DESC:Simple and Novel Process for Preparation of Diuron
FIELD OF THE INVENTION
The present invention relates to a novel and improved process for the preparation of Diuron [N’-(3,4-Dichlorophenyl)-N, N-dimethylurea] of formula 1 which is a cost effective one pot synthetic process provides superior yield.

formula 1
BACKGROUND OF THE INVENTION
The background description provided herein is only for understanding the present invention and not to be as prior art or relevant to the present invention.
In the field of synthetic agrochemical industry, yield improvement and selectivity of chemical processes have substantial impact on the industry. Along with the improvement, focus is on lowering costs, simplifying operations, and considering the environmental effect of processes are important.
Diuron chemically known as (3-(3,4-dichlorophenyl)-1,1-dimethylurea) and also known as DCMU, is an herbicide and algaecide belongs to aryl urea class which is used in agriculture for pre-emergent and post-emergent control of broadleaved and grass weeds with a long duration of action by inhibiting the photosynthesis in weeds. DCMU is a very specific and sensitive inhibitor of photosynthesis by blocking electron transport at a critical point.
US2768971 A discloses a process for the preparation of diuron by reacting 3,4-dichloroaniline with urea using cyclohexanol and dimethyl amine to produce diuron.
The above said process suffers with several disadvantages i.e., reaction requires high temperature conditions. Said reaction also involves usage of dimethyl amine in gaseous state which requires pressure reactor and additional precaution needed. By considering all the above disadvantages, the above said process is not suitable on commercial scale production.
CN103539704A discloses a process for the preparation of Diuron as shown in the scheme given below:

CN105294504A discloses a process for the preparation of Diuron as shown in the scheme given below:

The above said processes suffers from several disadvantages includes multiple steps, usage of dimethyl amine in gaseous state, time-consuming processes and/or difficult operating procedures, but also limits the yields of product.
Thus, there is a need to develop a process for the preparation of diuron which overcomes above said drawbacks and to provide a product with high yield and purity in low cost which is suitable in large scale production.
The present invention satisfies the existing needs and overcomes the disadvantages found in the prior art by one pot process for the preparation of diuron of formula 1 which involves mild reaction conditions, operating procedures, and cost-effective process. Thus, the present invention involves technical advancement as compared to the existing knowledge and having economic significance that makes the invention not obvious to a person skilled in the art.
OBJECT OF THE INVENTION
The main objective of the present invention is to provide a simple, economical, commercially feasible and cost-effective process for the synthesis of diuron of formula 1 with a high yield and purity which can used in large scale.
SUMMARY OF THE INVENTION
The first embodiment of the present invention provides a process for the preparation of diuron of formula 1.
DESCRIPTION OF THE INVENTION
For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiment illustrated in the figures and specific language will be used to describe them. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Such alterations and further modifications in the illustrated system, and such further applications of the principles of the disclosure as would normally occur to those skilled in the art are to be construed as being within the scope of the present disclosure.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this disclosure belongs. The system, methods, and examples provided herein are only illustrative and not intended to be limiting.
In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings. The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
The term "solvent" used in the present invention refers to but not limited to "non-polar solvents like “hydrocarbon solvents" selected from n-hexane, n-heptane, cyclohexane, petroleum ether, benzene, toluene, xylene or mixtures thereof; "ether solvents" selected from dimethyl ether, diisopropyl ether, diethyl ether, methyl tert-butyl ether, 1,2-dimethoxy ethane, tetrahydrofuran, 1,4-dioxane or mixtures thereof; "ester solvents" selected from methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate or mixtures thereof; "polar-aprotic solvents selected from dimethylacetamide (DMAc), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP) or mixtures thereof; "chloro solvents" selected from dichloromethane, dichloroethane, chloroform, carbon tetrachloride or mixtures thereof; "ketone solvents" selected from acetone, methyl ethyl ketone, methyl isobutyl ketone and thereof; "nitrile solvents" selected from acetonitrile, propionitrile, isobutyronitrile or mixtures thereof; "alcoholic solvents" selected from methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol or mixtures thereof; "polar solvents" selected from water or mixtures thereof.
The term "acid" used in the present invention selected from but not limited to inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, or phosphoric acid; and organic acids such as formic acid, acetic acid, propionic acid, methane sulfonic acid, para toluene sulfonic acid, ethane-1,2-disulfonic acid, camphor sulfonic acid, ethane sulfonic acid, naphthalene-2-sulfonic acid, benzene sulfonic acid, and thereof.
The term “agrochemical acceptable salts” or “salts” described in hereinbefore are obtained by reacting compound with acid selected from the above description.
The term "base" used in the present invention selected from but not limited to inorganic bases selected from "alkali metal carbonates" such as sodium carbonate, potassium carbonate, lithium carbonate and the like; "alkali metal bicarbonates" such as sodium bicarbonate, potassium bicarbonate and the like; "alkali metal hydroxides" such as sodium hydroxide, potassium hydroxide, lithium hydroxide and the like; alkali metal hydrides such as sodium hydride, potassium hydride, lithium hydride and the like; alkali metal amides such as sodium amide, potassium amide, lithium amide and the like; and organic bases like dimethylamine, diethylamine, diisopropyl amine, diisopropylethylamine, diisobutylamine, trimethylamine, triethylamine, tertiary butyl amine, benzyl amine, pyridine, 4-dimethylaminopyridine (DMAP), N-methyl morpholine (NMM), 2,6-lutidine, lithium diisopropylamide; "alkali metal alkoxides" such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, sodium tert.butoxide, potassium tert.butoxide, lithium tert.butoxide mixtures thereof.
The term "room temperature" as used in the present invention herein refers to the temperature in the range from about 25-35°C.
The present inventive process provides a simple synthetic method with less overall reaction time for the industrial preparation of diuron. In this process, we can make the diuron, in one-pot two-step process (without isolation of intermediate), that has several advantages for industrial manufacturing.
The present inventive chemical process describes the one pot two-step synthesis of diuron at industrial scale with high yields and having best quality from the commercially available starting materials, such as 3,4-dichloroaniline, phenyl chloroformate and dimethylamine as follows:

Here, 3,4-dichloroaniline is reacted with phenyl chloroformate in the presence of inorganic base to get phenyl(3,4-dichlorophenyl) carbamate, which up on reaction with aqueous dimethyl amine results in the formation of diuron.

The present invention deals with various factors associated with process improvement, recovery, reuse of solvents, cycle time reduction, using commercially available raw materials and process optimization of diuron.
The present inventive process provides a simple synthetic method with less overall reaction time for the industrial preparation of Diuron of formula 1. In this process, we can make the Diuron of formula 1, in one-pot two-step process (without isolation of intermediate), having several advantages for industrial manufacturing.
The first embodiment of the present invention provides a process for the preparation of Diuron of formula-1, comprising: reacting 3,4-dichloroaniline with phenyl chloroformate in presence of inorganic base in a solvent followed by in-situ reaction with dimethyl amine to provide Diuron of formula-1.

In the first aspect of first the embodiment, solvent is selected from but not limited to hydrocarbon solvent, preferably xylene or toluene; inorganic base is selected from but not limited to metal carbonate or metal bicarbonate, preferably sodium bicarbonate.
In the second aspect of the first embodiment dimethyl amine is in aqueous form.
In the third aspect of first the embodiment, reacting 3,4-dichloroaniline with phenyl chloroformate in presence of sodium bicarbonate in xylene followed by in-situ reaction with dimethyl amine to provide Diuron of formula-1.
ADVANTAGES OF THE PRESENT INVENTION
• The present disclosure provides a process for the preparation of diuron that overcomes one or more limitations associated with the conventional methods.
• The present disclosure provides a continuous one pot synthesis process for preparation of diuron that reduces the reaction time cycle, and the process doesn’t involve the isolation of intermediate which eventually decreases the formation of unwanted products makes process ecofriendly.
• The present disclosure provides a process for preparation of diuron that provides diuron in high yield and purity along with good impurity control.
• The present disclosure provides a process for preparation of diuron that is cost-effective and technically advanced by a single pot synthesis where the extremely hazardous isocyanate intermediate formed is taken forward to Diuron formation in telescopic manner with out isolation.
• The present invention replaces usage of the gaseous dimethyl amine to aqueous dimethyl amine which avoiding the use of pressure reactor/ high temperature for the reaction.
• An important advantage of the present invention is that the reaction is operated in continuous manner it avoids additional operations of work up, filtrations and drying of solids in each stage. Which will have impact on time cycle, energy, and manpower consumption that makes the process commercially viable, cost effective.
EXAMPLES
Example-1:
3,4-dichloroaniline (100 g, 0.61 moles, 1.0 eq.) and sodium bicarbonate (62.3 g, 0.74 moles, 1.2 eq.) were added to xylene (200 ml) at room temperature and stirred for 10 minutes at same temperature. Phenyl chloroformate (101.5 g, 0.647 moles, 1.05 eq.) was slowly added to the above reaction mixture at room temperature. Reaction mixture was heated to 50-55°C and stirred for 5 hours. Further the reaction mixture was cooled to room temperature. Aqueous dimethyl amine (104.3 g, 0.925, moles, 1.5 eq.) was added to the above mixture at room temperature and stirred for 8 hours at same temperature. Water was added to the above reaction mixture and cooled to 0-5°C. Filtered the mixture with water and xylene and dry to get the titled compound.
Yield: 141.85 (98.60%). ,CLAIMS:CLAIMS:
We Claim:
1. A process for the preparation of Diuron of formula-1 comprising:
reacting 3,4-dichloroaniline with phenyl chloroformate in presence of an inorganic base in a solvent followed by in-situ reaction with dimethyl amine to provide Diuron of formula-1.

2. The process as claimed in claim 1, wherein solvent is selected from the group but not limited to hydrocarbon solvent.
3. The process as claimed in claim 4, wherein hydrocarbon solvent selected from xylene or toluene.
4. The process as claimed in claim 1, wherein inorganic base is selected from metal carbonate or metal bicarbonate.