matriculation chemistry amines part 2
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8/12/2019 Matriculation Chemistry Amines Part 2
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Reaction with acyl chlorides
1 and 2 amines are acylated to formN-substituted amides
3 amines are not acylated because they
do not have a H atom attached to N atom.
+
1oamine
R N H
H
Cl C CH3
2 R N C CH3
H
2oamide
+
2oamine
R N H
R
Cl C CH3
2 R N C CH3
R
3oamide
+ HCl
+ HCl
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Reaction with acid anhydride
1 and 2 amines are acylated to form
N-substituted amides
3 amines are not acylated because they
do not have a H atom attached to N atom.
R N C CH3
H
2oamide
+
1o
amine
R N H
H
CH3 C C CH3
acid anhydride
+ CH3CH
+
2oamine
R N H
R
CH3 C C CH 3
acid anhydride
R N C CH3
R
3oamide
+ CH3CH
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Reaction with ben!enesul"honyl chloride
Hinsber#$s test
%his reaction is used to differentiate
between 1& 2and 3 amines.
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'en!enesul"honyl chloride reacts with a1 amine to form a white "reci"itate
(N-substituted sul"honamides)
11 amineaminess
(-HCl)
Acidic hydrogen
NaOHN-substituted sul"honamides have an
acidic hydro#en& N-H.
%herefore& it dissolve in a*ueous NaH.
R-N-H
H
+
Cl-S-
O
O
OH-
1 amineo
O
O
-S-R-N
H
(precipitate)
N-substituted
benzenesulphonamides
O
O
-S-R-N
Na
water soluble salt
(clear solution)
Acidic hydrogen
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N,N-disubstituted sul"honamides do not
have an acidic hydro#en& N-H.
22 amineaminess
(-HCl)
%herefore& it dissolve in a*ueous NaH.
'en!enesul"honyl chloride reacts with a
2 amines to form a white "reci"itate
(N,N-disubstituted sul"honamide)
NaOHNo reaction
Cha"ter 1 , mines
1.3 , hysical ro"erties 1./ , re"aration 1.0 , Chemical "ro"erties
1.1 , ntroduction 1.2 , Nomenclature
1.0
Reaction with ,Reaction with ,
cyl chloride
cyl chloride
cid anhydridecid anh
ydride
'en!enesul"honyl'en!enesul
"honyl
chloridechloride
Nitrous acidNitrous acid
'romine water'romine water
ormation of dye
R-N-H
R'
+ Cl-S-
O
O
OH-
2 amineo
O
O
-S-R-N
R'
(precipitate)
NN-disubstitutedbenzenesulphonamides
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33 amineaminess
3 amine do not #ives visible reactionwith ben!enesul"honyl chloride
1 amineswhite "reci"itate clear
solution
NaH
ummary of Hinsber#$s test,
2 amines
white "reci"itate
do notdissolved
NaH
3 aminesdo not #ive any visible
chan#e
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Reaction with nitrous acid (NaN2+ HCl)
Nitrous acid (HN2) is a wea4 and unstableacid.
t is always "re"ared in situ& by treatin#
cold sodium nitrite (NaN2)with an
a*ueous solution of a cold dilutehydrochloride acid (-0C).
Nitrous acid reacts with all classes of
amines
Nitrous acid test can be used to distin#uish,51 ali"hatic and 1 aromatic amines51 and 2 ali"hatic amines
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rimary ali"hatic amines react with
nitrous acidto yield hi#hly unstable
aliphatic diaonium salts
11 amineamines (Aliphatic)s (Aliphatic)
C!C + ROH + R"bservation ,
ormation of #as bubbles
(N2)
R-N-H
H
1 amineo
NaNO2 H"
-# to $ Co% R-N N" &
+
aliphaticdiazonium salt
(unstable)
-N2R
++
"
-
carbocation
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rimary arylamines react with nitrousacidto #ive arenediaonium salts
11 amineamines (Aromatic)s (Aromatic)
NH2N2
+Cl
+NaN2& HCl
cold
NaCl H2+
arenediazonium salt
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rimaryali"haticamines
orm a mi6ture of al!enes&alcohols& al!yl halidesandnitro#en #as.
econdary
ali"haticamines
orm secondary "-
nitrosaminesas yello# oil&whichis stable under thereaction conditions.
1 ali"hatic amines and 2 ali"hatic amines
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Reaction with bromine water
niline reacts with a$ueous bromineto
yield #hite precipitates
"H2#rou" is an acti%atingand ortho-
para directors group
+
NH2 NH2
'r
'r
'r3'r2(a*)
room tem"erature 3H'r
(2&/&7-tribromoaniline)
bservation, 8hite "reci"itate formed
dentificationtest
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ormation of dye
rimary arylamines react with nitrous acidto #ive arenedia!onium salts which are
stable at & C
renedia!onium salts also under#o coupling
reactionwith aromatic com"ounds with
stron# electron donatin# #rou"& such as 9H
and 9NR2at thepara"osition to yield a!o
com"ounds
!o com"oundsare usually intensely
colouredand relatively ine6"ensive
com"ounds& they are used as dyes
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N N ":
-+
OH
N!N
N
(orane)
OH
CH
CH
N!N
(ellow)
NCH
CH
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