In Victor Meyer’s test, the colour given by 1⁰, 2⁰ and 3⁰ alcohols are respectively

• A) red, colourless, blue
• B) red, blue, colourless
• C) colourless, red, blue
• D) red, blue, violet

In Victor Meyer’s test, the colors produced by primary (1⁰), secondary (2⁰), and tertiary (3⁰) alcohols are indeed distinctive and help in identifying the type of alcohol present. The correct answer to your question is B) red, blue, colourless. Let’s break down the reasoning behind this result.

Understanding Victor Meyer’s Test

Victor Meyer’s test is a qualitative analysis method used to differentiate between primary, secondary, and tertiary alcohols based on their reaction with iodine and phosphorus trichloride (PCl₃). The test involves the formation of colored complexes that indicate the type of alcohol being tested.

Color Indicators for Alcohol Types

• Primary Alcohols (1⁰): When a primary alcohol is tested, it reacts to produce a red color. This occurs because the reaction leads to the formation of a stable intermediate that exhibits this characteristic hue.
• Secondary Alcohols (2⁰): In the case of secondary alcohols, the resulting color is blue. The reaction mechanism is slightly different, leading to a different colored complex.
• Tertiary Alcohols (3⁰): Tertiary alcohols do not produce a colored complex in this test, resulting in a colorless solution. This is due to the lack of a suitable reaction pathway that would lead to a colored product.

Why the Colors Matter

The colors observed in Victor Meyer’s test are crucial for chemists because they provide immediate visual cues about the structure of the alcohol being tested. This is particularly useful in organic chemistry for identifying compounds without the need for more complex analytical techniques.

Practical Application

In a laboratory setting, if you were to conduct Victor Meyer’s test, you would add the alcohol to a test tube containing PCl₃ and iodine. After shaking the mixture, you would observe the color change. If you see red, you know you have a primary alcohol; blue indicates a secondary alcohol; and if the solution remains colorless, it confirms the presence of a tertiary alcohol.

Conclusion

In summary, the colors produced in Victor Meyer’s test—red for primary alcohols, blue for secondary alcohols, and colorless for tertiary alcohols—are essential for identifying the type of alcohol present. This test is a classic example of how chemical reactions can provide insight into molecular structure and classification.