Question

What is Victor Meyer's reagent?

Answer 1

Victor Meyer reagent

1. In Victor Meyer's reaction, nitroalkanes are formed when alkyl halide reacts with silver nitrate.
2. Victor Meyer test is used to differentiate primary, secondary and tertiary alcohols.
3. The reagent used in the Victor Meyer test is,$\mathrm{P}/{\mathrm{I}}_2\left(\mathrm{Phosphorus}/\mathrm{Iodine}\right),{\mathrm{AgNO}}_2\left(\mathrm{Silver}\mathrm{Nitrate}\right),{\mathrm{HNO}}_3\left(\mathrm{Nitric}\mathrm{acid}\right)$ and alkali$\left(\mathrm{NaOH}/\mathrm{KOH}\right)SodiumHydroxide/PotassiumHydroxide$.
4. Primary alcohol shows blood-red color, secondary alcohol shows blue color, and tertiary alcohol shows no color.

Victor Meyer's reaction

For Primary alcohol

1. Victor Meyer's test for primary alcohols includes the reaction of Primary alcohol with $\mathrm{P}/{\mathrm{I}}_2$ forms primary Iodoalkane which on reaction with Silver nitrate gives Nitroalkane
2. Nitro alkane then reacts with Nitrous acid-forming Nitrolic acid which is red in color.

$$\begin{gathered} \mathrm{R}-{\mathrm{CH}}_2\mathrm{OH}+\mathrm{P}/{\mathrm{I}}_2\to \mathrm{R}-{\mathrm{CH}}_2\mathrm{I}+{\mathrm{AgNO}}_2\to {\mathrm{RCH}}_2{\mathrm{NO}}_2 \\ \mathrm{Primary}\mathrm{alcohol}\mathrm{Iodoalkane}\mathrm{Silver}\mathrm{nitrate}\mathrm{Nitroalkane} \end{gathered}$$

$$\begin{gathered} {\mathrm{RCH}}_2{\mathrm{NO}}_2+{\mathrm{HNO}}_2\to \mathrm{R}-\mathrm{C}\left(\mathrm{N}-\mathrm{OH}\right)+\mathrm{KOH} \\ \mathrm{Nitroalkane}\mathrm{Nitrous}\mathrm{acid}\mathrm{Nitrolic}\mathrm{acid}(\mathrm{red}\mathrm{color}) \end{gathered}$$

For Secondary alcohol

1. Victor Meyer's test for secondary alcohols includes the reaction of secondary alcohol with $\mathrm{P}/{\mathrm{I}}_2$forms secondary Iodoalkane which on reaction with Silver nitrate gives Nitroalkane.
2. Nitro alkane then reacts with Nitrous acid pseudo Nitrol which is blue in color.

$$\begin{gathered} {\mathrm{R}}_2\mathrm{CH}-\mathrm{OH}+\mathrm{P}/{\mathrm{I}}_2\to {\mathrm{R}}_2\mathrm{CH}-\mathrm{I}+{\mathrm{AgNO}}_2\to {\mathrm{R}}_2\mathrm{CH}-{\mathrm{NO}}_2 \\ \mathrm{Secondary}\mathrm{alcohol}\mathrm{Iodoalkanes}\mathrm{Nitroalkane} \end{gathered}$$

$$\begin{gathered} {\mathrm{R}}_2\mathrm{CH}-{\mathrm{NO}}_2+{\mathrm{HNO}}_2\to {\mathrm{R}}_2\mathrm{C}\left(\mathrm{N}=\mathrm{O}\right)+\mathrm{KOH} \\ \mathrm{Nitroalkane}\mathrm{Pseudo}\mathrm{Nitrol}(\mathrm{Blue}\mathrm{color}) \end{gathered}$$

For tertiary alcohol

1. With tertiary alcohols, Victor Meyer's reagent does not give any reaction.