Sythesis of isopentyl acetate report questions

[osumc2014]

Couple questions about the fischer esterification of isopentyl alcohol + acetic acid -----> (acid catalyzed) to form isopentyl acetate or banana oil. Refluxed, used sodium bicarb and na2So4, distilled.
1) how do I know that the final solution did not contain any alcohols?

2)What could have caused a low yield?

3)How to improve the yield? Iknow something w Le chatelier's but anything else?

Thanks!

 

[AbedeuS]

The hint is in the use of Na2SO4

Sorry: I Mean its in the use of distillation

(Even though getting a completely pure substance from one distillation is unlikely..)

 

[chemisttree]

1) NO, the hint is in the use of bicarbonate.
2) time, temperature, catalyst, water in reagents, sloppy work, larger glassware than necessary, warm condenser in the distillation, too much Na2SO4, bad Na2SO4, not enough time over the Na2SO4, bad extraction technique (emulsion), it just goes on and ON!
3) Improve the yield by sequestering one of the products as it is formed. (Dean-Stark?)

 

[AbedeuS]

Whoops, this is what I get for late posting ^^

But why does the use of bicarb have its effects? Surely its just to reduce the acidity after the acid catalysed esterification takes place?

 

[chemisttree]

The first step of the workup is to extract with water or bicarb. Probably water first followed by a bicarb wash to scavenge the acid. Water is the key of course since the alcohol is isopropyl (water-soluble).

Edit: Whoops! Strike that! Isopentyl alcohol not isopropyl. And isopentyl alcohol is not very water soluble. AbedeuS is right about the distillation being important.

 

[dianar]

what purpose does refluxing serve ?please help.

 

[dianar]

yield was 38.13% and the final ester was 6.87g s opposed to 18.01g.. problems like wat could have caused this?