaction as subsitution reaction occurs in butyne1 not in butyne 2 hope this answers the question

Answer

Reagent to Distinguish between 1-butyne and 2-butyne

To distinguish between 1-butyne and 2-butyne, we can use a reagent called bromine (Br2) in an organic solvent such as carbon tetrachloride (CCl4). This reaction is known as the bromine test or bromination.

Bromine Test
The bromine test is a commonly used chemical test to determine the presence of unsaturation in organic compounds. It involves the addition of bromine across a double or triple bond, resulting in the decolorization of the reddish-brown bromine solution.

Procedure
1. Take equal amounts of 1-butyne and 2-butyne in separate test tubes.
2. Add a few drops of bromine solution (Br2) in carbon tetrachloride (CCl4) to each test tube.
3. Observe the color change and note the observations.

Observations
1. 1-Butyne: When bromine is added to 1-butyne, there will be an immediate decolorization of the reddish-brown bromine solution. The solution will turn colorless or pale yellow. This indicates the occurrence of an addition reaction between bromine and the triple bond of 1-butyne, resulting in the formation of a dibromoalkane.
2. 2-Butyne: When bromine is added to 2-butyne, there will be no immediate decolorization of the bromine solution. The reddish-brown color of bromine will persist, indicating that no reaction has occurred. This lack of reaction is because the triple bond of 2-butyne is not susceptible to addition by bromine under normal conditions.

Explanation
The difference between 1-butyne and 2-butyne lies in the position of the triple bond. In 1-butyne, the triple bond is present at the terminal carbon, while in 2-butyne, the triple bond is present at the internal carbon. The bromine test is based on the reactivity of the triple bond with bromine.

In the case of 1-butyne, the triple bond readily undergoes an addition reaction with bromine, resulting in the formation of a dibromoalkane. This addition reaction causes the decolorization of the bromine solution.

On the other hand, the triple bond in 2-butyne is less reactive towards bromine due to the presence of the internal carbon. The internal carbon is more substituted and stabilized, making it less susceptible to addition reactions. Hence, no decolorization occurs when bromine is added to 2-butyne.

Conclusion
The bromine test can be used as a reagent to distinguish between 1-butyne and 2-butyne. The decolorization of the bromine solution indicates the presence of a terminal triple bond in 1-butyne, while the persistence of the reddish-brown color indicates the absence of a reactive triple bond in 2-butyne.

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