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Orgo2 > Ch. 24 > Flashcards

Ch. 24 Flashcards

1
Q

Amines

A

Organic derivative of ammonia

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2
Q

Are arylamines and heterocyclic amines or alkylamines more basic? Why?

A

Alkylamines are more basic b/c the nitrogen lone-pair electrons are delocalized by interation with the aromatic pi system and resonance stabilization is lost when protonated

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3
Q

Heterocyclic Amines

A

Compounds with one more nitrogen atoms as part of a ring

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4
Q

How are alkylamines prepared?

A
  1. SN2 reaction of ammonia/amine with an alkyl halide

2. Gabriel Amine Synthesis

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5
Q

Reductive Amination Reaction

A

Ketone/aldehyde is treated with amine in the presences of a reducing agent. (ex. NaBH4)

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6
Q

What are amines a result of?

A

Hofmann and Curtius rearrangements of carboxylic acid derivatives

migration of the -R group bonded to the carbonyl carbon to yield a product that has one less carbon atom than the starting material

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7
Q

Hofmann Elimination

A

E2 elimination of amines to yield alkenes

  1. Quaternized treatment with iodomethane (CH3I)
  2. Heated with silver oxide (Ag2O)
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8
Q

Diazotization

A

Conversion of arylamines with nitrous acid into arenediazonium salts (ArN2+X-)

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9
Q

Sandmeyer Reaction

A

Replacement of diazonio group with other subsitutents to give variety of substitued aromatic compounds.

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10
Q

Diazonium Salts undergo? What is the result?

A

Coupling with phenols and arylamines; brightly colored azo compounds

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11
Q

What common function group is the most abundant and have the richest chemistry?

A

Amines

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12
Q

Are amines basic or nucleophilic? Why?

A

Both; due to the domination of the lone-pair electrons on nitrogen

larger the Kb; smaller the pKb= stronger the base; weak acid ~vice versa
larger the Ka; smaller the pKa= weaker the base; strong acid~ vice versa

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13
Q

How does electron-withdrawing substituents affect substitued aniline? What about electron donating substituents?

A 
EWS = weaken the basicity
EDS = increase basicity
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14
Q

Are alkylamines basic or acidic?

A

Basic; pH=7.3; exist almost entirely in their protonated form

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15
Q

Saturated Heterocyclic Amines vs Unsaturated Heterocyclic Amines

A

Saturated have the same chemistry as their open-chain analogs
Unsaturated are aromatic; (ex. imidazole, pyridine, and pyrimidine)
Amides (ex. pyrrole) are nonbasic b/c all electrons are used in bonding

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16
Q

How are arylamines prepared?

A
  1. Nitration of an aromatic ring

2. Reduction

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17
Q

What are reductive methods of amines?

A

LiAlH4 reduction of amides, nitriles and azides

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18
Q

Amines Reactions

A
  1. SN2 reaction with alkyl halides
  2. Nucleophilic acyl substitution with acid chlorides
  3. Hofmann Elimination; E2 Elimination
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19
Q

What can be prepared from arenediazonium salts?

A

Aryl chlorides, bromides, iodides, and nitriles

20
Q

Reduction of nitriles reagents

A
  1. NaCN or

2. 1.LiAlH4,ether 2. H2O

21
Q

Reduction of amides reagents

A
  1. LiAlH4, ether

2. H2O

22
Q

Reduction of nitrobenzenes reagents

A
  1. H2, Pt or
  2. Fe, H3O+ or
  3. SnCl2, H3O+
23
Q

SN2 Alkylation of alkyl halides reagent

A

NaOH

24
Q

SN2 Alkylation of alkyl halides reactants/products

A

Ammonia –> Primary
Primary –> Secondary
Secondary –> Tertiary
Tertiary –> Quarternary ammonium

25
Q

Gabriel Amine Synthesis reagents

A
    1. KOH 2. R-X

2. NaOH, H2O

26
Q

Reduction of Azides reagents

A
  1. Na+ -N3, ethanol

2. 1. LiAlH4, ether 2. H2O

27
Q

Reductive Amination reagents

A

NH3, NaBH4/NaBH(OAc)3

28
Q

Hoffman Rearrangement reagents

A

NaOH, Br2, H2O

29
Q

Curtius Rearrangement reagents

A
  1. Na+ -N3, ethanol

2. H2O, heat

30
Q

Hoffman Elimination Reagents

A
  1. CH3I

2. Ag2O, heat

31
Q

Diazotization reactants

A

HNO2, H2SO4

32
Q

Structure of Amines

A

three amine bonds with lone pair occupy the corners of a tetrahedron

33
Q

Properties of Amines

A
  1. amine with three different substituents is chiral
  2. two amine enantiomers interconvert by pyramidal inversion
  3. rapid at room temperature
  4. amines with fewer than 5 carbons are water-soluble and form hydrogen bonds
  5. smell nasty
34
Q

Do amines or alkanes have higher boiling points?

A

Amines

35
Q

What type of amines do not undergo reductive amination?

A

Tertiary amines

36
Q

Sandmeyer Reaction reactants/prodcuts

A

CuCl, CuBr, or NaI –> aryl halides
CuCN –> aryl nitriles
Cu2O and Cu(NO3)2 –> Phenols

37
Q

Diazonium Coupling Reaction

A

electrophilic aromatic substitution usually occuring at the p-position of the activated ring

38
Q

Heterocylic amines undergo what reaction?

A

Electrophilic substitution; reaction occurs at the 2-position b/c the positions are more stable

39
Q

Is pyridine a stronger or weaker base than pyrrole? How about alkylamines? Pyrimidine?

A

Pyridine is a stronger base than pyrrole but a weaker base for alkylamines. Pyridine is a more basic than pyrimidine.

40
Q

Pyridine

A

nitrogen-containing analog of benzene

41
Q

Pyrimidine

A

Two nitrogens in the 1 and 3 positions of a six-membered ring

42
Q

What does the reactivity of polycyclic heterocylic compound depend on?

A

Type of heteroatom and size of the ring

43
Q

Purines

A

4 nitrogens (3 pyridine-like and 1 pyrrole-like) in a fused ring

44
Q

Primary and secondary amines IR absorption range?

A

Primary: 3350-3450 cm-1
Secondary: 3350 cm-1

sharper and less intense than alcohol absorptions

45
Q

Nitrogen Rule

A

compound with an odd number of nitrogens has an odd numbered molecular weight/ion.

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