Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
2002-06-20
2004-01-20
Kumar, Shailendra (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C564S237000, C564S230000
Reexamination Certificate
active
06680408
ABSTRACT:
The invention relates to processes for the preparation of &agr;-substituted benzylnitroguanidines. The invention further relates to processes for isolation of &agr;-substituted benzylnitroguanidines from aqueous alcoholic compositions.
BACKGROUND OF THE INVENTION
&agr;-Substituted benzylnitroguanidines can be used as agricultural chemicals to increase crop yields, provide pre-emergent control of weeds, and promote defoliation. Controlled defoliation of plants has important agricultural uses. For example, cotton defoliation prior to harvest eliminates the main source of stain and trash, resulting in better grade cotton.
Speltz et al., U.S. Pat. Nos. 4,594,092, 4,804,780, and 4,944,788, teach the preparation of substituted benzylnitroguanidines by reacting a substituted benzylamine with 2-alkyl-1 (or 3)-nitro-2-thiopseudourea and isolating the solid product by filtration. Speltz et al. also teach the preparation of substituted benzylnitroguanidines by reacting a substituted benzylamine with N-alkyl-N-nitroso-N′-nitroguanidine in the presence of an aqueous aliphatic alcohol solution, followed by removal of the precipitate by filtration and washing of the solid product.
Arotin et al., U.S. Pat. Nos. 4,639,268 and 5,175,365, teach the preparation of substituted benzylnitroguanidines by reacting a substituted benzylamine with a 1-alkyl-3-nitro-1-nitrosoguanidine in the presence of an aqueous aliphatic alcohol solution, followed by removal of the precipitate by filtration and washing of the solid product.
Unfortunately, many prior art processes include steps of filtering and washing substituted benzylnitroguanidines, and such step can result in a loss of product. Additionally, many prior art processes require the use of large amounts of solvents.
There is a need for processes for preparing a-substituted benzylnitroguanidines which do not require the filtering and washing of the &agr;-substituted benzylnitroguanidines. It would be desirable if the processes did not require the use of large amounts of solvents.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to obviate problems of the prior art.
It is a further object of the present invention to provide processes for preparing &agr;-substituted benzylnitroguanidines which do not require the filtering and washing of the &agr;-substituted benzylnitroguanidines.
It is a another object of the present invention to provide processes for isolating &agr;-substituted benzylnitroguanidines from aqueous alcoholic compositions which do not require the filtering and washing of the &agr;-substituted benzylnitroguanidines
According to one aspect of the invention there are provided processes for preparing &agr;-substituted benzylnitroguanidines having the formula (I):
wherein R is an unsubstituted or an OH—or OCH
3
-substituted C
1
-C
3
alkyl, CH
2
OCH
3
, C
6
H
5
, CH
2
C
6
H
5
, or CH
2
CH═CH
2
; and W, X, Y, Z are each individually hydrogen, halogen, OH, straight or branched chain C
1
-C
4
alkyl, straight or branched chain C
1
-C
4
alkoxy; CF
3
, C(OH)
2
CF
3
, OCHF
2
, OCF
3
, NO
2
, OCF
2
CHF
2
, N(CH
3
)
2
, CH
2
N(CH
3
)
2
, CH
2
NH
2
, CH
2
CH
2
COOC
2
H
5
, C
6
H
4
, CH
2
OH, CH
2
OCH
3
, COOCH
3
, CH
2
CH
2
COOC
2
H
5
, OC
6
H
5
, OSO
2
CH
3
, SCH
3
, CN, CH
2
CN or tetrahydro-H-pyran-2-yl; and the salts, tautomers and optical isomers thereof.
The processes for preparing the &agr;-substituted benzylnitro-guanidines comprise the steps of:
(a) providing a reaction mixture comprising water, alcohol, an S-alkyl nitroisothiourea, and an &agr;-substituted benzylamine;
(b) heating the reaction mixture;
(c) steam distilling the alcohol from the reaction mixture; and
(d) isolating an &agr;-substituted benzylnitroguanidine from the remaining water layer.
According to another aspect of the invention there are provided processes for preparing &agr;-substituted benzylnitroguanidine, comprising the steps of:
(a) providing a reaction mixture comprising S-methyl nitroisothiourea, &agr;-substituted benzylamine, water and alcohol;
(b) heating the reaction mixture;
(c) steam distilling the alcohol from the reaction mixture; and
(d) filtering an &agr;-substituted benzylnitroguanidine from the remaining water layer.
According to a further aspect of the invention there are provided processes for isolating of an &agr;-substituted benzylnitroguanidine from a composition comprising water, alcohol and &agr;-substituted benzylnitroguanidines, comprising the steps of:
(a) steam distilling the alcohol from the composition; and
(b) filtering the 1-(&agr;-ethylbenzyl)-3-nitroguanidine from the remaining water layer.
These and additional aspects, objects and advantages of the invention are more fully described in the following detailed description.
DETAILED DESCRIPTION
The present invention is directed to processes for the preparation of &agr;-substituted benzylnitroguanidines and processes for isolation of &agr;-substituted benzylnitroguanidines from aqueous alcoholic compositions.
The &agr;-substituted benzylnitroguanidines which may be prepared using processes in accordance with the invention include compounds of the formula (I):
wherein R is a C
1
-C
3
alkyl optionally substituted with OH or OCH
3
;
CH
2
OCH
3
, C
6
H
5
, CH
2
C
6
H
5
, or CH
2
CH═CH
2
; and W, X, Y, Z are each individually hydrogen, halogen, OH, straight or branched chain C
1
-C
4
alkyl, straight or branched chain C
1
-C
4
alkoxy; CF
3
, C(OH)
2
CF
3
, OCHF
2
, OCF
3
, NO
2
, OCF
2
CHF
2
, N(CH
3
)
2
, CH
2
N(CH
3
)
2
, CH
2
NH
2
, CH
2
CH
2
COOC
2
H
5
, C
6
H
4
, CH
2
OH, CH
2
OCH
3
, COOCH
3
, CH
2
CH
2
COOC
2
H
5
, OC
6
H
5
, OSO
2
CH
3
, SCH
3
, CN, CH
2
CN or tetrahydro-H-pyran-2-yl; and the salts, tautomers and optical isomers thereof.
The &agr;-substituted benzylnitroguanidine salts include inorganic salts, such as alkali metal, alkaline earth metal, Co, Cu, Zn, and Ag salts, and organic amine salts, such as ammonium compounds having the structure, N
+
R
a
R
b
R
c
R
d
, wherein R
a
, R
b
, R
c
, and R
d
are each independently selected from hydrogen and C
1
-C
30
straight or branched chain alkyl optionally substituted with one or two OH, C
3
-C
6
alkenyl or C
3
-C
6
alkynyl groups. Preferred salts include the sodium, calcium, magnesium, potassium, ammonium, methylamine, trimethylamine, dodecylamine, tributylamine, diisopropylamine, triethylamine, tetrabutylamine, and tallow-amine salts of the substituted guanidine.
In one embodiment R is CH
3
, C
2
H
5
, CF
3
, n-C
3
H
7
, CH
2
OCH
3
or CH
2
CH═CH
2
. In another embodiment R is CH
3
, CF
3
, C
2
H
5
, or C
6
H
5
. In one preferred embodiment R is C
2
H
5
.
In one embodiment W, X, Y, Z are each individually hydrogen, halogen, OH, straight or branched chain C
1
-C
4
alkyl, straight or branched chain C
1
-C
4
alkoxy; CH
2
OH, or CH
2
OCH
3
. In another embodiment W, X, Y, Z are each individually hydrogen, halogen, OH, OCH
3
, OC
2
H
5
, OC
3
H
7
-n, OC
4
H
9
-sec, OCF
3
, F, Cl, Br, I, CH
3
, C
2
H
5
, CF
3
, or CN. In one preferred embodiment W, X, Y and Z are all hydrogen.
In one embodiment the &agr;-substituted benzylnitroguanidines prepared using processes in accordance with the invention are selected from the group consisting of (+)isomers, (−)-isomers and mixtures thereof of compounds having the formula (I) wherein R is CH
3
, C
2
H
5
, CF
3
, n-C
3
H
7
, CH
2
OCH
3
or CH
2
CH═CH
2
; W is hydrogen, o-F, m-F, p-F, m-OCH
3
, m-OH or p-Cl; and X, Y, and Z are all hydrogen, and the salts, tautomers and optical isomers thereof.
Examples of &agr;-substituted benzylnitroguanidines include 1-(&agr;-methylbenzyl)-3-nitroguanidine, 1-(&agr;-ethylbenzyl)-3-nitroguanidine, 1-(&agr;-ethyl-m-fluorobenzyl)-3-nitroguanidine, 1-(&agr;-ethyl-m-methoxybenzyl)-3-nitroguanidine, 1-(o-fluoro-&agr;-methylbenzyl)-3-nitroguanidine, 1-(p-fluoro-&agr;-methylbenzyl)-3-nitroguanidine, 1-(&agr;-trifluoromethylbenzyl)-3-nitroguanidine, 1-(&agr;-propylbenzyl)-3-nitroguanidine, 1-(&agr;-methyoxymethyllbenzyl)-3-nitroguanidine, and 1-(&agr;-allylbenzyl)-3-nitroguanidine.
In one pr
Desai Vijay C.
Mayes David M.
Rivadeneira Eric
Bayer Cropscience LP
Gil Joseph C.
Henderson Richard E. L.
Kumar Shailendra
LandOfFree
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