Practical Organic Chemistry Lab Manual PDF

Practical Organic Chemistry First Year students Biotechnology Program By Dr. Mohammad Mahmoud Aboul Fotouh Course Content Lab no. Experiment 1 Solubility of Organic compounds 2...

Practical Organic Chemistry First Year students Biotechnology Program By Dr. Mohammad Mahmoud Aboul Fotouh Course Content Lab no. Experiment 1 Solubility of Organic compounds 2 Chemical Solubility 3 Function Group tests (Baeyer – Fehling – Schiff) 4 Function Group tests (Tollens – Iodoform – Tollens –Borax) 5 Differentiation between liquid carboxylic acids 6 Differentiation between solid carboxylic acids 7 Identification of Alcohols 8 Identification of Aldehydes and Ketones (2,4-DNP – Na2SO3 – NaHSO3 - Periodic ) 9 Identification of Aldehydes and Ketones (Condensation – Cannizzaro – Bromination ) 10 Identification of Hydrocarbons and Aromatic Hydrocarbons (Bromination – Sulfonation ) 11 Identification of Aromatic Hydrocarbons (Phenols – Diazonium Salts) 12 lassaigne's test  Tools and Glasswares Reagent Bottles Droppers Test tube holder Test tubes Test tube Rack Tripod Stand Wire Gauze Bunsen Burner Tools and Glass wares Graduated Filter papers Spatula Litmus paper Pipette Water bath Glass rod (Stirrer) Cylinders Fume Hood Qualitative Analysis of Organic compounds Solubility Test The solubility of organic compounds can be divided into two major categories: 1. Physical solubility: in which simple miscibility (attraction between molecules) is the only mechanism involved, such as dissolving in water or ether without undergoing chemical reaction between solvent and solute e.g. dissolving benzene in ether. 2. Chemical solubility: in which a chemical reaction responsible for solubility, takes place between solvent and solute e.g. dissolving phenol in 5% NaOH. Insoluble Soluble Intermolecular Forces The Coulombic forces between molecules and atoms, namely intermolecular forces, were described and defined by Johannes Diderik van der Waals in 1873. These are weak forces between atoms and molecules that do not involve the transfer or sharing of electrons, and therefore do not result in bonding. They can be divided into three categories: 1- Dipole – Dipole 2- Dipole – Induced Dipole 3- Induced dipole – induced dipole or London dispersion forces Dipole moment (µ) This expression is a vector quantity which can be used to refer to the net polarity of molecules. Molecules such as carbon dioxide, methane, ethane, and benzene have zero dipole moments. Because of the symmetrical structures of these molecules, the individual bond polarities and lone- pair contributions exactly cancel. Dipole-Dipole (D-D) interaction Hydrogen bond (special D-D interaction) Dipole-Induced Dipole (D-ID) interaction  Induced Dipole-Induced Dipole (ID-ID) interaction 𝛿+ 𝛿− 𝛿+ 𝛿− Non-polar Non-polar Instantaneous Induced Polarization Dipole ID-ID in Pentane Intermolecular forces between dissimilar molecules Absorbed Energy Separation (Endothermic) 𝛿+ 𝛿− Solute Solute Released E > Absorbed E = Solubility Absorbed Absorbed E > Released E ≠ Solubility Energy Separation (Endothermic) Solvent Solvent Released Energy Association (Exothermic) Solute Solvent Solvents Solvents are divided according to their polarity to polar solvents e.g. water and non-polar solvents e.g. ether. Experiments Organic compounds are divided to three classes based on their solubility in different solvents: 1. Compounds with balanced polarity: Compounds that are soluble in both water and ether (1-5 Carbon atoms + only one polar group) e.g. Ethanol 2. Polar compounds - Compounds that have more than one polar group e.g. Ethylene glycol - Salts of organic acids (ionic) e.g. Sodium acetate (CH3COONa) 3. Non-polar compounds Polar groups are hydroxyl, amine, thiol, nitro, nitrile and carbonyl groups. - Hydrocarbons without polar groups While halides, double and triple bonds are e.g. n-pentane not polar groups. e.g. Benzene - More than 5 carbon atoms + only one polar group e.g. Benzaldehyde Summary Solubility test gives some information about: 1- Prescence or absence of function group in the unknown compound. 2- Length of the chain in compounds with balanced polarity. Like dissolves like Compound water Ether Balanced polarity + + Polar + - Non-polar - + Solubility Test Place 0.15 mL (approximately 3 drops) or 0.1 g of the compound in a small test tube and add 3 mL of solvent in small portions. Shake vigorously after the addition of each portion of solvent, being careful to keep the mixture at room temperature. If the compound dissolves completely, record it as soluble. Care should be taken in weighing the sample; it should weigh 0.1 g approximately. Measure all liquids with a graduated pipet that permits the accurate measurement of the liquid. When two colorless liquid phases lie one above the other, it is often possible to overlook the boundary between them and thus to see only one phase. You may shake the two phases vigorously. If the solution becomes cloudy, you have two phases.