FIELD OF THE INVENTION 
This invention relates to certain arylphosphonoamidate compounds which 
demonstrate herbicidal activity. 
The article by Kamai et al, Zh. Obshch. Khim., vol. 42, p. 1295 (1972) 
discloses some phenylmethylphosphonoamidates which are said to show "weak 
herbicidal activity". British Patent Application 2,037,771 of Sandoz Ltd. 
discloses some .alpha.-substituted or .alpha.,.alpha.-disubstituted 
benzylphosphonic acid esters, including ester amides, as herbicides. 
DESCRIPTION OF THE INVENTION 
According to this invention, compounds of the following structure have been 
found to exhibit herbicidal activity: 
##STR2## 
in which R is halogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, 
C.sub.1 -C.sub.4 haloalkoxy, C.sub.1 -C.sub.4 alkylcarbamoyl, C.sub.1 
-C.sub.4 mono- or dialkylamino, phenoxy or nitro; 
n is 0, 1 or 2; 
X is oxygen or sulfur; 
R.sub.1 is C.sub.2 -C.sub.8 alkyl, C.sub.3 -C.sub.6 cycloalkyl, phenyl, 
2-trifluoromethylphenyl, 3-trifluoromethoxyphenyl, 4-methoxyphenyl, 
4-nitrophenyl, 3,4-dichlorophenyl or benzyl; 
R.sub.2 is hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 cycloalkyl, 
phenyl, C.sub.3 -C.sub.6 alkenyl or C.sub.3 -C.sub.6 alkynyl; and 
R.sub.3 is C.sub.2 -C.sub.6 alkyl, C.sub.3 -C.sub.6 cycloalkyl, phenyl, 
phenyl(C.sub.1 -C.sub.2)-alkyl, 3,4-methylenedioxyphenyl or pyridyl; or 
R.sub.2 and R.sub.3 taken together with the nitrogen atom form a 4-7 member 
ring; 
provided that: 
a) if X is sulfur, R.sub.2 is not hydrogen; and 
b) if R.sub.2 is hydrogen, R.sub.3 is alkyl, cycloalkyl or phenylalkyl. 
Some compounds within this genus are known in the art by way of articles 
relating to research in organic chemical synthesis or spectroscopy, but 
have not been disclosed as having any use, particularly not any herbicidal 
use. Such references include Duddeck et al, Phosphorus and Sulfur, vol. 
29, p. 169 (1987); Petrov et al, Zh. Prikl. Khim., vol. 37, p. 429 (1974); 
Rizpolozhenskii et al, Izv. AN SSR, ser. khim., p. 622 (1970); Shagidullin 
et al, it., p. 1024 (1974); and Genkina et al, Zh. Obshch. Khim., vol. 40, 
p. 1496 (1970). Burger et al, JACS, vol. 79, p. 3575 (1957) discloses some 
pharmaceuticals. Some compounds within formula (I) in which R.sub.1 is 
benzyl have been disclosed as fungicides in Japanese Patent Publications 
43/4341 and 43/5746 (1968) of Sumitomo. 
However, many of the compounds of this invention are novel and thus form a 
second aspect of the invention. These compounds have the formula 
##STR3## 
in which: R is halogen, C.sub.1 -C.sub.4 alkyl, C.sub.1 -C.sub.4 alkoxy, 
C.sub.1 -C.sub.4 haloalkoxy, C.sub.1 -C.sub.4 alkylcarbamoyl, C.sub.1 
-C.sub.4 mono- or dialkylamino, phenoxy or nitro; 
n is 0, 1 or 2; 
X is oxygen or sulfur; 
R.sub.1 is C.sub.2 -C.sub.8 alkyl, C.sub.3 -C.sub.6 cycloalkyl, phenyl, 
2-trifluoromethylphenyl, 3-trifluoromethoxyphenyl, 4-methoxyphenyl, 
4-nitrophenyl or 3,4-dichlorophenyl; 
R.sub.2 is hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.3 -C.sub.6 cycloalkyl, 
phenyl, C.sub.3 -C.sub.6 alkenyl or C.sub.3 -C.sub.6 alkynyl; 
R.sub.3 is C.sub.2 -C.sub.6 alkyl, C.sub.3 -C.sub.6 cycloalkyl, phenyl, 
phenyl(C.sub.1 -C.sub.2)-alkyl, 3,4-methylenedioxyphenyl or pyridyl; or 
R.sub.2 or R.sub.3 taken together with the nitrogen atom form a 4-7 member 
ring; 
provided that: 
a) if X is sulfur, R.sub.2 is not hydrogen; 
b) if R.sub.2 is hydrogen, R.sub.3 is alkyl, cycloalkyl or phenylalkyl; 
and further excluding the compounds in which: 
1) X is oxygen, R.sub.1 is ethyl, R.sub.2 is hydrogen and R.sub.3 is 
n-butyl or pyridyl; 
2) X is oxygen, R.sub.1 is ethyl, R.sub.2 is ethyl and R.sub.3 is phenyl; 
or 
3) X is oxygen, R.sub.2 and R.sub.3 are both ethyl and R.sub.1 is n-butyl, 
isobutyl or isoamyl. 
Preferred compounds are those in which R.sub.n includes halogen 
(particularly 3-halo), alkoxy (particularly methoxy), and haloalkoxy 
(particularly trifluoromethoxy); X is oxygen; R.sub.1 is C.sub.2 -C.sub.6 
alkyl; R.sub.2 is C.sub.1 -C.sub.6 alkyl; and R.sub.3 is C.sub.2 -C.sub.6 
alkyl, phenyl, 3,4-methylenedioxyphenyl or pyridyl. 
The term "alkyl" includes straight and branched chained saturated acyclic 
hydrocarbyl moieties having the indicated number of carbon atoms. 
Preferred alkyl groups include methyl, ethyl, n-propyl, isopropyl, 
n-butyl, s-butyl, t-butyl, i-butyl, n-amyl and n-hexyl. The term 
"cycloalkyl" includes saturated cyclical hydrocarbyl moieties, such as 
cyclopentyl and cyclohexyl. The terms "alkenyl" and "alkynyl" indicate 
unsaturated straight or branched chain hydrocarbyl groups having an 
olefinic and acetylenic bond, respectively. The terms "halogen" or "halo" 
include chloro, bromo, fluoro and iodo. 
As used herein, the term "herbicide" means a compound or composition which 
adversely controls or modifies the growth of plants. By the term 
"herbicidally effective amount" is meant any amount of such compound or 
composition which causes an adverse modifying effect upon the growth of 
plants. By "plants", it is meant germinant seeds, emerging seedlings and 
established vegetation, including roots and above-ground portions. Such 
controlling or modifying effects include all deviations from natural 
development, such as killing, retardation, defoliation, desiccation, 
regulation, stunting, tillering, leaf burn, dwarfing, and the like. 
The compounds of this invention have been found to be active herbicides, 
particularly post-emergent herbicides; i.e. they may be applied to control 
or kill existing vegetation which has already emerged from the soil. Some 
of the compounds of this invention have demonstrated such post-emergence 
herbicidal activity in a relatively short time, and against some weeds, 
with a very strong effect. Herbicides having such rapid and extensive 
post-emergence activity are sometimes referred to as "contact and burn" or 
"burn-down" herbicides and are used, among other applications, for 
clearing vegetation from land such as building lots, highway median 
strips, railroad track beds, and crop land prior to planting or in minimum 
till or no-till farming. Some of the compounds of this invention also 
demonstrate pre-emergence activity, that is, control or killing of 
vegetation by application prior to the emergence of vegetation from the 
soil. Pre-emergence herbicides may be applied by techniques such as 
incorporation into, or spraying or spreading onto, the surface of the 
soil. 
Compounds showing "contact-and-burn" effect, but little or no pre-emergence 
activity, may be useful in clearing land prior to planting since planting 
of a crop can be done relatively soon after the herbicide is applied. 
The compounds of this invention may be prepared from starting 
phosphonodichlorides, amines and appropriate alcohols or thiols or their 
metal (particularly alkali metal) salts, in one or two steps, by the 
general reaction 
##STR4## 
in which M is hydrogen or an alkali metal (preferably sodium or 
potassium). 
This process may be conducted in a single step, or stepwise, in sequence. 
In the latter case, the phosphonyl dichloride may be reacted first with 
two equivalents of an amine, followed by isolation and purification of the 
chloroamide intermediate, which can then be treated with an alkali metal 
salt of the appropriate alcohol. Alternatively, the phosphonyl dichloride 
may be treated with an alcohol in the presence of a tertiary amine base 
such as triethylamine, and the intermediate chloroester reacted with two 
equivalents of the appropriate amine, preferably without isolation. 
Single-step processes of this type in general are carried out at 
temperatures of from about -60.degree. to about +50.degree. C., preferably 
from about -20.degree. to about +25.degree. C. Hydrogen chloride or amine 
hydrochloride salt produced is generally removed by washing with water. 
Two-step processes in which the dichloride is first reacted with an amine 
are preferably carried out at temperatures of from about -20.degree. to 
+25.degree. C. Those in which the first step is a reaction between the 
dichloride and an alcohol conduct this step at a temperature of between 
about -40.degree. and +25.degree. C., with the second step at 25.degree. 
C. up to reflux temperature. 
All processes are carried out in the presence of a solvent, such as an 
aromatic solvent (preferably toluene) or tetrahydrofuran. 
The following represent examples of preparation of compounds of this 
invention: