Organic Chemistry Ch. 3

Front 1

Characteristics of a carbonyl

Back 1

-Carbon double bonded to oxygen
-double bond is shorter and stronger than an alkene
-planar stereochemistry
-partial negative charge on oxygen, partial positive charge on carbon

Front 2

Carbonyl: Nucleophilic addition or substitution?

Back 2

-Aldehydes and ketones typically undergo nucleophilic addition
-Other carbonyl compounds prefer nucleophilic substitution

Front 3

Physical properties of aldehydes and ketones

Back 3

-More polar and have higher boiling points than alkanes and alkenes of similar molecular weight.
-cannot H-bond with each other, so have lower b.p. than corresponding alcohols
-less acidic than alcohols.
-any electron withdrawing groups attache to an alpha carbon or the carbonyl tend to stabalize the conjugate base- increase acidity.
-exist at room temp. as enol tautomers.

Front 4

Chemical properties of aldehydes and ketones

Back 4

Typically act in one of two ways:
1. substrate in nucleophilic addition
2. Bronsted-Lowry acid by donating an alpha-hydrogen.

-form an enolate ion when the alpha-H is removed, stabilized by resonance.

Front 5

alpha-carbon

Back 5

-A carbon that is attached to a carbonyl carbon

Front 6

Tautomerization

Back 6

A reaction at equilibrium that involves a proton shift.

Front 7

Carboxylic acids-reactions

Back 7

-Typically behave as an acid or as a substrate in a nucleophilic substitution reaction
-when the hydroxyl group is protonated, it makes a good leaving group and substitution results.

Front 8

Acid strength of carboxylic acid

Back 8

-considered very strong organic acids- when the proton is removed the conjugate base is stabilized by resonance.
-electron withdrawing groups on the alpha carbon further stabilize the conjugate base, thus increasing the acidity of the corresponding carboxylic acid

Front 9

M.P. and B.P of carboxylic acids

Back 9

-make strong hydrogen bonds to form a dimer, increases b.p. of carboxylic acids by effectively doubling the MW of the molecules leaving the liquid phase.
-double bonds in unsaturated carboxylic acids impede the crystal lattice and lower the MP.

Front 10

Solubility of carboxylic acids

Back 10

-Carboxylic acids with 4C or less are miscible with water
-soluble in most nonpolar solvents because the dimer formed allows the carboxylic acid to solvate without disrupting the H-bonds of the dimer.

Front 11

Physical properties of amines

Back 11

-ammonia and amines hydrogen bond, raising the boiling point and increasing solubility with water.
-higher b.p than alkanes, lower b.p. than alcohols

Front 12

Chemical properties of amines

Back 12

-Nitrogen can take either 3 or 4 bonds
-act as weak bases by donating their pair of electrons
-electron donating substituents (ex. methyl groups) increase the basicity of an amine.

3 important things to remember for MCAT:

1. may act as Lewis base donating pair of electrons
2. may act as a nucleophile where the lone pair of electrons attacks a positive charge
3. nitrogen can take on a fourth bond

Front 13

Properties of amides

Back 13

-Can act as either weak bases or acids
-Less basic than amines due to electron withdrawing properties of the carbonyl
-hydrolyzed by either strong acids or strong bases
-amides with a hydrogen attached to a nitrogen are able to H-bond to each other.

Front 14

lactams

Back 14

-cyclic amides are called lactams
-highly reactive due to ring strain (even though amides are typically the least reactive carboxylic acid derivatives).