amines 2.pdf

Amines which are derivatives of ammonia are explain in this chapter

1. Amines
Lecture Presented by:
Victor R. Oribe

2. Amines
Aminesarecarbon–hydrogen–nitrogen
compounds.
Aminesoccurswidelyinlivingorganisms.
Manyaminesarenaturallyoccurring
compounds thatareveryactive
physiologically.
Numerousdrugsusedforthetreatmentof
mentalillness,hayfever,heartproblems,
andotherphysicaldisordersareamines.

3. Bonding Characteristics of Nitrogen
Atoms in Organic Compounds
An understanding ofthebonding
characteristicsoftheNitrogenatomisa
prerequisitetoourstudyofamines.
NitrogenisamemberofGroupVAofthe
periodictable;ithasfivevalenceelectrons
anditwillformthreecovalentbondsto
completeitsoctetofelectrons.

4. InOrganicChemistry,
nitrogen forms three bonds
carbonformsfourbonds.
4 valence electron
4 covalent bond
No nonbonding electron pair
5valence electron
3covalent bond
1nonbonding electron pair
Oxygen forms two bonds
6 valence electron
2 covalent bond
2 nonbonding electron pair

5. Structure and Classification of
Amines
AnAmineisanorganicderivativeof
ammonia (NH
4)inwhichoneormore
alkyl,cycloalkyl,orarylgroupsare
attachedtothenitrogenatom.
Aminesareclassifiedasprimary(1
0
),
secondary(2
0
),ortertiary(3
0
)onthe
basisofhowmanyhydrocarbongroupsare
bondedtotheammonianitrogenatom.

6. Primary Amine
Isanamineinwhichthenitrogenatom
isbondedtoonehydrocarbongroup
andtwohydrogenatoms.
Thegeneralizedformulaforaprimary
amineisRNH
2
.
CH
3–NH
2
The functional group
presentinaprimaryamine,
theNH
2groupiscalledan
Aminogroup.
AnAminogroupisthe-
NH
2functionalgroup.

7. Secondary Amine
Isanamineinwhichthenitrogenatom
isbondedtotwohydrocarbongroups
andonehydrogenatom.
Thegeneralizedformulaforasecondary
amineisR
2NH.
CH
3–NH –CH
3

8. Tertiary Amine
Isanamineinwhichthenitrogenatom
isbondedtothreehydrocarbongroups
andnohydrogenatom.
Thegeneralizedformulaforatertiary
amineisR
3N.

9. Classify Amines each of the
following Amines as a Primary,
Secondary, or Tertiary
1) CH
3–NH
2) CH
3–N –CH
3
CH
3
Thisisasecondary
amine becausethe
nitrogenisbondedto
bothamethylgroupand
phenylgroup
Herewehaveatertiary
amine becausethe
nitrogenatomisbonded
tothreemethylgroups.

10. 3) N
CH
3
4) CH
3
NH
2
Thisisalsoatertiary
amine;thenitrogen
atomisbondedtotwo
phenylgroupsanda
methylgroup.
Thisisaprimary
amine.Thenitrogen
atomisbondedtoonly
onecarbonatom.

11. 5) CH
3–CH
2 -CH
2–NH
2
6) –NH
2
7) CH
3–NH-CH
2–CH
3
8) CH
3–N –
CH
3
1
0
1
0
2
0
3
0

12. NH
2
NH
2
1
0
1
0
1
0
NH
2
NH
2
0
N
3
0
1)
2)
3) 4)
5)

13. Physical Properties of Amines
Themethylamines(mono-,di-,tri-)andethylamineare
gasesatroomtemperatureandhaveammonia-like
odors.
Mostotheraminesareliquid,andmanyhaveodor
resemblingthatofrawfish.
Afewamines,particularlydiamines,havestrong,
disagreeableodors.
Thefoulodorarisingfromdeadfishanddecayingflesh
isduetoaminesreleasedbythebacterial
decompositionofprotein.

14. Diaminesputrescineandcadaverinearetwo
“odoriferous”compounds.
H
2N –(CH
2)
4–NH
2 H
2N –(CH
2)
5–NH
2
Putrescine
1,4-butanediamine
Cadaverine
1,5-pentanediamine
Thesimplesaminesareirritatingtotheskin,eyes,and
mucousmembranesandaretoxicbyingestion.
Aromaticaminesaregenerallytoxic.
Manyaminesarereadilyabsorbedthroughtheskinand
affectboththebloodandthenervoussystem.

15. Theboilingpointsofaminesareintermediate
betweenthoseofalkanesandalcoholsofsimilar
molecularmass.
Aminesarehigherthanalkaneboilingpoint,
becausehydrogenbondingispossiblebetween
aminemoleculesbutnotbetweenalkanemolecules.
Intermolecularhydrogen
bondingofaminesinvolves
thehydrogenatomsand
nitrogenatomsoftheamino
group.

16. Tertiaryamineshavelowerboilingpoint
thanprimaryandsecondaryamines
becauseintermolecularhydrogen
bondingisnotpossibleintertiary
amines.
Secondaryandtertiaryamineshaveno
hydrogenatomsdirectlybondedtothe
nitrogenatom.

17. Theboilingpointofaminesarelowerthanthoseof
correspondingalcohols,becauseN–Hbondsare
weakerthanO–Hbonds.
Note:Thedifferenceinhydrogen-bond
strengthresultsfromelectronegativity
differences,nitrogenislesselectronegative
thanoxygen.
ElementElectronegativity
values
Difference
Nitrogen 3.0
0.9
Hydrogen 2.1
Oxygen 3.5
1.4
Hydrogen 2.1

18. Amineswithfewerthansixcarbonatomsare
infinitelysolubleinwater.
Thissolubilityresultsfromhydrogenbonding
betweentheaminesandwater.
Eventertiaryaminesarewater-
soluble,becauseamine
nitrogenatomhasa
nonbondingelectronpairthat
canformahydrogenbondwith
ahydrogenatomofwater.

19. Basicity of Amines
Amines, like ammonia, are weak bases.
Ammonia’sweak-basebehaviorresultsfromits
acceptingaproton(H
+
)fromwatertoproduce
ammoniumion(NH
4
+
)andhydroxylion(OH
-
)
ammonia Ammonium ionHydroxide ion
NH
3
Amines behave in a similar manner.
+
Methylamine MethylammoniumionHydroxide ion
+HOH NH
4
+
+OH
-
CH
3–NH
2
H OH CH
3+ NH
3
OH
-
+
=
= +

20. Amines,likeammonia,haveapairofunshared
electronsonthenitrogenatompresent.
ammonia amine
Theseunsharedelectrons
canacceptahydrogenion
fromwater.
Thus,bothaminesand
ammonia produce
basicaqueoussolution

21. Theresultoftheinteractionofanamine
withwaterisabasicsolutioncontaining
substitutedammonium ionsand
hydroxideions.
Asubstitutedammonium ionisan
ammoniumioninwhichoneormorealkyl,
cycloalkyl,orarylgroupshavebeen
substitutedforhydrogenatom.
Substitutedammonium ionsalways
containoneormorehydrogenatomthan
their“parent”amine.Theyalsoalways
carrya+1charge,whereasthe“parent”
amineisaneutralmolecule.

22. Naming the positive ion that results from
the interaction of an amine with water is
based on the following two rules:
Rule1:Foralkylamine,theendingofthe
nameoftheamineischangedfromamine
toammoniumion
CH
3–CH
2–NH
2
H
2O
CH
3–CH
2–NH
3+ OH
Ethylamine Ethylammonium
ion
+ -
CH
3–N–CH
2–CH
3
H
2O
CH
3–NH –CH
2–CH
3+ OH
+ -
CH
3
CH
3
Ethyldimethylamide Ethyldimethylammonium
ion

23. Rule2:Foraromaticamines,thefinal–eof
thenameoftheamineisreplacedby–ium
ion.
NH
2
CH
3-NH
2
NH
3
+
+
Aniline
Aniliniumion
N–methylanilinium
ion

24. Name the following substituted ammonium
or substituted aniliniumions.
1) CH
3–CH
2–NH
2–CH
2–CH
3
2) CH
3–NH –CH
3
+
+
+
+
CH
3
3) CH
3–CH –CH
2–NH
3
CH
3
4) CH
3–NH –CH
3
1) diethylammonium ion
2) trimethylammonium ion
3) isobutylammonium ion
4) N,N dimethylanilinium
ion

25. 5) CH
3–CH
2–NH
2–CH
3
5) Ethylmethylammonium ion
6) CH
3–CH –NH
3
CH
3
7) CH
3–CH
2–NH –CH
2–CH
3
CH
3
6) Isopropylammonium ion
7) Diethylmethylammonium ion
8) NH
2–CH
2–CH
2–CH
3
8) N-propylaniliniumion

26. Amine Salt
Thereactionofanacidwithabase
(neutralization)producesasalt.
CH
3–NH
2
CH
3–NH
2Cl
+ -..
amine acid Amine salt
H–Cl+
Aromaticaminesreactwithacidsinasimilar
manner.
CH
3–NH
..
+
amine
H–Cl
acid
CH
3–NH
2Cl
+ -
Amine salt

27. Anaminesaltisanorganiccompoundin
whichthepositiveionisamono-,di-,or
trisubstitutedammonium ion(RNH
3
+
,
R
2NH
2
+
,orR
3NH
+
)andthenegativeion
comesfromanacid.
Aminesaltcanbeobtainedincrystalline
form(odorless,whitecrystals)by
evaporatingthewaterfromtheacidic
solutionsinwhichaminesaltareprepared.

28. Aminesaltarenamedusingstandard
nomenclature procedures forionic
compound.
Thenameofthepositiveion,the
substitutedammonium oraniliniumion,is
givenfirstandfollowedbyaseparateword
forthenameofthenegativeion.
CH
3–CH
2–NH
3Cl
+
-
12
Cl chlorideEthylammonium
CH
3–NH
2–CH
3Br CH
3 CH
3
methyldi
+
ammonium
-
bromideBr

29. Anoldersystemforamineslats,stillused
inthepharmaceuticalindustry,treatamine
saltsasamine-acidcomplexesratherthan
asioniccompound.
CH
3–NH
3HCl
CH
3
Dimethylaminehydrochloride
Rather than as
CH
3–NH
3Cl
CH
3
CH
3
methyl
CH
3
di
+
ammonium
-
Cl
chloride

30. Manypeopleunknowinglyuseacidstoformamine
slatswhentheyputvinegarorlemonjuiceonfish.
Suchactionconvertsaminesinfish(oftensmelly
compounds)tosalts,whichareodorless.
Theprocessofformingaminesaltswithacidsisan
easilyreversedprocess.
Treatingaminesaltswithastrongbasesuchas
NaOHregeneratesthe“parent”amine.
CH
3–NH
3ClNaOH CH
3–NH
2NaClH
2O+ + +
Amine salt base Amine salt

31. The“oppositenature”oftheprocessesofaminesalt
formationfromanamineandtheregenerationofthe
aminefromitsaminesaltcanbediagrammedas
follows:
An Amine An Amine Salt
Acid
Protonation
Base
Deprotonation
Anaminegainshydrogeniontoproduceanamine
saltwhentreatedwithanacid(protonation.
Anaminesaltlosesahydrogeniontoproducean
aminewhentreatedwithabase(deprotonation
reaction)

32. Write the structures of the products that forms
when each of the following reactions involving
amines or amine salts takes place.
1) CH
3–NH –CH
3+ HCl
CH
3–NH –CH
3+ HCl¨
+ -
CH
3–NH
2–CH
3Cl
2) CH
3–NH
2–CH
3Cl
+ -
CH
3–NH
2–CH
3Cl
¨
+ -
+NaOH
CH
3–NH –CH
3
+NaCl+H
2O

33. 3) NH –CH
3
+ H
2SO
4
NH
2–CH
3
HSO
4
+ -¨
4) CH
3–CH
2–N –CH
3+ HCl
CH
3
CH
3–CH
2–NH –CH
3Cl
CH
3
+ -
5) CH
3–CH
2–NH
2–H
2SO
4
CH
3–CH
2–NH
3HSO
4
+ -

34. 6) CH
3–CH
2–NH –CH
3Br + NaOH
CH
3
+ -
CH
3–CH
2––CH
3
CH
3
+NaBr HOH+N

35. Heterocyclic Amines
Heterocyclicamineisanorganiccompound
inwhichnitrogenatomsofaminegroupare
partofeitheranaromaticoranonaromatic
ringsystem.
Heterocyclicaminearethemostcommon
typeofheterocyclicorganiccompound
Heterocyclicamines arethefirst
heterocyclic compounds we have
encountered that have nitrogen
heteroatoms.

36. Selected Structural Formulas of
Heterocyclic amines that serve as
“parent” molecule for complex amine
derivatives.
Pyridine
Pyrrolidine
Pyrrole
Imidazole
Quinoline
Indole
Pyrimidine
Purine

37. Heterocyclicaminesoftenhavestrongodor,
someagreeableandothersdisagreeable.
Thepleasantaromaofmanyheat-treated
foodiscausedbyheterocyclicamines
formedduringthetreatment.
Thecompounds responsibleforthe
pervasiveodorsofpooppopcornandhot
peanutareheterocyclicamines.
C
O
CH
3
Methyl-2-pyridylketone
odor of popcorn
OCH
3
CH
3
2-Methoxy-5-methylpyrazine
odor of peanut

38. Isomerism for Amines
Constitutionalisomerisminaminescan
arisefromseveralcauses.
1.Differentcarbonatomarrangements
produceisomers,asin
CH
3–CH
2–CH
2–CH
2–CH
2NH
2
1-Pentanamine
CH
3–CH
2–CH–CH
2–NH
2
CH
3
2 Methyl-1-butanamine
C
5H
11–NH
2
C
5H
11–NH
2

39. 2)Differentpositioningofthenitrogen
atomonacarbonchainsisanother
causeforisomerism.
CH
2–CH
2–CH
2–CH
3
NH
2
1-Butanamine
CH
3–CH–CH
2–CH
3
NH
22-Butanamine

40. 3)Forsecondaryandtertiaryamines,
differentpartitioningofcarbonatoms
among thecarbonchainspresent
producesconstitutionalisomers.
CH
2–CH
2–NH –CH
2–CH
3
CH
3–CH
2–CH
2–NH –CH
3
CH
3–CH –NH –CH
3
CH
3
N-Ethylethanamine
N-Methyl -1-propanamine
N-Methyl -2-propanamine

41. Nomenclature for Amines
A. Naming Primary Amines
CH
3–CH –CH
2–CH
3
NH
2
1.Selectastheparent
carbonchainthelongest
chaintowhichthenitrogen
atomisattached.
4321
1 methane
2 ethane
3 propane
4 butane
5 pentanebutan
2.Nametheparentchainby
changingthe–eendingof
thecorrespondingalkane
nameto–amine.
amine
3.Numbertheparentchain
fromtheendnearestthe
nitrogenatom.
4.Thepositionof
attachmentofthenitrogen
atomisindicatedbya
numberinfrontofthe
parentchainname.
2
2-

42. CH
3–CH –CH
2–CH
2 -NH
2
CH
3
4 32 1
1 methane
2 ethane
3 propane
4 butane
5 pentane
butanamine
NH
2
1
1 -
CH
3
Methyl -
3
3-

43. Indiamines,thefinal–eofthecarbon
chainname isretainedforease
pronunciation.
H
2N –CH
2–CH
2–CH
2–CH
2–NH
2
4 3 2 1
1 methane
2 ethane
3 propane
4 butane
5 pentane
butane
NH
2
amine
1
1
H
2N
12
di
4
,4-

44. SecondaryandTertiaryAminesarenamed
asN-substitutedprimaryamines.
Thelargestcarbongroupbondedtothe
nitrogenisusedastheparentamine
name.
Thenamesoftheothergroupattachedto
thenitrogenareappendedtothefrontof
thebasename,andN-orN,N-prefixesare
usedtoindicatethatthosegroupsare
attachedtothenitrogenatomratherthan
tothebasecarbonchain.

45. CH
3–CH
2–CH –CH
3
NH –CH
3
4 32 1
1 methane
2 ethane
3 propane
4 butane
5 pentane
butanamine
2
2-
CH
3
1
Methyl-
Tertiary amine
N-
CH
3–CH
2–N –CH
2–CH
2–CH
3
CH
3
1 2 3
propanamine
1
1-
1
methyl-N-
12
Ethyl-N-

46. CH
3–N –CH
2–CH
2–CH
3
CH
3
1 methane
2 ethane
3 propane
4 butane
5 pentane
321
propanamine
1
1-
CH
3
methyl
CH
3
methyl
Di
N-N-
N,N –Dimethyl –1 -propanamine

47. Simplestaromaticamine,abenzenering
bearinganaminogroup,iscalled
aniline.
Othersimplearomaticaminesarenamed
asderivativesofaniline.
NH
2 NH
2
Cl
NH
2
Cl
Cl
Aniline m -Chloro
di
aniline
anilinechloro
Di
2 –3,
1
2
3

48. Insecondaryandtertiaryaromaticamines,
theadditionalgrouporgroupsattachedto
thenitrogenatomarelocatedusingacapital
N-
NH –CH
2–CH
3
N-Ethylaniline
H
3C –N –CH
3
N-N Dimethylaniline
NH –CH
3
CH
3
3,N Dimethylaniline

49. Assign IUPAC name to each of the
following amines.
1) CH
3–CH
2–NH –(CH
2)
4–CH
3
N-ethyl-1-pentanamine
2) NH
2
Br 4-bromoaniline
3) H
2N –CH
2–CH
2–NH
2
1,2-Ethanediamine
4) N
N,N -Dimethylethanamine

50. 5)
NH
2
3-Hexanamine
6) CH
3–CH
2–CH
2–NH –CH
2–CH
2–CH
3
N-Propyl-1-propanamine
7) CH
3–N –CH
3
CH
3
N,N-Dimethylmethanamine
8)
NH –CH
3
N-Methylaniline