Lab 10: Reduction of Vanillin to Vanillyl Alcohol Flashcards
When should you consider a chemical hazardous in the lab?
trick question - consider all chemicals hazardous in the lab
What is the purpose of the sodium hydroxide inthe reaction?
to keep the sodium borohydride solution at a high pH
The addition of the hydride ion to vanillin would be correctly identified as what type of addition
nucleophilic addition
When the reaction is complete and acid has been added, how much of a change in pH is expected?
pH 10 to pH 4
What effect might a hydroxyl group on a benzene ring of the reactant have on this reaction?
The hydroxyl groups act to neutralize sodium borohydride which reduces yield
When using sodium borohydride in this reaction, what are possible products of the reaction?
boric acid
hydrogen gas
sodium hydroxide
In what step might hydrogen gas be generated?
When decomposing any remaining sodium borohydride at the end of the reaction
If the reaction rate law for this reaction were rate=K[vanillin]0[NaBH4]2, what is the rate with respect to NaBH4?
second order
When adding the sodium borohydride solution to the vanillin solution, why are you told to do so in a dropwise fashion?
to prevent formation of unwanted sodium borohydride products
What might be the effects of running this experiment at room temperature?
Unwanted by products tend to form at higher temperatures which reduce yield
What is pKa?
the negative log of the dissociation constant for a substance
What does pH=pKa mean?
there is equal concentration of acid and its conjugate base
Whigh functional group on vanillin would you expect to be responsible for an infrared band at about 1245cm-1?
ether
What would be an excepted proton chemical shift range for protons attached to a methyl group as shown: Ar-O-CH3?
3.8-4.5 ppm
