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Topic: Preparation of Octyl Acetate  (Read 12914 times)

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Offline joeflsts

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Preparation of Octyl Acetate
« on: September 04, 2006, 08:23:46 PM »
I have mentioned before that my current focus is on esters.. Here is a new one:

Work up:
Carboxylic Acid:  Glacial Acetic Acid - (0.30 mole = 18.0ml)
Concentrated Sulfuric Acid (1 - 2.0ml)
Alcohol:  Octyl Alcohol (1-Octanol) - (0.20 mole = 26.0ml)

Materials:
18ml Glacial Acetic Acid
26ml Octyl Alcohol (1-Octanol)
2ml Sufuric Acid
5g Sodium Bicarbonate
100ml Distilled Water

Experimental Procedure:
Add to 250ml flask a boiling chip and

(in the following sequence and with good mixing after each addtion):

Carboxylic Acid (0.30 mole)
Alcohol (0.20 mole)
1 - 2.0ml Concentrated H2SO4 (Sulfuric Acid)

Add reactants and gently relux for approximately 30 minutes.  Collect reaction mixture, isolate ester.  Isolate Octyl Acetate by removing excess acid and drying.

Experiment:

Mix 18ml GAA with 26ml Octanol and add 1-2 ml of concentrated Sulfuric Acid.

Acid was slowly, drop for drop, added to the reaction mixture.  No noticeable Orange smell was present.

The solution was gently mixed and place on reflux for 35.30 minutes.  Removed heat to allow reaction mixture to cool to room temperature.

5g Sodium Bicarbonate was added to 100ml distilled water to be used as nuetralizing agent for the unreacted acids.

Once the impure mixture was cooled to room temperature I transfered to a sep. funnel and added about 40ml of distilled water.  A small amount of water was added to the reaction flask and transfered to the sep. funnel.  The funnel was shaken vigorously and I allowed it to sit until to layers formed.

The scent reminds me of apple and not orange.

After removing the lower, aqueous layer, I charged the organic layer with a 5% Sodium Bicarbonate solution until no further CO2 was formed (visible) and decanted a sample for future testing.

Yeild: 5-10ml  - I consider this experiment unsuccessful.

Offline AWK

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Re: Preparation of Octyl Acetate
« Reply #1 on: September 05, 2006, 06:20:21 AM »
An esterification reaction is an equilibrium reaction which equlibrate very slowly at aproximate yield of 60-70 %, To obtain good yiield you need remove water azeotropically or use a large excess of a cheaper reagent. I think for your experimental condition your yield is too good.
AWK

Offline joeflsts

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Re: Preparation of Octyl Acetate
« Reply #2 on: September 05, 2006, 07:13:12 AM »
An esterification reaction is an equilibrium reaction which equlibrate very slowly at aproximate yield of 60-70 %, To obtain good yiield you need remove water azeotropically or use a large excess of a cheaper reagent. I think for your experimental condition your yield is too good.

Good point.  I should have mentioned that I didn't distill the final product so my measurements of final yield are not correct.

Joe

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