Question

How many of the reagents from the list above would give effervescence, when treated with propyne?
(I)$NaOH$
(II) $C{H_3}C{H_2}ONa$
(II) $C{H_3}C{H_2}MgBr$
(IV) $NaH$
(V) $NaN{H_2}$
(VI) $Na$
(VII) $NaHC{O_3}$
(VIII) ${\\{ {(C{H_3})_2}CH\\} _2}NLi$
(IX) $C{H_3}C{H_2}Li$

Answer 1

As we know that effervescence is basically the formation of gas bubbles in a liquid solution which generally involves the liberation of gaseous molecules from an aqueous solution in the course of a reaction. We also know that weak acids or bases do not react with propyne easily.

Complete solution:
As we know that in a course of a reaction gases are usually escaped which can be easily seen as the bubble formation in an aqueous solution. Also, propyne is an alkyne compound and it is commonly used in gas welding and can be safely condensed.
Let us talk about the reactions between propyne and the given reagents now.
The first one is sodium hydroxide $(NaOH)$and we know that alkynes are weak acids therefore, the propyne does not react with sodium hydroxide, hence it is not a correct option.
Next we have $(C{H_3}C{H_2}ONa)$, sodium methoxide which is not a strong base and thus does not deprotonate a terminal alkyne group, therefore it does not react with propyne.
Then we have $C{H_3}C{H_2}MgBr$, though it can react with propyne and results into the formation of haloalkane and an alkane, thus no gas is released and hence no effervescence will be there. Hence, it is also incorrect.
Then we have sodium hydride which reacts with propyne and releases hydrogen gas thereby giving effervescence and thus it is a correct answer. We can show this reaction as below: $NaH + C{H_3} - C \equiv CH \to C{H_3} - C \equiv CNa + {H_2}$
Next is sodium amide $NaN{H_2}$, and when it reacts with propyne results in the formation of ammonia gas thereby giving effervescence. Thus it is also correct.
Then, $Na$ reacts with alkynes giving carbanions liberating hydrogen gas thus effervescence is released.
Then we have acid like sodium hydrogen carbonate gives only brisk effervescence by evolving carbon dioxide from the carboxylic acids.
Lastly we have, (VIII) and (IX) both are weak bases and thus no effervescence is given.

Therefore, the correct answer is (IV), (V), (VI) and (VII).

Note: Remember that propene reacts with basic and acidic compounds but does not necessarily result in the formation of gaseous products. But, when propyne reacts with metals gives carbanions and carbocations liberating hydrogen and carbon dioxide gases.