Wurtz reaction: Alkyl halide when heated with metallic sodium and zinc powder in ether gives alkane by joining two alkyl groups. $ 2RX+2Na\xrightarrow{\text{ether}}R.R+2NaX $ Williamson synthesis: It is the laboratory preparation of ether. $ \underset{\text{Sod}\text{.alkoxide}}{\mathop{RONa}}\,+\underset{\text{Alkyl}}{\mathop{XR}}\,\xrightarrow{\Delta }\underset{\text{Ether}}{\mathop{ROR}}\,+NaX $ Hell-Volhard-Zelinsky reaction: $ \alpha - $ chloro or $ \alpha - $ bromo acids are usually prepared by first converting the acid into its chloride and bromide and then carrying out chlorination or bromination. Thus is called HV Z reaction. So, is for $ \alpha - $ halogenation. $ \underset{\text{Add}}{\mathop{RC{{H}_{2}}COOH}}\,\xrightarrow{\text{P + B}{{\text{r}}_{\text{2}}}}\underset{\text{Acid}\,\text{bromide}}{\mathop{RC{{H}_{2}}CO.Br}}\, $
Aldol condensation: When aldehydes and ketones having $ \alpha - $ hydogen atoms are treated with alkali they undergo self-addition between two molecules to form a $ \beta - $ hydroxy aldehyde or ketone (known as aldol). This addition is usually followed by elimination of a water molecule resulting in overall condensation reaction. $ C{{H}_{3}}CHO+C{{H}_{3}}CHO\xrightarrow{O{{H}^{-}}}\underset{\begin{smallmatrix} \beta -\text{hydroxy}\,\text{butyraldehyde} \\ \text{(Aldol)} \end{smallmatrix}}{\mathop{C{{H}_{3}}-\underset{OH}{\mathop{\underset{|}{\mathop{CH}}\,}}\,-C{{H}_{2}}CHO}}\, $ Molasses: Ethyl alcohol is obtained from molasses. It is obtained as a byproduct of sugarindustry.