esters Flashcards
You are converting what to what
I am converting Carboxylic acids and alchohol into an ester with water
What type of reaction is Ester sythesis lab?
Equilibrium reacition
What does sulfuric acid do in this lab?
- catalyst
Helps with the ratio between a carboxylic acid and an alcohol to form an ester and water. The acid protonates the carbonyl oxygen of the carboxylic acid, making the carbonyl carbon more electrophilic and thus more susceptible to nucleophilic attack by the alcohol. - dehydrating reagent
Helps to remove the water produced during the reaction, which shifts the equilibrium towards the formation of more ester –> helps with increasing the yield of the ester formed.
How is esterification reaction reversible?
When the concentration of one of the reactants is increased, the equilibrium shifts in the direction that will decrease its concentration.
How to increase the yield of ester:
Shift the equilibrium towards (right) ester formaiton by removing water or using an excess of one of the reactants
Why increasing the sulfuric acid will not increase the yiled of ester
Sulfuric acid does not increase the yield of ester because it does not affect the equilibrium position of the reaction.
NMR is useful to tell us that this reaciton is complete?
No, each peak in the ester has a comparable peak in either the alch or carboxylic acid, so it wont be clear whether the NMR is for the product, reactant, or both.
IR will be useful?
Yes, the functional groups are different so you can look for the disappearance of the alcohol Oh peak or look for the C=O peak to shift.
why is the equilibrium constant for this particular reaction close to 1?
Carboxylic acids and esters have similar stabilities so both sides of the reaction are similarly favorable
How do we adjust the procedure to get a good yield of the ester product?
We can use 1 of the reactants as the solvent to push the equilibrium to the right
Also
Water with a drying agent to pull the equilibrium to the right.
Why do we use acetic acid as the solvent rather than using a standard solvent like diethyl ether?
To push the equilibrium towards the with using Le Chatelier’s principle by using more of 1 reactant.
Which has the longest GC retention time: Pentanol, Pentyl, Acetate, or acetic acid
Pentanol might have the longest time : higher boiling point and stronger intermolecular hydrogen bonding compared to other compounds. The higher the boiling point, the longer it stays in the GC.
Pentyl Acetate: relatively larger molecular size and lower volatility compared to acetic acid. larger molecules generally move more slowly through the GC column
Acetic Acid: polar nature and ability to form hydrogen bonds. Polarity can cause interactions with the stationary phase in the GC column. leading to a longer retention time.
Why were the acid base extractions you performed NOT successful in separating your reactant alchohol and product ester?
Both the alcohol and ester are moderately large non-acidic organic compounds, so neither will ionize or move into the water layer.
What would have happened to the yield of your ester if you had omitted the dyring tube on top of the reflux condenser?
Yield would decrease. Water would have gotten in to the reaction which would push the equilibrium back towards the left.
Does pentanol and Butanol have the same functional groups?
yes, so IR would not be helpful to distinguish between the two
