Title of Invention	"A PROCESS FOR THE SYNTHESIS OF 1-AMINO-8-NAPTHOL-2, 6-DISULPHONIC ACID"
Abstract	This invention relates to a process for the preparation of 1-amino-8-napthol-2, 6-disulphonic acid or H-acid which is a dye intermediate and comprises in the steps of subjecting naphthalene to the step of nitration in a conventional manner in presence of a catalyst platinum, rhodenium or rhodium in a reaction vessel and in presence of a solvent consisting of organic alcohol such as butyl alcohol and leaving the residual solvent in the said vessel without any production of pollutant, such as sulphuric acid and nitric acid; subjecting nitronaphthalene and residual-solvent in said vessel to the step of reduction in the presence of a catalyst nickel and hydrazine hydrate to produce aminonaphthalene and without any production of pollutant, such as iron chloride; subjecting aminonaphthalene to the step of sulphonation in the presence of trace amounts of sulphuric acid, sulphur dioxide or trioxide and butyl sulphate and said solvent to produce aminodisulphonic naphthalene acid and without production of pollutants; subjecting said aminodisulphonic naphthalene acid and solvent to a known step of oxidation to produce l-amino-8-napthol-2, 6-disulphonic acid or H acid.

Title of Invention

"A PROCESS FOR THE SYNTHESIS OF 1-AMINO-8-NAPTHOL-2, 6-DISULPHONIC ACID"

Abstract

This invention relates to a process for the preparation of 1-amino-8-napthol-2, 6-disulphonic acid or H-acid which is a dye intermediate and comprises in the steps of subjecting naphthalene to the step of nitration in a conventional manner in presence of a catalyst platinum, rhodenium or rhodium in a reaction vessel and in presence of a solvent consisting of organic alcohol such as butyl alcohol and leaving the residual solvent in the said vessel without any production of pollutant, such as sulphuric acid and nitric acid; subjecting nitronaphthalene and residual-solvent in said vessel to the step of reduction in the presence of a catalyst nickel and hydrazine hydrate to produce aminonaphthalene and without any production of pollutant, such as iron chloride; subjecting aminonaphthalene to the step of sulphonation in the presence of trace amounts of sulphuric acid, sulphur dioxide or trioxide and butyl sulphate and said solvent to produce aminodisulphonic naphthalene acid and without production of pollutants; subjecting said aminodisulphonic naphthalene acid and solvent to a known step of oxidation to produce l-amino-8-napthol-2, 6-disulphonic acid or H acid.

Full Text	This invention relates to a process for the synthesis of l~amino-8- napthol -2, 6-disulphoriic acid or H acid . It is generally known that H-acid is a dye intermediate. The known process for the preparation of H-acid consists in subjecting naphthaline to the step of nitration in the presence of sulphuric acid and nitric acid for a period of 6 to 8 hours to produce nitronaphthaline and a pollutant discharge of sulphuric acid and nitric acid. Nitrohaphthaiine is subjected to the step of reduction in the presence of iron and hydrochloric acid for a period of another eight hours to produce amino nehthaline and pollutant discharge containing iron choride. Amonaphthaline obtained from the step of reduction is subjected to the step of sulphonation in presence of oleum for a period of 16 to 18 hours at a temperature of 100'C to produce amino disulphonic acid a pollutant discharge containing sulphuric acid which is finally subjected to the step of oxidation. Several distinct disadvantages are associated with such a known process. One of the essential disadvantage is that of the pollutant streams discharged from such a process. Thus, each step of the process produces a pollutant stream. Yet another disadvantage is that of the considerable period required for completion of the process. A still further disadvantage is that the process is not continuous in nature. An object of this invention is to propose an improved process for the preparation of l-amino-8-naphthol-2, 6-disulphonic acid. Another object of this invention is to propose a process for the preparation of l-amino-8-naphthol-2, 6-disulphonic acid which obviates the disadvantages associated with those of the prior art. Still another object of this invention is to propose a process for the preparation of l-amino-8-naphthol-2, 6-disulphonic acid which is a continuous process. Yet another object of this invention is to propose a process for the preparation of l-amino-8-naphthol-2, 6-disulphonic acid which has a high yield. According to this invention there is provide a process for the preparation of l-amino-8-napthol-2, 6-disulphonic acid or H-acid which is a dye intermediate and comprises in the steps of: i) subjecting naphthalene to the step of nitration in a conventional manner in presence of a catalyst platinum, rhodenium or rhodium in a reaction vessel and in presence of a solvent consisting of organic alcohol such as butyl alcohol and leaving the residual solvent in the said vessel without any production of pollutant, such as sulphuric acid and nitric acid; ii) subjecting nitronaphthalene and residual-solvent in said vessel to the step of reduction in the presence of a catalyst nickel and hydrazine hydrate to produce aminonaphthalene and without any production of pollutant, such as iron chloride; iii) subjecting aminonaphthalene to the step of sulphonation in the presence of trace amounts of sulphuric acid, sulphur dioxide or trioxide and butyl sulphate and said solvent to produce aminodisulphonic naphthalene acid and without production of pollutants; iv) subjecting said aminodisulphonic naphthalene acid and solvent to a known step of oxidation to produce 1-amino-8-napthol-2, 6-disulphonic acid or H acid. Broadly, the present invention consists in the steps of nitration, reduction, sulphonation and oxidation. Such steps were also employed in the known step of preparation of l-amino-8-naphthol-2, 6- disulphonic acid. However, several disadvantages were associated with such a known process, one such distinct disadvantage being the presence of a pollutant in the discharge in each step of the process. Yet another disadvantage is that of the yield and purity. Such disadvantages are obviated by the process of the present invention and, wherein, a pollutant is no longer present in each discharge, and that an acid is no longer used in the various reactions. The step of nitration, in accordance with the process of the present invention, consists in reacting naphthalene in the presence of an organic nitrate in a solvent medium and in the presence of a catalyst. The solvent medium is alcohol, though butyl alcohol is preferred. The catalyst is an inorganic metal, such as platinum, rhodenium and/or rhodium acid present in trace amounts of 0.001 to 0.05%C. The reaction is carried out at a temperature of 65 to 850C and in which butyl nitrate releases 3 nitro group to react with naphthalene to give nitronaphthalene. The reaction is represented as follows: (Figure Removed) As described hereinabove, an alcohol other than butyl alcohol may be used as the solvent. Thus, and as by way of example, ethanol or methanol may be used as the solvent. However, a disadvantage is that a mixture of solvents is then obtained which reduces the purity. The step of nitration is carried out at a temperature of 65-850C. If temperatures above 850C is employed, dinitro naphthalene is obtained, which is not a desired intermediate. Temperatures below 650C result in longer reaction periods. (Figure Removed) The next step consists in reduction, and which may advantageously be carried out in the same reaction vessel as that, of nitration. Dinitro naphthalene is reacted with hydrazine hydrate in the presence of a nickel catalyst. As the medium consists of butyl alcohol, it is necessary to add additional medium to the reaction vessel. Such a reaction provides H2, which in presence of the catalyst, converts No2 to NH2 + water. The reaction is as follows: The reaction is carried out for a period of 20-60 mins. and at a temperature of 60-850C . If temperatures higher than 850C are employed, side products are obtained. Catalyst is present in trace amounts. The next step in the process consists of sulphonation, and which in a likewise manner may be carried out in the same vessel and in the medium already present in said vessel. Aminonaphthalene produced by the step of reduction is subjected to the step of sulphonation in the presence of butyl sulphate and trace amounts of sulphuric acid. Thus, only by way of example, 0.17. sulphuric acid is added to the reaction medium, but which does not produce a discharge. Such a reaction is carried out in the same vessel as the previous steps of nitration and reduction. The step of sulphonation is carried out in the presence of a catalyst such as platinum. Trace amounts of sulphur dioxide or sulphur trioxide are purged into the reaction medium and the reaction is carried out a temperature of 60* to 800C so as to produce amino disulphonic naphthalene acid. The final step of the process consists in the step of oxidation in the presence of KMNO4 to produce the end product. The reaction for the steps of sulphonation and oxidation are as follows: (Figure Removed) Naphthene (1 mol)m o 1 ) was reacted with butyl nitrite (1.l mol ) in organic solvent media consisting butyl alcohol with a metal catalyst (0.01 permol) at 600C for 4 hrs. The nitronaphthelene mass (1 mol ) thus obtained was subjected to reduction with hydrazine hydrate (1.2 mol) using nickel as catalyst trace in the presence butyl alcohol for 20 min, which save the amino naphthene. The ammino naphthalene (1 mal) is sulphonated with butyl sulphate in sulphuric acid media (0.01%) and purged with sulphur dioxide in the presence of platinum as catalyst (0.01% ) for 4 hours to produce 2 , 6 disulphonoic amino-naphthaline. This is oxidized to H-acid to obtain a yield of 95% having a purity of 98%.. WE CLAIM; 1. A process for the preparation of l-amino-8-napthol-2, 6- comprises in the steps of: i) subjecting naphthalene to the step of nitration in a conventional manner in presence of a catalyst platinum, rhodium in a reaction vessel and in presence of a solvent consisting of organic alcohol such as butyl alcohol and leaving the residual solvent in the said vessel without any production of pollutant, such as sulphuric acid and nitric acid; ii) subjecting nitronaphthalene and residual-solvent in said vessel to the step of reduction in the presence of a catalyst nickel and hydrazine hydrate to produce aminonaphthalene and without any production of pollutant, such as iron chloride; iii) subjecting aminonaphthalene to the step of sulphonation in the presence of trace amounts of sulphuric acid, sulphur dioxide or trioxide and butyl sulphate and said solvent to produce aminodisulphonic naphthalene acid and without production of pollutants; iv) subjecting said aminodisulphonic naphthalene acid and solvent to a known step of oxidation to produce 1-amino-8-napthol-2, 6-disulphonic acid or H acid. 2. A process as claimed in claim 1 wherein the step of nitration is carried out at a temperature of 65 to 85°C. 3. A process as claimed in claim wherein the step of reduction is carried out at a temperature of 60-85°C for a period of 2d to 60 mins. 4. A process as claimed in claim 1 wherein the step of oxidation is carried out in the presence of KMNO4. 5. A process for the preparation of l-amino-8, napthol-2, 6- disulphonic acid substantially as herein described and illustrated in the example.

Full Text

This invention relates to a process for the synthesis of l~amino-8- napthol -2, 6-disulphoriic acid or H acid .
It is generally known that H-acid is a dye intermediate. The known process for the preparation of H-acid consists in subjecting naphthaline to the step of nitration in the presence of sulphuric acid and nitric acid for a period of 6 to 8 hours to produce nitronaphthaline and a pollutant discharge of sulphuric acid and nitric acid. Nitrohaphthaiine is subjected to the step of reduction in the presence of iron and hydrochloric acid for a period of another eight hours to produce amino nehthaline and pollutant discharge containing iron choride. Amonaphthaline obtained from the step of reduction is subjected to the step of sulphonation in presence of oleum for a period of 16 to 18 hours at a temperature of 100'C to produce amino disulphonic acid a pollutant discharge containing sulphuric acid which is finally subjected to the step of oxidation.
Several distinct disadvantages are associated with such a known process. One of the essential
disadvantage is that of the pollutant streams discharged from such a process. Thus, each step of the process produces a pollutant stream. Yet another disadvantage is that of the considerable period required for completion of the process. A still further disadvantage is that the process is not continuous in nature. An object of this invention is to propose an improved process for the preparation of l-amino-8-naphthol-2, 6-disulphonic acid.
Another object of this invention is to propose a process for the preparation of l-amino-8-naphthol-2, 6-disulphonic acid which obviates the disadvantages associated with those of the prior art.
Still another object of this invention is to propose a process for the preparation of l-amino-8-naphthol-2, 6-disulphonic acid which is a continuous process.
Yet another object of this invention is to propose a process for the preparation of l-amino-8-naphthol-2, 6-disulphonic acid which has a high yield.
According to this invention there is provide a process for the preparation of l-amino-8-napthol-2, 6-disulphonic acid or H-acid which is a dye intermediate and comprises in the steps of:
i) subjecting naphthalene to the step of nitration in a conventional manner in presence of a catalyst platinum, rhodenium or rhodium in a reaction vessel and in presence of a solvent consisting of organic alcohol such as butyl alcohol and leaving the residual solvent in the said vessel without any production of pollutant, such as sulphuric acid and nitric acid;
ii) subjecting nitronaphthalene and residual-solvent in said vessel to the step of reduction in the presence of a catalyst nickel and hydrazine hydrate to produce aminonaphthalene and without any production of pollutant, such as iron chloride;
iii) subjecting aminonaphthalene to the step of sulphonation in the presence of trace amounts of sulphuric acid, sulphur dioxide or trioxide and butyl sulphate and said solvent to produce aminodisulphonic naphthalene acid and without production of pollutants;
iv) subjecting said aminodisulphonic naphthalene acid and solvent to a known step of oxidation to produce 1-amino-8-napthol-2, 6-disulphonic acid or H acid.
Broadly, the present invention consists in the steps of nitration, reduction, sulphonation and oxidation. Such steps were also employed in the known step of preparation of l-amino-8-naphthol-2, 6-
disulphonic acid. However, several disadvantages were associated with such a known process, one such distinct disadvantage being the presence of a pollutant in the discharge in each step of the process. Yet another disadvantage is that of the yield and purity.
Such disadvantages are obviated by the process of the present invention and, wherein, a pollutant is no longer present in each discharge, and that an acid is no longer used in the various reactions. The step of nitration, in accordance with the process of the present invention, consists in reacting naphthalene in the presence of an organic nitrate in a solvent medium and in the presence of a catalyst. The solvent medium is alcohol, though butyl alcohol is preferred. The catalyst is an inorganic metal, such as platinum, rhodenium and/or rhodium acid present in trace amounts of 0.001 to 0.05%C. The reaction is carried out at a temperature of 65 to 850C and in which butyl nitrate releases 3 nitro group to react with naphthalene to give nitronaphthalene. The reaction is represented as follows:
(Figure Removed)
As described hereinabove, an alcohol other than butyl alcohol may be used as the solvent. Thus, and as by way of example, ethanol or methanol may be used as the solvent. However, a disadvantage is that a mixture of solvents is then obtained which reduces the purity.
The step of nitration is carried out at a temperature of 65-850C. If temperatures above 850C is employed, dinitro naphthalene is obtained, which is not a desired intermediate. Temperatures below 650C result in longer reaction periods.
(Figure Removed)
The next step consists in reduction, and which may advantageously be carried out in the same reaction vessel as that, of nitration. Dinitro naphthalene is reacted with hydrazine hydrate in the presence of a nickel catalyst. As the medium consists of butyl alcohol, it is necessary to add additional medium to the reaction vessel. Such a reaction provides H2, which in presence of the catalyst, converts No2 to NH2 + water. The reaction is as follows:
The reaction is carried out for a period of 20-60 mins.
and at a temperature of 60-850C . If temperatures higher than 850C are employed, side products are obtained. Catalyst is present in trace amounts.
The next step in the process consists of sulphonation, and which in a likewise manner may be carried out in the same vessel and in the medium already present in said vessel. Aminonaphthalene produced by the step of reduction is subjected to the step of sulphonation in the presence of butyl sulphate and trace amounts of sulphuric acid. Thus, only by way of example, 0.17. sulphuric acid is added to the reaction medium, but which does not produce a discharge. Such a reaction is carried out in the same vessel as the previous steps of nitration and reduction. The step of sulphonation is carried out in the presence of a catalyst such as platinum. Trace amounts of sulphur dioxide or sulphur trioxide are purged into the reaction medium and the reaction is carried out a temperature of 60* to 800C so as to produce amino disulphonic naphthalene acid.
The final step of the process consists in the step of oxidation in the presence of KMNO4 to produce the end product. The reaction for the steps of sulphonation and oxidation are as follows:
(Figure Removed)
Naphthene (1 mol)m o 1 ) was reacted with butyl nitrite (1.l mol ) in organic solvent media consisting butyl alcohol with a metal catalyst (0.01 permol) at 600C for 4 hrs. The nitronaphthelene mass (1 mol ) thus obtained was subjected to reduction with hydrazine hydrate (1.2 mol) using nickel as catalyst trace in the presence butyl alcohol for 20 min, which save the amino naphthene. The ammino naphthalene (1 mal) is sulphonated with butyl sulphate in sulphuric acid media (0.01%) and purged with sulphur dioxide in the presence of platinum as catalyst (0.01% ) for 4 hours to produce 2 , 6 disulphonoic amino-naphthaline.
This is oxidized to H-acid to obtain a yield of 95% having a purity of 98%..

WE CLAIM;
1. A process for the preparation of l-amino-8-napthol-2, 6-

comprises in the steps of:
i) subjecting naphthalene to the step of nitration in a conventional manner in presence of a catalyst platinum, rhodium in a reaction vessel and in presence of a solvent consisting of organic alcohol such as butyl alcohol and leaving the residual solvent in the said vessel without any production of pollutant, such as sulphuric acid and nitric acid;
ii) subjecting nitronaphthalene and residual-solvent in said vessel to the step of reduction in the presence of a catalyst nickel and hydrazine hydrate to produce aminonaphthalene and without any production of pollutant, such as iron chloride;
iii) subjecting aminonaphthalene to the step of sulphonation in the presence of trace amounts of sulphuric acid, sulphur dioxide or trioxide and butyl sulphate and said solvent to produce aminodisulphonic naphthalene acid and without production of pollutants;
iv) subjecting said aminodisulphonic naphthalene acid and solvent to a known step of oxidation to produce 1-amino-8-napthol-2, 6-disulphonic acid or H acid. 2. A process as claimed in claim 1 wherein the step of nitration is
carried out at a temperature of 65 to 85°C.
3. A process as claimed in claim wherein the step of reduction
is carried out at a temperature of 60-85°C for a period of 2d
to 60 mins.
4. A process as claimed in claim 1 wherein the step of oxidation
is carried out in the presence of KMNO4.
5. A process for the preparation of l-amino-8, napthol-2, 6-
disulphonic acid substantially as herein described and
illustrated in the example.

Documents:

2264-del-1997-abstract.pdf

2264-del-1997-claims.pdf

2264-del-1997-correspondence-others.pdf

2264-del-1997-correspondence-po.pdf

2264-del-1997-description (complete).pdf

2264-del-1997-form-1.pdf

2264-del-1997-form-19.pdf

2264-del-1997-form-2.pdf

2264-del-1997-form-26.pdf

2264-del-1997-form-3.pdf

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Patent Number

214506

Indian Patent Application Number

2264/DEL/1997

PG Journal Number

08/2008

Publication Date

22-Feb-2008

Grant Date

12-Feb-2008

Date of Filing

12-Aug-1997

Name of Patentee

YADVENDRA KUMAR AGARWAL

Applicant Address

HEAD OF CHEMISTRY DEPARTMENT, UNIVERSITY OF GUJRAT, AHMEDABAD, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	Y.K.AGARWAL	HEAD OF CHEMISTRY DEPARTMENT, UNIVERSITY OF GUJARAT, AHMEDABAD, INDIA.
2	YADVENDRA KUMAR AGARWAL	HEAD OF CHEMISTRY DEPARTMENT, UNIVERSITY OF GUJARAT, AHMEDABAD, INDIA.

PCT International Classification Number

C07C143/66

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA