Dr. Wolf's CHM 201 & 202 22-1
22.1522.15
Nitrosation of AlkylaminesNitrosation of Alkylamines
Dr. Wolf's CHM 201 & 202 22-2
Nitrite Ion, Nitrous Acid, and Nitrosyl CationNitrite Ion, Nitrous Acid, and Nitrosyl Cation
HH++
––OO••••••••
••••NN OO
•••• ••••••••
OO•••• ••••
NN OO•••• ••••
••••HH
HH++
OO••••NN OO
•••• ••••
HH
HH
++••••++
••••NN OO
•••• ••••++OO ••••
HH
HH
••••
Dr. Wolf's CHM 201 & 202 22-3
Nitrosyl Cation and NitrosationNitrosyl Cation and Nitrosation
++••••NN OO
•••• ••••
Dr. Wolf's CHM 201 & 202 22-4
Nitrosyl Cation and NitrosationNitrosyl Cation and Nitrosation
++••••NN OO
•••• ••••++••••NN
NN••••NN OO
•••• ••••++
Dr. Wolf's CHM 201 & 202 22-5
Nitrosation of Secondary AlkylaminesNitrosation of Secondary Alkylamines
++••••NN OO
•••• ••••••••NN
HH
++
NN••••NN OO
•••• ••••++
HH++
HH
++
NN••••NN OO
•••• •••••••• nitrosation of secondary nitrosation of secondary
amines gives an amines gives an NN--
nitroso aminenitroso amine
Dr. Wolf's CHM 201 & 202 22-6
ExampleExample
(CH(CH33))22NNHH•••• NaNONaNO22, HCl, HCl
HH22OO(88-90%)(88-90%)
••••(CH(CH33))22NN
••••NN OO
•••• ••••
Dr. Wolf's CHM 201 & 202 22-7
Some N-Nitroso AminesSome N-Nitroso Amines
NN-nitrosopyrrolidine-nitrosopyrrolidine(nitrite-cured bacon)(nitrite-cured bacon)
NN
NNOO
NN-nitrosonornicotine-nitrosonornicotine(tobacco smoke)(tobacco smoke)
NN
NNOONN
(CH(CH33))22NN NN OONN-nitrosodimethylamine-nitrosodimethylamine
(leather tanning)(leather tanning)
Dr. Wolf's CHM 201 & 202 22-8
Nitrosation of Primary AlkylaminesNitrosation of Primary Alkylamines
++ analogous to analogous to
nitrosation of nitrosation of
secondary amines to secondary amines to
this pointthis point
++••••NN OO
•••• ••••••••NN
HH
HHRR
NN••••NN OO
•••• ••••++
HH
HHRR
++HH
++
NN••••NN OO
•••• ••••••••
RR
HH
Dr. Wolf's CHM 201 & 202 22-9
Nitrosation of Primary AlkylaminesNitrosation of Primary Alkylamines
NN••••NN OO
•••• ••••••••
RR
HH
HH++
NN••••NN OO
••••••••
RR
HH HH
++
this species reacts furtherthis species reacts further
••••NN
••••NN OO
••••••••
RR
HHHH
++
++
HHHH
++••••NN
••••NN OO••••
RR
HH
Dr. Wolf's CHM 201 & 202 22-10
Nitrosation of Primary AlkylaminesNitrosation of Primary Alkylamines
++
HH
••••NN••••NN OO••••
RR
HH
++NN NN ••••RR
HH
••••OO
HH
••••++nitrosation of a nitrosation of a
primary alkylamine primary alkylamine
gives an alkyl gives an alkyl
diazonium iondiazonium ion
process is called process is called
diazotizationdiazotization
Dr. Wolf's CHM 201 & 202 22-11
Alkyl Diazonium Ions Alkyl Diazonium Ions
++NN NN ••••RR
alkyl diazonium ions alkyl diazonium ions
readily lose Nreadily lose N22 to to
give carbocationsgive carbocations
RR++ ++ NN NN ••••••••
Dr. Wolf's CHM 201 & 202 22-12
Example: Nitrosation of 1,1-DimethylpropylamineExample: Nitrosation of 1,1-Dimethylpropylamine NNHH22
NN NN++
HONOHONO
HH22OO
OOHH
(80%)(80%) ++
(2%)(2%)(3%)(3%)
++
– – NN22
Dr. Wolf's CHM 201 & 202 22-13
There is no useful chemistry associated with the There is no useful chemistry associated with the nitrosation of tertiary alkylamines.nitrosation of tertiary alkylamines.
Nitrosation of Tertiary Alkylamines Nitrosation of Tertiary Alkylamines
••••NNRR
RR
RR
NN••••NN OO
•••• ••••++RR
RR
RR
Dr. Wolf's CHM 201 & 202 22-14
22.1622.16
Nitrosation of ArylaminesNitrosation of Arylamines
Dr. Wolf's CHM 201 & 202 22-15
reaction that occurs is reaction that occurs is electrophilic aromatic substitutionelectrophilic aromatic substitution
Nitrosation of Tertiary ArylaminesNitrosation of Tertiary Arylamines NN(CH(CH22CHCH33))22
(95%)(95%)
1. NaNO1. NaNO22, HCl,, HCl,
H H22O, 8°CO, 8°C
2. HO2. HO––
NN(CH(CH22CHCH33))22
NNOO
Dr. Wolf's CHM 201 & 202 22-16
similar to secondary alkylamines;similar to secondary alkylamines;
gives gives NN-nitroso amines-nitroso amines
Nitrosation of N-AlkylarylaminesNitrosation of N-Alkylarylamines
NaNONaNO22, HCl,, HCl,
HH22O, 10°CO, 10°C
NNHCHHCH33
(87-93%)(87-93%)
NNCHCH33
NN OO
Dr. Wolf's CHM 201 & 202 22-17
Nitrosation of Primary Nitrosation of Primary ArylaminesArylamines
gives aryl diazonium ionsgives aryl diazonium ions
aryl diazonium ions are much more stable thanaryl diazonium ions are much more stable than
alkyl diazonium ionsalkyl diazonium ions
most aryl diazonium ions are stable under the most aryl diazonium ions are stable under the
conditions of their formation (0-10°C) conditions of their formation (0-10°C)
ArArNN NN++
RRNN NN++ fastfast
slowslow
RR++ ++ NN22
ArAr++ ++ NN22
Dr. Wolf's CHM 201 & 202 22-18
Example:Example: (CH(CH33))22CHCH NNHH22
NaNONaNO22, H, H22SOSO44
HH22O, 0-5°CO, 0-5°C (CH(CH33))22CHCH NN NN
++HSOHSO44
––
Dr. Wolf's CHM 201 & 202 22-19
Synthetic Origin of Aryl Diazonium SaltsSynthetic Origin of Aryl Diazonium Salts
ArAr HH
ArAr NNOO22
ArAr NNHH22
ArAr NN NN++
Dr. Wolf's CHM 201 & 202 22-20
22.1722.17
Synthetic TransformationsSynthetic Transformations
ofAryl Diazonium SaltsofAryl Diazonium Salts
Dr. Wolf's CHM 201 & 202 22-21
Transformations of Aryl Diazonium SaltsTransformations of Aryl Diazonium Salts
ArAr NN NN++
ArAr HH
ArAr OOHH
ArAr II
ArAr FF
ArAr BrBrArAr ClCl
ArAr CNCN
Dr. Wolf's CHM 201 & 202 22-22
Preparation of PhenolsPreparation of Phenols
ArAr NN NN++
ArAr OOHH
HH22OO, heat, heat
Dr. Wolf's CHM 201 & 202 22-23
ExampleExample
2. H2. H22O, heatO, heat
(CH(CH33))22CHCH NNHH22
1. NaNO1. NaNO22, H, H22SOSO44
HH22O, 0-5°CO, 0-5°C (CH(CH33))22CHCH OOHH
(73%)(73%)
Dr. Wolf's CHM 201 & 202 22-24
Transformations of Aryl Diazonium SaltsTransformations of Aryl Diazonium Salts
ArAr NN NN++
ArAr HH
ArAr OOHH
ArAr II
ArAr FF
ArAr BrBrArAr ClCl
ArAr CNCN
Dr. Wolf's CHM 201 & 202 22-25
Preparation of Aryl IodidesPreparation of Aryl Iodides
ArAr NN NN++
ArAr II
reaction of an aryl diazonium salt with reaction of an aryl diazonium salt with
potassium iodidepotassium iodide
KKII
Dr. Wolf's CHM 201 & 202 22-26
ExampleExample
2. K2. KII, room temp., room temp.
1. NaNO1. NaNO22, HCl, HCl
HH22O, 0-5°CO, 0-5°C
(72-83%)(72-83%)
NNHH22
BrBr
II BrBr
Dr. Wolf's CHM 201 & 202 22-27
Transformations of Aryl Diazonium SaltsTransformations of Aryl Diazonium Salts
ArAr NN NN++
ArAr HH
ArAr OOHH
ArAr II
ArAr FF
ArAr BrBrArAr ClCl
ArAr CNCN
Dr. Wolf's CHM 201 & 202 22-28
Preparation of Aryl FluoridesPreparation of Aryl Fluorides
ArAr NN NN++
ArAr FF
heat the tetrafluoroborate salt of a diazonium ion;heat the tetrafluoroborate salt of a diazonium ion;
process is called the Schiemann reactionprocess is called the Schiemann reaction
Dr. Wolf's CHM 201 & 202 22-29
ExampleExample
(68%)(68%)
NNHH22 CCHCCH22CHCH33
OO
2. HBF2. HBF44
1. NaNO1. NaNO22, HCl,, HCl,
HH22O, 0-5°CO, 0-5°C
3. heat3. heat
FF CCHCCH22CHCH33
OO
Dr. Wolf's CHM 201 & 202 22-30
Transformations of Aryl Diazonium SaltsTransformations of Aryl Diazonium Salts
ArAr NN NN++
ArAr HH
ArAr OOHH
ArAr II
ArAr FF
ArAr BrBrArAr ClCl
ArAr CNCN
Dr. Wolf's CHM 201 & 202 22-31
Preparation of Aryl Chlorides and Preparation of Aryl Chlorides and BromidesBromides
ArAr NN NN++
ArAr BrBrArAr ClCl
aryl chlorides and aryl bromides are prepared by heating aryl chlorides and aryl bromides are prepared by heating
a diazonium salt with copper(I) chloride or bromidea diazonium salt with copper(I) chloride or bromide
substitutions of diazonium salts that use copper(I) substitutions of diazonium salts that use copper(I)
halides are called halides are called SandmeyerSandmeyer reactionsreactions
Dr. Wolf's CHM 201 & 202 22-32
ExampleExample
(68-71%)(68-71%)
NNHH22 NONO22
2. Cu2. CuClCl, heat, heat
1. NaNO1. NaNO22, HCl,, HCl,
HH22O, 0-5°CO, 0-5°C
ClCl NONO22
Dr. Wolf's CHM 201 & 202 22-33
ExampleExample
(89-95%)(89-95%)
2. Cu2. CuBrBr, heat, heat
1. NaNO1. NaNO22, HBr,, HBr,
HH22O, 0-10°CO, 0-10°CNNHH22
ClCl
BrBr ClCl
Dr. Wolf's CHM 201 & 202 22-34
Transformations of Aryl Diazonium SaltsTransformations of Aryl Diazonium Salts
ArAr NN NN++
ArAr HH
ArAr OOHH
ArAr II
ArAr FF
ArAr BrBrArAr ClCl
ArAr CNCN
Dr. Wolf's CHM 201 & 202 22-35
Preparation of Aryl NitrilesPreparation of Aryl Nitriles
ArAr NN NN++
ArAr CNCN
aryl nitriles are prepared by heating a diazonium aryl nitriles are prepared by heating a diazonium
salt with copper(I) cyanidesalt with copper(I) cyanide
this is another type of Sandmeyer reactionthis is another type of Sandmeyer reaction
Dr. Wolf's CHM 201 & 202 22-36
ExampleExample
(64-70%)(64-70%)
2. CuCN, heat2. CuCN, heat
1. NaNO1. NaNO22, HCl,, HCl,
HH22O, 0°CO, 0°CNNHH22
CHCH33
CNCN CHCH33
Dr. Wolf's CHM 201 & 202 22-37
Transformations of Aryl Diazonium SaltsTransformations of Aryl Diazonium Salts
ArAr NN NN++
ArAr HH
ArAr OOHH
ArAr II
ArAr FF
ArAr BrBrArAr ClCl
ArAr CNCN
Dr. Wolf's CHM 201 & 202 22-38
Transformations of Aryl Diazonium SaltsTransformations of Aryl Diazonium Salts
ArAr NN NN++
ArAr HH
hypophosphorous acid (Hhypophosphorous acid (H33POPO22) reduces diazonium ) reduces diazonium
salts; ethanol does the same thingsalts; ethanol does the same thing
this is called this is called reductive deaminationreductive deamination
Dr. Wolf's CHM 201 & 202 22-39
ExampleExample
(70-75%)(70-75%)
NaNONaNO22, H, H22SOSO44,,
HH33POPO22
NNHH22
CHCH33 CHCH33
Dr. Wolf's CHM 201 & 202 22-40
Value of Diazonium SaltsValue of Diazonium Salts
1) 1) allows introduction of substituents such as OH, F, allows introduction of substituents such as OH, F,
I, and CN on the ringI, and CN on the ring
2) 2) allows preparation of otherwise difficultly allows preparation of otherwise difficultly
accessible substitution patternsaccessible substitution patterns
Dr. Wolf's CHM 201 & 202 22-41
ExampleExample BrBr
BrBrBrBr
NNHH22
BrBr
BrBr
BrBr
(74-77%)(74-77%)
NaNONaNO22, H, H22SOSO44,,
HH22O, CHO, CH33CHCH22OHOH
NNHH22 BrBr22
HH22OO
(100%)(100%)
Dr. Wolf's CHM 201 & 202 22-42
22.1822.18
Azo CouplingAzo Coupling
Dr. Wolf's CHM 201 & 202 22-43
Azo CouplingAzo Coupling
Diazonium salts are weak electrophiles.Diazonium salts are weak electrophiles.
React with strongly activated aromatic compounds React with strongly activated aromatic compounds
by electrophilic aromatic substitution.by electrophilic aromatic substitution.
ArAr NN NN++
Ar'Ar' HH++ ArAr NN NN Ar'Ar'
an azo compoundan azo compound
Ar'Ar' must bear a strongly electron-releasing group must bear a strongly electron-releasing group such as OH, OR, or NR such as OH, OR, or NR22..
Dr. Wolf's CHM 201 & 202 22-44
ExampleExample OHOH
++ CC66HH55NN NN++ OHOH
NN NCNC66HH55
ClCl––
Dr. Wolf's CHM 201 & 202 22-45
Section 22.19Section 22.19
Spectroscopic Analysis of AminesSpectroscopic Analysis of Amines
Dr. Wolf's CHM 201 & 202 22-46
the N—H stretching band appears in the rangethe N—H stretching band appears in the range3000-3500 cm3000-3500 cm-1-1
primary amines give two peaks in this region, oneprimary amines give two peaks in this region, onefor a symmetrical stretching vibration, the other forfor a symmetrical stretching vibration, the other foran antisymmetrical stretchan antisymmetrical stretch
Infrared SpectroscopyInfrared Spectroscopy
RR NN
HH
HH
symmetricsymmetric
RR NN
HH
HH
antisymmetricantisymmetric
Dr. Wolf's CHM 201 & 202 22-47
Infrared SpectroscopyInfrared Spectroscopy
RNHRNH22 RR22NHNH
primary amines give two N—H stretching peaks, primary amines give two N—H stretching peaks,
secondary amines give onesecondary amines give one
Dr. Wolf's CHM 201 & 202 22-48
compare chemical shifts in:compare chemical shifts in:
11H NMRH NMR HH33CC CHCH22NNHH22
HH33CC CHCH22OOHH
NN CC HH is more shielded than is more shielded than
3.9 ppm3.9 ppm 4.7 ppm4.7 ppm
OO CC HH
Dr. Wolf's CHM 201 & 202 22-49
1313C NMRC NMR
Carbons bonded to N are more shielded than Carbons bonded to N are more shielded than
those bonded to O.those bonded to O.
CHCH33NNHH22 CHCH33OHOH
26.9 ppm26.9 ppm 48.0 ppm48.0 ppm
Dr. Wolf's CHM 201 & 202 22-50
maxmax
204 nm204 nm256 nm256 nm
maxmax
230 nm230 nm280 nm280 nm
maxmax
203 nm203 nm254 nm254 nm
An amino group on a benzene ring shifts An amino group on a benzene ring shifts maxmax
to longer wavelength. Protonation of N causesto longer wavelength. Protonation of N causesUV spectrum to resemble that of benzene.UV spectrum to resemble that of benzene.
UV-VISUV-VIS NHNH22
NHNH33
++
Dr. Wolf's CHM 201 & 202 22-51
Mass SpectrometryMass Spectrometry
Compounds that contain only C, H, and O have Compounds that contain only C, H, and O have
even molecular weights. If an odd number of N even molecular weights. If an odd number of N
atoms is present, the molecular weight is odd.atoms is present, the molecular weight is odd.
A molecular-ion peak with an odd A molecular-ion peak with an odd mm//zz value value
suggests that the sample being analyzed contains suggests that the sample being analyzed contains
N.N.
Dr. Wolf's CHM 201 & 202 22-52
Mass SpectrometryMass Spectrometry
Nitrogen stabilizes Nitrogen stabilizes
carbocations, which carbocations, which
drives the fragmentation drives the fragmentation
pathways.pathways.
(CH(CH33))22NCHNCH22CHCH22CHCH22CHCH33••••
ee––
(CH(CH33))22NCHNCH22CHCH22CHCH22CHCH33
••++
••CHCH22CHCH22CHCH33++(CH(CH33))22NN CHCH22
++
Dr. Wolf's CHM 201 & 202 22-53
Mass SpectrometryMass Spectrometry
Nitrogen stabilizes Nitrogen stabilizes
carbocations, which carbocations, which
drives the fragmentation drives the fragmentation
pathways.pathways.
CHCH33NHCHNHCH22CHCH22CH(CHCH(CH33))22••••
ee––
CHCH33NHCHNHCH22CHCH22CH(CHCH(CH33))22
••++
••CHCH22CH(CHCH(CH33))22++CHCH33NHNH CHCH22
++
Dr. Wolf's CHM 201 & 202 22-54
End of Chapter 22End of Chapter 22