Answer:
Step-by-step explanation:
The fourth member of a carboxylic acid is known to be butanoic acid.
The reaction between the conversion of butanoic acid to butanal undergoes a reduction process.
At the initial stage, butanoic acid reacts with socl₂ (thionyl chloride) to form an aryl chloride known as butyryl chloride. However, the final stage proceeds by a reduction reaction where butyryl chloride is being treated with a mild reducing agent called Lithium tri-tert-butoxyaluminium hydride (LiAlH(O-t-Bu)₃ to form butanal.
The two reaction stages can be seen from the image attached below.