Question

give chemical equation of Condensation of methanal and ethanal in the presence of ammonia

Answer 1

Question: give chemical equation of Condensation of methanal and ethanal in the presence of ammonia

Answer:

Way 1

$$\begin{array}{c} \mathrm{H} \\ \mathrm{H} - \mathrm{C} = \mathrm{O} + \mathrm{CH_2} - \mathrm{CHO} \xrightarrow{\text{aldol condensation}} \mathrm{CH_2} - \mathrm{CH_2} - \mathrm{CHO} \\ \mathrm{HOCH_2} - \mathrm{C} - \mathrm{CHO} \xrightarrow{\text{HCHO/OH}} \mathrm{CH_2OH} \\ | \\ \mathrm{CH_2OH} \\ | \\ \mathrm{CH_2OH} \\ | \\ \mathrm{HO} \\ \end{array} \xrightarrow{\text{HCHO}} \begin{array}{c} \mathrm{CH_2OH} \\ | \\ \mathrm{CH_2OH} \\ \end{array} \begin{array}{c} \mathrm{CH_2OH} \\ | \\ \mathrm{CH_2OH} \\ \end{array} \begin{array}{c} \mathrm{CH_2OH} \\ | \\ \mathrm{CH_2OH} \\ \end{array} \begin{array}{c} \mathrm{CH_2OH} \\ | \\ \mathrm{CH_2OH} \\ \end{array} \begin{array}{c} \mathrm{CH_2OH} \\ | \\ \mathrm{CH_3} \\ \end{array}$$

Formaldehyde and acetaldehyde combine to form trihydroxy aldehyde (Claisen-Schmidt reaction) which reacts with alkali to give pentaerythritol (Cannizaro reaction):

Way 2

$$\mathrm{CH_3CHO} + \mathrm{CH_2O} + \mathrm{NH_3} \xrightarrow[\text{350}^\circ\text{C}]{\text{zeolite}}$$ $$\begin{array}{c} \mathrm{O} \\ | \\ \mathrm{N} \end{array} \quad + \quad \begin{array}{c} \mathrm{CH_3} \\ | \\ \mathrm{N} \end{array}$$

In industry pyridine and $\beta$-picoline (3-methylpyridine) are generally coproduced by condensing formaldehyde, acetaldehyde and ammonia. Also small amounts of $\alpha$- and $\gamma$-picoline and of higher alkylated pyridines are formed.

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