Question

Pre-Laboratory Assignment • What particular precautions should you take 3. Methyl alcohol, CH,OH, reacts with benzoic acic when doing the following: CHECO,H, to form an ester. (1) using concentrated sulfuric acid (1) Using structural formulas, write the equatic for this reaction. (2) using glacial acetic acid (3) using a warm-water bath (2) What is the name of this ester? (4) Smelling ester odors 2. What is the purpose of the concentrated sulfuric acid used in this experiment?

Answer 1

1.

(1) Concentrated sulfuric acid is highly oxidizing agent and it is a burning agent. So, we should avoid its skin contact. Best to wear gloves during handling it.

(2) Glacial acetic acid has a bad and little bit choking smell. So, we should not inhale it. So, best to wear musk.

(3) Warm water bath has a high temperature, Direct contact to skin can cause burning. So, always use some non-conducting thing like clothes to handle a warm water bath.

(4) Directly inhaling some reaction mixture is not a good practice. You can take the vessel not very close to your nose, then blow wind from opposite direction by your hand and then smell it. Otherwise we can put our thumb on the vessel for some time, then smell our thumb to get the smell of ester.

2.

During the experiment, water comes out as a side product. Now, if we can take out water then the equilibrium will be shifted towards product side more, to generate more water in mixture according to the Le Chatelier's principle. Sulfuric acid has very high affinity for water, it does that job.

3.

(1) Due to the reaction water comes out. So we can just write the structural formula, take out water and recombine the left over parts.

$C_6H_5CO{\color{Red} OH}(aq)+CH_3O{\color{Red} H}(aq)\overset{conc H_2SO_4}{\rightarrow}C_6H_5COOCH_3 (aq)+ {\color{Red} H_2O}(l)$

(2) The acid is benzoic acid, so, alkanoate part is benzoate and alcohol is methanol so alkyl part is methyl. So, ester name is 'alkyl alkanoate' means methyl benzoate.