This invention relates to the herbicide N,N'-(N''-isopropylcarbamyl,N'''-isopropylcarbamyl)-S-ethylisothiourea, its use and process for making the same.

This invention relates to a herbicide compound. More specifically, this 
invention relates to a single compound that is selective to sugarcane and 
plantation crops such as coffee, citrus fruits, mangoes and the like.

DESCRIPTION OF THE INVENTION 
It has been found that the compound identified as 
N,N'-(N''-isopropylcarbamyl,N'''-isopropylcarbamyl)-S-ethylisothiourea has 
very selective herbicidal activity in regard to sugarcane and plantation 
crops. This compound is not tolerant to crops such as corn, cotton, 
soybeans, sunflower and rice. 
The process of manufacturing this compound is basically a twostep operation 
as follows: 
(a) One mole of thiourea is reacted with 1.0 to 1.6, preferably 1.1 moles 
of ethyl bromide, ethyl iodide or ethyl chloride in the presence of a 
polar solvent such as water or ethyl alcohol. This reaction is carried out 
at reflux temperature or under pressure at elevated temperature to form 
S-ethylisothiouronium halide intermediate compound. 
(b) The S-ethylisothiouronium halide salt formed in step (a) is reacted 
with isopropyl isocyanate in the presence of triethylamine, alkali metal 
carbonate such as sodium or potassium carbonate or sodium or potassium 
bicarbonate in the presence of a polar solvent such as dioxane, 
dimethylsulfoxide, dimethylformamide, ethyl acetate or water with a 
non-polar co-solvent such as toluene. This reaction is carried out at 
temperatures ranging between ambient and about 100.degree. C. to form the 
product 
N,N'-(N"-isopropylcarbamyl,N"'-isopropylcarbamyl)-S-ethylisothiourea. When 
the reaction of this step is completed, the solution is washed with dilute 
hydrochloric acid and/or water and the organic phase is stripped to give 
the product. If triethylamine is used, the aqueous layer is made basic 
with 50% caustic and the triethylamine is separated, distilled and 
recycled. The aqueous layer is neutralized and discarded and the 
distillation residues are also discarded. 
The reaction, as noted in steps (a) and (b) above, provide a yield of about 
70-90% of the end product. The isopropyl isocyanate used in step (b) as 
defined above is normally purchased from the open commercial market, but 
can be manufactured by reacting isopropylamine with phosgene in the 
presence of an inert solvent to provide isopropyl isocyanate. 
The compound of this invention is active as a pre-emergent surface 
herbicide and as a post-emergent surface applied herbicide. In order to 
illustrate the merits of this herbicide, the following Table is provided 
on the test procedures. 
The active ingredient of the application was formulated into an acceptable 
form for spraying. Thus, a solution was made containing 240 milligrams 
(mg) of herbicide in a 1:1 mixture of 20 milliliters (ml) acetone and 20 
ml of water. To this mixture was added 1% by volume Tween.RTM. 20 
(polyoxyethylene sorbitan monolaruate). In all of the tests, the 
cultivated plants were reared from seed in trays containing a sandy, 
fumigated soil. For the pre-emergent surface (PES) tests, the trays were 
seeded the day prior to application. For the post-emergent (POES) tests, 
the trays were seeded 12 days prior to application. At the proper time, 
the trays were sprayed with the active ingredient at various levels of 
application for treatment. The treated plants were kept at optimum light, 
water and temperature during the test procedures. The results of this test 
are as follows. 
TABLE I 
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Rate 
Grasses Broadleaves Perennials 
kg/ha 
BRP 
CEE 
DIH 
ECG ELI 
SEG 
X ACH BIP 
BRC 
CAO CON EMS 
IPA 
SIR 
X SOH CYR 
__________________________________________________________________________ 
% WEED CONTROL - PRE-EMERGENT APPLICATION 
0.25 
0 0 0 0 0 0 0 0 0 98 98 75 20 95 0 48 
0 0 
0.50 
95 50 60 98 75 70 75 50 95 100 
100 80 90 100 
60 84 
0 0 
1.00 
98 98 90 100 90 90 94 60 98 100 
100 100 99 100 
80 92 
0 0 
2.00 
99 98 100 
100 95 96 98 90 98 100 
100 100 100 
100 
90 97 
0 0 
4.00 
100 
100 
100 
-- 100 
100 
100 
100 100 
-- 100 -- 100 
100 
90 99 
-- -- 
% WEED CONTROL - POST-EMERGENCE APPLICATION 
0.25 
50 0 51 90 05 
15 28 80 0 100 
90 90 0 -- 95 65 
0 0 
0.50 
100 
95 20 100 15 25 59 100 80 100 
95 95 100 
-- 100 
96 
0 30 
1.00 
100 
98 30 100 30 50 68 100 90 100 
95 100 100 
-- 100 
98 
50 50 
2.00 
100 
100 
40 100 25 80 74 100 95 100 
100 100 100 
-- 100 
99 
80 80 
__________________________________________________________________________ 
X = Average 
-- = not tested 
kg/ha -- kilograms/hectare 
BRP = Brachiaria plantaginea 
CEE = Cenchrus echinatus 
DIH = Digitaria horizontalis 
ECG = Echinochloa crusgalli 
ELI = Eleusine indica 
SEG = Setaria geniculata 
ACH = Acanthospermum hispidum 
BIP = Bidens pilosa 
BRC = Brassica campestris 
CAO = Cassia occidentalis 
CON = Commelina nudiflora 
EMS = Emilia sonchifolia 
IPA = Ipomoea acuminata 
SIR = Sida rhombifolia 
SOH = Sorghum halepense 
CYR = Cyperus rotundus 
TABLE II 
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CROP SELECTIVITY: PRE-EMERGENT AND 
POST-EMERGENT APPLICATIONS 
Rate 
kg/ha Corn Cotton Soybeans 
Sunflower 
Rice Sugarcane 
______________________________________ 
% Control - Pre-Emergent 
0.25 0 0 40 30 50 0 
0.50 10 10 70 100 95 0 
1.00 70 60 80 100 100 0 
2.00 100 100 90 100 100 0 
% Control - Post-Emergent 
0.25 5 35 60 100 95 0 
0.50 40 80 90 100 100 0 
1.00 95 90 95 100 100 45* 
2.00 100 100 95 100 100 50* 
______________________________________ 
kg/ha = kilogram/hectare 
*Stunted, but recovered. 
As can be seen from the above tables, the compound of this invention is 
very active as a broadleaf and grass control compound and is very 
selective in its crop tolerances. Specifically, sugarcane is the only one 
that is tolerant at all rates. 
The same pre-emergent and post-emergent surface application of the active 
compound of this invention was also applied to citrus and coffee crops 
with the same results. All the weeds as defined above in Table I were 
controlled and there was no residual phytoxicity in regard to the crop 
plants. 
The active compound of this invention can be used in any form, but is most 
preferably formulated with inert adjuvant carriers such as emulsifiable 
concentrate, a powder, liquid, wettable powder, granules, and like 
formulations. The amount of active ingredient used for application can 
range between about 0.25 kg/ha to about 10 kg/ha.