Question

Which of the following compound will not give a precipitate with tollens reagent
1.ethyne
2.1-butyne
3.3-methyl-1-butene
4.1-pentene

Answer 1

3-methyl-1-butene will not give a precipitate with tollens reagent

Answer 2

Tollen's reagent is an alkaline solution of ammonical silver nitrate.

It is used to test the following-

• aldehyde
• $\alpha -$hydroxy ketone
• terminal alkyne

When tested with the above solutions, it gives a white precipitate.

Explanation for correct options

3,4:

3-methyl-1-butene and 1-pentene contain neither an aldehyde group, nor an $\alpha -$hydroxy ketone, and are also not a terminal alkyne.

Thus, it will not give a precipitate when tested with the tollen's reagent.

Explanation for incorrect options

1,2:

SInce, ethyne nd 1-butyne are terminal alkynes, hence, they will give white precipitate on reacting with the tollen's reagent.

Thus, options 1 and 2 are incorrect.

Hence, options 3 and 4 are correct.

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