Wolff–Kishner reduction converts a ketone (or aldehyde) into a hydrocarbon (alkane) by completely removing the carbonyl group ($\mathrm{C=O}$).It uses hydrazine ($\mathrm{NH_2NH_2}$) and a strong base under high temperature.Reimer–Tiemann reaction $\rightarrow$ Introduces a formyl group (–CHO) into phenols.Aldol condensation $\rightarrow$ Forms β-hydroxy aldehydes/ketones.Stephen reaction $\rightarrow$ Converts nitriles into aldehydes.Therefore, the reaction used to convert a ketone into a hydrocarbon is Wolff–Kishner reduction.