Answer:
the acid is used in removing water, hence converting RCH-OH NHNH-CCHCHC(NO₂)C(NO₂)CH to RCH=NNH-CCHCHC(NO₂)C(NO₂)CH.
Explanation:
When hydrazine is reacted with a carbonyl group containing compound, RCH=O, it gives the product, RCH-OH NHNH-CCHCHC(NO₂)C(NO₂)CH as given in the chemical reaction shown in step one below:
STEP ONE:
H₂NH-CCHCHC(NO₂)C(NO₂)CH + RCH=O <--------------------> RCH-OH NHNH-CCHCHC(NO₂)C(NO₂)CH.
Kindly note that this reaction is a reversible reaction.
STEP TWO:
This step shows the the addition of the acid to RCH-OH NHNH-CCHCHC(NO₂)C(NO₂)CH, this addition of acid causes the removal of H₂O from this compound, hence forming 2,4-dinitrophenylhydrazones.
RCH-OH NHNH-CCHCHC(NO₂)C(NO₂)CH + HA ----------------> H₂O + HA + RCH=NNH-CCHCHC(NO₂)C(NO₂)CH.
