Title of Invention

"A METHOD FOR THE PREPARATION OF LITHIUM META ARSENATE-LiAsO2"

Abstract The present invention provides a novel solid state method for the synthesis of lithium meta arsenate (LiAsO2) by mixing a lithium source with arsenious trioxide under controlled conditions to obtain the lithium meta arsenate.
Full Text Field of the invention
The present invention provides a novel process for the preparation of lithium meta arsenate (LiAsO2) useful as an intermediate for the preparation of lithium hexafluro arsenate (LiAsFe) which is a secondary lithium ion battery electrolyte for nonaqueous solid state and polymer electrolyte.
Lithium meta arsenate (LiAsCh) is not well documented in literature although the corresponding equivalent sodium compound known as sodium meta arsenate (NaAs02) is well documented in literature. This compound easily decomposes in acid media to arseneous trioxide (As2C>3). Since other methods are not available to prepare this compound, as of today there is nothing to write about the disadvantages.
The main object of this invention is to provide a novel hitherto unattempted method for the synthesis of lithium meta arsenate (LiAsO2) salt.
Another object of this invention is to provide a simple thermal method for the synthesis of lithium meta arsenate (LiAsOj).
Yet another object of this invention is to get a pure product from solid state reactions without any side or partial reaction.
Still yet another object of this invention is to synthesis lithium meta arsenate (LiAsO2) by thermal method.
Yet another object of this invention is to provide a clean reaction by mixing equimolar proportions of lithium salts and arsenous trioxide under closed controlled conditions.
Accordingly, the present invention provides a novel method for the preparation of lithium meta arsenate (LiAsOz) comprising mixing a lithium source selected from the group consisting of lithium carbonate (dry and AR), lithium oxide (dry and AR quality), lithium nitrate (dry and AR), lithium hydroxide (dry and AR) and any mixture thereof with arsenious trioxide (dry and AR), grinding the mixture and heating the ground mixture to obtain lithium meta arsenate (LiAsO2) and cooling the product so obtained.
In one embodiment of the invention, the reactions are conducted in solid state with the lithium source and arsenious trioxide both being taken in the form of solids.
In another embodiment of the invention, the lithium source is selected from the group consisting of lithium oxide (dry and AR quality), lithium nitrate (dry and AR) and lithium

hydroxide (dry and AR) and the heating of the ground mixture of said lithium source with arsenious trioxide is done at a temperature of 400°C for 4 hours.
In another embodiment of the invention, the lithium source comprises lithium carbonate (dry and AR) and the heating of the ground mixture of said lithium source with arsenious trioxide is done at a temperature of 600°C for 10 hours.
In another embodiment of the invention, the ground mixture of solid lithium source and solid arsenious trioxide are taken in a silica or porcelain crucible and introduced into a preheated furnace kept at a preheat of 100°C.
In an embodiment of the invention LiOH or Li2O or Li2CO3 or LiNO3 is allowed to react with arseneous trioxide (As2O3) by a solid state thermal procedure.
In still another embodiment of the invention the lithium source and the arsenious trioxide are taken in the molar ratio of 1:1 such that lithium : arsenic are in 1:1 proportion. In yet another embodiment of the invention the process is carried out in a single step.
In yet another embodiment of the invention no side or partial reactions occur. Brief description of the accompanying drawing
. ' ', X-ray analysis of the product sample obtained by the process of the invention confirming the purity of the product.
Lithium meta arsenate (LiAsCh) is prepared in the present invention by the following procedure which can be considered as pure solid state reaction between two solid state material namely lithium salts of lithium hydroxide or lithium oxide or lithium carbonate or lithium nitrate and arsenous trioxide on specific conditions of heating. Hence, lithium meta arsenate (LiAsCh) is prepared by reacting LiOH or LiNO3 or L'^COi, or Li2O with As2O3 under controlled heating conditions. A solid state reaction occurs between the salts of lithium mentioned above with arseneous trioixide at specific temperatures and the product lithium meta arsenate (LiAsO2) is formed. Arsenous trioxide is mixed with equimolar proportions of LiOH or LiN03 or Li2Co3 or Li2O salt and the mixture was ground well and the ground mixture was transferred into a silica/porcelain crucible. The crucible containing the lithium salt and arsenous trioxide mixture was slowly heated to 100°C and then heated to 400°C for 10 hours in an electric furnace continuously maintaining the temperature. However, in the case of lithium carbonate, arsenous troxide mixture the heating was raised to 600°C keeping the same time as 10 hours for maintaining the temperature.
The reaction occurring during the solid state process is given below 2 LiX + As2O3 — -> 2 LiAsO2 + 2X where X is OH", O2', NO3", CO32'

A novel method for the preparation of lithium meta arsenate (LiAsOi) was developed wherein lithium carbonate (dry and AR) or lithium oxide (dry & AR quality) or lithium nitrate (dry and AR) and lithium hydroxide (dry and AR) are mixed with equimolar quantity or arsenous trioxide (dry and AR). The mixture is ground well and then transferred to a silica or porcelain crucible. The crucible is inserted into a preheated electric furnace kept at a temperature of 100°C and the heating was slowly raised to 400°C and the temperature maintained for 4 hours for the mixture containing any of the following lithium salts - LiOH or LiNOs or Li2O salt. For the mixture containing I^COa however the temperature was raised to 600°C and the heating continued for 10 hours. The product was then removed from the furnace after cooling and analysed the sample by X-ray to confirm the purity and identity of the product.
The reactions that occur are:
a. 2LiOH + As2O3 -» 2 LiAsO2 + H2O
b. 2 LiNO3 + As2O3 -> 2LiAsO2 + 2NO2
c. Li2CO3 + As2O3 -> 2 LiAsO2 + CO2
d. Li2O + As2O3 -> 2LiAsO2
LiOH or Li2O or l^COa or LiNOa is allowed to react with arseneous trioxide (As2Os) by a solid state thermal procedure. The lithium salt and the arsenic salt are taken in the molar ratio of 1:1 such that lithium : arsenic is in 1:1 proportion. A feature of this invention is that the process is carried out in a single step. No side or partial reactions occur.
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention. Example 1
Pure and dry l^COa is mixed with pure and dry arsenous oxide in equimolar
proportion. The mixture was ground well and then the ground mixture was transferred into a
silica/porcelain crucible. The mixture was introduced into an electric furnace kept at 100°C.
After keeping the mixture for an hour at 100°C the temperature of the furnace was elevated to
600°C. The heating was done for 10 hours. The heating was discontinued and the furnace was
cooled to room temperature. The product obtained was analyzed.
Components Composition
Li2C03 0.74 g
As2O3 1.98 g
Initial Temperature 100°C
Time 1 hours

Final Temperature 600°C
Time 10 hours
Colour of the product White
Efficiency of the process > 92% Example 2
Pure and dry LiOH is mixed with pure and dry arsenous oxide in equimolar
proportions. The mixture was ground well and then the ground mixture was transferred into a
silica/porcelain crucible. The mixture was introduced into an electric furnace kept at 100°C.
After keeping the mixture for an hour at 100°C the temperature of the furnace was elevated to
400°C. The heating was done for 10 hours. The heating was discontinued and the furnace was
cooled to room temperature. The product obtained was analyzed.
Components Composition
LiOH 0.84g
As2O3 1.98g .
Initial Temperature 100°C
Time 1 hour
Final Temperature 400°C
Time 10 hours
Colour of the product White
Efficiency of the process > 95% Example 3
Pure and dry LiNOa is mixed with pure and dry arsenous oxide in equimolar
proportions. The mixture was ground well and then the ground mixture was transferred into a
silica/porcelain crucible. The mixture was introduced into an electric furnace kept at 100°C.
After keeping the mixture for an hour at 100°C the temperature of the furnace was elevated to
400°C. The heating was done for 10 hours. The heating discontinued and the furnace was
cooled to room temperature. The product obtained was analyzed.
Components Composition
LiNO3 2.46g
As203 7.5g
Initial Temperature 100°C
Time 1 hour
Final Temperature 400°C
Time 10 hours

Colour of the product White
Efficiency of the process > 92% Example 4
Pure and dry Li2O is mixed with pure and dry arsenous oxide in equimolar
proportions. The mixture was ground well and then the ground mixture was transferred into a
silica/porcelain crucible. The mixture was introduced into an electric furnace kept at 100°C.
After keeping the mixture for an hour at 100°C the temperature of the furnace was elevated to
400°C. The heating was done for 10 hours. The heating was discontinued and the furnace was
cooled to room temperature. The product obtained was analyzed.
Components Composition
Li2O 0.6 g
As2O3 1.98g
Initial Temperature 100°C
Time 1 hour
Final Temperature 400°C
Time 10 hours
Colour of the product White
Efficiency of the process > 95% Conclusion
1. Lithium salts like Li2O, LiaCOa, LiOH, LiNOa or the mixtures are used to react with
arseneous trioxide in the molar ratio 1:1.
2. Lithium salts Li2O, LisCOa, LiOH, LiNOa react with As2Oa to form LiAsCh.
3. A solid state reaction occurs when arseneous trioxide reacts with Li2O,
LiOH, LiNOa.
4. It is a single step procedure.



We Claim
1 . A method for the preparation of lithium meta arsenate (LiAsCh) comprising mixing a lithium source selected from the group consisting of lithium carbonate (dry and AR), lithium oxide (dry and AR quality), lithium nitrate (dry and AR), lithium hydroxide (dry and AR) and any mixture thereof with arsenious trioxide (dry and AR), grinding the mixture and heating the ground mixture to obtain lithium meta arsenate (LiAsC^) and cooling the product so obtained.
2. A method as claimed in claim 1 wherein the reaction is conducted in solid state with
the lithium source and arsenious trioxide both being taken in the form of solids.
3. A method as claimed in claims 1&2, wherein the ground mixture of solid lithium
source and solid arsenious trioxide are taken in a silica or porcelain crucible and
introduced into a preheated furnace.
4. A method as claimed in claims 1-3, wherein the furnace is kept at a pre heat of 100°C.
5. A method as claimed in claims 1-4, wherein the lithium source used is selected from
the group consisting of lithium oxide (dry and AR quality), lithium nitrate (dry and
AR) and lithium hydroxide (dry and AR) and the heating of the ground mixture of
said lithium source with arsenious trioxide is done at a temperature of 400°C for 4 to
10 hours.
6. A method as claimed in claims 1-5, wherein the lithium source use lithium carbonate
(dry and AR) and the heating of the ground mixture of said lithium source with
arsenious trioxide is done at a temperature of 600°C for 10 hours.
7. A method as claimed in claims 1-6, wherein the LiOH or Li2O or I^COs or LiNO} is
reacted with arseneous trioxide (AsaCb) by a solid state thermal procedure.
8. A method as claimed in claims 1-7, wherein the lithium source and the arsenious
trioxide are taken in the molar ratio of 1:1 such that lithium:arsenic are in 1:1
proportion.
9. A method as claimed in claims 1-8, wherein the process is carried out in a single step.
10. A method as claimed in claims 1-9, wherein no side or partial reactions occur.
11. A method for the preparation of lithium meta arsenate substantially as herein
described with reference to the examples - ' ' accompanying this
specification.

Documents:

256-DEL-2002-Abstract(18-1-2008).pdf

256-del-2002-abstract.pdf

256-DEL-2002-Claims(18-1-2008).pdf

256-del-2002-claims.pdf

256-DEL-2002-Correspondence-Others(18-1-2008).pdf

256-del-2002-correspondence-others.pdf

256-DEL-2002-Description (Complete)(18-1-2008).pdf

256-del-2002-description (complete).pdf

256-DEL-2002-Form-1(18-1-2008).pdf

256-del-2002-form-1.pdf

256-del-2002-form-18.pdf

256-DEL-2002-Form-2(18-1-2008).pdf

256-del-2002-form-2.pdf

256-DEL-2002-Form-3(18-1-2008).pdf

256-del-2002-form-3.pdf

256-DEL-2002-Petition-138(18-1-2008).pdf


Patent Number 222210
Indian Patent Application Number 256/DEL/2002
PG Journal Number 33/2008
Publication Date 15-Aug-2008
Grant Date 28-Jul-2008
Date of Filing 20-Mar-2002
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110001, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 ANGAIAH SUBRAMANIAN EXTENDED SRF, DEPT. OF INDUSTRIAL CHEMIST ALAGAPPA UNIVERSITY, KARAIKUDI 63000
2 THIAGARAJAN VASUDEVAN PROF. & HEAD, ALAGAPPA UNIVERSITY, KARAIKUDI
3 RAMAIYER GANGADHARAN EMERITUS SCIENTIST, ALAGAPPA UNIVERSITY, KARAIKUDI 630 003
PCT International Classification Number C21D 9/62
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA