Problem 170 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following compounds can be detected by Molisch's test? (a) Amines (b) Sugars (c) Nitro compounds (d) Primary alcohols

Step-by-Step Solution

Answer

Molisch's test detects sugars.

Step 1: Understand Molisch's Test

Molisch's test is a chemical test for the presence of carbohydrates. It identifies carbohydrates by forming a reddish-violet complex upon the reaction with concentrated sulfuric acid and a few drops of Molisch's reagent, which is a solution of alpha-naphthol in alcohol.

Step 2: Analyze the Options

Examine each option provided to see which one fits the criterion of containing carbohydrates. (a) Amines - Organic compounds derived from ammonia with no carbohydrates. (b) Sugars - Sugars are carbohydrates composed of carbon, hydrogen, and oxygen. (c) Nitro compounds - Organic compounds containing one or more nitro functional groups, not carbohydrates. (d) Primary alcohols - Organic compounds with the hydroxyl group not classified as carbohydrates.

Step 3: Identify the Correct Answer

From the analysis, sugars are the only option that contains carbohydrates. Therefore, sugars will give a positive result in Molisch's test.

Key Concepts

Understanding Carbohydrates Detection

Carbohydrates detection is a fascinating aspect of organic chemistry that explores how we identify these essential biomolecules. Carbohydrates, commonly known as sugars, are made up of carbon, hydrogen, and oxygen. They play a crucial role in providing energy to living organisms. Detecting carbohydrates accurately is important in various fields like biology and food chemistry.

Molisch's test is a classical method used for the detection of carbohydrates. This effective strategy is based on the reaction of carbohydrates with a specific reagent, called Molisch's reagent. When carbohydrates are present and interact with this reagent in the presence of concentrated sulfuric acid, a deep reddish-violet ring forms. This visual confirmation is straightforward yet powerful in identifying carbohydrates.

This test is sensitive and can detect even trace amounts of carbohydrates in samples. It doesn't matter if the carbohydrate present is a simple sugar like glucose or a more complex polysaccharide. The result is the same impressive coloration, making it a versatile option for various applications.

Chemical Testing for Organic Compounds

Chemical testing is fundamental in understanding various organic compounds and their functions. Different tests have been developed to identify specific types of compounds based on their unique chemical properties.

The importance of chemical testing lies in its ability to provide clear insights into the composition of substances. For example, Molisch's test specifically targets the identification of carbohydrates. By adding Molisch's reagent and acid, we trigger a reaction that clearly indicates the presence of this organic compound.

This type of testing isn't limited to just Molisch's method. There are many tests available, each designed to detect different functional groups or compounds. It is essential for students to familiarize themselves with these varied testing techniques to understand the complexities of organic chemistry better.

Introduction to Organic Compounds Analysis

Organic compounds analysis is a broad field that focuses on identifying and characterizing organic molecules. Such molecules structure the basis of all living organisms, and knowing how to analyze them is crucial in many areas of research and industry.

The analysis typically involves qualitative and quantitative methods to determine the presence and concentration of specific compounds. Techniques like spectroscopy, chromatography, and specific chemical reactions are frequently utilized in this process.

In educational settings, simpler tests like Molisch's are often used to introduce students to organic analysis concepts. They demonstrate fundamental principles while highlighting the importance of empirical demonstration in scientific inquiry. Understanding these analyses helps in fields like pharmacology and bioengineering, where organic compounds play a pivotal role.