Carbonyl Structure H,C c=6: H Formaldehyde Acetone 4=2.27D 4=2.88D The oxygen of the Electrostatic carbonyl group is a nucleophilic center. Potential Map The carbonyl carbon is an electrophilic center Negatively polarized Positively oxygen polarized carbon 丙酮
Carbonyl Structure 丙酮 Electrostatic Potential Map Positively polarized carbon Negatively polarized oxygen The oxygen of the carbonyl group is a nucleophilic center. The carbonyl carbon is an electrophilic center
Nature of the Carbonyl Group R R Name Nomenclature Dipole moment -R or -Ar H aldehyde -al 2.7D -R or -Ar -R or-Ar ketone -one 2.9D -R or-Ar OH carboxylic acid -oic acid 1.7D -R or-Ar -OR" ester -oate 1.7D -R or-Ar -NH2 amide -amide 3.8D -R or-Ar -X acid halide -oyl halide 2.7D
Boiling Points More polar,so higher boiling point than comparable alkane or ether. Cannot H-bond to each other,so lower boiling point than comparable alcohol. CH.CH,CH,CH CH,一O-CHCH3 butane methox yethane bp 0C bp 8C 0 CHCH2一C一H CH,一 C-CH CH,CH,CH,一OH propanal acetone 1-propanol bp 49C bp 56 C bp 97C
Boiling Points ◼More polar, so higher boiling point than comparable alkane or ether. ◼Cannot H-bond to each other, so lower boiling point than comparable alcohol
H Solubility H-bond H3C CH3 Good sovent foracoh(Fig.2.Intermolecular hydrogen bonding of a ketone with water. Lone pair of electrons on oxygen of carbonyl can accept a hydrogen bond from O-H or N-H. Low molecular weight aldehydes and ketones (e.g.formaldehyde and acetone)are soluble in water. large molecular weight aldehydes and ketones are insoluble in water. Aromatic ketones and aldehydes are insoluble in water due to the hydrophobic aromatic ring. Acetone and acetaldehyde are miscible in water
Solubility ◼Good solvent for alcohols. ◼Lone pair of electrons on oxygen of carbonyl can accept a hydrogen bond from O-H or N-H. ◼Low molecular weight aldehydes and ketones (e.g. formaldehyde and acetone) are soluble in water. ◼large molecular weight aldehydes and ketones are insoluble in water. ◼Aromatic ketones and aldehydes are insoluble in water due to the hydrophobic aromatic ring. ◼Acetone and acetaldehyde are miscible in water
Formaldehyde Gas at room temperature. Formalin is a 40%aqueous solution. H H h、H-8HE HO _H 0→ OH H-C >H formaldehyde, b.p.-21C formalin trioxane,m.p.62C
Formaldehyde ◼Gas at room temperature. ◼Formalin is a 40% aqueous solution. O C O C O C H H H H H H heat H C O H H2O H C H OH HO trioxane, m.p. 62C formaldehyde, b.p. -21C formalin