TITLE
PROCESS FOR PRODUCTION OF SUBSTITUTED PHENOLS FROM
SUBSTITUTED ANILINES
FIELD OF THE INVENTION
This invention relates to a technology wherein conversion of substituted aniline to substituted phenol wherein in-situ diazotization and hydrolysis carried out in non polar nonprotic organic solvent at high temperature with a technique of one pot reaction. Also, the field of invention includes energy saving wherein both diazotization and subsequent hydrolysis steps carried out in same reactor and above ambient temperature. Also, the field of invention includes recycle of effluent without purification or pretreatment in diazotization and subsequent hydrolysis .
BACKGROUND OF THE INVENTION
Substiuted phenols are useful starting materials for pharma and agro products. Also Substiuted phenols are useful in synthesis of dyes and fuel additive. In particular 2,4-xylenol is used as pharmaceutical intermediate for Abafungin ; Oxymetazoline ; vortioxetine as well as intermediate for dyes, agrochemicals ,fuel additive. Conventionally, there have various processes available for production of Phenols from Aniline and its ring substituted alkali derives wherein diazotization reaction needs separate reactor and sufficient chilling means lower temperature 0-5°c during diazotization stage. Also, in the conventional method, the hydrolysis carried out in one more separate reactor with generation of heavy foam during the reaction . Also passing of diazonium salt from one reactor to another reactor wherein this diazonium salt may be decomposes fastly and causes lots of inconveniences at the industrial scale with considering safety concerns. This traditional route suffers from the disadvantages of high capital, utility cost , safety and also needs a waste acid treatment.
The JP patent application No. 51095030 discloses method of preparation phenol wherein aniline is mixed with an organic solvent which is insoluble or sparingly
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soluble in water (such as the one selected from the solvents like ketones or esters),
which is followed by mixing it with water and an acid (sulfuric acid or hydrochloric
acid) and then adding a nitrite salt, under heating condition. However disadvantage
of said patent provides use of solvents such as isobutyl acetate ,methyl ethyl ketone
, methyl isobutyl ketone which are partially soluble in water and cause a problem
during effluent treatment . Also the use of said solvents having property of
entrainment with substituted phenols during final distillation cause to get impure
product means presence of said solvent. Also hydrolysis of said solvents may
possible during diazotization means subsequent hydrolysis step .
The US6989467 patent discloses synthesis of 2,6-dimethoxy-4-vinylphenol, 2-hydroxy-4-vinylphenol, 3-hydroxy-4-vinylphenol etc. by condensation of malonic acid and 4-hydroxyphenylaidehydes or its derivatives. However, in this process the type of reaction involves condensation, which again has its own disadvantages as regards to diazotization and hydrolysis.
The US6828466 patent discloses a process wherein Ir-catalyzed borylation of arenes using pinacolborane (HBPin) followed by oxidation of the intermediate arylboronic ester by ozone to produce phenols. However, the process disclosed in the above patent also has its own disadvantages as a reaction is carried on by borylation and oxidization.
The United States Patent 5214210 patent completely irrelevant because the patent discloses production of aniline from phenols using amination process in the presence of catalyst. However, this patent has its own disadvantages as there is an additional cost of catalyst required in the said process and the reaction is through amination and the cost of catalylst is an additional burden in this process.
The US3998804 patent discloses an improved process for the manufacture of azo compounds by coupling of a diazotized o-nitroaniline and a water-insoluble 2,4-disubstituted phenol.
In the present circumstances, the industry demands a process which is having an economical significance and other advantages.
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The present invention is an attempt wherein the technology of one pot process for
diazotization and subsequent hydrolysis is carried out to overcome disadvantages of
conventional diazotization and hydrolysis reaction. It is also attempt of the invention
by using the one pot reaction technology to evade the chilling of diazo mass at 0-5°c.
Hence, a lower utility cost compared to conventional diazotizations. Overall, the
improvements flowing from this invention provide very significant annual savings in
the total production with reducing the number of synthesis steps and thus lead to
saving time and resources.
OBJECT OF THE INVENTION
It is the object of the invention to provide a process of production of substituted phenols wherein diazotization and hydrolysis is carried out simultaneously in one reactor in presence of water insoluble non polar nonprotic organic solvent such as toluene with recycle of effluent to reduce the load on effluent treatability.
It is also the another object of the invention to provide for a process which can recycle the effluent and to reduce overall cost; utility and load on effluent treatability with considering eco-friendly aspects.
It is also the another object of the invention to provide for a process wherein use of non polar water insoluble organic solvent such as toluene wherein said solvent can not hydrolysis itself throughout the reaction and also easy rectification of final pure product.
DETAIL DESCRIPTION OF THE INVENTION
Accordingly in the first embodiment the present invention provides a process of preparation of substituted phenols comprising step of in-situ diazotization and hydrolysis of substituted aniline in presence of nonpolar nonprotic organic solvent at high temperature with technique of one pot reaction.
The present invention also provides for a process wherein the effluent generated in the process can be recycled partially except the water required adding to make NaN02 solution. This way it can be recycled during the reaction .

According to present invention, the reaction is particularly carried out above
ambient temperature and at atmospheric pressure.
According to present invention, the aromatic amine is selected from substituted anilines such as various dimethyl anilines.
In second embodiment of the invention, all reaction steps are performed in a one-pot process in the presence of an organic nonpolar nonprotic solvent such as toluene, xylene, Cumene . Toluene is particularly preferred. The following example illustrate the invention.
Example 1 :
The present invention provides one pot process for reaction wherein to 3-necked 5 liter RBF provided with heating mantle , stirrer, thermometer and reflux condenser 800g water, 244g of 2,4-xylidine ,221 g of sulfuric acid (99%) and 865 g toluene were placed and it was heat to 82°c while stirring. Add slowly of sodium nitrite solution (obtained by dissolving 141 g of sodium nitrite in 600 g water) within 5 hrs maintaining temperature between 80-85°c .The reaction mass is further stirred for 2hrs at 80-85°c. Then reaction mixture was cooled to 35- 40°c and separated using separating funnel and the solvent layer was separated from the acid phase solution . About 1184 g of the organic solvent layer was distilled and initially 855 g of toluene was recovered which was recycled in next batch and then 221.4 g of 99.5 % pure 2,4-xylenol was obtained by distillation at a reduced pressure . The yield was 90 %. Example 2:
The acid phase solution separated in example 1 ( 14% w H2S04) was charged into the Into the 51it RBF to which 2,4-xylidine ( 244g ) was added . Toluene (865g) was then added and it was heat to 82°c while stirring. The sodium Nitrite solution was then added by procedure described in example 1. Organic layer of 2,4-xylenol ( 209g , 85% yield ) was isolated .
NAYAN
Constituted Attorney for Applicant
Patent Agent no.654

We Claim:
1. A one pot process for preparation of substituted phenol comprising step of in-situ
diazotization and subsequent hydrolysis of substituted aniline in presence of
nonpolar nonprotic organic solvent above ambient temperature ;
wherein, the effluent generated is partially recycled without purification or pretreatment in diazotization and subsequent hydrolysis .
2. The process as claimed in claim 1 to 2 , wherein the solvent is selected from nonpolar nonprotic organic solvents such as toluene, xylene, cumene .
3. The process as claimed in claim I to 3, wherein the substituted aniline is selected from different dimethyl anilines.
4. The process as claimed in claim 1 to 4, wherein the effluent generated in the process can be recycled partially in diazotization and subsequent hydrolysis means in salt formation.
5.The process as claimed in claim 1, wherein the diazotization and subsequent hydrolysis step are carried out within the same reaction kettle with a technique of one pot reaction.
6. A one -part process for preparation of phenol as described in the description.
7. A process as claimed in claim 1 to 7 wherein the amount of water required and utilized is reduced half at the time of reactions.