Title of Invention	A PROCESS FOR THE PREPARATION OF PARA NITRO TOLUENE
Abstract	The present invention relates to a process for the preparation of para nitro toluene. More particularly it relates to the said process using acid over a beta zeolite catalyst. Still more particularly it relates to regioselective nitration of toluene to para-nitrotoluene by vapor phase nitration of toluene using nitric acid over beta zeolite. By the process of present invention para-nitrotoluene has been prepared in high yield in a continuous process without any waste byproduct formation making it an enviornment friendly process.

Title of Invention

A PROCESS FOR THE PREPARATION OF PARA NITRO TOLUENE

Abstract

The present invention relates to a process for the preparation of para nitro toluene. More particularly it relates to the said process using acid over a beta zeolite catalyst. Still more particularly it relates to regioselective nitration of toluene to para-nitrotoluene by vapor phase nitration of toluene using nitric acid over beta zeolite. By the process of present invention para-nitrotoluene has been prepared in high yield in a continuous process without any waste byproduct formation making it an enviornment friendly process.

Full Text	The present invention relates to a process for the preparation of para nitro toluene. More particularly it relates to the said process using nitric acid over a beta zeolite catalyst. Still more particularly it relates to regioselective nitration of toluene to para-nitrotoluene by vapor phase nitration of toluene using dilute nitric acid over beta zeolite. By the process of present invention para-nitrotoluene has been prepared in high yield in a continuous process without any waste byproduct formation making it an environment friendly process. Nitrotoluenes are important intermediates in organic synthesis of dyes, perfumes, drugs, pesticides and explosives. Nitrotoluenes are convertible by reduction iiito primary amines, which in turn are valuable intermediates in the synthesis of dyes, Pharmaceuticals, photographic developers and antioxidants. Conventionally nitrotoluenes are produced by liquid phase reactions employing mixed acids (Nitration Methods and Mechanism, VCH, New York, 1989, pp. 5-15). A sulfuric acid/nitric acid mixture is the most commonly used nitrating agent. Even though the process has the advantage of using cheaper and readily available reactants its main drawbacks are the non-selectivity, low yields, formation of oxidation byproducts because of excess nitric acid, corrosive nature of acid mixture and handling hazards. Large quantity of dilute sulfuric acid is generated as a waste and its disposal or recycle is very expensive. Generation of large amount of dilute sulfuric acid, organic wastes and products oftheir neutralization makes the nitration one of the most environmentally harmful processes. Other process has been reported wherein use of these acids have been avoided by using nitrogen dioxide/ozone mixture (J. Chem. Soc. Commun, 1049-1050. 1991 Suzuki et.al.), but this process suffers because of powerful nature nitrating agent that selective production ofmononitrated products is difficult. Catalytic vapor phase nitration of toluene with aqueous nitric acid over solid acid catalyst would be an interesting alternative environmental friendly route for the production ofnitrotoluenes, A number of heterogeneous catalysts have been proposed for this process. In the prior art, vapor phase nitration of aromatic compounds, benzene and toluene at temperature ranging from about 275° C to about 310°C is described in McKee and Wilhelm, Industrial and Engineering Chemistry, 28(6), 662-667 (1936) and U.S. Pat. No. 2,109,873. McKee and Wilhelm catalyzed their reaction with silica gel. Bauxite and alumina were reported to be ineffective as catalyst in the vapor phase nitration of toluene. US Patent No. 2,431.585 describes vapor phase nitration of aromatic hydrocarbons at temperature from 130°C to 430°C, using metal metalphosphates of calcium, iron, magnesium and solid supported phosphoric acid catalysts. Vapor phase nitration of toluene has been described in U.S. pat. No. 4,112,006 where silica and/or alumina-catalyst impregnated with high boiling sulfuric acid or phosphoric acid and optionally with metal salts of such acids is used as catalyst. The reaction is carried out under reduced pressure at temperature from 80 to 180°C. U.S. Pat. No. 3,966,830, Jpn. Pat. No. 58-157748, and U.S. Pat. No. 4,426,543 describes the nitration of aromatics using zeolite catalysts. Preliminary screening studies (D. Vasa.na, D. Malossa, A. Kogelbaur and R. Prins, proceedings of 12th International zeolite conference 1999) using 65% nitric acid as industrially preferred nitrating agent confirmed that the zeolites provide a higher para to ortho ratio and zeolite beta in its proton form showed promising results. Nevertheless, activity and selectivity decreased over a period of five hours on stream due to pore filling/blockage by strongly adsorbed products/products. The lower conversion of toluene to nitrotoluenes and faster deactivation of zeolite catalysts are the drawbacks of these processes for commercial application. International patent WO 96/36587 describes a solvent free process for the nitration of aromatic compounds in which the aromatic compound is reacted with nitric acid in presence of an acid anhydride wherein the process is catalyzed by an aluminosilicate catalyst. Nitric acid and acid anhydride react with each other in-situ to form acyl nitrate and this acts as a nitrating agent for aromatic compounds. For example benzene, naphthalene, anthracene, toluene etc. are nitrated to mononitrated compounds. A mixture of orth-meta-para nitrotoluenes is obtained which is then distilled at a pressure of 30mm Hg and a temperature of 30° C to remove acetic acid as a byproduct. U.S. patent 5,946,638 and European patent 0949240 Al describe nitration of toluene using concentrated nitric acid over ZSM-5 and modified clay catalyst respectively. These prior art processes for the vapor phase nitration of toluene for the preparation of nitrotoluenes use 65 to 70 % nitric acid which favors the formation of side chain oxidation products. These products deactivate the catalyst, which leads to low conversions, low space time yield, short catalyst life, contamination of the nitrated aromatic hydrocarbon products by undesirable by-products. The objective of the present invention is to provide a process for the preparation of para nitrotoluene in high yield. Another objective is to provide a process with high selectivity by vapor phase nitration of toluene using dilute nitric acid over beta zeolite catalyst. Accordingly the present invention provides a process for the preparation of para nitro toluene which comprises reacting toluene in vapor phase in an inert atmosphere characterized in that with dilute nitric acid of concentration in the range of 20 to 30% in a molar ratio of toluene to nitric acid in the range of 1:1 to 4:1 in the presence of beta zeolite catalyst having Si/Al=30 and particle size -10 to +20 mesh, at a temperature in the range of 100 to 300°C, at an atmospheric pressure, at a weight hourly space velocity in the range of 0.1 to 1.0, for a period of at least 4 hours and collecting the para nitro toluene in a receiver having temperature 0-5°C. In one of the embodiment, the catalyst used is a commercially available beta zeolite in powder form or formulated extrudate form using alumina as a binder. In another embodiment, strength of dilute nitric acid used as nitrating agent is preferably 20 to 30%. In another embodiment, the molar ratio of toluene to nitric acid is preferably in the range ofl.5:lto3.5: 1.0. In yet another embodiment, the reaction temperature used is preferably in the range of 140 to 200°C. In yet another embodiment, the WHSV (Weight hourly space velocity) is preferably in the range of 0.2 to 0.5. The vapor phase nitration is carried out in conventional down flow reactor containing inert ceramic packing as preheater and granulated zeolite as a catalyst. Toluene and dilute HNO3 are fed to the reactor using syringe pumps along with a carrier gas. The product is condensed and collected in a container and washed with alkali and then analyzed by gas chromatograph after extraction with diethyl ether. The present invention is described with reference to the examples, herein below, which are illustrative only and should not be construed to restrict the scope of the present invention, in any manner. EXAMPLE 1 Commercially available formulated beta zeolite (Si/Al = 30) in the form of extrudates was procured from United Catalyst India Ltd. 10 g of zeolite was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe pumps. Reaction conditions are as follows. Reaction temperature = 120° C Carrier gas = N2 Toluene/HN03 = 1.7:1 (molar ratio) WHSV =0.17 The product was condensed at 5° C and collected in a receiver. The product was analyzed by gas chromatography. Results after 100 hours from beginning of reaction are shown below. There was no deactivation in the activity and selectivity of the catalyst during this period. Conversion of toluene (%) 45.68 Selectivity ofp-nitrotoluene (%) 70.5 Selectivity of o-nitrotoluene (%) 29.5 Yield for p- nitrotoluene (%) 32.2 p/o ratio of nitrotoluene 2.4 EXAMPLE 2 This example illustrates the effect of the reaction temperature on the conversion and selectivity of para nitrotoluene. 10 g of beta zeolite (formulated) was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe pumps. Reaction conditions are as follows. Reaction Temperature = 175 ° C Carrier gas = N2 HNO3 = 20% Toluene/HNO3 = 1.7: 1 (molar ratio) WHSV =0.17 Results after 100 hours from beginning of reaction are shown below. There was no deactivation in the activity and selectivity of the catalyst during this period. Conversion of toluene (%) 37.6 Selectivity ofp-nitrotoluene (%) 65.7 Selectivity of o-nitrotoluene (%) 34.3 Yield for p- nitrotoluene (%) 24.7 p/o ratio of nitrotoluene 1 -92 EXAMPLE 3 This example illustrates the effect of the WHSV on the conversion and selectivity of para nitrotoluene. 10 g of beta zeolite (formulated) was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe pumps. Reaction conditions are as follows. Carrier gas = N2 Toluene/HN03 = 2.3: 1 HNO3 = 20% WHSV = 0.5 The reaction results are as follows. There was no deactivation in the activity and selectivity of the catalyst during this period. Conversion of toluene (%) 22.35 Selectivity ofp-nitrotoluene (%) 74.5 Selectivity of o-nitrotoluene (%) 25.5 Yield for p- nitrotoluene (%) 16.65 p/o ratio of nitrotoluene 2.9 EXAMPLE 4 In this example, the influence of toluene/HN03 ratio is demonstrated on the conversion of toluene to nitrotoluenes. 10 g of beta zeolite (formulated) was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe pumps. Reaction conditions are as follows. The reaction conditions are as follows. Reaction temperature = 120° C Carrier gas = N2 Toluene/HN03 = 3.2: 1 (molar ratio) HNO3 =20% WHSV = 0.5 No deactivation of the catalyst was seen during this period. Results after 100 hours from beginning of reaction are shown below. Conversion of toluene (%) 16.5 Selectivity for p-nitrotoluene (%) 75.2 Selectivity for o-nitrotoluene (%) 24.S Yield for p-nitro toluene (%) 12.4 p/o ratio of nitrotoluene 3 EXAMPLE 5 This example illustrates the effect of dilution of nitric acid on the conversion and selectivity of para nitrotoluene. In this example 30% HNO3 is used. 10 g of beta zeolite (formulated) was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (30%) were fed to the reactor using syringe pumps. Reaction conditions are as follows. Reaction temperature = 120°C Carrier gas = N2 Toluene/HNO3 = 1.1: 1 (molar ratio) WHSV =0.17 No deactivation of the catalyst was seen during this period. Results after 50 hours from beginning of reaction are shown below. Conversion of toluene (%) 50.6 Yield for nitrotoluene (%) 71 Selectivity for p-nitrotoluene (%) 29 Selectivity for o-nitrotoluene (%) 35.9 p/o ratio ofnitrotoluene 2.5 EXAMPLE 6 Commercially available beta zeolite (Si/Al = 30) powder was compacted in the form of pellet and further granulated to -10 + 20 mesh size for using in nitration reaction. 10 g of granulated zeolite was loaded in tubular glass reactor of 15mm diameter and 25 mm length. The upper part of the reactor is packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe purnps. Reaction conditions were as follows. Reaction Temperature = 120 ° C Carrier gas = N2 Toluene/HN03 = 1.5:1 (molar ratio) WHSV =0.17 Results after 100 hours from beginning of reaction are shown below. No deactivation of the catalyst was seen during this period. Conversion of toluene (%) 25.76 Selectivity of p-nitrotoluene (%) 71.62 Selectivity of o-nitrotoluene (%) 28.38 Yield for p- nitrotoluene (%) 18.45 p/o ratio of nitrotoluene 2.5 Advantages of invention: Present invention has following advantages over the conventional process. 1. No use of sulfuric acid for nitration and no formation of dilute sulfuric acid waste and hence process is environmentally friendly. 2. Use of dilute nitric acid is cost effective as well as negligible formation of oxidation products. 3. Higher selectivity for para nitro toluene. 4. Use of solid catalyst, which makes the process easy for operation. 5. Present process is clean compared to the conventional process. We Claim: 1. A process for the preparation of para nitro toluene which comprises reacting toluene in vapor phase in an inert atmosphere characterized in that with dilute nitric acid of concentration in the range of 20 to 30% in a molar ratio of toluene to nitric acid in the range of 1:1 to 4:1 in the presence of beta zeolite catalyst having Si/Al=30 and particle size -10 to +20 mesh, at a temperature in the range of 100 to 300°C, at an atmospheric pressure, at a weight hourly space velocity in the range of 0.1 to 1.0, for a period of at least 4 hours and collecting the para nitro toluene in a receiver having temperature 0-5°C. 2. A process as claimed in claim 1 wherein the catalyst used is a commercially available beta zeolite in powder form or formulated extrudate form using alumina as a binder. 3. A process as claimed in claims 1-3, wherein the molar ratio of toluene to nitric acid preferably in the range of 1.5: 1 to 3.5 : 1. 4. A process as claimed in claims 1-4 wherein the reaction temperature used is preferably in the range of 140 to 200°C. 5. A process for the preparation of para nitro toluene substantially as herein described with reference to the examples accompanying this specification.

Full Text

The present invention relates to a process for the preparation of para nitro toluene. More particularly it relates to the said process using nitric acid over a beta zeolite catalyst. Still more particularly it relates to regioselective nitration of toluene to para-nitrotoluene by vapor phase nitration of toluene using dilute nitric acid over beta zeolite. By the process of present invention para-nitrotoluene has been prepared in high yield in a continuous process without any waste byproduct formation making it an environment friendly process.
Nitrotoluenes are important intermediates in organic synthesis of dyes, perfumes, drugs, pesticides and explosives. Nitrotoluenes are convertible by reduction iiito primary amines, which in turn are valuable intermediates in the synthesis of dyes, Pharmaceuticals, photographic developers and antioxidants.
Conventionally nitrotoluenes are produced by liquid phase reactions employing mixed acids (Nitration Methods and Mechanism, VCH, New York, 1989, pp. 5-15). A sulfuric acid/nitric acid mixture is the most commonly used nitrating agent. Even though the process has the advantage of using cheaper and readily available reactants its main drawbacks are the non-selectivity, low yields, formation of oxidation byproducts because of excess nitric acid, corrosive nature of acid mixture and handling hazards. Large quantity of dilute sulfuric acid is generated as a waste and its disposal or recycle is very expensive. Generation of large amount of dilute sulfuric acid, organic wastes and products oftheir neutralization makes the nitration one of the most environmentally harmful processes.
Other process has been reported wherein use of these acids have been avoided by using nitrogen dioxide/ozone mixture (J. Chem. Soc. Commun, 1049-1050. 1991 Suzuki et.al.), but this process suffers because of powerful nature nitrating agent that selective production ofmononitrated products is difficult.

Catalytic vapor phase nitration of toluene with aqueous nitric acid over solid acid catalyst would be an interesting alternative environmental friendly route for the production ofnitrotoluenes, A number of heterogeneous catalysts have been proposed for this process.
In the prior art, vapor phase nitration of aromatic compounds, benzene and toluene at temperature ranging from about 275° C to about 310°C is described in McKee and Wilhelm, Industrial and Engineering Chemistry, 28(6), 662-667 (1936) and U.S. Pat. No. 2,109,873. McKee and Wilhelm catalyzed their reaction with silica gel. Bauxite and alumina were reported to be ineffective as catalyst in the vapor phase nitration of toluene. US Patent No. 2,431.585 describes vapor phase nitration of aromatic hydrocarbons at temperature from 130°C to 430°C, using metal metalphosphates of calcium, iron, magnesium and solid supported phosphoric acid catalysts.
Vapor phase nitration of toluene has been described in U.S. pat. No. 4,112,006 where silica and/or alumina-catalyst impregnated with high boiling sulfuric acid or phosphoric acid and optionally with metal salts of such acids is used as catalyst. The reaction is carried out under reduced pressure at temperature from 80 to 180°C.
U.S. Pat. No. 3,966,830, Jpn. Pat. No. 58-157748, and U.S. Pat. No. 4,426,543
describes the nitration of aromatics using zeolite catalysts. Preliminary screening
studies (D. Vasa.na, D. Malossa, A. Kogelbaur and R. Prins, proceedings of 12th
International zeolite conference 1999) using 65% nitric acid as industrially preferred
nitrating agent confirmed that the zeolites provide a higher para to ortho ratio and
zeolite beta in its proton form showed promising results. Nevertheless, activity and
selectivity decreased over a period of five hours on stream due to pore
filling/blockage by strongly adsorbed products/products. The lower conversion of

toluene to nitrotoluenes and faster deactivation of zeolite catalysts are the drawbacks of these processes for commercial application.
International patent WO 96/36587 describes a solvent free process for the nitration of aromatic compounds in which the aromatic compound is reacted with nitric acid in presence of an acid anhydride wherein the process is catalyzed by an aluminosilicate catalyst. Nitric acid and acid anhydride react with each other in-situ to form acyl nitrate and this acts as a nitrating agent for aromatic compounds. For example benzene, naphthalene, anthracene, toluene etc. are nitrated to mononitrated compounds. A mixture of orth-meta-para nitrotoluenes is obtained which is then distilled at a pressure of 30mm Hg and a temperature of 30° C to remove acetic acid as a byproduct.
U.S. patent 5,946,638 and European patent 0949240 Al describe nitration of toluene using concentrated nitric acid over ZSM-5 and modified clay catalyst respectively.
These prior art processes for the vapor phase nitration of toluene for the preparation of nitrotoluenes use 65 to 70 % nitric acid which favors the formation of side chain oxidation products. These products deactivate the catalyst, which leads to low conversions, low space time yield, short catalyst life, contamination of the nitrated aromatic hydrocarbon products by undesirable by-products.
The objective of the present invention is to provide a process for the preparation of para nitrotoluene in high yield.
Another objective is to provide a process with high selectivity by vapor phase nitration of toluene using dilute nitric acid over beta zeolite catalyst.

Accordingly the present invention provides a process for the preparation of para nitro toluene which comprises reacting toluene in vapor phase in an inert atmosphere characterized in that with dilute nitric acid of concentration in the range of 20 to 30% in a molar ratio of toluene to nitric acid in the range of 1:1 to 4:1 in the presence of beta zeolite catalyst having Si/Al=30 and particle size -10 to +20 mesh, at a temperature in the range of 100 to 300°C, at an atmospheric pressure, at a weight hourly space velocity in the range of 0.1 to 1.0, for a period of at least 4 hours and collecting the para nitro toluene in a receiver having temperature 0-5°C.
In one of the embodiment, the catalyst used is a commercially available beta zeolite in powder form or formulated extrudate form using alumina as a binder.
In another embodiment, strength of dilute nitric acid used as nitrating agent is preferably 20 to 30%.
In another embodiment, the molar ratio of toluene to nitric acid is preferably in the range ofl.5:lto3.5: 1.0.
In yet another embodiment, the reaction temperature used is preferably in the range of 140 to 200°C.
In yet another embodiment, the WHSV (Weight hourly space velocity) is preferably in the range of 0.2 to 0.5.
The vapor phase nitration is carried out in conventional down flow reactor containing inert ceramic packing as preheater and granulated zeolite as a catalyst. Toluene and dilute HNO3 are fed to the reactor using syringe pumps along with a carrier gas. The product is condensed and collected in a container and washed with alkali and then analyzed by gas chromatograph after extraction with diethyl ether.

The present invention is described with reference to the examples, herein below, which are illustrative only and should not be construed to restrict the scope of the present invention, in any manner.
EXAMPLE 1 Commercially available formulated beta zeolite (Si/Al = 30) in the form of extrudates was procured from United Catalyst India Ltd. 10 g of zeolite was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe pumps. Reaction conditions are as follows.
Reaction temperature = 120° C Carrier gas = N2
Toluene/HN03 = 1.7:1 (molar ratio) WHSV =0.17
The product was condensed at 5° C and collected in a receiver. The product was analyzed by gas chromatography. Results after 100 hours from beginning of reaction are shown below. There was no deactivation in the activity and selectivity of the catalyst during this period.
Conversion of toluene (%) 45.68
Selectivity ofp-nitrotoluene (%) 70.5
Selectivity of o-nitrotoluene (%) 29.5
Yield for p- nitrotoluene (%) 32.2
p/o ratio of nitrotoluene 2.4

EXAMPLE 2
This example illustrates the effect of the reaction temperature on the conversion and selectivity of para nitrotoluene. 10 g of beta zeolite (formulated) was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe pumps. Reaction conditions are as follows. Reaction Temperature = 175 ° C Carrier gas = N2 HNO3 = 20%
Toluene/HNO3 = 1.7: 1 (molar ratio) WHSV =0.17
Results after 100 hours from beginning of reaction are shown below. There was no deactivation in the activity and selectivity of the catalyst during this period.
Conversion of toluene (%) 37.6
Selectivity ofp-nitrotoluene (%) 65.7
Selectivity of o-nitrotoluene (%) 34.3
Yield for p- nitrotoluene (%) 24.7
p/o ratio of nitrotoluene 1 -92
EXAMPLE 3
This example illustrates the effect of the WHSV on the conversion and selectivity of para nitrotoluene. 10 g of beta zeolite (formulated) was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid

(20%) were fed to the reactor using syringe pumps. Reaction conditions are as
follows.
Carrier gas = N2
Toluene/HN03 = 2.3: 1
HNO3 = 20%
WHSV = 0.5
The reaction results are as follows. There was no deactivation in the activity and selectivity of the catalyst during this period.
Conversion of toluene (%) 22.35
Selectivity ofp-nitrotoluene (%) 74.5
Selectivity of o-nitrotoluene (%) 25.5
Yield for p- nitrotoluene (%) 16.65
p/o ratio of nitrotoluene 2.9
EXAMPLE 4 In this example, the influence of toluene/HN03 ratio is demonstrated on the conversion of toluene to nitrotoluenes. 10 g of beta zeolite (formulated) was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe pumps. Reaction conditions are as follows.
The reaction conditions are as follows. Reaction temperature = 120° C Carrier gas = N2 Toluene/HN03 = 3.2: 1 (molar ratio)

HNO3 =20% WHSV = 0.5
No deactivation of the catalyst was seen during this period. Results after 100 hours from beginning of reaction are shown below.
Conversion of toluene (%) 16.5
Selectivity for p-nitrotoluene (%) 75.2
Selectivity for o-nitrotoluene (%) 24.S
Yield for p-nitro toluene (%) 12.4
p/o ratio of nitrotoluene 3
EXAMPLE 5
This example illustrates the effect of dilution of nitric acid on the conversion and selectivity of para nitrotoluene. In this example 30% HNO3 is used. 10 g of beta zeolite (formulated) was loaded in tubular glass reactor of 15mm diameter and 25mm length. The upper part of the reactor was packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (30%) were fed to the reactor using syringe pumps. Reaction conditions are as follows. Reaction temperature = 120°C Carrier gas = N2
Toluene/HNO3 = 1.1: 1 (molar ratio) WHSV =0.17

No deactivation of the catalyst was seen during this period. Results after 50
hours from beginning of reaction are shown below.
Conversion of toluene (%) 50.6
Yield for nitrotoluene (%) 71
Selectivity for p-nitrotoluene (%) 29
Selectivity for o-nitrotoluene (%) 35.9
p/o ratio ofnitrotoluene 2.5
EXAMPLE 6
Commercially available beta zeolite (Si/Al = 30) powder was compacted in the form of pellet and further granulated to -10 + 20 mesh size for using in nitration reaction. 10 g of granulated zeolite was loaded in tubular glass reactor of 15mm diameter and 25 mm length. The upper part of the reactor is packed with inert ceramic beads as preheating zone. Toluene and dilute nitric acid (20%) were fed to the reactor using syringe purnps. Reaction conditions were as follows. Reaction Temperature = 120 ° C Carrier gas = N2
Toluene/HN03 = 1.5:1 (molar ratio) WHSV =0.17
Results after 100 hours from beginning of reaction are shown below. No deactivation of the catalyst was seen during this period.
Conversion of toluene (%) 25.76
Selectivity of p-nitrotoluene (%) 71.62
Selectivity of o-nitrotoluene (%) 28.38

Yield for p- nitrotoluene (%) 18.45
p/o ratio of nitrotoluene 2.5
Advantages of invention:
Present invention has following advantages over the conventional process.
1. No use of sulfuric acid for nitration and no formation of dilute sulfuric acid waste and hence process is environmentally friendly.
2. Use of dilute nitric acid is cost effective as well as negligible formation of oxidation products.
3. Higher selectivity for para nitro toluene.
4. Use of solid catalyst, which makes the process easy for operation.
5. Present process is clean compared to the conventional process.

We Claim:
1. A process for the preparation of para nitro toluene which comprises reacting toluene in vapor phase in an inert atmosphere characterized in that with dilute nitric acid of concentration in the range of 20 to 30% in a molar ratio of toluene to nitric acid in the range of 1:1 to 4:1 in the presence of beta zeolite catalyst having Si/Al=30 and particle size -10 to +20 mesh, at a temperature in the range of 100 to 300°C, at an atmospheric pressure, at a weight hourly space velocity in the range of 0.1 to 1.0, for a period of at least 4 hours and collecting the para nitro toluene in a receiver having temperature 0-5°C.
2. A process as claimed in claim 1 wherein the catalyst used is a commercially available beta zeolite in powder form or formulated extrudate form using alumina as a binder.
3. A process as claimed in claims 1-3, wherein the molar ratio of toluene to nitric acid preferably in the range of 1.5: 1 to 3.5 : 1.
4. A process as claimed in claims 1-4 wherein the reaction temperature used is preferably in the range of 140 to 200°C.
5. A process for the preparation of para nitro toluene substantially as herein described with reference to the examples accompanying this specification.

Documents:

162-DEL-2002-Claims-(10-06-2008).pdf

162-DEL-2002-Correspondence-Others-(10-06-2008).pdf

165-DEL-2002-Abstract (09-10-2007).pdf

165-DEL-2002-Abstract-23-04-2008.pdf

165-DEL-2002-Claims-(05-03-2008).pdf

165-DEL-2002-Claims-(09-10-2007).pdf

165-DEL-2002-Claims-23-04-2008.pdf

165-DEL-2002-Correspondence-Others-(05-03-2008).pdf

165-DEL-2002-Correspondence-Others-(09-10-2007).pdf

165-DEL-2002-Correspondence-Others-23-04-2008.pdf

165-DEL-2002-Correspondence-Others-29-05-2008.pdf

165-DEL-2002-Description (Complete)-(05-03-2008).pdf

165-DEL-2002-Description (Complete)-(09-10-2007).pdf

165-DEL-2002-Description (Complete)-10-06-2008.pdf

165-DEL-2002-Description (Complete)-23-04-2008.pdf

165-DEL-2002-Form-2-(05-03-2008).pdf

165-DEL-2002-Form-3-(09-10-2007).pdf

abstract.pdf

correspondence-po.pdf

description complete.pdf

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Patent Number

221052

Indian Patent Application Number

165/DEL/2002

PG Journal Number

31/2008

Publication Date

01-Aug-2008

Grant Date

13-Jun-2008

Date of Filing

28-Feb-2002

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	DONGARE MOHAN KERABA	NATIONAL CHEMICAL LABORATORY,PUNE-411008, INDIA
2	DAGADE SHARDA PRABHAKAR	NATIONAL CHEMICAL LABORATORY,PUNE-411008, INDIA
3	KADAM VIJAY SHIVAJI	NATIONAL CHEMICAL LABORATORY,PUNE-411008, INDIA
4	PAUL RAT NASAMY	NATIONAL CHEMICAL LABORATORY,PUNE-411008, INDIA

PCT International Classification Number

C07C 201/06

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA