Organic Chemistry Lab Post-Lab Discussion PDF

POST LABORATORY DISCUSSION MT-MLS104L INORGANIC AND ORGANIC CHEMISTRY LABORATORY DEPARTMENT OF NATURAL SCIENCES AND MATHEMATICS COLLEGE OF ALLIED SCIENCES DE LA SALLE MEDICAL AND HEALTH SCIENCES INSTITUTE...

POST LABORATORY DISCUSSION MT-MLS104L INORGANIC AND ORGANIC CHEMISTRY LABORATORY DEPARTMENT OF NATURAL SCIENCES AND MATHEMATICS COLLEGE OF ALLIED SCIENCES DE LA SALLE MEDICAL AND HEALTH SCIENCES INSTITUTE 1 PRELIM LAB EXAM COVERAGE ❖ Expt. 1 – Solubility of Organic Compounds (10 items) ❖ Expt. 2 – Reactions of Hydrocarbons and Alkyl Halides (10 items) ❖ Naming and Formula Writing of Inorganic Compounds (5 items) ❖ Nomenclature: Alkanes, Alkenes, Alkynes, and Alkyl Halides (15 items) ❖ Lab Safety and Familiarization (10 items) 2 REMINDERS ✓50-item LAB Exam ✓Multiple Choice ✓Face to Face – coordinate with your lab teachers ✓Review Materials: Post Lab File, Textbook, and uploaded pdf files 3 Naming and Formula Writing of Inorganic Cpds. Study the uploaded files and Gen. Chem. references Naming of Hydrocarbons ✓ Study the uploaded files and textbook Lab Safety ▪ Video ▪ Uploaded file 4 Solubility of Organic Compounds EXPERIMENT NO. 1 POST-LAB DISCUSSION 5 WHAT IS SOLUBILITY? Solubility is the amount of solute that dissolves in a given amount of solvent. BASIC PRINCIPLES OF SOLUBILITY The solubility of a compounds depends on the strength of the interactions between the compound and the solvent. Thumb Rule: “Like dissolves like” 6  BASIC PRINCIPLES OF SOLUBILITY Most of ionic compounds are soluble in water. 7  BASIC PRINCIPLES OF SOLUBILITY Water-soluble compounds are molecules that can form a hydrogen bond with water. 8  BASIC PRINCIPLES OF SOLUBILITY Water solubility for neutral molecules occurs only with small polar molecules or those with many O or N atoms that can hydrogen bond to water. 9 BASIC PRINCIPLES OF SOLUBILITY 10  BASIC PRINCIPLES OF SOLUBILITY Nonpolar compounds are soluble in nonpolar solvents. 11 MOLECULAR WEIGHT AND SOLUBILITY Generally, an increase in molecular weight leads to an increase in intermolecular forces in a solid, thus, decreasing solubility. BRANCHING AND SOLUBILITY Compounds having a branched chain is more soluble than the corresponding straight chain compound. Branching reduces the size or volume of the molecule, allowing the solvent to solvate it easier. 12  IMPORTANCE OF KNOWING A COMPOUND’S SOLUBILITY A compound’s solubility can be used as a preliminary test for determining the identity of an organic compound. It can also be used in various separation techniques such as extraction and chromatography. 13  COMMON SOLVENTS USED IN SOLUBILITY TESTS distilled water 5% NaOH 5% NaHCO3 5% HCl cold conc. H2SO4 Diethyl ether 14  SCHEMATIC DIAGRAM OF SOLUBILITY TEST * With correct answers Sucrose Acetone Ethanol Aniline Benzoic acid Phenol Benzamide Benzaldehyde Benzyl alcohol Hexane, Toluene 15 Tert-butyl chloride  COMPOUND CLASSIFICATION BASED ON SOLUBILITY S1: – arylsulfonic acids – monofunctional carboxylic acids, amines, alcohols, aldehydes, ketones, esters, nitriles, and amides with not more than five carbons 16  COMPOUND CLASSIFICATION BASED ON SOLUBILITY S2: – salts of organic acids – amine hydrochlorides – amino acids – polyfunctional compounds with hydrophilic functional groups carbohydrates, polyhydroxy compounds, polybasic compounds 17  COMPOUND CLASSIFICATION BASED ON SOLUBILITY A1: – strong organic acids such as: – carboxylic acids with more than six carbons – phenols with electron withdrawing groups in the ortho and/or para positions – 1,3-diketones 18  COMPOUND CLASSIFICATION BASED ON SOLUBILITY A2: – weak organic acids such as: – phenols, enols, oximes, imides, sulfonamides, thiophenols – all with less than six carbons – 1,3-diketones – nitro compounds with hydrogens 19 COMPOUND CLASSIFICATION BASED ON B: SOLUBILITY – aliphatic amines with eight or more carbons – anilines (only one phenyl group attached to nitrogen) – some ethers M: – miscellaneous neutral compounds containing nitrogen or sulfur and having more than five carbon atoms 20 COMPOUND CLASSIFICATION BASED ON SOLUBILITY N: – monofunctional alcohols, aldehydes, ketones, esters with more than five but fewer than nine carbons – ethers, epoxides, alkenes, alkynes, some aromatic compounds (particularly with activating groups) 21 COMPOUND CLASSIFICATION BASED ON SOLUBILITY I: – saturated hydrocarbons, haloalkanes, aryl halides, deactivated aromatic compounds, diaryl ethers 22  EXPECTED RESULTS IN THE EXPERIMENT S1: acetone and ethanol – Small oxygenated organic compounds that can form hydrogen bonding with water Methanol (below) or ethanol exhibit similar solubility in water. 23  EXPECTED RESULTS IN THE EXPERIMENT S2: sucrose – Sucrose is not soluble in ether because it contains various hydrophilic (water-loving) functional groups. 24  EXPECTED RESULTS IN THE EXPERIMENT A1: benzoic acid (pKa = 4.2) A2: phenol (pKa = 9.9) – Both are weak acids but benzoic acid is stronger than phenol. – Both acids will react to a strong base (i.e. NaOH) to form water soluble salts. 25  EXPECTED RESULTS IN THE EXPERIMENT A1: benzoic acid (pKa = 4.2) A2: phenol (pKa = 9.9) – Both are weak acids but benzoic acid is stronger than phenol. – Weaker acids (i.e. phenols) will not react with weak bases (i.e. NaHCO3). 26  EXPECTED RESULTS IN THE EXPERIMENT B: aniline – The phenyl ring increases the basicity of the nitrogen atom allowing it to attract the proton from HCl easily. Amines react with acids to form water- soluble ammonium salt. 27  EXPECTED RESULTS IN THE EXPERIMENT M: benzamide N: benzaldehyde, benzyl alcohol I: tert-butyl alcohol, toluene, hexane 28 BONUS: Phenol solution was used as sample. It should be in its pure solid form that is why some have erroneous results.  EXPERIMENT NO. 2 Reactions of Hydrocarbons and Alkyl Halides  SAMPLES USED IN THE EXPERIMENT Saturated hydrocarbons - carbon–carbon single bonds. Unsaturated hydrocarbons - carbon–carbon multiple bonds like double bonds, triple bonds, or both. Samples: Hexane Cyclohexene Toluene tert-butyl chloride 31 SAMPLES USED IN THE EXPERIMENT 32  BROMINE TEST Addition of Bromine REAGENT: Bromine water Orange-red or red-brown liquid (freshly prepared) Toxic and corrosive Harmful if inhaled Causes respiratory tract irritation and possible burns Causes eye and skin irritation and possible burns May cause digestive tract irritation with nausea, vomiting, and diarrhea ✓ Should be done under the fume hood This Photo by Unknown Author is licensed under CC BY-SA 33  BROMINE TEST Addition of Bromine TEST FOR: ❖ unsaturated hydrocarbons CONFIRMATION: ❖ disappearance of orange-red color in solution ❖decolorized bromine water 34  BROMINE TEST Addition of Bromine As the bromine solution is added to the unsaturated compound, the bromine color disappears. If the compound being tested is saturated, it will not react with bromine under these conditions, and the color will persist. 35 BROMINE TEST Addition of Bromine Reaction with Bromine using Reaction with Bromine using H2O as CCl4 as reagent: reagent: Bromine water (actual experiment) 36  BAEYER’S TEST Oxidation Reaction REAGENT: Alkaline KMnO4 Purple-colored solution Strong oxidizing reagent TEST FOR: unsaturated hydrocarbons CONFIRMATION: disappearance of purple color in solution and formation of brown precipitate BAEYER’S TEST Oxidation Reaction This Photo by Unknown Author is licensed under CC BY-SA As the reaction occurs, the purple color of the permanganate ion is replaced by the brown precipitate of manganese dioxide. Alkanes normally do not react with potassium permanganate. 38  ETHANOLIC SILVER NITRATE TEST TEST FOR: – 2º and 3º alkyl halides REAGENTS: – 0.1 M silver nitrate in ethanol CONFIRMATION: – white for silver chloride, pale yellow for silver bromide, and yellow for silver iodide 39 ETHANOLIC SILVER NITRATE TEST 40 Conc. H2SO4 This reaction is used to make alcohol 41 Conc. H2SO4 Reaction mixture shortly Reaction mixture after after the addition of about 2 minutes and sulfuric acid. continuously turns darker. 42  Conc. H2SO4 Cloudy upper layer When heated with mixing or stirring, toluene reacts producing yellow solution and toluene eventually amber with further heating 43  BROMINE BAEYER’S ETHANOLIC TEST TEST SILVER NITRATE TEST TEST FOR: Unsaturation Unsaturation Halides CONFIRMATION 44 Test Sample BROMINE BAEYER’S TEST ETHANOLIC Conc. H2SO4 TEST AgNO3 TEST TEST FOR: Unsaturation Unsaturation Halides --- (-) (-) (-) (-) (+) (+) (-) (+) (-) (-) (+) (-) (-) (-) (-) (+) BLANK (-) (-) (-) (-) 45  https://www.facebook.com/delasallelipa https://seedingfaith.com/products/i-can-do-all-things-through-christ-philippians-413-bible-verse-poster/ 46