CH15: AMINES

BIOPHRM 3311

ammonia structure

NH3

ammonium ion structure

NH4+

in ammonia, N atom as ___ v e-

5

in ammonia, ___ e- from N and ___ e- from ___ H atoms form ___ polar covalent bonds

3 (all spots)

ammonia is a ___ molecule

polar

in ammonia the remaining 2 e- (lone pair of nonbonding e-) can serve as ___ or ___.

• H+ acceptor

• e- donor

ammonia is a ___.

base

ammonium ion (cation) form a ___ w/ 4th H+ b/c H+ has ___ to form a bond.

• coordinate bond

• no e-

amine group is a functional group ___ from ammonia (NH3), in which 1 or more H atoms are replaced by ___.

• derived

• R-groups (alkyl or aryl)

amines can be classified as ___, ___, or ___, according to how many ___.

• primary, secondary, tertiary

• R-groups are individually bound directly to the N atom

primary amine definition

• N atom is attached to only 1 R-group and 2 Hs

• can be located on the end or attached to an internal C of a chain

primary amine general formula

R—NH2

secondary amine definition

N atom is attached to 2 R-groups and 1 H

secondary amine general formula

R2—NH

tertiary amine definition

N atom is attached to 3 R-groups and 0 Hs

tertiary amine general formula

R3—N

quaternary amine definition

N atom is attached to 4 R-groups and a (+) charge

quaternary amine general formula

R4—N+

amines are ___ b/c the N atom has a lone pair of e-, and this lone pair can accept a H+, leading to the formation of ___.

• bases

• an ammonium ion

what class of amine is this

primary amine

what class of amine is this

secondary amine

what class of amine is this

tertiary amine

what class of ammonium ion is this

primary ammonium ion

what class of ammonium ion is this

secondary ammonium ion

what class of ammonium ion is this

tertiary ammonium ion

Acid-Base Theories — Summary Chart (KNOW)

nonpolar covalent bond’s electronegativity difference between atoms

0 — 0.4

polar covalent bond’s electronegativity difference between atoms

0.5 — 1.9

ionic bond’s electronegativity difference between atoms

2.0 and above

conjugate acid-base pairs definition

• occur within acid-base equilibrium rxns

• an acid and its conjugate base, as well as its base and conjugate acid, differ only by 1 proton.

• HA + B ←→ A- + HB+

  • [acid + base ←→ conjugate base + conjugate acid]

amine + acid —> ___ + base

ammonium ion

3 major types of amines depends upon ___.

the structure of the backbone

3 major types of amines are

• aliphatic

• heterocyclic - saturated and unsaturated

• aromatic

aliphatic amine definition

• N atom bonds only to alkyl or alkyl-like group(s)

• NO aromatic rings bind directly to the N atom

heterocyclic saturated amine definition

N is part of a ring structure; categorized as either secondary or tertiary amine

heterocyclic unsaturated amine definition

N is part of a ring structure; categorized as either secondary or tertiary amine - BUT THE RING IS UNSATURATED (CONTAINS DOUBLE BONDS)

ID this structure

cadaverine - derived from Lysine

ID this structure

lysine - amino acid

ID this structure

pyrrolidine

what is pyrrolidine in?

nicotine and other alkaloids

ID this structure

proline - amino acid

ID this structure

Imidazole

ID this structure

Histidine - amino acid

ID this structure

cytosine (C) - DNA, RNA

ID this structure

adenine (A) - DNA, RNA

aromatic amine definition

aromatic ring directly attached to an amine functional group

___ is the simplest amine and is used as the root name of its derivatives

aniline

ID this structure

aniline

the ranking of functional groups holds significance in nomenclature since the higher-priority group represents the ____, determining the compound's organic family. Additionally, it is usually numbered to obtain the _____.

• primary functional group

• lowest possible location number

rank the functional groups from highest priority to lowest priority

1. Carboxylic Acid

2. Ester

3. Amide

4. Aldehyde

5. Ketone

6. Alcohol

7. Thiol

8. Amine

9. Ether

10. Alkene = Alkyne

11. Alkyl = Halide

naming primary amines: ID the Alkyl group that bonds to the NH2 group. Name as ____.

"alkylamine"

naming primary amines: If amine group is bound to a cycloalkane, name as ____.

"cycloalkylamine"

naming Secondary & Tertiary Amines w/ Identical Alkyl Groups: Name the identical alkyl groups bonded to the N atom. For secondary, use ___ before the alkyl group name and then add the suffix ___. For tertiary, use the ____ before the alkyl group name.

• "di-"

• "-amine"

• "tri-"

naming Secondary & Tertiary Amines w/ Different Alkyl Groups: ID and name the alkyl groups attached to the N atom. The ____, gets the root name.

longest alkyl group w/ N

naming Secondary & Tertiary Amines w/ Different Alkyl Groups: The shorter alkyl group(s), add the prefix ___ to each and put them in ____.

• "N-"

• alphabetical order

naming Secondary & Tertiary Amines w/ Different Alkyl Groups: If any 2 substituent alkyl groups are identical (w/in tertiary), name as ____.

"N,N-" (NO numbers)

naming ammonium ions: same rules the others, but after naming the alkyl group, follow it with ____.

“ammonium ion”

naming primary aromatic amines: Aryl amines are named using ____as the parent, w/ the C attached to the amine group as ____. Substituents are then numbered based upon ____.

• "aniline"

• "1"

• their position

Simplest aromatic amine consists of a phenyl group attached to an amine group and is commonly called ____, which can accept a H+ to form ____.

• aniline

• anilinium ion

ID this structure

anilinium ion

naming Secondary & Tertiary Amines Derived from Aniline: ID the parent compound and use ____ as the root name.

aniline

naming Secondary & Tertiary Amines Derived from Aniline: Name the substituent(s), add the prefix ____ to each and place in ____.

• "N-"

• alphabetical order

amine functional group is ___.

polar

Electronegativity refers to an atom's ____.

capability to draw e- towards itself in a covalent bond

Both the C-N and N-H bonds exhibit polarity due to ____.

N's electronegativity

In the case of N on primary amines, it bonds w/ 2 Hs, showcasing its ability _____.

to participate in H-bonding

Amines are the only ___ functional group.

BASIC

In primary amines, the N atom has a lone pair of e- that can act as a ____, while the 2 Hs bound to N can act as ____.

• H-bond acceptor

• H-bond donors

primary amines can form a total of 3 H bonds w/ ___.

other amine molecules as well as w/ H2O molecules, enhancing their intermolecular interactions and H2O solubility.

Primary, secondary, and tertiary amines all exhibit ____! And only primary and secondary amines exhibit ____.

• LDFs and Dipole-Dipole forces

• H-bonding capabilities w/ each other, but tertiary amines cannot due to the absence of an H atom bound to N.

Primary amine has 2 N-H bonds + 1 lone pair e-, which means it can ____.

H-bond w/ itself & H2O

Secondary amine has 1 N-H bond + 1 lone pair e-, which means it can ___.

H-bond w/ itself & H2O

Tertiary amine has 0 N-H bonds + 1 lone pair e-, which means it can ____.

H-bond acceptor w/ H2O, only

Primary and Secondary amines, but not Tertiary amines, ____.

can form intermolecular H-bonds

Primary amines can form ____ than Secondary Amines.

1 more H-bond

boiling point variations in amines is all due to ____.

H-bonding ability

highest to lowest BPs in amongst amines

1. primary

2. secondary

3. tertiary

O is more ___ than N. —OHs have stronger ___ than amines.

• electronegative

• dipole-dipole force and H-bonding

increased EN = increased ___

polarity

highest to lowest BPs amongst alkanes, amines, and alcohols

1. alcohols

2. amines

3. alkanes (of similar Molecular Weight)

differences in molecular weight could be 1 but have a large impact on ___.

BP differences

All classes of amines can form ____.

1 or more H-bonds w/ H2O

Small amines w/ 1-5 Cs are ___ in H2O.

SOLUBLE

As H-C hydrophobic parts increase in size, larger amines have _____.

less H2O solubility

Larger amines w/ 6 or more Cs are ____ in H2O — relates to molecules and their ____.

• INSOLUBLE

• non-polar vs. polar parts

Ammonia is a base b/c _____, resulting in the formation of an _____.

• its lone pair of e- can form a covalent bond w/ H+ from H2O or acids

• ammonium cation (NH4+)

generally, ionic compounds are more _____ than neutral non-ionic compounds.

H2O soluble

Like ammonia, aliphatic amines act as bases b/c _____.

the lone pair on the N can accept a H+ to form ammonium salt (also called amine salt)

Factors Affecting Basicity: e- donating groups (alkyl groups push e- density towards N) _____.

increase basicity (more negative)

Factors Affecting Basicity: e- withdrawing groups (benzene rings) _____.

decrease basicity (more positive)

lower pKb =

stronger base

higher pKb =

weaker base

Alkyl amines are _____ than ammonia

more basic

The alkyl groups donates more e- than H to N. Hence, the e- density on the alkyl amine's N is ____ than the N of ammonia — making the lone pair on alkyl amines a stronger ____ and stronger ___.

• greater

• H+ acceptor

• base

Aniline is a much ____ than Ammonia

Weaker Base

Aromatic amines are ____ than ammonia.

weaker base

In aniline, the lone pair of e- on N are drawn towards _____. Hence, the lone pair in aniline is ____. As a result, aniline is a ____ than ammonia.

• the resonance e- in the benzene ring

• no longer fully available to combine w/ H ions as in ammonia

• weaker H+ acceptor and a weaker base

most to least basic ranked b/t ammonia, aniline, and alkyl amine

1. alkyl amine

2. ammonia

3. aniline

Amine salt is formed when ____ reacts w/ an acid.

amine base

characteristics of amine salts

• generally odorless (compared to amines general bad smell)

• ionic compound