Thin Lenses Lab Report
Fischer Esterification – nucleophilic substitution reaction
Strong acid catalyst (concentrated sulfuric acid
Purpose of a reflux is to heat a reaction mixture at its boiling temperature to form products, without losing any of the compounds in the reaction flask
TO HAVE GREAT PERCENT YIELD: As reaction is reversible, removal of water or the addition of an excess of one of the reactants (cheaper one) drives the reaction towards formation of ester. (Excess carboxylic acid is used)
Adding excess carboxylic acid is preferred as it is easier to separate carboxylic acid and ester compared to removing water
solvent used is (ClCH2CH2Cl), as water is insoluble in the solvent, so reverse reaction will not take place
using concentrated acid as catalyst rather than aqueous drives equilibrium to the right
Reactivity of alcohol: CH3OH > primary > secondary > tertiary > phenol
In the reaction, no anion can exist, as it is in acidic condition, or acid will react
Why dilute the reaction mixture after refluxing? When it is diluted, the ester will be deprotonated anion and thus unreactive as electrophiles
Why sodium bicarbonate is added? To remove excess carboxylic acid and sulfuric acid in mixture
Why add brine? Brine is added to remove any water in the mixture as the by product
Anhydrous sodium sulfate is added to dry the ester
For IR spectrum:
1740.51cm^-1 (C=O strong absorption shows there is an ester)
3500-3100 cm^-1 (lack of broad O-H peak shows substance is not alcohol)
Wittig Reaction – regiospecific (only trans product is being generated The solvent is DMF because it is a polar (aprotic) solvent that will dissolve the ylide form. It is also used to dissolve the organic and inorganic product.
NaOH is used to deprotonate to form the ylide. NaOH has a more acidic H than n-BuLi
Color change could be seen then
Strong acid catalyst (concentrated sulfuric acid
Purpose of a reflux is to heat a reaction mixture at its boiling temperature to form products, without losing any of the compounds in the reaction flask
TO HAVE GREAT PERCENT YIELD: As reaction is reversible, removal of water or the addition of an excess of one of the reactants (cheaper one) drives the reaction towards formation of ester. (Excess carboxylic acid is used)
Adding excess carboxylic acid is preferred as it is easier to separate carboxylic acid and ester compared to removing water
solvent used is (ClCH2CH2Cl), as water is insoluble in the solvent, so reverse reaction will not take place
using concentrated acid as catalyst rather than aqueous drives equilibrium to the right
Reactivity of alcohol: CH3OH > primary > secondary > tertiary > phenol
In the reaction, no anion can exist, as it is in acidic condition, or acid will react
Why dilute the reaction mixture after refluxing? When it is diluted, the ester will be deprotonated anion and thus unreactive as electrophiles
Why sodium bicarbonate is added? To remove excess carboxylic acid and sulfuric acid in mixture
Why add brine? Brine is added to remove any water in the mixture as the by product
Anhydrous sodium sulfate is added to dry the ester
For IR spectrum:
1740.51cm^-1 (C=O strong absorption shows there is an ester)
3500-3100 cm^-1 (lack of broad O-H peak shows substance is not alcohol)
Wittig Reaction – regiospecific (only trans product is being generated The solvent is DMF because it is a polar (aprotic) solvent that will dissolve the ylide form. It is also used to dissolve the organic and inorganic product.
NaOH is used to deprotonate to form the ylide. NaOH has a more acidic H than n-BuLi
Color change could be seen then