How do you prepare an ester in the lab using alcohols?
Answer:
"Esterification" (condensation of an alcohol and an acid) is not the only way to synthesize an ester. Esters can be prepared in the laboratory in a number of other ways:
-by transesterifications between other esters
-by Dieckmann condensation or Claisen condensation of esters carrying acidic α-protons
-by Favorskii rearrangement of α-haloketones in presence of base
-by nucleophilic displacement of alkyl halides with carboxylic acid salts
-by Baeyer-Villiger oxidation of ketones with peroxides
-by Pinner reaction of nitriles with an alcohol
Knocking Method :
INTRO: When an organic acid (R-C-OH) and an alcohol (R-OH) are mixed together and heated in the presence of an acid catalyst (such as H2SO4), the two will react to form an ester (plus H2O). This process is called esterification.
Each ester has its own unique odor, and with a discriminating nose, one can use this fact to help identify
them. In this lab you will be reacting various organic acids (acetic acid & salicylic acid) with various alcohols (methanol, isopentanol, & ethanol). You will make three different esters with odors that should be familiar to you.
Procedure: GOGGLES MUST BE WORN AT ALL TIMES!
1. Get 3 test tubes, labeled: “1”, “2”, & “3”
2. Test Tube #1: Add 10 drops of acetic acid, 10 drops of isopentanol, and 2 drops of H2SO4.
3. Test Tube #2: Add 1 scoop of salicylic acid, 15 drops of methanol, and 2 drops of H2SO4.
4. Test Tube #3: Add 10 drops of acetic acid, 10 drops of ethanol, and 2 drops of H2SO4.
5. Mix the contents of each test tube by the knocking method.
6. Place all 3 test tubes together in the warm water bath for approximately 1 minute.
7. Remove (carefully!) the test tubes from the hot water and place them in the test tube rack.
8. Note the smell of each ester by wafting the vapors towards your nose, one at a time. (Knocking the test tube before wafting helps!) .
9. To clean-up, empty out your test tubes into the waste container, and place the test tubes inside the soaking bin.
by reacting your alcohol with an organic acid (things like ethanoic acid...others C(2n)H(n)COOH where n is any number ) in presence of an acid preferably HCl. about knocking..
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