OOOwwwww – made it by 33 minutes…..you guys can have 24 hours for this one. Michel – I’ll get to your answer soon I promise……so far looking good – keep it up!!
The flow chart shows a series of steps involved in the production of ethyl benzoate
Glucose …………mixture containing ethanol…….pure ethanol……..ethyl butanoate
Describe the chemistry and procedure involved in each of these steps, using diagrams where appropriate…
7 MARKS………don’t worry about trying to show me diagrams etc….although you can e-mail this if you like….
Classy Chemistry! 
quick question….are we looking for ethyl benzoate, or butanoate?… i’ll just assume butanoate as its more conventional…
The flow chart shows a series of steps involved in the production of ethyl benzoate
Glucose …………mixture containing ethanol…….pure ethanol……..ethyl butanoate
Describe the chemistry and procedure involved in each of these steps, using diagrams where appropriate…
There’s so much to do!!!! No wonder its 7marks….ok here we go.
The first step, to produce an ethanol mixture from glucose involves the fermentation of glucose, using a catalyst of yeast. The glucose is first dissolved in water to form a solution, and then yeast is added for fermentation, with the conditions of 37°C, absence of oxygen, and maybe some nutrients to help the yeast do its work. The following occurs:
C6H12O6(aq) –> C2H5OH(aq) + CO2(g)
– basically the yeast helps to break down glucose to ethanol and cabon dioxide.
However because the glucose was in a solution, there is still the presence of water, and ethanol will dissolve fully in water (strong hydorgen bonding). To extract pure ethanol distillation must be undertaken, and this is based on the fact that ethanol and water have different boiling points.
(I would draw a diagram here…but I can’t)
To produce ethyl butanoate, esterfication is used. Ethanol and butanoic acid are mixed together, with a little conc. sulfuric acid as a catalyst. The mixture is then refluxed; heated with a bunsen burner, and condensed simultaneously with a condensation jacket surrounding it. This allows the mixture to be heated, in order to increase the rate of reaction, but also prevents the loss of volatile products and reactants.
The reaction that occurs is:
C2H5OH + C4H9COOH –> (big long thing which I can’t draw here) + H2O
Lastly to obtain pure ethyl butanoate, a seperating funnel is used. The mixture is poured into the separating funnel along with water, which will form two immiscible layers, with the ester on top. The water acts to dissolve all the other substances (i.e. sulfuric acid, ethanol, butanoic acid) but leaves the ester, and so they can be separated. The tap at the bottom is opened to let out the other substances, and shut quickly to leave the ester remaining. This is done many times, to ensure greater purity.
– ok that was really brief…should i have expanded more to get the 7 marks
By the way, why doesn’t the ester dissolve in water? I wasn’t here when we did it….
Don’t take my word for this, but id guess its because theres a domincance of dispersion forces over dipole-dipole forces between the molecules.
yeah miss told me it was really big so the water molecules can’t break them apart (very very high dispersion forces), and also there isn’t any hydogen bonding…no OH left….
Hey miss…do esters have a higher or lower bp/mp than alkanoic acids and alkanols? I’m not sure because esters are much bigger, hence much stronger dispersion forces, but there isn’t any hydrogen bonding…
I have another question…sorry if im getting annoying…at least im doing my work!
For the ester prac, we tried to purify the ester by adding water and then separating with the separating funnel right? Then we added sodium hydrogen carbonate. By adding this we got rid of any sulfuric acid, but then we still have sodium ions in it. Did we just leave them in there? Would they affect the semll of the ester?