Nucleophilic addition Flashcards
what is a carbonyl group
C=O within a molecule
where is the carbonyl group on a aldehyde
the end of a molecule
what is R-CHO the formula for
an aldehyde
where is the carbonyl group for a ketone
the middle of the molecule
what is R-CO-R’ the formula for
a ketone
colour change when fehling’s is added to an aldehyde
blue to brick red
colour change when fehling’s is added to a ketone
no change
colour change when tollen’s is added to an aldehyde
silver mirror
colour change when tollen’s is added to a ketone
no change
how is an aldehyde formed
reacting a primary alcohol with acidified potassium dichromate (VI) and immediately distilling
generic reaction for making an aldehyde from a primary alcohol
ROH + [O] -> R-CHO + H2O
how to make a carboxylic acid from an aldehyde
reacting the aldehyde with potassium dichromate (VI) and running through a reflux
the two reactions for making a carboxylic acid from an aldehyde and a primary alcohol
R-CHO + [O] -> R-COOH + H2O for an aldehyde
ROH + 2[O] -> R-COOH + 2H2O
how do you form a ketone
react
a secondary alcohol with acidified potassium dichromate (VI)
generic reaction for forming a ketone from a secondary alcohol
ROH-R’ + [O] -> R-CO-R’ + H2O
what is the chemical used to reduce an aldehyde or ketone in a non-aqueous solvent
lithium tetrahydridoaluminate (LiAlH4)
what is the chemical used to reduce an aldehyde and ketone in a water or alcohol solution
sodium tetrahydridoborate (NaBH4)
is NaBH4 or LiAlH4 more likely to be used
NaBH4
which ions are used in nucleophilic addition
CN (cyanide) and hydride (H)
why does the product of nucleophilic addition have optical isomers
the carbonyl group is planar so there’s an equal likelihood of attacking on either side. there ends up being a chiral carbon and produces a racemic mixture of products
steps in nucleophilic addition
CN attacks delta positive carbon and double bond on oxygen becomes single bond
this makes the O negative
the negative O bonds to positive H
