Chemistry Reference
In-Depth Information
Phenyl ketoxime carbamates, which are useful as selective herbicides, were pre-
pared by treating a phenyl ketoxime with either a base and a carbamoyl halide or
phosgene and a substituted amine. Field tests demonstrating the e
cacy of emul-
sions of 316 as pre- and post-emergence herbicides in the presence of Loium per-
enne (English ryegrass), Avena sativa (oats), Beta vulgaris (beet), and Sinapis alba
(mustard) have been reported [242].
R
1
R
2
R
1
R
2
R
1
R
2
HNR
3
R
4
COCl
2
O
O
R
3
N
N
N
O
N
OH
O
Cl
R
4
316
R
1
, R
2
, R
3
, R
4
= Ph, Me, allyl, allyl
2-MeOC
6
H
4
, Me, Me, Me
2-O
2
NC
6
H
4
, Me, Me, Me
Ph, Me,
i
Pr,
i
Pr
Organic azidoformates, R(O
2
CN
3
)
n
, exhibit high biological activity and are useful
as fungicides and bacteriocides [243]. Such compounds are prepared by the reac-
tion of a cyclic organic haloformate with an azide (see Chapter 4). The haloformate
is prepared by passing phosgene through a solution of a hydroxy-substituted cyclic
hydrocarbon and heating the solution to reflux.
NaN
3
was added to a solution of 317 in dry acetone. The resulting mixture was
stirred under reflux for 2 h to yield 318.
O
l
OH
O
N
NaN
3
3
COCl
2
O
O
dry Me
2
CO
317
318
The compounds ( p-N
3
CO
2
C
6
H
4
)
2
CMe
2
(75.4%), [3,5,4-Cl
2
(N
3
CO
2
)C
6
H
2
]
2
CMe
2
,
and 1-naphthyl azidoformate (100%) were prepared in a similar manner.
5.4
Topics in Polymer Synthesis
The main uses of phosgene are in the production of isocyanates and polycarbonates.
Whilst not involving any new chemistry (as far as phosgene is concerned), the
scope for preparation of new polymeric materials is enormous, if not infinite.
5.4.1
Polyurethanes
The production of isocyanates represents the major output. Reaction of diisocya-
nates with polyhydroxylic compounds is the basis of polyurethane manufacture
