FORM 2
THE PATENTS ACT, 1970
(Act 39 of 1970)
COMPLETE SPECIFICATION
(See Section 10)
Title: "An improved process for manufacturing high purity Guaiacol"
Name: M/s. Gujarat Alkalies and Chemicals Limited.
Address: P.O. Petrochemicals - 391 346,
Dist: Vadodara, Gujarat - India.
Nationality: Indian
The following specification particularly describes the invention and the manner in which it is to be performed.

Title of the present Invention:
An improved process for manufacturing high purity Guaiacol
Field of the present Invention:
This invention relates to process of manufacturing Guaiacol, more particularly, manufacturing of Guaiacol for use as raw material for synthesis of Vanillin.
Background of the Present Invention:
Guaiacol is an essential raw material that is used in synthesis of Vanillin at an industrial scale. Guaiacol also finds application in perfumes and aroma therapy. The methods reported in the prior art for the preparation of Guaiacol include both vapor phase & liquid phase reactions.
Japanese Patent 76,105,021 has reported 37.2% Catechol conversion with 96.7% selectivity for Guaiacol by the reaction of Catechol & Methanol in presence of Para-Toluene Sulphonic Acid at 180°C for 2 hrs. in autoclave.
Japanese Patent 78,12,790 has reported the preparation of Guaiacol with 57.8% conversion and 96.2% selectivity by passing 1 : 1 mixture of Catechol & Methanol over a Al - B - P - Ca catalyst with Nitrogen as a carrier gas at 280°C.
German Patent DD 287, 027 has reported a process wherein the product mixture containing 48.5% Guaiacol is obtained by heating the mixture of Catechol, Methanol and water to 320°C and passing the same over a solid bed reactor containing a catalyst.
German Patent 874,445 has reported the formation of 5 - 10% Dimethoxy derivative (Veratrole) beside Guaiacol by Aikylation of Catechol using Dimethyl Sulphate & 25% Alkali Hydroxide.

There are several drawbacks in the known processes such as the use of a catalyst, high temperature conditions, and reactions that are to be performed under pressure or the use of both organic & aqueous phase systems depending upon the reaction conditions adopted.
Additionally, the prior art processes cited above, despite being highly selective, provide low yield. The formation of by-product Dimethoxy derivative (Veratrole) has been reported to be greater than or equal to 2%.
Summary of the Present Invention:
The present invention discloses an improved & economical process for manufacturing high purity Guaiacol comprising the reaction of Catechol with Dimethyl Sulphate in presence of alkaline agent Sodium Aluminate and reaction medium Toluene.
The manufacturing process in accordance with the present invention is very easy to operate, with a simple reactor system. Ali the reactions are conducted in the liquid phase under very moderate temperature conditions. The manufacturing process in accordance with the present invention does not require any separate extraction step. Toluene is used as a reaction medium and works as a solvent for the final product.
The manufacturing process for Guaiacol in accordance with the present invention, successfully uses Sodium Aluminate as an alkaline agent in the reaction which gives a viable alternative to the use of conventional alkaline agents such as Sodium Carbonate & Bicarbonate, Potassium Carbonate and Sodium Hydroxide in the reaction. The use of Sodium Aluminate as an alkaline agent ensures the pH range of 8 - 9 being maintained throughout the reaction, which in turn is able to control the formation of Dimethoxy derivative (Veratrole) to less than 2%.
The present invention does not make use of any catalyst and the reactions are carried out in the liquid phase under moderate temperature and atmospheric pressure conditions. Therefore, no high pressure conditions are required. Toluene used in the

reaction serves the dual purpose of providing the reaction medium as well as the solvent for the final product. The use of Sodium Aluminate in the process is able to control the formation of Dimethoxy derivative (Veratrole) to less than 2% making the process highly selective and at the same time attaining the high yield. It is the above mentioned characteristics which makes the manufacturing process in accordance with the present invention economical.
The manufacturing process in accordance with the present invention produces Guaiacol, which is suitable for use as a raw material in the synthesis of Vanillin.
Detailed Description of the Present Invention:
The process of manufacturing high purity Guaiacol in accordance with the present invention has provided an improved & economical industrial process. The various parameters like the reactant ratio, temperature and downstream processing have been modified / improved in a such a way that the process is very easy to operate at commercial scale with desired specifications and quality of the final product suitable for various industrial applications. According to the present invention, the product yield is > 80% of the theoretical value with high conversion and selectivity. In the present invention, it is the use of the Sodium Aluminate as alkaline agent which makes the process unique and different.
Equipments required: 100 Itr. glass reactor system provided with agitator, solid charging port, addition funnel & temperature indicator.
Chemicals required: quantities of Catechol, Toluene, Sodium Aluminate used as an alkaline agent and Dimethyl Sulphate.
The best mode of performing the present invention comprises the following steps:

Step-1:
The required quantities of Catechol, Sodium Aluminate & Toluene are charged in 100 Itr. glass reactor system provided with agitator, solid charging port, addition funnel & temperature indicator. The mixture is put to efficient stirring for 1 hour to make a homogenous slurry. The weight ratio of the components is an essential part of the process. Hence, the weight ratio of the Catechol:SodiumAluminate:Toluene is from 1.0:1.05:7.0 to 1.0:1.40:11.50.
Step - 2:
The required quantity of Dimethyl Sulphate is gradually added to the slurry in the reactor at room temperature under efficient stirring for 4 - 6 hrs. The weight of Dimethyl Sulphate charged in the reactor is 1.0 -1.2 times the weight of Catechol taken.
Step - 3:
The temperature of the contents is gradually increased to 85° ± 5°C. The reaction is continued for 10 - 12 hrs. at the same temperature.
Step - 4:
After the completion of the reaction, the solids are separated by filtration and the liquid phase is put back in the reactor for further processing.
Step - 5:
The liquid phase is subjected to distillation under vacuum to recover Toluene at 30° -35°C leaving behind Crude Guaiacol. The Toluene is recycled in the subsequent batches.
Step - 6;
Crude Guaiacol is further distilled at 90° - 120°C under high vacuum to yield the high purity Guaiacol.

The final product shows > 96% purity & the formation of Dimethoxy derivative (Veratrole) is restricted to less than 2%. The product yield is > 80% making the process highly economical.
The present invention will be described in terms of specific examples and examples should be considered as illustrative of the invention and not as limiting the same. The examples described herein will substantiate the claims.
Example -1
5.0 kg. Catechol, 6.825 kg. Sodium Aluminate and 57.0 kg. Toluene are taken in a reactor and the contents are stirred for 1 hr. to make homogeneous slurry at room temperature, followed by the gradual addition of 5.725 kg. Dimethyl Sulphate at room temperature for 4 hrs. The temperature of the reactor is gradually increased to 85° ± 5°C and the reaction is continued for 10 - 12 hrs at pH 8 - 9. After the completion of reaction, the solids are separated from the liquid phase by filtration at room temperature: The Toluene is recovered from the liquid phase by vacuum distillation at 30° - 35°C leaving behind the Crude Guaiacol, which is further distilled at 90° - 120°C at high vacuum to yield the pure Guaiacol.
Example - 2
5.0 kg. Catechol, 6.825 kg. Sodium Aluminate and 34.0 kg. Toluene are taken in a reactor and the contents are stirred for 1 hr. to make homogeneous slurry at room temperature, followed by the gradual addition of 5.725 kg. Dimethyl Sulphate at room temperature for 5 hrs. The temperature of the reactor is gradually increased to 85° ± 5°C and the reaction is continued for 10 - 12 hrs at pH 8 - 9. After the completion of reaction, the solids are separated from the liquid phase by filtration at room temperature. The Toluene is recovered from the liquid phase by vacuum distillation at 30° - 35°C leaving behind the Crude Guaiacol, which is further distilled at 90° - 120°C at high vacuum to yield the pure Guaiacol.

Example - 3
5.0 kg. Catechol, 5.118 kg. Sodium Aluminate and 34.0 kg. Toluene are taken in a reactor and the contents are stirred for 1 hr. to make a homogeneous slurry at room temperature, followed by the gradual addition of 5.725 kg. Dimethyl Sulphate at room temperature for 4 hrs. The temperature of the reactor is gradually increased to 85° ± 5°C and the reaction is continued for 10 - 12 hrs at pH 8 - 9. After the completion of reaction, the solids are separated from the liquid phase by filtration at room temperature. The Toluene is recovered from the liquid phase by vacuum distillation at 30° - 35°C leaving behind the Crude Guaiacol, which is further distilled at 90° - 120°C at high vacuum to yield the pure Guaiacol.
The product yield in all the examples have been > 80% and the pure Guaiacol obtained shows > 96% purity with < 2% Dimethoxy derivative (Veratrofe).

We Claim:
1. An improved process for manufacturing Guaiacol comprising
the step of charging Catechol, Sodium Aluminate, and Toluene in a reactor
resulting into a mixture;
the step of efficient stirring to make the said mixture a homogenous slurry;
the step of adding Dimethyl Sulphate;
the step of reacting the said homogenous slurry with the added Dimethyl
Sulphate;
the step of separating the liquid phase from the solid;
the step of recovering Toluene from the liquid phase by distillation under vacuum
to yield crude Guaiacol;
the step of distillation of crude Guaiacol under vacuum to yield Guaiacol having
>96% purity and Dimethoxy derivative (Veratrole) < 2%.
2. The process as per claim 1, wherein Sodium Aluminate is used as an alkaline agent to maintain the pH of the reaction in between 8 - 9.
3. The process as per claim 1, wherein the weight ratio of Catechol: Sodium Aluminate: Toluene is from 1.0:1.05:7.0 to 1.0:1.40:11.50.
4. The process as per claim 1 wherein the weight of Dimehtyl Sulphate charged in the reactor is 1.0 - 1.2 times the weight of Catechol taken.
5. The process as per claim 1, wherein the charging of the reactants, formation of the homogenous slurry and addition of Dimethyl Sulphate is carried out at room temperature.
6. The process as per claim 1 wherein the reaction is carried out at 85 ±5oC for 10-12 hrs.

7. The process as per claim 1 wherein the liquid phase separated after the completion of the reaction is subjected to distillation under vacuum to recover Toluene at 30 - 35°C.
8. The process as per claim 1 wherein crude Guaiacol is subjected to distillation at 90 - 120°C under vacuum to get pure Guaiacol with > 80% yield and > 96% purity.