Introduction. One important property that organic compounds exhibit is that their structure is related to their solubility. Solubility is the amount of a substance that will dissolve in a given amount...

Introduction. One important property that organic compounds exhibit is that their structure is related to their solubility. Solubility is the amount of a substance that will dissolve in a given amount of another substance and is typically expressed as the number of parts by weight dissolved by 100 parts of solvent at a specified temperature and pressure or as percent by weight or by volume. The general rule used in determining whether a solute is soluble or insoluble in a given solvent is “like dissolves like” where nonpolar solutes dissolve in nonpolar solvents; polar solutes dissolve in polar solvents or chemical reactions may occur between the solvent and the solute causing dissolution. Compounds that are branch-chained are more soluble than the corresponding straight-chained compound. Branching lowers intermolecular forces and decreases intermolecular attraction. The position of the functional group in the carbon chain also affects solubility. Methodology and materials: Part 1 (water solubility): 150 mg (or 4 drops) are taken from each of following organic compounds: Propanol, Benzyl alcohol, 2- methylphenol, Di- n- butyl ether, Propanoic acid, Ethyl benzoate, n- propylamine, Analine and Benzamide. Each 150mg (or 4 Drops) of these compounds are added to separate test tubes, which contain 3 ml of water at room temperature. Part 2 (acid- base solubility): Four 4 drops of Benzyl alcohol and four drops of 2- methylphenol were added to separate test tubes contain 3 ml of 10% of NaOH solution. Then, 3 ml of 10% HCl solution are placed in two-separated test tubes and then four drops of analine and benzamide are added to these two test tubes. Part 3 (solubility and acid- base properties): Five known samples are provided and they are M- cresol, Bromobenzen, Analine, Propanoic acid and Acetophenone. Four drops from each sample are placed in a separate test tube filled with 3 ml of water. If the sample is soluble in water, litmus paper test is the second step. Turning the red litmus to blue means the sample is base (amines), turning the blue to red color means acid (carboxylic acids) and if there is no change, this intends to be neutral. If the sample is insoluble in water, a fresh sample of the required known sample (four drops) is placed in a test tube filled with 3 ml of 10% NaOH solution. If the result is soluble in NaOH solution, a fresh sample (four drops) is added to a test tube contains 3 ml of NaHCO3 solution. A strong acid is the result if the sample is soluble in NaHCO3 solution and weak acid if it is not. When the sample is insoluble in NaOH solution, three ml of 10% HCl solution is placed in a test tube and then four drops from the sample. Soluble of the sample in HCl solution means that the sample is base (amine). If it is not soluble in HCl solution, four drops of the sample is added to three ml of H2SO4 in a test tube. The sample is soluble in H2SO4, when it is neutral compound, inert compound if it is not. The same previous solubility test is applied on unknown sample of organic compound. result : 1- Water solubility: Table A Water solubility Solute Structure Water Propanol Soluble Benzyl alcohol Insoluble 2- methylphenol Insoluble Di- n- butyl ether Insoluble Propanoic acid Soluble Ethyl benzoate Insoluble N- propylamine Soluble Analine Insoluble Benzamide Insoluble XXXXXXXXXXBase- acid solubility: Table B Base solubility Solute Structure 10% NaOH Benzyl alcohol Insoluble 2- methylphenol Soluble XXXXXXXXXXTable C Acid solubility Solute Structure 10% HCl Analine Soluble Benzamide Insoluble XXXXXXXXXXSolubility and acid- base properties: Table D XXXXXXXXXXSolvents Solute H2O 10% NaOH NaHCO3 Result M- cresol Insoluble Soluble Insoluble Weak acid XXXXXXXXXXTable E Solvents Solute H2O 10% NaOH 10% HCl H2SO4 Result Bromobenzen Insoluble Insoluble Insoluble Insoluble Inert compound Table F XXXXXXXXXXSolvents Solute H2O 10% HCl Result Analine Insoluble Soluble Amine Tablet G Solvent Solute H2O Red Litmus Blue litmus Result Propanoic Acid Soluble No change Red color Carboxylic acid Tablet H Solvents Solute H2O 10% NaOH 10% HCl H2SO4 Result Acetophenone Insoluble Insoluble Insoluble Soluble Neutral compound Table J Solvents Solute H2O 10% NaOH 10% HCl H2SO4 Result unknown Insoluble Insoluble Insoluble Soluble Neutral compound