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Expt 17
 

Expt 17

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    Expt 17 Expt 17 Presentation Transcript

    • Post Lab Discussion Experiment 17
    • Prelaboratory Assignment 1. Draw the structure of the following compounds:  Acetyl chloride  Acetyl salicylic acid  Acetic anhydride  Salicylic acid  Acetamide Acetyl Acetic Acetamide chloride anhydride
    • Prelaboratory Assignment 1. Draw the structure of the following compounds:  Acetyl chloride  Acetyl salicylic acid  Acetic anhydride  Salicylic acid  Acetamide Salicylic acid Acetyl salicylic acid (ASA)
    • Prelaboratory Assignment 2. What is the purpose of adding ferric chloride to the filtrate of acetyl salicylic acid? Ferric chloride is added as an indicator which detects the presence of salicylic acid in the products. When FeCl3 ionizes, Iron(III) forms complexes with phenolic compounds, such as salicylic acid. The color of these complexes range from red to purple.
    • Prelaboratory Assignment 3. How would you test for ammonia vapor in the basic hydrolysis of amides? Since it is the vapor that is being tested, the most reliable method available would be to suspend a damp piece of red litmus paper at the mouth of the test tube. Ammonia vapor is basic and would thus turn the red litmus paper blue upon exposure.
    • ResultsExperiment 17
    • ResultsHydrolysis of Acetic Chloride Observation It became slightly warmer after 2 drops of Acetyl Acetyl chloride chloride. It turned to a cloudy white solution after adding AgNO3 •No temperature change Acetic anhydride •No change on the appearance of solution after adding AgNO3Reactions of Esters ObservationAcid Hydrolysis of Minimal amounts of ASA dissolved. When cooledAcetyl Salicylic Acid crystals, removed through filtering formed. Solution turned purple after addition of FeCl3.Esterification Separation of layers after heating. Strong scent of bananas.
    • ResultsReaction of Amides Observation The vapor of the solution changed the blue litmus paper Acetamide + HCl to red. Smelled like vinegar The red litmus paper turned blue. Pungent odor Acetamide + NaOH
    • Hydrolysis of Acetic Chloride Experiment 17
    • OBSERVATIONS It became slightly warmer after 2 Acetyl chloride drops of Acetyl chloride It turned to a cloudy white solution after adding AgNO3 •No temperature change Acetic anhydride •No change on the appearance of solution after adding AgNO3
    • Reaction of an Acyl Chloride with water Acetyl Chloride or ethanoyl chloride : or acyl chloride The Equation:
    • The Mechanism 1st 2nd
    •  Acetic Acid and hydrogen chloride gas is produced - the hydrogen coming from the -OH group, and the chlorine from the Acetyl chloride. Adding an acyl chloride to water produces the corresponding carboxylic acid together with steamy acidic fumes of hydrogen chloride.
    •  The reaction is usually extremely vigorous at room temperature. Addition with AgNO3 produced a cloudy solution. The precipitate formed is from the reaction between AgNO3 and HCl, forming AgCl3. This is done to indicate that a halide ion is present, in this case Cl
    • THE REACTION OF ACID ANHYDRIDES WITH WATER Acetic anhydride or ethanoic anhydride : Equation:
    •  Acetic acid is formed as the second product rather than hydrogen chloride gas.
    •  The reactions are slower. Acid anhydrides arent so violently reactive as acyl chlorides Ethanoic anhydride can’t be said to dissolve in water. When Ethanoic anhydride reacts with water, it would give Acetic acid.
    • The only difference is that Ethanoic acid (Acetic acid) isproduced as the second product of the reaction rather thanHydrogen chloride
    • Reactions of Esters Experiment 17
    • Results ObservationAcid Hydrolysis Minimal amounts of ASA dissolved.of Acetyl When cooled crystals, removed throughSalicylic Acid filtering formed. Solution turned purple after addition of FeCl3.Esterification Separation of layers. Strong scent of bananas.
    • Acid Hydrolysis of Acetyl Salicylic Acid
    • Acid Hydrolysis of Acetyl Salicylic Acid Acetyl Acetic Acid Salicylic Acid and WaterSalicylic Acid The reaction can proceed either way depending in the conditions. At equilibrium, this reaction favors a high concentration of SA and a very small one of ASA.
    • Acid Hydrolysis of Acetyl Salicylic Acid Acetyl Acetic Acid Salicylic Acid and WaterSalicylic Acid Hydrolysis of acetylsalicylic acid is an equilibrium reaction catalyzed by acid (as in this case) or by base. Normally the hydrolysis is driven to the right by low pH, as well as by losses of HOAc to the air.
    • Acid Hydrolysis of Acetyl Salicylic Acid Addition of ferric chloride is done in order to detect the presence of a phenolic group. The purple coloration results fro the formation of ferric salicylate complexes.
    • Esterification Isopentyl alcohol Acetic acid Isoamyl Water acetate The aroma of bananas is due to the synthesis of isoamyl acetate from isopentyl alcohol and acetic acid.
    • Reaction of Amides
    • Observations • The vapor of the solution changed the blue litmus Acetamide + HCl paper to red • Smelled like vinegar • The red litmus paper turned blueAcetamide + NaOH • Pungent odor
    • Acetamide with HCl
    • Acetamide with NaOH
    • Basic Hydrolysis Acetamide If Acetamide is heated with NaOH, ammonia gas is given off and left with a solution containing sodium ethanoate Ammonia evolved
    • Acid Hydrolysis Acetamide is heated with a dilute HCl ethanoic acid is formed together with ammonium ions. The final solution would contain ammonium chloride and ethanoic acid. Ammonia did not evolve, ammonium chloride was present
    • With the addition of HCl on acetamide, it smelled likevinegar since acetic acid was formed. The color of theblue litmus paper turned red due to the acetic acid.With the addition of NaOH, the color of the red litmuspaper turned blue indicating the basicity of thesubstance since ammonia was formed.