aldehydes and ketones (cont.)

carbonyl plus h2O makes HOOH

generating a hydrate

carbonyl plus ROH makes HOOR

generating a hemiacetal

carbonyl plus ROH/H+, H3O+ makes ROOR

generating an acetal

aldehyde, 1) ROH like EtOH, 2) acid source like TsOH, HCl or MeOH, process is favored

generating acetal for aldehyde (reagents, is it favored?)

ketone, 1) ROH like EtOH (2 eq), 2) acid source like TsOH, HCl, or MeOH, process not favored so remove H2O with distillation

generating acetal for ketone (reagents, is it favored?)

hydroxyl/ketone containing structure plus H2SO4 or HCl generates cyclic hemiacetal

generating cyclic hemiacetal

1) diol, 2) acid source like TsOH, HCl, MeOH, -H2O generates acetal group

protecting group for carbonyl

1) H+, 2) H2N-NH2, 3) -H2O to form hydrazone, 4) KOH, H2O, heat to form alkane

conversion of aldehyde or ketone to alkane

acidic conditions (H3O+)

reversal of acetal to aldehyde or ketone

aldehyde/ketone, 1) TsOH, 2) primary amine, 3) -H2O

imine formation

+H2O and H+

how do you deprotect acetal group for carbonyls?

alkyl, hydroxyl, other amine group

types of r groups to use with primary amines

aldehyde/ketone, 1) H+, 2) H2N-NH2, 3) -H2O

formation of hydrazone

aldehyde/ketone, 1) TsOH, 2) secondary amine, 3) -H2O

formation of enamine

acidic conditions (H3O+)

reversal of imine and enamine to aldehyde/ketone

aldehyde/ketone, KCN, HCl

aldehyde/ketone to cyanohydrin

aldehyde/ketone, KCN, HCl, LiAlH4, H2O or Et2O

aldehyde/ketone to cyanohydrin to alcohol with amine group (same molecule)

aldehyde/ketone, 2RSH, H+

formation of thioacetal

cyclic thioacetal, Ra-Ni forms alkane

raney nickel reaction

imine plus h3o+ generates aldehyde and primary amine

reversing imine to aldehyde or ketone

enamine plus H3O+ generates ketone and secondary amine

reversing enamine to aldehyde or ketone