Answer:
Compound A is succinic anhydride and B is methyl succinate (the monomethyl ester).
Structural Diagram is attached.
Explanation:
A.
Succinic anhydride appears as colorless needles or white crystalline solid. ... Succinic anhydride, also called dihydro-2, 5-furandione, is an organic compound with the molecular formula C4H4O3. It is the acid anhydride of succinic acid.
B.
Monomethyl succinate is a dicarboxylic acid monoester that is succinic acid in which one of the carboxy groups has been converted to its methyl ester. It is a dicarboxylic acid monoester and a hemisuccinate. ... They have the general structure RC(=O)OR', where R=fatty aliphatic tail or organyl group and R'=methyl group.