Chapter 19 Flashcards by evan kang

Nitrogens that are a part of a ring are called _______, that are an important group of biologically active amines (drugs)

alkaloids

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Amines are classified by counting how many _______ groups are attached to the N

alkyl

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1) NH3 =
2) R-NH2 =
3) R2-NH =
4) R3-N =
5) R4-N+ =

1) ammonia
2) 1° amine
3) 2° amine
4) 3° amine
5) ammonium salt

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Common nomenclature of amines:
name the groups attached to N as _______ followed by the suffix _______

substituents
amine

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IUPAC: in amines with more complicated structures, where the NH2 group is a substituent it is called _______

amino
- When there is a functional group with a higher root priority

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IUPAC: 2° and 3° amine substituents are named by classifying the N atom as an alkylamino group. The _______ or _______ complicated alkyl group is taken to be the parent molecule (root)

largest
more
- use when other functional group is present on root with higher priority

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IUPAC: In aromatic amines, the amino group is bonded to a benzene ring. The parent compound is called _______

aniline

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IUPAC: When naming a heterocylic amine, the N is assigned position number _____

1
ex) in pyridine

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IUPAC: simple amines are named like alcohols but with _______ ending

amine
- for 1° amines with only C on root

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IUPAC: the substituents (not main chain) of more complicated amines are given the number for their location of _____

N
- ex) N,2-dimethylcyclopentamine
- use when only C’s are present on root

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Nitrogen is Sp3 hybridized with a lone pair of electrons resulting in an angle _______ than 109.5

less

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Nitrogen may have 3 different groups and a lone pair, but enantiomers cannot be isolated because they _______ rapidly. This is known as _______

interconvert
nitrogen inversion

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What are the 3 scenarios when chiral amines can be resolved into enantiomers?

1) when on a chiral carbon
2) when quaternary ammonium salt with asymmetric nitrogens
3) when nitrogen is a part of a restricted ring (3C & 4C) thats not meso

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N-H bond is _______ polar than O-H bond

less

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1° and 2° amines are hydrogen bond _____ and _____. They have weaker hydrogen bonds and _______ boiling points than the corresponding alcohols

donor
acceptor
lower

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3° amines are hydrogen bond _______ only, which = ________ boiling points than primary and secondary amines

acceptor
lower

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All amines form hydrogen bonds with hydroxylic solvents, such as water and alcohol. Therefore, amines tend to be _______ in alcohols and water. Amines also have the characteristic odor of rotting fish

soluble

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An amine is a _______ (_______) because its lone-pair of nonbonding electrons can form a bond with an electrophile

nucleophile
Lewis base

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An amine can also act as a _______ by accepting a proton from a proton acid

bronsted lowry base

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Amines are strongly _______ and can abstract a proton from water. The equilibrium constant for this reaction is called the base dissociation constant (_____), which is used to measure the strength of the amine

basic
Kb

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Strong bases = _______ pKb and _______ pKa values

small
large
- mainly use pKa so universal

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What are the 3 things that affect amine basicity?

1) Resonance
2) substitution by alkyl groups
3) hybridization
- this is the order to determine

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Rank NH3, 1°, 2°, 3° amine basicity based on substitution by alkyl group (EDG) and solvation effect

NH3 < 1° = 3° < 2°
- EDG’s stabilize positive charge
- 3° R blocks solvent that would stabilize + charge

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Resonance = _______ basic

less
- breaking aromaticity is worse than breaking conjugation

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Hybridization: electrons are held more tightly by orbitals with more _______ character making them a weaker base

S - Sp3 better base than Sp2 and Sp

Because -NH2 is a strong activator and op-director, reaction with Br2, NaHCO3 will result in _________ substitutions

multiple - EAS

Protonation of the amine under acidic conditions converts the group into a strong _______ (_____)

strong deactivator (R-NH3+) - Can lead to formation of TNT

EAS of pyridine: 1) strongly _______ toward electrophilic attack 2) substitutes in the _______ in a manner analogous to the m-substitution

1) deactivated - no Friedel-crafts 2) 3-position - ex. SO3H to aniline is added at 3 position

NAS of pyridine: pyridine is deactivated toward EAS attack, but it is ______ toward Nucleophilic aromatic substitution

activated

In NAS of pyridine, nucelophile will replace a good **leaving group** in the _____ or _____ position

2- 4-

Ammonia and alkyl amines are good nucleophiles, but these reactions don't stop cleanly after a single addition. 1) with excess amine, you get ______ 2) with excess alkyl halide you get _______

1) 1° amine 2) 4° amine (ammonium salt)

**Both 1° and 2°** amines will undergo acylation reactions to form _______

amide - proceeds by nucleophilic acyl substitution mechanism

Amides are _______ basic and _______ nucleophilic than amines because of resonance structures

less less - allows it to be a good protecting group

Amides can be used as protecting groups to prevent _______ and allow _______

polysubstitutions friedel-crafts reactions (to para position)

Under acidic conditions, what are the reagents for hydrolysis to remove the amide-protecting group?

H3O+

Under basic conditions, what are the reagents for hydrolysis to remove the amide-protecting group?

NaOH, H2O

Hoffman elimination converts an **amine** to **alkene** by _____ elimination

Because -NH2 and -NHR are poor leaving groups, they need to be converted into better leaving groups via _______

exhaustive methylation - creates ammonium salt, which is a good leaving group - Always use **CH3I** in hoffman elimination

What reagents are needed to create the base -OH for Hoffman elimination?

Ag2O, H2O, Δ

Hoffman elimination gives the _______ substituted double bond and eliminates the _______ H with respect the the LG Nitrogen

less anti

What are the reagents needed for cope oxidation?

any peroxy-acid + heat - ex H2O2 or mCPBA

Cope oxidation: 2° amines oxidize to _______

hydroxylamine (--NOH)

Cope oxidation: 3° amines oxidize into _______ often in good yields

amine oxide (R3N+--O-)

The N-oxide can undergo _______ to form alkenes in a reaction analogous to the Hoffman elimination

elimination - syn elimination and intramolecular

Arene diazonium salts are useful synthetic intermediates. _____ is readily replaced by different nucleophiles

N2+

Reaction of amines with nitrous acid: 1) _______ 2) _______ the nitro group 3) Generation of _______ salt 4) _______ replacement

1) nitration 2) reduce 3) Diazonium 4) nucleophile (can vary)

What reagents are needed to go from amine group to diazonium group?

NaNO2, H2SO4

The _______ reaction uses reagents such as: 1) Ar-Cl 2) Ar-Br 3) Ar-CN

Sandmeyer (Cu)

For all diazonium salt reactions check quizlet

https://quizlet.com/1025427418/reactions-of-amines-with-nitrous-acid-diagram/?i=1ha23w&x=1jqt

_______ is the most general synthesis for amines, capable of adding a **1° or 2°** alkyl group to an amine

reductive amination

What are the 2 steps for reductive amination?

1) form imine or oxime - imine for 2° product and oxime for 1° product 2) reduce the amine - have to start with aldehyde or ketone

What reagents are used to reduce an imine or oxime to 1° or 2° amine in reductive amination?

Reducing reagents: H2/Ni LiAlH4, H2O NaBH(OAc)3

How many steps are in the reduction amination for 3° amine product?

1 step | - For the formation of 3° amines, condensation of a ketone or aldehyde

What are usually the reagents for reduction amination for a 3° amine product starting from a ketone or aldehyde?

any 2° amine NaBH(OAc)3 CH3COOH

In acylation-reduction, the added alkyl group is always _____ because the C bonded to the N is derived from the carbonyl group of the amide which is reduced to a _______ group

1° CH2 (methylene)

What are the steps, with reagents, to acylation reduction?

1) acylation - needs pyridine or NaOH in addition to the acid chloride because it will neutralize the acid 2) reduction - always use LiAlH4

Ammonia and 1° amines are very reactive and can lead to over alkylation, to avoid this problem, use the reagent _______ to **make 1° amines**

pthalimide - Gabriel synthesis - forms 1° amines

When using gabriel reagent, _______ is used to activate it, and _______ is used to unmask the reagent

-OH 2 eq NH2NH2, Δ

Two good nucleophiles for introducing a N atom are the _______ and _______ ion

azide (-N3) and cyanide (-CN) ion

addition of an azide introduces a _______ group after reduction, while addition of a Cyanide ion introduces a _______ group after reduction

NH2 CH2NH2 - cyanide ion is good for adding amine and one carbon

To reduce nitro to amine use:

1) H2/ Pd or 2) clemmenson - 1) (Fe or Sn or Zn), H3O+ 2) NaOH

Chapter 19 Flashcards

(61 cards)