Chem 2211 Lab Final UGA ALL SOLUTION 2023 EDITION AID GRADE A+

Recapitalization a technique used to purify organic solid compounds with the goal to dissolve and subsequently crystallize a pure substance from the solution. What are the four characteristics of a good solvent? -Target must be soluble in high temp with impurities soluble at room temp or at high temps -Must be chemically inert (non-reactive) -Low boiling point, or highly volatile What are the 5 basic steps to Recrystallization -Choose suitable solvent -Dissolve the impure mixture in the hot solvent -Remove the insoluble impurities via high temp gravity filtration -Cool the solution to induce recrystallization -Isolate pure crystals via suction filtration If crystals do not form, what went wrong? How do you fix it? Too much solvent was used. Boil the solvent off and try to recrystallize again How do impurities affect the Melting Point of a compound? Impurities both broaden and depress a pure compounds melting point range. What is the eutectic point? The Lowest possible melting point of a mixture of substances What kind of Melting Point did you conduct to verify your unknown? A 50:50 Mixed Melting point How do you induce recrystallization? Bring to room temperature, Scratch inside flask walls, Ice baths Distillation process of separating the component substances from a liquid mixture by selective evaporation and condensation. Distillation may result in essentially complete separation What are the two types of distillation? Simple and Fractional How is separation achieved? based on the difference in boiling point of miscible (able to mix in all proportions) liquids Dalton's Law The total vapor pressure exerted by a solution at a given temperature is equal to the sum of the partial vapor pressures of individual components. Pt= Pa + Pb + Pc Raoult's Law Partial vapor pressure of each component in a solution is equal to the vapor pressure of pure component multiplied by its mole fraction within the mixture. Pa = P°aCa Dalton's Law and Raoult's Law Combined PT = P°aCa + P°bCb + P°cCc What is the fractionating column and how it is efficiency measured? A glass tube filled with tightly packed steel wool or glass beads added to the simple distillation apparatus to create fractional distillation. Helps to better separate liquids with close boiling points. Its effectiveness is measured by its column length, density of packing material, and by the number of theoretical plates that it can generate. What is a theoretical plate? Each separate "mini distillation" is called a theoretical plate. What is an Azeotrope? An azeotrope is a mixture of two or more liquids that form a constant boiling liquid of distinct proportions. Example: Ethanol, which is a mixture of 95.63% ethanol and 4.37% water. What are some common examples of distillation? Separation of pure water, Gasoline separation from crude oil, Alcohol distillation in the beer industry. Extraction A physical/chemical process of separating a single component from a complex mixture Examples of Extraction Extraction of caffeine from coffee beans Isolation of medicinal compounds from plant sources Taxol - cancer drug, produced through derivatization of medicinal compounds that are extracted from the bark of the Pacific Yew tree. What are the two different types of Extraction? Solid-Liquid Liquid-Liquid Solid-Liquid Extraction Extraction of a compound from a solid using a liquid media. Separation depends on compound's solubility in the particular solvent. Liquid-Liquid Extraction Separation of compound based on their relative solubilities in two different immiscible liquids What did we extract from Nutmeg in this experiment? trimyristin, a triglyceride of myristic acid What technique was used in this experiment? Reflux What is reflux? Process of boiling reactants while continually cooling and condensing the vapor thereby returning it back to the boiling flask. What is the purpose of this technique (reflux)? Heat mixtures for extended periods of time without solvent loss to extract compounds or carry out rxns Acid/Base Extraction Liquid-Liquid Extraction Liquid-Liquid Extraction Separation of compounds based on their relative solubilities in two different immiscible liquids Two ways to have a Liquid-Liquid Extraction Two liquids can either be. . . . -an aqueous solvent-organic solvent -two organic solvents of differing densities/polarities What are some common solvents used in Extractions? Methylene Chloride Diethyl Ether Ethyl Acetate Characteristics of an Extraction Solvent -immiscible with the original solution -Component to be separated must be more soluble in the extraction solvent than the liquid part of the original solution -extraction solvent should be more volatile than the liquid component of the original solution -The extraction solvent should be non-toxic (if possible) Two types of Liquid-Liquid Extractions 1.Organic Solvent Extraction 2.Acid/Base Extraction What was the solvent used in our experiment? Methylene Chloride an organic & non-polar solvent REMEMBER THAT LIKE DISSOLVES ______. LIKE; meaning polar compounds are more soluble in polar solvents. Many organic compounds are nonpolar and therefore less soluble in polar solvents. See General Flow Chart of Extraction How is the proper way to use the separatory funnel? -Gently shake the funnel with the stopcock closed and the stopper inserted -Point the funnel away from the body/partner and slowly release any built up pressure What happens in an amine in acidic conditions? Deprotonated to form ammonium salt What happens to a carboxylic acid in basic conditions? Deprotonated to form carboxylate salt Which layer is on the top/bottom? Based on what? Organic layer Aqueous layer Densities What were the three components? Thin Layer Chromatography Thin-layer chromatography (TLC) is a chromatography technique used to separate non-volatile mixtures. TLC is a separation based on Stationary phase and mobile phase What is TLC used for primarily? Identifying individual components of a mixture. Following the progress of a reaction. What is acting as the solid stationary phase? Silica gel, alumina What is acting as the mobile liquid phase? the low boiling point organic solvent What is the effect of polarity in regards to TLC? Polar compounds give strong interactions with polar stationary phase, so elutes slower up TLC plate. Measuring Rf values distance traveled by solute/distance traveled by solvent Distances traveled by solute that are close to solvent line (elute faster) more attracted to mobile phase and therefore more non-polar in nature. Shorter distances closer to origin line (elute slower) are more attracted to stationary phase and are more polar in nature. What were the TLC Plates visualized with? UV Light True or False: Two components with the same Rf values are considered the same substance. False; two components that contain the same Rf values are not necessarily the same substance. The four ingredients? Four analgesic ingredients studied: Acetaminophen, Acetylsalicyclic Acid, Caffeine, Ibuprofen What is Hydrogenation? Addition of H2 to an alkene -decreases # of unsaturated carbon-carbon bonds -increases # of saturated bonds What is Oxidation/Reduction? Oxidation: increases the number of bonds to more electronegative elements (loose electrons) reduction: reduces number of bonds to less electronegative elements, usually hydrogen (gains electrons) What was the catalyst in this experiment? Pd/C Palladium on Carbon What was the Hydrogen Donor? Cyclohexene What was the byproduct in this experiment? benzene What drives this reaction? The formation of benzene What is the balanced equation for this reaction experiment? (2 mol olive oil; 3 mol cyclohexene -> 2 mol shortening, 3 mol benzene Molecular Modeling is used for. . . finding the least stable or most stable conformations for various compounds Ranking base pairs involves. . . Elemental Effect Resonance of delocalized charge Inductive effects: adjacent electronegative atom The stronger the conjugate base the _____ the ____ ____. weaker, parent acid. Strong base = highly localized charge Strongest acid = most stable conjugate base, the one with the most resonance and inductive effects. Preparation of Diphenylacetylene How did we from the carbon-carbon triple bond? Halogenation of an alkene, followed by double dehydrohalogenation Review Mechanism What were the reagents used in this experiment? Pyridinium hydrobromide perbromide (PHPB) - (because liquid Br2 is highly toxic) CONTINUED...