Which is more reducible, lithium aluminum hydride or sodium hydride?

Lithium aluminum hydride is a strong negative hydrogen reducing agent that rapidly decomposes when encountering compounds containing active hydrogen; And sodium borohydride is a relatively mild negative hydrogen reducing agent. So the use of lithium aluminum hydride as a reducing agent is generally carried out in ether solution, while sodium borohydride can be carried out in water and ethanol.

Lithium aluminum hydride can reduce almost all functional groups, including carbonyl, carboxyl, cyano, nitro, ester, amide, halogenated hydrocarbon, etc., except for the carbon carbon double bond and triple bond. Sodium borohydride can only reduce aldehydes and ketones Due to the electronegativity of heteroatoms on pyrrole, the carbonyl group on the pyrrole ring is more easily reduced compared to aliphatic and aromatic aldehydes and ketones, especially the adjacent ones. So for reducing the carbonyl group on the pyrrole ring, sodium borohydride is sufficient. And compared to lithium aluminum hydride, sodium borohydride is easier to store and cheaper.