THE PATENTS ACT 1970
COMPLETE
SPECIFICATION
SECTION-10
TITLE
A NOVEL PROCESS FOR PREPARATION OF 4-CHLORO, 4'-HYDROXY BENZOPHENONE USING ANISOL
APPLICANT
GHARDA CHEMICALS LTD R&D CENTRE, B-27, MIDC DOMBIVLI (E) MAHARASHTRA INDIA
The following specification particularly describes and ascertains the nature of the invention and the manner in which it is to be performed

FIELD OF INVENTION
The invention relates to a process for preparation of 4-Chloro, 4'-Hydroxy Benzophenone in high yields for the use of an important precursor to the preparation of poly (arylene ether ketones). In further details, the present invention relates to a novel process for manufacture of 4-Chloro,4'-Hydroxy Benzophenone, with high yield and purity by the benzoylation of Anisole and subsequent demetnylation.
BACKGROUND OF INVENTION
4-Chloro, 4'-Hydroxy Benzophenone(l) is prepared via Fries rearrangement of

Phenyl p-chlorobenzoate in the presence of AICI3 without solvent according to the reference (VP Malik & GS Saharia, J.Sci.lnd.Res.,Vol.15B, pp.633-635 .November
1956).
GB 1,574,441 has further described a process for preparing (I) by the reaction of p-Chlorobenzoic acid and Phenol in the presence of a molar excess of liquid anhydrous HF.
EP 75i390 and JP 03127753 A2 have also described the manufacture of (I) by the reaction of p-Chlorobenzoic acid and Phenol in the presence of Trifluoromethane sulphonicacid.
Recently, JP 03041047 A2 have disclosed a method of making (I) by the reaction of p-Hydroxy benzoyl chloride and excess Chlorobenzene in the presence of AICI3, to give pure (I) in 51% yield. Pure (I) is prepared by acetylating the crude (I) with Acetic anhydride and crystallizing the acetylated (I) and then hydrolyzing in refluxihg NaOH solution.
2

The above methods of preparation of (I), suffer from a number of disadvantages, which make it unattractive for an industrial process.
The first method via Fries rearrangement requires the isolation of the ester and its subsequent rearrangement. The second method, involving the single step reaction of p-Chlorobenzoic acid and Phenol uses the very expensive and corrosive acylating agents like Trifluoromethane sulphonic acid and HF. Morover with HF; there is a necessity to use pressure equipment.
In view of above, none of the methods addressed the preparation of 4-Chloro, 4'-Hydroxy Benzophenone(l) in a simple method with high yield and purity without the use of hazardous chemicals and conditions. Accordingly the present invention tries to find .out the method for preparation of the said compound to overcome the prior art defects.
OBJECT OF INVENTION
In these respects, hence it is desired to overcome the disadvantages of the past methods of preparation by developing a process, which uses safe raw materials and also gives product of high purity in high yield.
Hence,it is the object of invention to overcome the disadvantages of the prior art methods of manufacture of 4-Chloro,4'-Hydroxy Benzophenone (I) , in high purity , by developing a process using a single step procedure using starting materials p-Chlorobenzoyl chloride and Anisole which are cheaply available and easy to handle followed by demethylation of the product insitu.
Another object of the present invention is to obtain the product in a cost effective manner, so that it can be available as a cheaper source for preparation of Poly (arylene ether ketones).
3

STATEMENT OF THE INVENTION
Process for preparation of 4-Chloro, 4'-hydroxy benzophenone, (I) comprises of the following steps:
(a) Reacting p-Chlorobenzoyl chloride with anisole and Aluminum chloride in a suitable solvent at a particular temperature during charging and thereafter heating for a certain period in a "one-pot" process for subsequent de-methylation insitu to obtain the desired product (I).
(b) Purification of the product (I) through re-crystallization from suitable solvent 1o make it ready for polymerization.
DESCRIPTION OF THE INVENTION
According to the invention described below, that 4-Chloro, 4'-hydroxy benzophenone, (I), can be prepared in high yield by reacting p-Chlorobenzoyl chloride with anisole and Aluminum chloride in a suitable solvent and subsequent insitu de-methylation. The reaction proceeds via the methyl ester of (I). This method can be operated in a conventional industrial plant as a "one-pot" process. Moreover relatively cheaper starting materials are used in the process for preparation of compound (I). Also the yield of 4-Chloro, 4'-hydroxy benzophenone is 90% and purity >99%. The 4-Chloro, 4'-hydroxy benzophenone produced by the process of this invention can be purified by conventional process as described elsewhere to make it suitable for polymerisation.
In a preferred process according to this invention, Anisole is added to a slurry of p-Chlorobenzoyl chloride, Aluminium chloride and solvent. Subsequently anisole is added slowly to the reaction mixture while maintaining the reaction mixture at a particular temperature. When all the anisole has been added, the temperature is raised gradually to a sufficiently high level to ensure complete demethylation. The process of the invention may be conveniently effected at a temperature in the range from 30- 150°C.
4

The rate of the reaction including demethylation increases with the increase in AICI3 used. The ratio of AICI3 to Anisole is 1.05-2.0
The reaction may be carried out in an inert solvent. Suitable inert solvents include Nitrobenzene and o-Dichlorobenzene.
While carrying out the process of this invention it is also observed that the evolution of HCI and Methyl Chloride is continuous throughout the reaction and commences with the addition of Anisole to the slurry of Aluminum Chloride, p-ChlorobenzoyI chloride and o-Dichlorobenzene. The methyl chloride that is evolved can be recycled to make anisole from phenol.
After workup the desired product is obtained in high yield (90%) and in high purity (>99%) with very little of the isomeric impurity, 4-Chloro, 2'-hydroxy Benzophenone. The product thus obtained is crystallized using Toluene and acetone to make it suitable for polymerization.
The invention is illustrated without limited to the following examples. Example 1
In a 5 Liter round bottom flask is charged 2,250 ml o-Dichlorobenzene followed by 660 gm AICI3. 788 gm p-Chlorobenzoyl chloride is charged over 3 hours and stirred for one hour at 30-35cC. To he above solution 486 gm anisole in 100 ml 0-Dichlorobenzene is added over 3 hours at 30-35°C. The reaction mass is gradually heated to 80°C and maintained at this temperature for 12 hours. The reaction mass is further heated to 120°C over 10 hours and maintained at his temperature for 11 hours There is continuous evolution of HCI and Methyl Chloride. The reaction mass 'is drained into 0.5N HCI The solids that are precipitated are filtered and washed with water. The cake is purified by dissolving in NaOH solution, filtration and acidification to give crude Crop (I), (yield 942 gms), 90% yield with 4-Chloro, 4'-hydroxy benzophenone purity >99%. The cake is further purified to make it suitable for polymerization by crystallization from Toluene and acetone to get 99.9% HPLC purity, melting point of 180-181°C and overall yield (78%).
5

Example 2
In a 5 Liter round bottom flask is charged 2,250 ml o-Dichlorobenzene followed by 900 gm AICI3. 788 gm p-Chlorobenzoyl chloride is charged over 3 hours and stirred for one hour at 30-35°C. To he above solution 486 gm anisole in 100 ml o-Dichlorobenzene is added over 3 hours at 30-35°C. The reaction mass is gradually heated to 80°C and maintained at this temperature for 4 hours. Over the next 10 hours it is further heated to 120°C and maintained at this temperature . There is continuous evolution of HCI and Methyl Chloride. The reaction mass is drained into 0.5N HCI The solids that are precipitated are filtered and washed with water. The cake is purified by dissolving in NaOH solution, filtration and acidification to give crude Crop (I), (yield 950 gms), 91% yield with 4-Chloro, 4'-hydroxy benzophenone purity >99%. The cake is further purified to make it suitable for polymerization by crystallization from Toluene and acetone to get 99.9% HPLC purity, melting point of 180-181°C and overall yield (79%).
Different embodiments of the invention are possible to achieve the best method of performance and to obtain the effective and better product as stated earlier. It will be understood that skilled persons with many modifications, variations and adaptations may carry out the invention into practice without departing from its sprit or exceeding the scope of claims in describing the invention for the purpose of illustration.
6

WE CLAIM
1. Process for preparation of 4-Chioro, 4'-hydroxy benzophenone, (I) comprises of
the following steps:
(a) Reacting p-Chlorobenzoyl chloride with anisole and Aluminum chloride in a suitable solvent at a particular temperature during charging and thereafter heating for a certain period in a "one-pot" process for completion of reaction and subsequent de-methylation insitu to obtain the desired product (I).
(b); Purification of the product (I) through re-crystallization from suitable solvent to make it ready for polymerization.
2. Process as claimed in claim 1 wherein the temperature and duration of charging
in step (a) are 30-35°C for 3-4 hours.
3. Process as claimed in claim 1 wherein the temperature and duration of reaction after charging the reactants to obtain the desired product in step (a) are 130°C for 10-12 hours.
4. Process as claimed in claim 1 wherein the amount of Aluminium chloride used is
in the range 1.05 to 1.5.
5. Process as claimed in claim 1 wherein the solvent used in step (a) is
Nitrobenzene and o-Dichlorobenzene.
6. Process as claimed in claim 1 wherein the Methyl chloride evolved in the process
of demethylation insitu can be reused for the conversion of phenol to anisole.
7. Process as claimed in claim 1 wherein the final product obtained from step (a) is purified by re-crystallization from the solvent Toluene and Acetone.
8. Process as claimed in preceding claims substantially as herein described.
Dated the
7

-:ABSTRACT:-
Process for preparation of 4-Chloro, 4'-hydroxy benzophenone, (I) by reacting p-Chlorobenzoyl chloride with anisole and Aluminum chloride in a suitable solvent at a particular temperature during charging and thereafter heating for a certain period in a "one-pot" process for subsequent de-methylation insitu to obtain the desired product (I) followed by purification of the product (I) through re-crystallization from suitable solvent to make it ready for polymerization.
8