MCAT Biology Ch11: Kap

Question 1

primary amine

Answer 1

amine attached to one alkyl (or aryl) group

Question 2

secondary amine

Answer 2

amine attached to two alkyl (or aryl) groups

Question 3

tertiary amine

Answer 3

amine attached to three alkyl (or aryl) group

Question 4

quaternary ammonium compound

Answer 4

amine attached to four alkyl groups will carry a pos. charge (lost lone pair forming fourth bond); exists as salt

Question 5

-amine

Answer 5

IUPAC, naming amines this way, in the name of longest alkane chain to which N is attached

Question 6

amino-

Answer 6

another group w/ higher priority than amine on the molecule

Question 7

common system

Answer 7

alkylamine

Question 8

N

Answer 8

used to label substituents attached to nitrogen in 2 or 3 amines; used separately for each diff sub

Question 9

aromatic amines

Answer 9

named as derivatives of aniline (C6H5NH2) in common system or derivatives of benzenamine w/ IUPAC

Question 10

amides

Answer 10

condensation products of carboxylic acids and amines

Question 11

carbamates

Answer 11

• gen. formula RNHC(O)OR’
• N attached to carbonyl, fallling into amides category, however special since O on the other side of carbonyl w/ alkyl or aryl group attached to it
• derived from compound isocyanates (RNCO),
• also called urethanes

Question 12

isocyanates

Answer 12

• this is where carbamates are derived from
• its carbon is double bonded to both an oxygen and nitrogen, so polar and ripe of nucleophilic attack
• when attacked by alcohol, carbamate is formed

Question 13

urthethane

Answer 13

• carbamates also called this.

- they can form polyurethanes

Question 14

polyurethanes

Answer 14

formed from urethanes

Question 15

enamines

Answer 15

• N analogs of enols

- amine group attached to C-C double bond (enamines are to N as enols are to oxygen)

Question 16

imines

Answer 16

N-C double bonds

Question 17

nitriles or cyanides

Answer 17

• triple bond between C atom and N atom

- named either w/ prefix cyano- or the suffix -nitrile

Question 18

nitro

Answer 18

compounds containing nitro group, NO2

Question 19

az

Answer 19

whenever you see this, it contains N

Question 20

diazo compounds

Answer 20

• N2 functionality
• two nitrogens at end of chain resonating between double and a triple bond
• lose N2 as nitrogen gas and form carbenes

Question 21

carbenes

Answer 21

• formed when diazo compounds lose N2 as nitrogen gas
• highly reactive
• only six valence electrons (two R groups and a lone pair of electrons)

Question 22

azide compounds

Answer 22

• linear N3 (DBs between 3 nitrogens)

- when lose nitrogen gas (N2), they form nitrenes (analogs of carbenes)

Question 23

nitrenes

Answer 23

• when azide lose nitrogen gas (N2), they form nitrenes (analogs of carbenes)
• six valence electrons distributed in one bond R group and two lone pair electrons

Question 24

BP of amines

Answer 24

• between those of alkanes and alcohols
• as MW incs, so do BP
• primary and secondary amines form H bonds, not tertiary

Question 25

properties of amines

Answer 25

• sp3; only three substituents to complete octet and one lone pair – basic and nucleophilic
• tech chiral, is geo of orbitail
• enantiomers can’t be isolated because they interconvert rapidly
• activation energy is only 6 kcal/mol, so not optically active; however at very low temp or structure prevents inversion, it will be optically active (ex: quaternary ammonium salts, which lack electrons and don’t interconvert)
• bases, accept protons, forming ammonium (pKb of alkyl amine around 4), more basic than ammona (4.76) but less than hydroxide
• aromatic like aniline (9.42) less basic than aliphatic due to EWG —> reduced basicity of amino group; presence of other substituents alters this (EDG inc, EWB dec)
• WA (pKa - 35), need strong base for deprotonation

Question 26

Synthesis: Alkylation of Ammonia

Answer 26

Direct:

• alkyl halides + ammona –> alkylammonium halide salts + base –> alkylamine product
• ammonia is Nu and displaces halides
• often form side products
• alkylamine is also Nu (better due to alkyl e- donation) –> complex w/ alkyl halide
• Sn2, product

Gabriel Synthesis:

• primary alkyl halide –> primary amine
• diguised form of ammonia (deprotonated phthalimide) to prevent side products
• pithalimide (condensation product of phthalic acid and ammonia) is good Nu –> displaces halide –> N-alkylphthalimides (don’t react w/ other alkyl halides), when rxn complete, hydrolyze w/ aq. base–> alkylamine
• Sn2 (ammonia good nuc and halides (except F) good LG)

Question 27

Synthesis: Reduction

Answer 27

Nitro Compounds:

• reduce nitro compounds to primary amines
• most common reducing agents is iron or zinc w/ dilute HCl
• useful for aromatic rings since easy and converts deactivating to activating group

Nitriles:
-reduced w/ H and a metal catalyst, or w/ lithium aluminum hydride (LAH) –> primary amines

Reductive Amination:
-aldehyde or ketone + ammonia (primary amine or secondary amine) –> primary, secondary, or tertiary amine and carbonyl becomes -OH (carbinolamine) –> loses H20 –> exposed to H and a metal catalyst –> reduction –> amine

Amides:
-amides + LAH –> amines

Question 28

Reductive Amination:

Answer 28

-aldehyde or ketone + ammonia (primary amine or secondary amine) –> primary, secondary, or tertiary amine and carbonyl becomes -OH (carbinolamine) –> loses H20 –> exposed to H and a metal catalyst –> reduction –> amine

Question 29

Reactions of Amines

Answer 29

Exhaustive Methylation (Hoffman Elimination)

Question 30

Hoffman Elimination (exhaustive methylation)

Answer 30

• amide w/ excess methyl iodide—> quaternary ammonium iodide + silver oxide and H20 –> displaces iodide ion –> ammonium hydroxide + heat –> alkene and amine by elimination
• least substituted due to bulk of quarternary ammonium salt LG

Question 31

amine

Answer 31

NR3