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BRANDEIS UNIVERSITY CHEMISTRY 29A PRELAB WRITEUP AND EXPERIMENTAL REPORT SHEET NAME_ T.A.’S NAME _________ EXPERIMENT # __7_____ TITLE Ketone Identification Purpose: to characterize an unknown carbonyl compound using BP analysis, MP derivative analysis, NMR and IR spectra analysis PRELIMINARY WRITEUP* (INCLUDING EQUATIONS, TABLE OF MATERIALS, THEIR AMOUNTS AND CONSTANTS. AND PRELAB QUESTIONS. Place these questions on the reverse of this page) (* use reverse of both sheets if necessary) Substance Purpose Melting Point (Celsius) Other notes Water Solvent, cleaning agent, catalyst in multiple reactions N/A Sodium hydroxide Reacts with iodine and aldehyde or methyl ketone to form iodide ion and carboxylic acid anion N/A Iodine solution Source of iodine for reaction in iodoform test, the iodine turns into the iodide ion in presence of hydroxide and an aldehyde or methyl ketone, the yellow insoluble iodide provides the positive test N/A 1,2 dimethoxymethane Solvent for water insoluble ketones in iodoform test N/A Phosphoric acid Catalyst for DNP reaction with aldehyde N/A Unkown aldehyde (2,3- pentadione) The unknown N/A 2,4 dinitrophenylhydrazine Substance which reacts with the aldehyde or ketone via a condensation reaction forming an imine, an insoluble compound N/A Schiff’s reagent Tests for presence of aldehyde, by color formation N/A Methylene chloride Cleaning IR plates, and IR solvent N/A Trichloro dutero methane NMR solvent N/A TMS NMR reference compound N/A Nitrogen gas Purging oxygen from NMR samples N/A EXPERIMENTAL PROCEDURES* (include in preliminary writeup) Iodoform test 1. if unknown is water soluble dissolve 4 drops of liquid or 50 mg of solid in 2mL of water 2. if unknown is not water soluble dissolve it in 2 mL in 1,2 dimethoxymethane 3. add 2 mL of 3M sodium hydroxide 4. slowly add 3 mL of iodine solution 5. dilute to 10 mL with water if ketone was insoluble in water 6. observe results of reaction Schiff’s test 1. add 3 drops of unknown to 2 mL of Schiff’s reagent 2. allow 10 min for the reaction DNP synthesis 1. add 0.05g of unknown to 5mL solution of 2,4 dinitrophenylhydrazine in phosphoric acid 2. warm reaction for 1-3 min, then allow to air cool 3. help crystallization by ice cooling 4. collect crystals by suction filtration 5. wash crystals with large excess water to remove phosphoric acid, until litmus paper does not read as acidic 6. dry further with filter paper 7. determine melting point MODIFICATIONS AND OBSERVATIONS* (Obtained from the lab experience.) The iodoform tested yielded positive results for formation of
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