Chemistry Reference
In-Depth Information
CH
3
CH
3
Si
H
2
NCONH
2
o
--Xylene
H
3
C
N
N
CH
3
Si
H
3
C
N
N
CH
3
O
O
O
O
N
C
O
Cl
CH
3
CH
3
CH
3
CH
3
12%
513
514
4.3.2
Carbamates
N-Substituted esters of carbamic acid (carbamic acid is the mono-amide of car-
bonic acid) are compounds containing the -NHCOOR group, and are named car-
bamates or urethanes. Urethane (or urethan) is also used as a name for ethyl carba-
mate 515, NH
2
COOEt (a compound which has been shown to act as a carcinogen
in some animals), and sometimes even for the whole class of carbamate esters. It
is formed by reaction of ethanol with isocyanic acid 516 or urea 517. Since ''ure-
thane'' nomenclature may be confusing there is little justification in its continued
use.
H
3
C
O
2
+
HNCO
H
3
C
H
O
516
515
H
2
N
D
+
2
H
3
C
H
O
517
As outlined in Scheme 4.2, carbamates are formed when chloroformates (R
2
OCOCl )
or N,N-disubstituted carbamoyl chlorides (R
1
R
3
NCOCl ) are treated with primary
amines or alcohols, respectively [359-362]. One equivalent of a base such as a ter-
tiary amine is used to promote these reactions.
N
R
2
O l
O
R
2
O
R
1
NH
2
R
1
+
O
518
R
3
R
3
R
1
N
l
R
2
ON
O
R
2
OH
+
R
1
O
519
