Chapter 6: Aldehydes & Ketones I Flashcards
a carbonyl group
a functional group consisting of a carbon double bonded to an oxygen
what makes a carbonyl group such a common functional group
can behave as either a nucleophile or an electrophile !!
ketone
2 alkyl groups bonded to a carbonyl
aldehyde
one alkyl group and one hydrogen bonded to a carbonyl
characteristic physical property of aldehydes and ketones
they are both often strong smelling compounds
ex. cinnamon, vanilla, cumin, etc.
aldehydes suffix
replace -e from alkane name with -al
prefix for aldehydes when named as substituents
oxo-
ketones suffix
replace -e from alkane name with -one
common names: the 2 alkyl groups are named alphabetically, followed by -ketone
prefix for ketones when named as substituents
oxo- or keto-
the dipole of a carbonyl is _______ (stronger/weaker) than the dipole of an alcohol. why?
stronger
the double bonded oxygen is more electron-withdrawing than the single bond to oxygen in the hydroxyl
boiling points of aldehydes and ketones
higher than their parent alkanes because of the polar carbonyl groups
lower than that of alcohols because there is no hydrogen bonding to occur
aldehydes and ketones both act as ___________ (electrophiles/nucleophiles)
electrophiles (electron loving)
due to the electron withdrawing properties of the carbonyl oxygen, which leaves a partial positive charge on the carbon
the carbonyl carbon is a ________ (electrophile/nucleophile)
electrophile!!
bears a partial positive charge = electron loving
name 1 way an aldehyde can be produced
through the partial oxidation of a primary alcohol (by PCC)
name 1 way a ketone can be produced
through the oxidation of an secondary alcohol
reagents: sodium or potassium dichromate salts, or chromium trioxide, PCC, and others
nucleophilic addition reactions
a chemical addition reaction in which a nucleophile is added to a carbonyl
recall: the carbonyl carbon is an electrophile, ready for nucleophilic attack
nucleophilic addition reaction mechanism (aldehydes and ketones)
the nucleophile attacks; a covalent bond is formed between the nucleophile and the carbonyl carbon, breaking the pi bond in the carbonyl
the electrons from the pi bond are pushed onto the oxygen atom
the new O- will accept H+ from the solvent to form a hydroxyl group, resulting in an alcohol
tetrahedral intermediate
a reaction intermediate in which the bond arrangement around an initially double-bonded carbon atom has been transformed from trigonal to tetrahedral
result from nucleophilic addition to a carbonyl group
general nucleophilic addition mechanism
hydration mechanism of aldehydes and ketones
the nucleophilic oxygen from water attacks the electrophilic carbonyl carbon
requires a small amount of catalytic acid or base
in the presence of water, aldehydes and ketones react to form _____
geminal diols: an organic compound with 2 hydroxyl groups attached to the same carbon atom
hemiacetals
result when 1 equivalent of alcohol are added to an aldehyde
hemiketals
result when 1 equivalent of alcohol are added to a ketone
acetals
result when 2 equivalents of alcohol are added to an aldehyde
ketals
result when 2 equivalents of alcohol are added to a ketone
hemiacetal formation mechanism
the oxygen in the alcohol functions as the nucleophile, attacking the carbonyl carbon and generating a hemiacetal
of aldehydes and ketones, which are slightly more reactive than the other?
(toward nucleophiles)
aldehydes are slightly more reactive toward nucleophiles than ketones
PCC
pyridinium chlorochromate (an oxidant)
can form aldehydes from primary alcohols
can NOT completely oxidize primary alcohols
can completely oxidize secondary alcohols
