January 16, 2022, 11:10:31 PM
Forum Rules: Read This Before Posting


Topic: Isopentyl Acetate (Banana Oil)  (Read 54377 times)

0 Members and 1 Guest are viewing this topic.

Offline DDD

  • Very New Member
  • *
  • Posts: 2
  • Mole Snacks: +0/-0
Isopentyl Acetate (Banana Oil)
« on: November 07, 2006, 08:09:55 PM »
Why is it easier to remove excess acetic acid from products than excess isopentyl alcohol?
How do you outline a seperation scheme for isolating pure isopentyle acetate from the reaction mixture?
and how do you write a mechanism for the acid-catlyzed esterification of acetic acid with isopentyl alcohol?

I've tried to google them but I am not making any progress. Would someone give me some ideas on how to answer these questions?

Offline Yggdrasil

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3214
  • Mole Snacks: +484/-21
  • Gender: Male
  • Physical Biochemist
Re: Isopentyl Acetate (Banana Oil)
« Reply #1 on: November 07, 2006, 10:54:23 PM »
Why is it easier to remove excess acetic acid from products than excess isopentyl alcohol?

How do you normally remove acids from an organic mixture? (hint: think about extractions)

Quote
How do you outline a seperation scheme for isolating pure isopentyle acetate from the reaction mixture?

Well, the first place to start when thinking of a separation scheme is to list the compounds you expect to be present in the reaction mixture.

Quote
and how do you write a mechanism for the acid-catlyzed esterification of acetic acid with isopentyl alcohol?

Look up Fischer esterification in your ochem text.
« Last Edit: November 08, 2006, 03:55:33 AM by Borek »

Offline DDD

  • Very New Member
  • *
  • Posts: 2
  • Mole Snacks: +0/-0
Re: Isopentyl Acetate (Banana Oil)
« Reply #2 on: November 08, 2006, 04:48:04 PM »
Is it b/c acids can be neutralized and form ions? 
I got my question answered by acetic acid can be extracted out from the solution because it's not miscible with the solution.  I just checked its solubility and it said that it's soluble. Little confused.

I found the other two answers though.  Thank you.

Offline Yggdrasil

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3214
  • Mole Snacks: +484/-21
  • Gender: Male
  • Physical Biochemist
Re: Isopentyl Acetate (Banana Oil)
« Reply #3 on: November 08, 2006, 08:01:11 PM »
You're on the right track when you say that it can be neutralized to form ions.  Since acetate ions are charged, they are much more soluble in water than in organics.  Therefore, if you wash your reaction mixture with aqueous sodium bicarbonate, the base will deprotonate the excess acetic acid, forming acetate ions.  These acetate ions will migrate out of the organic phase and into the aqueous phase, removing them from your product when you separate the organics from the water.

Isopentyl alcohol is much more poorly soluble in water than acetate ions, and is much more similar to your ester in terms of solubility products.  If you were to try a similar extraction to remove teh isopentyl alcohol, you would either leave a lot of alcohol with your product or lose much of your ester.

Offline ch3m_boy

  • Regular Member
  • ***
  • Posts: 19
  • Mole Snacks: +1/-2
  • Gender: Male
  • Lips of an Angel
Re: Isopentyl Acetate (Banana Oil)
« Reply #4 on: December 05, 2006, 12:19:49 AM »
FUNNY-  i did this same exact lab and had those same exact questions a few weeks ago! ;)

My answer for the using excess acetic acid was

2.)   It is easier to remove excess acetic acid versus excess Isopentyl alcohol because of solubility.  Acetic acid, being more polar than Isopentyl alcohol, has more of a tendency to dissolve in the aqueous layer vs. the organic layer.  The aqueous layer can be easily removed by extraction, using sodium bicarbonate and water, thereby removing most of the acetic acid.  On the other hand, excess Isopentyl alcohol will be harder to remove.  Isopentyl alcohol is not as polar are acetic acid and therefore not as soluble in water as acetic acid.  This means that Isopentyl alcohol will mostly be dissolved in the organic layer along with the ester.  This can not be removed from extraction with sodium bicarbonate and water.


Offline kokoike

  • Very New Member
  • *
  • Posts: 2
  • Mole Snacks: +0/-0
Re: Isopentyl Acetate (Banana Oil)
« Reply #5 on: April 04, 2008, 08:21:59 PM »
Hello, I have done the same experiment last week and I have same question.

How do you outline a seperation scheme for isolating pure isopentyle acetate from the reaction mixture?

I have searched everywhere but I still cannot get it.
Please help me. 


Offline Yggdrasil

  • Retired Staff
  • Sr. Member
  • *
  • Posts: 3214
  • Mole Snacks: +484/-21
  • Gender: Male
  • Physical Biochemist
Re: Isopentyl Acetate (Banana Oil)
« Reply #6 on: April 04, 2008, 09:05:41 PM »
Did you read the posts in this thread?  It contains most of the information you need on how to remove acetic acid from your solution.  Now, can you think of other contaminants that would be present and how to remove them?

Sponsored Links