Elementary Chemistry Exam 3

amides

carbonyl group (C=O) attached to a nitrogen atom (N attached to H or alkyl)

primary amide

nitrogen attached to one carbon

secondary amide

nitrogen attached to 2 carbons

tertiary amide

nitrogen attached to 3 carbons

lactones

cyclic esters

lactams

cyclic amides

nomenclature for carboxylic acids

• carboxylic acids have highest priority over all other functional groups

• use suffix -oic acid

• carboxylic acids don’t need a number; always at C1

• condensed form: COOH

ex: 4,5-dimethylhexanoic acid

ex: benzoic acid

• greek letters used to refer to carbon positions relative to the carboxylic acid carbon (a - carbon attached to the carboxylic acid carbon; b - carbon attached to the a carbon)

ex: a-hydroxy acid

nomenclature for esters

• use suffix -oate

1) name alkyl group as substituent (group directly attached to the oxygen)

2) name acyl chain as the parent chain name

ex: methyl butanoate

nomenclature for amides

• use suffix -amide

1) name alkyl groups as substituents (the group directly attached to the nitrogen)

• add N or N,N at the beginning to indicate alkyl groups on the nitrogen (treat them like numbers)

2) name the acyl chain as the parent chain name

ex: N,N-dimethylbenzamide

physical properties of carboxylic acids

have very high boiling points

double hydrogen bonding b/w 2 carboxylic acids

physical properties of esters

esters can’t hydrogen bond in pairs like carboxylic acids

physical properties of amides

primary/secondary amides can hydrogen bond

tertiary amides can’t hydrogen bond; have lower boiling points

acidity of carboxylic acids

• carboxylic acids are acids

• acid increases the amount of H3O+ when added to water

• carboxylic acids serve as a proton (H+) donor

acid-base reactions w/ carboxylic acids

• when carboxylic acids are deprotonated (lost their H+ proton) they form carboxylate salts

• whatever the counter ion for the base was (Na+ or K+), that becomes associated w/ the carboxylate (COO-)

• water also forms as a product

naming carboxylate salts

name of metal cation + parent + -ate (suffix)

ex: sodium octanoate

properties of carboxylic salts

much more soluble in water than the original carboxylic acid b/c they are charged

Fisher Esterification

esters formed by reacting a carboxylic acid w/ an acid catalyst + alcohol

1) carboxylic acid reacts w/ alcohol (H—OR’)

2) OR’ replaces OH of the carboxylic acid

3) ester and H2O are formed

amide formation reaction

amides are formed from carboxylic acids through substitution reactions

requires heat (Δ)

1) carboxylic acid reacts w/ ammonia (H—NH2)

2) NH2 replaces the OH of the carboxylic acid

• remove only one H from the nitrogen

3) amide and H2O are formed

hydrolysis

esters/amides can be converted back to carboxylic acids

uses excess water to cleave C-OR or C-NR2 bonds

ester hydrolysis

converts ester back to carboxylic acid

water is used to cut the C-OR bond

1) ester reacts with H2O

2) OH of the water replaces the OR’ of the ester

3) carboxylic acid and alcohol is formed

ester hydrolysis under basic conditions

ester hydrolysis can occur w/ a basic catalyst (NaOH)

a carboxylate salt is formed instead of a carboxylic acid

• OR’ group of the ester become O- and Na+

• carboxylate anion + alcohol is formed

amide hydrolysis

amide hydrolysis can be done under acidic or basic conditions

1) acid hydrolysis produces carboxylic acid + amine salt

• amide reacts w/ H2O; OH replaces N group

• nitrogen group bonds w/ H to form amine salt

2) base hydrolysis produces carboxylate salt + amine

• amide reacts w/ H2O

• NH2 becomes O- and Na+

• NH2 bonds w/ H to form ammonia

interesting esters and amides

esters are commonly pleasant/sweet smelling; many fruits contain esters to attract animals

melatonin contains amides

esters/amides present in many pain relievers

amines

nitrogen attached to carbon

R—NH2, R2—NH, or R3—N

primary amine

nitrogen is attached to one carbon

secondary amine

nitrogen attached to 2 carbons

tertiary amine

nitrogen attached to 3 carbons