Field of the Invention
This invention relates to produce a neonicotinoid insecticide by an improved
process of preparation of Imidaclothiz having excellent insecticidal activity.
Background of the Invention
According to prior art there are publications that describe about processes for
preparation of Imidaclothiz and other thiazole derivatives. Nantong Jiangshan
Agrochemical Co Ltd. developed the process of Imidaclothiz by condensation
reaction of 2-chloro-5-chloromethylthiazole (CCMT) and 2-nitroaminoimidazoline
(NII) with acid binding agent using solvent and a catalyst. The main side effect of
condensation reaction of Imidaclothiz is bis substitution of 2-
nitroaminoimidazoline resulting in formation of an impurity. In the process
described above , CCMT is easy to decompose and no optimum parameters are
described to control the formation of impurity of bis substitution of NII which in
turn affects the purity of Imidaclothiz. NII used 1.05 mole for 1 mole of CCMT
and less water for cleaning of excess NII. According to Chinese journal of
chemistry 28(3), 475-479, 20 10, Imidaclothiz is prepared by condensation of
CCMT and NII. But not much information is provided for removal of impurity
formed in the reaction, yield and the purity of the material.
With respect to PCT Int. Appl. WO 9832747 A1 , PCT Int. Appl (1998), WO
9827074 A1 and and Wu Guifang et a1 , 1401 646, 12 Mar. 2013 the details for
other thiazole derivatives and preparation of Imidaclothiz has not been provided.
Despite the aforesaid publications and the Nantong Jiangshan process that poses
difficulty in eliminating the byproduct generated due to bis substitution of NII as
they crystallize the crude material by ethanol and 5% HC1 i.e. in acidic condition,
therefore there is a need to develop an improved process for preparing
Imidaclothiz, which increases the yield, purity of the product as the byproduct is
eliminated by crystallizing the crude material with 80% methanol at pH 9-10.
According to the present process, NII uses 1.3 moles for 1 mole of CCMT and 5-
10% water is used for cleaning of excess NII.
Advantages and usefulness of the proposed invention
The product has many features and uses. They are as follows:
1. Strong absorption of pesticides: Activity of Imidaclothiz is very high for
I
example it is 20 times more active than Imidacloprid.
2. Independent of temperature to the level of restrictions: Imidaclothiz is
I
independent of high and low temperature. It overcomes Acetamiprid,
Imidacloprid and other Neonicotinoids in the control effect of low
temperature shortcomings.
3. Resistance: Imidaclothiz new single-dose pesticide varieties, currently in the
use a wide range of pests has no resistance
4. Low toxicity: Imidaclothiz is having low toxicity, in line with the
requirements of pollution-free agricultural production
5. Broad spectrum: Imidaclothiz is a broad spectrum insecticide available for a
variety of crops for prevention and treatment of rice leafhoppers, plant
hoppers, thrips, coleopteran, Diptera and Lepidoptera pests, also effective,
especially for the rice step borer and yellow stem borer. Other
Neonicotinoids like Acetamiprid and Imidacloprid can not match the
Imidaclothiz in broad spectrum.
6. Low cost: Imdiaclothiz control efficiency is 3-5 times more than that of
Acetamiprid, Imidacloprid and thiamethoxam. Hence less quantity is used
per acre of land. = 20 grams
7. Formulation: 10% wettable powder
0~~~5'"'
\BttO 3 bf\ I k LObjectives
of the Invention
The main objective of the present invention is to provide a process for the
preparation of Imidaclothiz and improve the yield and purity of Imidaclothiz.
Another objective of the present invention is to provide a process for the
preparation of Imidaclothiz that is low in cost and toxicity and is independent of
temperature.
Yet another objective of the present invention is to provide a process for the
preparation of Imidaclothiz that has a strong insecticidal activity as compared to
other insecticides like Imidacloprid, Acetamiprid and Thiamethoxam.
Summary of the Invention
The present invention relates to a process for preparing Imidaclothiz having the
formula with IUPAC name: c, NH-NO,
I 7 N q
C I
lm~daclothtz
EZ- 1 -[2-chloro- l,3-thiazol-5-yl methyl)-N-nitroimidazolidin-2-ylideneamine or 1 -
[(2-chloro-5-thiazolyl) methyl] methyl]-4,5-di hydro-N-nitro- 1 H-Imidazol-2 amine
or 1H-Imidazol-2-amine, 1 -[(2-chloro-5-thiazoly) methyl]-4,5- di hydro-N-nitro
Details of the product
Category : Neonicotinoid insecticide
4
Molecular Formula
Molecular weight
Melting point : 146.8 - 1473°C
CAS : 105843-36-5
Imidaclothiz is prepared by condensation reaction of CCMT and NII in the
presence of a catalyst and a s vent using acid binding agent 0' with strictly
controlling the temperature. From the reaction mechanism, the impurity is formed
due to bis substitution of NII. The formation of the impurity gets reduced as
quantity of NII is increased. According to a comparative study the impurity formed
in the reaction according to ratio of CCMT and NII, the material recipe impact is
given in the table below:
From the above data it is clear that impurity formed get reduced as quantity of NII
increases. Moreover unreacted NII also increases. After other batches were taken it
was optimized the quantity of NII in the ratio CCMT: NII = 1 : 1.29 as unreacted
NII is easily removed by filtering the material in water at 65-70°C. Crystallization
of wet crude material was performed at different pH to remove the impurity from
the material. It was optimized that impurity comes in the filtrate during
crystallization with methanol at pH 9-10. In the acidic condition the impurity
remains in the material after crystallization This is the innovative point in our
process to remove the impurity from the crude material during crystallization in
alkaline media.
B. No.
11
I2
I3
I4
CCMT
1 .OO
1 .OO
1 .OO
1 .OO
NII
1.04
1.29
1.40
1.80
Impurity
3.27
2.03
1.54
0.53
NII
unreacted
13.36
19.62
28.43
37.52
Details Description of the Process
According to preferred embodiment of the present invention for preparing
Imidaclothiz there are steps to carry out the process.
Following are the steps:
a. Condensation reaction of 1 mole of CCMT with 1.25-1.30 mole of NII in the
presence of an acidic binding agent, DMAP (Dimethyl amino pyridine) as the
catalyst and 80 % methanol as the solvent The reaction is given below: Cr NH-NO2
k ' C H 2 C l + HN 1"' \N - I + HCI
C I U "2F
CCMT NII 1
Cl
Imidaclothiz
NII exists in two forms due to tautomerism
A HN \N . 1
HN u Tautomerism
NII NII
In the condensation reaction of Imidaclothiz, bis substitution of 2-
nitroaminoimidazoline takes place which is a side effect of the condensation
reaction and forms an impurity.
b. NII, methanol and NaOH are taken in a reactor and agitated, while the CCMT
solution is trickled at a specified temperature in 6-7 hours.
c. Monitoring the reaction mechanism by Gas Chromatography (GC) and is
considered complete when CCMT is < 0.5% and NII is 12-15%. The solvent is
recovered under vacuum.
d. Addition of the water to the material and agitating it at 65-70°C for 30 minutes.
The material is filtered at 65OC to remove unreacted NII that comes in the filtrate
after removal of the solvent. From the filtrate, NII is recovered and is used for
further batches.
e. The pH of the wet crude material is checked and brought between 9-1O.The
crude material is crystallized by 80% methanol at pH 9-10 in the alkaline media to
eliminate the byproduct generated in the bis substitution of NII.
The quantity of NII is optimized so that byproduct formed and excess MI are
eliminated easily from the material. Material of the purity of 97-98% with 82%
yield is obtained.
According to another embodiment of the present invention comparatives studies
showed that the impurity formed in the reaction gets reduced as quantity of NII
increases. Moreover unreacted NII also increases. The quantity of NII was
optimized in the ratio CCMT: NII = 1: 1.29 as unreacted NII is easily removed by
filtering the material in water at 65-70°C. In the acidic condition the impurity
remains in the material after crystallization
The invention is described herein is illustrative only and should not be construed
to limit the scope of the present invention in any manner.
*
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We claim
1. A process for preparing Imidaclothiz , comprising the steps of :
a) condensation reaction of CCMT and NII in the presence of an acidic binding
agent, a solvent and a catalyst resulting in the formation of an impurity due
to bis substitution of said NII;
C r N H - N O 2
k,'CH2CI + HN 1"' \N - I + HCI
CI
CCMT
U
NII 7
.=is
C I
Imidaclothiz
b) optimization of said NII to remove said impurity and excess of said NII by
crystallization of said material with said solvent at pH between 9-10 in an
alkaline media; and
c) addition of water to said material and agitating said material between 65-
70°C for 30 minutes, wherein said material is filtered to remove unreacted
NII which increases with decrease in said impurity, thereby resulting in the
formation of a pure material.
2. A process for preparing Imidaclothiz as claimed in Claim 1, wherein said
catalyst is DMAP (Dimethyl amino pyridine).
3. A process for preparing Imidaclothiz as claimed in Claim 1,wherein
percentage of said solvent is 80%.
4. A process for preparing Imidaclothiz as claimed in Claim 1, wherein said
reaction uses 1 mole of said CCMT and 1.25- 1.30 mole of said NII.
8
5. A process for preparing Imidaclothiz as claimed in Claim 1, wherein said
process produces said material with 82% yield and 97-98% purity.
6. A process for preparing Imidaclothiz as claimed in Claim 1, wherein
percentage of said CCMT is less than 0.5%.
7. A process for preparing Imidaclothiz as claimed in Claim 1, wherein
percentage of said NII is between 12- 15 percent.
8. A process for preparing Imidaclothiz as claimed in Claim 1, wherein said
material is filtered at 65OC.
9. A process for preparing Imidaclothiz as claimed in any of the previous
claims substantially as herein described with reference to foregoing
examples.
Dated : 10 February 20 14 Attorney for the Applicant
Abstract
Process for preparing Imidaclothiz
A process for preparing Imidaclothiz that involves condensation reaction of
CCMT and NII in the presence of an acidic binding agent, a solvent and a
catalyst resulting in the formation of an irnp~rity~optimizinNg II to remove
impurity and excess of NII by crystallization at pH between 9-10 in an
alkaline media, adding water to the material and agitating between 65-70°C
for 30 minutes to remove unreacted NII which increases with decrease in
said impurity, thereby resulting in the formation of a material with 97-98%
purity.