what is the main difference between the reducing agent LiAlH4 and Ni/Hydrogen? when we have to use NI/H2and when we can use other?

Dear student,

LiAlH4 and NaBH4 both reduce carboxylic acids / ketones, but only LiAlH4 reduces a nitro group

H2/Nickel reduces C=C

LiAlH4 gives 4 H- in 1 mole. lialh4is specific and selective in nature and generally used in reduction of oxygenated compounds to corres. alcohols. further it cannot reduce.

ni/h2 works as a bulk to generally give alkanes from alkenes. it can reduce alkenes bt lialh4 cannot( bt conjugate are doneable).

it does not reduce easily compounds like cooh, ketone,ester etc.