Question

Discuss the chemical test to distinguish between terminal akyne snd other alkynes

Answer 1

Chemical test used to distinguish between terminal alkyne snd other alkynes involves combustion reaction, IR spectroscopy, and reaction ammonical silver nitrate.

Explanation:

Combustion reaction:-

• Alkene when undergoes combustion will burn with aluminous flame and give carbon dioxide and water.

$CnH2n + \frac{3n}{2}O2$ →$nCO2 + nH2O$

• In Alkene, while undergoing combustion will burn in the air with sooty flame

$CnH2n-2 +\frac{ 3n-1}{2} O2$ →$nCO2 + (n-1) H2O$

IR spectroscopy-

• In IR the graph obtained from the given data will help in identifying the double or triple bond. They are superior to other chemical tests.

Reaction with ammonical silver nitrate :-

When alkyne reacts with ammonical silver nitrate gives white precipitate-

$C2H2 + 2AgNO3 +2NH4OH$→ $C2Ag2 + 2NH4NO3 + 2H2O$

When alkene reacts it gives no reaction

$C2H4 + Tollen's reagent$ → No reaction.