(1) LiAlH₄ is mainly used for the reduction of polar unsaturation. Carbon-Carbon double bonds and triple bonds are unaffected due to non-polarity. Aldehydes (RCHO) and Ketones (RCOR) on treatment with Lithium Aluminium Hydride LiAlH4 in dry ether and subsequent acidification yield primary alcohols RCH₂OH and secondary alcohols RCH(OH)R’ respectively, for this purpose we can also use NaBH4 but LiAlH₄ is a power reducing agent and reduces many other functional groups such as carboxylic acid and its derivatives, nitro compounds. Acid chlorides (RCOOCl) on treatment with Lithium Aluminium Hydride LiAlH₄ in dry ether and subsequent acidification yield primary alcohols RCH₂OH. Esters (RCOOR) on treatment with Lithium Aluminium Hydride LiAlH₄ in dry ether and subsequent acidification yield primary alcohols RCH₂OH and ROH. Lactones (cyclic esters) are reduced to corresponding diols. Acid anhydrides (RCO)₂O on treatment with LiAlH4 yield primary alcohols RCH₂OH. Primary (RCONH₂), secondary (RCONHR) and tertiary amides (RCONR₂) on reaction with LiAlH₄ give primary (RCH₂NH₂), secondary (RCH₂NHR) and tertiary amines (RCH₂NR₂ respectively (can also be done using H₂/Ni) Cyclic amides (Lactams) on reduction give cyclic amines. Nitriles (RCN) are converted into primary amines (RCH₂NH₂). Isocyanides are converted into N-Methylamines (secondary amines) similar to H₂/Ni. Epoxides when treated with LiAH4 in dry ether and subsequent acidification with dilute sulphuric acid gives alcohols. Oximes (>C=NOH), both ketoximes and aldoximes are reduced to primary amines (>CH-NH₂Aliphatic nitro compounds are reduced to amines although for aromatic nitro compounds we use metal/HCl not LiAlH₄, if we use LiAlH₄ > for aromatic nitro compounds ArNO₂ we get azo compounds (Ar-N=N-Ar), nitroso compounds can also be reduced to azo compounds. Peroxides are reduced to 2 moles of alcohols. Sulfoxides (RSOR) are reduced to sulphides (RSR). Quinones are reduced to hydroquinones by LiAlH₄ as well as SnCl₂/HCl

(2) Primary and secondary alkyl halides and alkyl sulphonates are readily reduced to corresponding alkanes by treatment with LiAlH₄ in dry ether or THF solvent. Tertiary alkyl halides and sulphonates mainly undergo elimination reaction to give alkenes.