Chemistry Reference
In-Depth Information
10.3 carBamate InSectIcIdeS
The chemical and biological properties of carbamate insecticides (CBs) are described
in some detail in the texts of Kuhr and Dorough (1976) and Ballantyne and Marrs
(1992). An early model for their development was physostigmine, a natural product
found in Calabar beans. Many CBs came into use during the 1960s, sometimes as
substitutes for banned OC insecticides.
10.3.1 c
h e m i c a l
p
r o p e r T i e s
The general structure of CBs, with some examples, are given in Figure 10.6. As can
be seen, CBs are derivatives of carbamic acid, the unstable monoamide of carbonic
acid. CBs have one, occasionally two, methyl groups attached to the nitrogen atom.
A range of different organic groups are linked to the oxygen atom. The nature of
the R group is an important determinant of the properties of CBs. Distinct from
these compounds are carbamate herbicides, many of which have relatively complex
R groups attached to nitrogen (see Figure 13.1 and Hassall 1990 for further details).
The properties of some CBs are given in Table 10.3.
O
O
CH
3
C
O
NH(or CH
3
)
C
R
R = Organic group
HO
NH
2
Carbamic acid
Carbamate insecticide
Commercial insecticides
H
O
H
O
H
H
OC
NCH
3
O
C
N
CH
3
CH
3
O
CH
3
(CH
3
)
2
OC
H
O
CO
N
H
Carbaryl
Propoxur
CH
3
O
H
3
H
Carbofuran
CH
3
S
C
C
H
N
O
CN
CH
3
CH
3
Aldicarb
Natural product
CH
3
OC
O
NCH
3
H
N
N
CH
3
CH
3
Physostigmine
fIgure 10.6
Some insecticidal carbamates.
Search WWH ::
Custom Search