Organic Chemistry Lab #2 PDF
Document Details
Uploaded by AffordableThallium7410
College of Science
Tags
Summary
This document outlines several laboratory experiments for identifying different types of carbohydrates, such as monosaccharides, disaccharides, and polysaccharides. Common tests, like Molish test, Iodine test, Fehling test, Tollen's test, Osazone test, and Rapid Furfural test are detailed to differentiate between various sugars. The document provides step-by-step procedures and observations for these tests.
Full Transcript
# Organic Chemistry Lab #2 ## Carbohydrates are classified into 3 Parts: - Mono Saccharides: Glucose, Fructose - Di Saccharides: Lactose, Maltose, Sucrose - Reducing Sugar - Non-Reducing Sugar - Poly Saccharides: Starch *Note: Carbohydrates are aliphatic and don't contain acidic groups. ##...
# Organic Chemistry Lab #2 ## Carbohydrates are classified into 3 Parts: - Mono Saccharides: Glucose, Fructose - Di Saccharides: Lactose, Maltose, Sucrose - Reducing Sugar - Non-Reducing Sugar - Poly Saccharides: Starch *Note: Carbohydrates are aliphatic and don't contain acidic groups. ## Molish Test This test is not carried out for aromatic or presence of N, S or X. 1. 1mL of solution of organic salt (solid + H<sub>2</sub>O) 2. 1mL of α-naphthol + 2mL Conc. H<sub>2</sub>SO<sub>4</sub> (Drop Wisely) 3. A violet ring formed on the surface of separation of 2 liquids (without shaking) 4. By shaking, the mixture spreads to be all violet color. Therefore, the organic solid is a carbohydrate. ## Iodine Test 1. Solution of sugar in H<sub>2</sub>O + one drop of I<sub>2</sub> solution 2. A blue colored solution is a positive test for starch, while a pale yellow solution is a negative test for starch. ## Fehling Test This is a test for reducing sugar. 1. Solution of sugar in H<sub>2</sub>O + 2-3 drops of NaOH (30%) 2. Add an equal volume of - Fehling-A (CuSO<sub>4</sub>) - Fehling-B (Sodium Potassium Tartarate) 3. Then boil 4. A brown or reddish brown solution indicates a reducing sugar. No change in the solution's color indicates a non-reducing sugar. ## Tollen's Test 1. Solution of solid in H<sub>2</sub>O + Ammoniacal AgNO<sub>3</sub> 2. Heat in a water bath for 10 minutes. 3. A silver or grey precipitate indicates a reducing sugar. No precipitate indicates sucrose. ## Osazone Test 1. 1g solid + 3g osazone mix + few drops of H<sub>2</sub>O 2. Heat in the water bath for 20 minutes. *Note: The ratio between solid and osazone mix should be 1:3 3. Then heat in the water bath for 20 minutes. 4. Yellow crystals formed while heating indicates mono-saccharides. Yellow crystals formed after heating indicates di-saccharides. - Mono-saccharides - Glucose - Fructose - Di-saccharides - Lactose - Maltose ## Mono Saccharide Only ### To differentiate between Glucose and Fructose ## Rapid Furfural Test 1. 1mL solution of sugar + 1mL α-naphthol (alcoholic) + 6mL Conc. HCl 2. Heat 3. A violet color during boiling indicates fructose. A violet color after boiling for 2 minutes indicates glucose. ## Furfural Test 1. 1g solid sugar + 6mL Conc. HCl 2. Boil 3. Insert a paper moistened with aniline acetate (mixture of aniline + glacial acetic acid) at the top of the tube. 4. If the paper turns yellow, this is a negative result and indicates glucose. If the paper turns red, this is a positive result and indicates fructose.
