During a reduction reaction, the oxidation state of a compound decreases as it gains electrons. In other words, the compound is reduced by accepting electrons from a reducing agent, which in turn gets oxidized. This process is the opposite of an oxidation reaction, where the oxidation state of a compound increases as it loses electrons.An example of a reduction reaction in organic chemistry is the reduction of a carbonyl compound, such as an aldehyde or a ketone, to an alcohol using a reducing agent like sodium borohydride NaBH4 or lithium aluminum hydride LiAlH4 .For instance, let's consider the reduction of acetone a ketone to isopropanol an alcohol using sodium borohydride as the reducing agent:Acetone CH3COCH3 + NaBH4 Isopropanol CH3CHOHCH3 + NaBO2In this reaction, the carbonyl carbon in acetone has an oxidation state of +2. When it is reduced to isopropanol, the oxidation state of the carbon decreases to +1, as it gains a hydrogen atom and forms a new C-O bond. The reducing agent, NaBH4, loses a hydride ion H- and gets oxidized to NaBO2.