Title of Invention

AN ELECTROCHEMICAL CELL USEFUL IN THE REDUCTION OF NITRO COMPOUNDS

Abstract The invention relates to an electrochemical cell useful in the reduction of nitro compounds. The cell comprises: in combination a novel cathode consisting of Til ceramic TiO2 and the said cathode sheet being coated with a solution consisting of titanyl acetyl acetonate or titanyl butanoate, nitric acid or hydrochloric acid, water and isopropanol as herein described, lead as anode, a porous diaphragm, the nitro or dinitro compound in sulphuric acid as the catholyte and sulphuric acid as the anolyte.
Full Text This invention relates to an electrochemical cell useful in the reduction of nitro compounds.
Hitherto it has been the practise to reduce nitro compounds to the corresponding amines electrochemically
at a copper cathode indirectly by using inorganic redox
4 + 3+ 4 + 2 + systems, such as Ti /Ti , Ce /Ce in solution.
These methods however, have the following drawbacks. 1. The choice of a minimum redox concentration is to be evaluated since below this concentration, there could be competition due to direct reduction. 2. If the free base is to be isolated from the electrolysis product by neutralisation (for reductions in acid medium), it is likely that the redox species gets precipitated as hydroxide, thereby making the separation difficult. 3. Tendency of the electrolysis products for complex formation is sometimes seen as is the case with several amines, thereby reducing the product yield.
The object of the present invention is to provide
a process for the preparation of Ti/ceramic TiO cath-
ode and an electrochemical cell incorporating the said cathode useful in the electroreduction of nitro and
dinitro compounds, which obviates the disadvantages by
4+ 3 + immobilising the redox species Ti /Ti on the cathode
surface itself.
In our copending application no. 260/DEL/92 fjrom which this application has been divided out we have

provided a process for the preparation of Ti/ceramic TiO2 catrhode sused for the preparation of electrochemical cell useful in the reduction of nitro compounds which comprises (aO cleaning a titanium expanded metal sheet by known methods, (b) etching the cleaned sheet with an acid (c) applying to the etched sheet a solution consisting of titanium acetyl acetyl acetonate or titanium butyl butaonate, nitric acid or HC1, water and isopropanol, (d) drying the coated sheet and (3) firing at a temperature in the range of 450 to 550°C for a period of 5-10 minutes.
The etching of the metal sheet may be done using 10% oxalic acid or 50% HC1. The solution may consist of titanium butyl butanoate, hydrochloric acid, water and isopropanol. The amount of components may range from 4- 8 ml of concentrated nitric acid and 205 ml of water with the concentration of titanium, acetyl acetonate being 0.05M.
Accordingly the present invention provides an electrochemical cell useful in the reduction of nitro compounds comprising in combination a novel cathode consisting of Ti/ ceramic TiO2 and the said cathode sheet being coated with a solution consisting of titanyl acetyl acetonate or titanyl butanoate, nitric acid or hydrochloric acid, water and isopropanol as herein described, lead as anode, a porous diaphragm, the nitro or dinitro compound in sulphuric acid as the catholyte and sulphuric acid as the anolyte.
In our copending application which has been divided out of our application no. 260/DEL/92 (patent no. 184292) there is provide an improved process for the electro-reduction of nitro and dinitro compounds using the above said electrochem-
ical cell of this invention.
The following examples are given to illustrate the process of the present invention and should not be construed to limit the scope of the present invention.
Example 1: typical cell (a one litre glass beaker) consisting of 400 ml of 10% H SO and 8.5 gm of
2 4
nitro-benzene (NB) as catholyte and 100 ml of 10% H SO
2 4 2
as anolyte. Ti/ceramic TiO cathode of area 0.84 dm
2
and lead anode, with ceramic porous pot as diaphragm with the catholyte being constantly agitated using a mechanical stirrer.
Example 2: typical cell consisting of 400 ml of
20% H SO and 11 g of metadinitrobenzene (m-DNB) as 2 4
catholyte and 100 ml of 20% H SO as anolyte. Ti/ceram-
2 4
2
ic TiO cathode of area 0.84 dm and lead anode. 2
The following are the main advantages of the invention:
1. In the use of Ti/ceramic TiO cathode, there is
2
4+ 3 + heterogeneous redox catalysis due to the Ti /Ti on
the cathode surface and hence the reduction efficiency is better than at copper or tin cathodes.
2. The reduction by this method involves no effluent
problem.
3. This method affords the reuse of electrolyte
possible and the electrode performance during reuse is
extremely good.
4. During neutralisation of an electrolysis product,
the problem of complex formation does not arise in this
case in contrast to that observed during the use of
redox systems in solution with a copper cathode.



We Claim:
1. An electrochemical cell useful in the reduction of nitro compounds comprising in combination a novel cathode consisting of Ti/ ceramic TiO2 and the said cathode sheet being coated with a solution consisting of titanyl acetyl acetonate or titanyl butanoate, nitric acid or hydrochloric acid, water and isopropanol as herein described, lead as anode, a porous diaphragm, the nitro or dinitro compound in sulphuric acid as the catholyte and sulphuric acid as the anolyte.
2. An electrochemical cell useful in the reduction of nitro compounds substantially as herein described.


Documents:

1121-del-1998-abstract.pdf

1121-del-1998-claims.pdf

1121-del-1998-correspondence-others.pdf

1121-del-1998-correspondence-po.pdf

1121-del-1998-description (complete).pdf

1121-del-1998-form-1.pdf

1121-del-1998-form-19.pdf

1121-del-1998-form-2.pdf

1121-del-1998-form-3.pdf


Patent Number 215496
Indian Patent Application Number 1121/DEL/1998
PG Journal Number 11/2008
Publication Date 14-Mar-2008
Grant Date 27-Feb-2008
Date of Filing 27-Apr-1998
Name of Patentee COUNCIL OF SCIENTIFIC & INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110001
Inventors:
# Inventor's Name Inventor's Address
1 PAYYALLEER NARAYANAN ANANTHARAMAN CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE KARAI KUDI-630006 INDIA
2 DEVANATH VASUDEVAN SENIOR RESEARCH FOLLOW, ALL OF CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI 630006,INDIA
3 CINGARAN RAVICHANDRAN SENIOR RESEARCH FOLLOW, ALL OF CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI 630006,INDIA
PCT International Classification Number H01M 6/02
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA