Title of Invention	"AN IMPROVED PROCESS FOR THE PREPARATION OF 4,4` DIAMINOBENZANILIDE (DABA)"
Abstract	An improved process for the preparation of 4,4'-diaminobenzanilide (DABA) having formula 1 of the drawing accompanying the specifications where Z=NH2 which comprises: reducing 4,4-dinitrobenzanilide of the formula 1 where Z =NO2 of the drawing accompanying the specifications with hydrazine hydrate in a molar ratio of 1:4, adding graphite or carbon black as catalyst in 1:1 molar ratio by wt and solvent selected fi-om alcohol C2 - C5 carbon atoms at refluxing temperature and recovering DABA by evaporating and recovering graphite or carbon black by filteration it desired.

Title of Invention

"AN IMPROVED PROCESS FOR THE PREPARATION OF 4,4` DIAMINOBENZANILIDE (DABA)"

Abstract

An improved process for the preparation of 4,4'-diaminobenzanilide (DABA) having formula 1 of the drawing accompanying the specifications where Z=NH2 which comprises: reducing 4,4-dinitrobenzanilide of the formula 1 where Z =NO2 of the drawing accompanying the specifications with hydrazine hydrate in a molar ratio of 1:4, adding graphite or carbon black as catalyst in 1:1 molar ratio by wt and solvent selected fi-om alcohol C2 - C5 carbon atoms at refluxing temperature and recovering DABA by evaporating and recovering graphite or carbon black by filteration it desired.

Full Text	This invention relates to an improved process for the preparation of 4,4'-diaminobenzanilide (DABA). 4,4'-diaminobenzanilide having formula I of the drawing accompanying this specification wherein Z=NH2 is a useful intermediate in the preparation of dyes, pharmaceuticals and pesticides. 4,4'-Diaminobenzanilide (DABA) [785-30-8] I (Z=NH2, figure 1) is a classical substitute of carcinogenic benzidine getting recognition worldwide as a safer intermediate for azo and other class of dyes. The reduction of dinitrobenzanilide by conventional methods using catalyst such as Fe/acid (Hiroshima Daigaku Kayakubu Konkyu Hokuku,5,187-93,1956), another catalyst used in known methods is Na2S2/Py (Zhur Vsesogur Khim Obschchestra 6, 588 1961) etc., are highly objectionable because of environmental problems. The catalytic hydrogenation using hydrazine hydrate and a catalyst selected form Raney Nickel, Palladium and Platinum (Synthesis 8,640,1981) are not cost effective. As a result new process has been developed which is cost effective and eco-friendly. The process of invention produces 4,4'-diamiobenzanilide by simple reduction of 4.4'-dinitrobenzanilide with graphite 210 (iS)/72(BSS) mesh or carbon black 70 (IS)/22 (BSS) mesh in presence of hydrazine hydrate and dry alcohol having chain length C2 to C5 carbon atoms. The time taken is from 10 to 480 mts. The work up procedure has been reduced to simple filtration and concentration. The main objective of the present invention is to provide an improved process for the preparation of DABA avoiding use of costly hydrogenation catalysts such as Platinum, Palladium, Raney Nickel etc., and hazardous catalysts such as Fe-acid and Na2S2. Another objective of present invention is to make use of cost effective eco-friendly process for the preparation of DABA. Still another objective is to use readily available graphite or carbon black as a catalyst in presence of alcohols with C2-C5 carbon atoms. Accordingly the present invention provides An improved process for the preparation of 4,4'-diaminobenzanilide (DABA) having formula 1 of the drawing accompanying the specifications where Z=NH2 which comprises : (i) reducing 4,4-dinitroben2anilide of the formula 1 where Z = NO2 of the drawing accompanying the specifications with hydrazine hydrate in a molar ratio of 1:4, (ii) adding graphite or carbon black as catalyst in 1:1 molar ratio by wt and solvent selected from alcohol having C2 - C5 carbon atoms at refluxing temperature and recovering DABA by evaporating and recovering graphite or carbon black by filteration it desired. In an embodiment of the present invention alcohol having carbon atoms 2 to 5 used may be such as isomeric propyl, butyl and amyl alcohol. In another embodiment of the present invention graphite* or carbon black used may be of mesh 210(IS), 72(BSS) or 70(IS), 22(BSS) respectively: In still another embodiment ratio between 4,4'-dinitrobenzanilide and hydrazine hydrate (99-100%) may be 1:4 (molar) and between 4,4'- dinitrobenzanilide and graphite or carbon black may be 1:>1 by weight. The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the invention. Example 1 Procedure: To 28.7gms. of 4,4'-dinitrobenzanilide was added 20 ml hydrazine hydrate (99-100%). To this mixture 100 ml dry ethyl alcohol was added along with 30 gm. Carbon black. It was refluxed for 7 hrs. at 80° C. The reaction was monitored by TLC using benzene-ethylacetate solvent mixture (1:1). The catalyst was removed by filtering hot solution. The solvent was recovered on rotavapor. The yield was 20.88 gms. (92%) of 4,4'-diaminobenzaniiide m.p. 202-204° C. Example 2 Procedure: To 28.7 gms. Of 4,4'-dinitrobenzanilide added 20 ml hydrazine hydrate (99-100%). To this mixture 100 ml. dry ethyl alcohol was added along with 30 gms. Graphite. It was refluxed for 7 hrs. The reaction was monitored by TLC using benzene-ethylacetate solvent mixture (1:1). The catalyst was removed by filtering the hot solution. The yield was 19.6 gm. (86.4%) of 4,4'-diaminobenzanilide m.p. 200-202° C. In a similar way alcohols having carbon atom 3,4,5 such as isomeric propyl, butyl and pentyl alcohol can be used for the preparation of DABA. The main advantages of present invention are: This process avoids the use of hazardous chemicals such as Fe-acid and Na2 S 2and also costly chemicals such as Pt, Pd or Raney Ni,. Carbon black is preferred to graphite. We Claim : 1. An improved process for the preparation of 4,4'-diaminobenzanilide (DABA) having formula 1 of the drawing accompanying the specifications where Z=NH2 which comprises : (ill) reducing 4,4-dinitrobenzanilide of the formula 1 where Z = NO2 of the drawing accompanying the specifications with hydrazine hydrate in a molar ratio of 1:4, (iv) adding graphite or carbon black as catalyst in 1:1 molar ratio by wt and solvent selected from alcohol having C2 - C5 carbon atoms at refluxing temperature and recovering DABA by evaporating and recovering graphite or carbon black by filteration it desired. 2. An improved process as claimed in claim 1 wherein the alcohol having carbon atoms 2 to 5 used are isomeric propyl, butyl and amyl alcohol. 3. An improved process for the preparation of 4,4'-diaminobenzanilide (DABA) having formula 1 of the drawing accompanying in specifications where Z=NH2 substantially as herein described with reference to the examples.

Full Text

This invention relates to an improved process for the preparation of 4,4'-diaminobenzanilide (DABA). 4,4'-diaminobenzanilide having formula I of the drawing accompanying this specification wherein Z=NH2 is a useful intermediate in the preparation of dyes, pharmaceuticals and pesticides. 4,4'-Diaminobenzanilide (DABA) [785-30-8] I (Z=NH2, figure 1) is a classical substitute of carcinogenic benzidine getting recognition worldwide as a safer intermediate for azo and other class of dyes.
The reduction of dinitrobenzanilide by conventional methods using catalyst such as Fe/acid (Hiroshima Daigaku Kayakubu Konkyu Hokuku,5,187-93,1956), another catalyst used in known methods is Na2S2/Py (Zhur Vsesogur Khim Obschchestra 6, 588 1961) etc., are highly objectionable because of environmental problems. The catalytic hydrogenation using hydrazine hydrate and a catalyst selected form Raney Nickel, Palladium and Platinum (Synthesis 8,640,1981) are not cost effective. As a result new process has been developed which is cost effective and eco-friendly. The process of invention produces 4,4'-diamiobenzanilide by simple reduction of 4.4'-dinitrobenzanilide with graphite 210 (iS)/72(BSS) mesh or carbon black 70 (IS)/22 (BSS) mesh in presence of hydrazine hydrate and dry alcohol having chain length C2 to C5 carbon atoms. The time taken is from 10 to 480 mts. The work up procedure has been reduced to simple filtration and concentration.
The main objective of the present invention is to provide an improved process for the preparation of DABA avoiding use of costly hydrogenation catalysts such as Platinum, Palladium, Raney Nickel etc., and hazardous
catalysts such as Fe-acid and Na2S2.
Another objective of present invention is to make use of cost effective eco-friendly process for the preparation of DABA.
Still another objective is to use readily available graphite or carbon black as a catalyst in presence of alcohols with C2-C5 carbon atoms.
Accordingly the present invention provides An improved process for the preparation of 4,4'-diaminobenzanilide (DABA) having formula 1 of the drawing accompanying the specifications where Z=NH2 which comprises :
(i) reducing 4,4-dinitroben2anilide of the formula 1 where Z = NO2 of the drawing accompanying the specifications with hydrazine hydrate in a molar ratio of 1:4, (ii) adding graphite or carbon black as catalyst in 1:1 molar ratio by wt and solvent selected from alcohol having C2 - C5 carbon atoms at refluxing temperature and recovering DABA by evaporating and recovering graphite or carbon black by filteration it desired. In an embodiment of the present invention alcohol having carbon atoms 2 to 5 used may be such as isomeric propyl, butyl and amyl alcohol.
In another embodiment of the present invention graphite* or carbon
black used may be of mesh 210(IS), 72(BSS) or 70(IS), 22(BSS) respectively:
In still another embodiment ratio between 4,4'-dinitrobenzanilide and
hydrazine hydrate (99-100%) may be 1:4 (molar) and between 4,4'-
dinitrobenzanilide and graphite or carbon black may be 1:>1 by weight.
The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the invention.
Example 1 Procedure:
To 28.7gms. of 4,4'-dinitrobenzanilide was added 20 ml hydrazine hydrate (99-100%). To this mixture 100 ml dry ethyl alcohol was added along with 30 gm. Carbon black. It was refluxed for 7 hrs. at 80° C. The reaction was monitored by TLC using benzene-ethylacetate solvent mixture (1:1). The catalyst was removed by filtering hot solution. The solvent was recovered on rotavapor. The yield was 20.88 gms. (92%) of 4,4'-diaminobenzaniiide m.p. 202-204° C.
Example 2 Procedure:
To 28.7 gms. Of 4,4'-dinitrobenzanilide added 20 ml hydrazine hydrate (99-100%). To this mixture 100 ml. dry ethyl alcohol was added along with 30 gms. Graphite. It was refluxed for 7 hrs. The reaction was monitored by TLC using benzene-ethylacetate solvent mixture (1:1). The catalyst was removed by filtering the hot solution. The yield was 19.6 gm. (86.4%) of 4,4'-diaminobenzanilide m.p. 200-202° C.
In a similar way alcohols having carbon atom 3,4,5 such as isomeric propyl, butyl and pentyl alcohol can be used for the preparation of DABA.
The main advantages of present invention are:
This process avoids the use of hazardous chemicals such as Fe-acid and Na2 S 2and also costly chemicals such as Pt, Pd or Raney Ni,. Carbon black is preferred to graphite.

We Claim :
1. An improved process for the preparation of 4,4'-diaminobenzanilide
(DABA) having formula 1 of the drawing accompanying the specifications
where Z=NH2 which comprises :
(ill) reducing 4,4-dinitrobenzanilide of the formula 1 where Z = NO2 of the drawing accompanying the specifications with hydrazine hydrate in a molar ratio of 1:4,
(iv) adding graphite or carbon black as catalyst in 1:1 molar ratio by wt and solvent selected from alcohol having C2 - C5 carbon atoms at refluxing temperature and recovering DABA by evaporating and recovering graphite or carbon black by filteration it desired.
2. An improved process as claimed in claim 1 wherein the alcohol having carbon atoms 2 to 5 used are isomeric propyl, butyl and amyl alcohol.
3. An improved process for the preparation of 4,4'-diaminobenzanilide (DABA) having formula 1 of the drawing accompanying in specifications where Z=NH2 substantially as herein described with reference to the examples.

Documents:

1090-del-1999-abstract.pdf

1090-del-1999-claims-cancelled.pdf

1090-del-1999-claims.pdf

1090-del-1999-complete specification(granted).pdf

1090-del-1999-correspondence-others.pdf

1090-del-1999-correspondence-po.pdf

1090-del-1999-description (complete).pdf

1090-del-1999-drawings.pdf

1090-del-1999-form-1.pdf

1090-del-1999-form-2.pdf

1090-del-1999-form-4.pdf

1090-del-1999-form-9.pdf

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Patent Number

191481

Indian Patent Application Number

1090/DEL/1999

PG Journal Number

49/2003

Publication Date

06-Dec-2003

Grant Date

30-Jun-2004

Date of Filing

10-Aug-1999

Name of Patentee

COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	DATTARAY MANOHAR AKKEWAR	CHEMICAL TECHNOLOGY, HYDERABAD-500 007, ANDHRA PRADESH, INDIA.
2	LINGAIAH NAGARAPU	CHEMICAL TECHNOLOGY, HYDERABAD-500 007, ANDHRA PRADESH, INDIA.
3	CHANDRA SHEKHAR BOREDA	CHEMICAL TECHNOLOGY, HYDERABAD-500 007, ANDHRA PRADESH, INDIA.
4	MAKINENI PANDURANGA RAO	CHEMICAL TECHNOLOGY, HYDERABAD-500 007, ANDHRA PRADESH, INDIA.
5	SURESH NARAYAN MATHUR	CHEMICAL TECHNOLOGY, HYDERABAD-500 007, ANDHRA PRADESH, INDIA.

PCT International Classification Number

C07C 211/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA