Victor Meyer's Test: Identification of Alcohols | Chemca

Organic Chemistry

Victor Meyer's Test: Identification of Alcohols

By Chemca Editorial Team • Last Updated: January 2026 • 10 min read

Victor Meyer's Test is a classic and definitive qualitative test used to distinguish between Primary ($1^\circ$), Secondary ($2^\circ$), and Tertiary ($3^\circ$) alcohols based on the distinct colors produced at the end of a sequence of reactions.

1. General Procedure

The alcohol is subjected to a series of four reactions:

Reaction with Red Phosphorus and Iodine ($P/I_2$): Converts Alcohol to Alkyl Iodide ($R-I$).
Reaction with Silver Nitrite ($AgNO_2$): Converts Alkyl Iodide to Nitroalkane ($R-NO_2$).
Reaction with Nitrous Acid ($HNO_2$): Prepared in situ ($NaNO_2 + HCl$). Reaction depends on the number of $\alpha$-hydrogens.
Treatment with Alkali ($NaOH$ or $KOH$): Produces the characteristic color.

Mnemonic: RBC

The color sequence corresponds to the degree of alcohol:
$1^\circ$ (Primary) $\rightarrow$ Red
$2^\circ$ (Secondary) $\rightarrow$ Blue
$3^\circ$ (Tertiary) $\rightarrow$ Colourless

2. Detailed Reactions

A. Primary Alcohols ($1^\circ$)

The primary nitroalkane has two $\alpha$-hydrogens.

1. $R-CH_2OH \xrightarrow{P/I_2} R-CH_2I$
2. $R-CH_2I \xrightarrow{AgNO_2} R-CH_2-NO_2$ (Nitroalkane)
3. $R-CH_2-NO_2 + O=N-OH \xrightarrow{-H_2O} \underbrace{R-C(=N-OH)-NO_2}_{\text{Nitrolic Acid}}$
4. Nitrolic Acid $\xrightarrow{NaOH}$ Blood Red Color (Sodium Salt)

B. Secondary Alcohols ($2^\circ$)

The secondary nitroalkane has one $\alpha$-hydrogen.

1. $R_2CHOH \xrightarrow{P/I_2} R_2CHI$
2. $R_2CHI \xrightarrow{AgNO_2} R_2CH-NO_2$
3. $R_2CH-NO_2 + HO-N=O \xrightarrow{-H_2O} \underbrace{R_2C(N=O)-NO_2}_{\text{Pseudonitrol}}$
4. Pseudonitrol $\xrightarrow{NaOH}$ Blue Color

C. Tertiary Alcohols ($3^\circ$)

The tertiary nitroalkane has no $\alpha$-hydrogens.

1. $R_3COH \xrightarrow{P/I_2} R_3CI$
2. $R_3CI \xrightarrow{AgNO_2} R_3C-NO_2$
3. $R_3C-NO_2 + HNO_2 \rightarrow$ No Reaction (Lack of $\alpha$-H)
4. Solution $\xrightarrow{NaOH}$ Colourless

3. Comparison with Lucas Test

Feature	Victor Meyer's Test	Lucas Test
Basis	Color formation	Turbidity formation rate
Reagent	$P/I_2, AgNO_2, HNO_2, NaOH$	Conc. $HCl + Anhyd. ZnCl_2$
$1^\circ$ Alcohol	Red Color	No reaction at room temp
$3^\circ$ Alcohol	Colourless	Instant reaction

4. Key Chemical Structures

Nitrolic Acid: $R-C(NO_2)=N-OH$. Soluble in alkali giving red color.
Pseudonitrol: $R_2C(NO)(NO_2)$. Blue in color. Insoluble in water/alkali (no acidic H).

Victor Meyer Quiz

Test your concepts on Alcohol identification. 10 MCQs with explanations.

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