Title of Invention	A PROCESS FOR PREPARATION OF A pH INDICATOR
Abstract	A process for preparation of a pH indicator suitable for changing colour from orange to blue in pH range of 8 to 9.5, the process comprising: a) condensation of para tertiary butyl phenol by reacting para tertiary butyl phenol with formaldehyde in the presence of a conventional base in aqueous solution to obtain an oligomer of para tertiary butyl phenol; b) cyclisation and crystallization of reaction products of step a) under inert atmosphere to obtain matacyclophane, c) reacting the metacyclophane obtained from step b) with phenol and aluminium chloride to obtain macrocyclic metacyclophane; and d) reacting the product of step c) with a solution of diazotized aryl amine at a low temperature to obtain the pH indicator.

Title of Invention

A PROCESS FOR PREPARATION OF A pH INDICATOR

Abstract

A process for preparation of a pH indicator suitable for changing colour from orange to blue in pH range of 8 to 9.5, the process comprising: a) condensation of para tertiary butyl phenol by reacting para tertiary butyl phenol with formaldehyde in the presence of a conventional base in aqueous solution to obtain an oligomer of para tertiary butyl phenol; b) cyclisation and crystallization of reaction products of step a) under inert atmosphere to obtain matacyclophane, c) reacting the metacyclophane obtained from step b) with phenol and aluminium chloride to obtain macrocyclic metacyclophane; and d) reacting the product of step c) with a solution of diazotized aryl amine at a low temperature to obtain the pH indicator.

Full Text	Title of the Invention : A method of preparation of a novel molecular indicator for determination of small changes in pH, scavenging metal ions and complexometric applications, and products thereof. Inventor: The present invention is by Dr. Har Mohindra Chawla, Professor, Department of Chemistry, Indian Institute of Technology Delhi (IITD), Hauz Khas, New Delhi - 110016, India, an Indian National. Field of the Invention : The present invention relates to a method of preparation of a novel molecular indicator, particularly of a novel molecular indicator for determination of small changes in pH, more particularly of a novel molecular indicator for determination of small changes in pH and scavenging metal ions, even more particularly of a novel molecular indicator for determination of small changes in pH, and scavenging metal ions and complexometric applications. Background of the Invention : A large number of indicators are known in the prior art. Normally, indicators are synthetic or natural dye molecules, which change color when added in an acidic or a basic solution. Some of such known indicators are phenolphthalein, methyl orange, bromophenol. Such known indicators have one color in their ionic form and another color in their non-ionic form. The other known class of indicators is that of adsorption indicators, which reveal a different colour due to ionic adsorption. Potassium chromate is such known indicator, which changes colour due to adsorption of chromate ions in titrations involving chloride ions. The other known class of indicators is the one, wherein the indicator form complexes with the metallic species in the solution form at a specific pH. Such complexes of indicator and the metallic species have characteristic color, which help in their identification and have specific intensity depending upon the concentration of the said metallic species in its solution form and hence help in quantitative determination of the said metallic species. Such complexes, of indicator and the metallic species, are known as complexometric or metallic indicators, which on dissociation undergo ionisation and change into another color. Some of such known indicators are Acid Chrome Dark Blue, Eriochrome Black-T and Murexide, which are frequently used for titration of metal ions with ethylene diamine tertacetic acid and its derivatives in a natural or alkaline media. The major limitation of such known indicators is that they (acid base type indicators) are used only in aqueous phase and strong acids and bases. The another limitation of such known indicators is that they (metallic indicators) are used only with metallic species, particularly in alkaline range mostly in EDTA type titrations. Further limitation of such known indicators (metallic indicators) is that, the color change due to such known indicators (metallic indicators) is not stable and it reverts back to the original after elapse of some time occasionally a few minutes due to molecular or ionic equilibria set in the solution. Still another limitation of such known indicators (adsorption indicators) is that, the surface adsorption and counter ion interactions/attractions are required. Further, the color change is difficult to judge near the end point as it h obscured by the accompanying precipitate in the case of adsorption indicators. Still another class of known indicators, although limited, is the one wherein the indicator changes color with a narrow pH range of about 1 to 2. Though, the number of indicators, which change color in acid solution is large, the indicators, which change color within alkaline pH range of 8 to 12 are limited. Further, the indicators, which can change color in further narrow range, that is between 8 to 10 pH, more preferably between 8 to 9.5 pH are further limited. Hence, it is obvious from the foregoing description, that the currently known and used indicators are not sufficient to determine the small change in pH in a narrow range, particularly in a narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH.. Therefore, there had been a great emphasis on synthesis of indicators, which can chance color in narrow range, particularly in narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH, and also syntheses of compounds, which can be used for scavenging metal ions and for complexometric applications. Considerable efforts, therefore, have been put in to research to produce such indicators. Need of the invention : Therefo there is a need to have an indicator, which can change color in narrow range, particularly in narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH, and to compounds, which can be used for scavenging metal ions and for complexometric applications, and of method of preparation the of. Objects of the Invention : The main object of the present invention is to make available an indicator, which while over conning some of the limitations and disadvantages of the presently known and used indicators, as described herein above, can change color in a narrow range, particularly in a narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH, and to ones that can be used for scavenging metal ions and for complexometric applications. The another object of the present invention is to disclose a process for synthesis of an indicator, the use of which is not limited to metallic species and which can be used for organic as well as metallic ionic species. Still another object of the present invention is to disclose a process for the synthesis of an indicator, which changes color from yellow orange to blue, which is easy to detect and identify, and such color change is sharp. Further an object of the present invention is to propose for an indicator and its method of preparation, the use of which is not limited to the aqueous solution, but can also be used for non-aqueous solutions and in titrations as well even in titrations of organic bases. Still further an object of the present invention is to disclose a process for synthesis of an indicator, which can sequester metal ions from solution and hence can be used for developing molecular filters. Yet another an object of the present invention is to make a disclosure of a process for synthesis of an indicator, which can form complexes with aliphatic amines, organic bases, amino acids and sugars. This is yet another an object of the present invention to make a disclosure of a process for synthesis of an indicator, which can recognise specific organic and metallic species with a color change or formation of a precipitate. Other objects of the present invention will become more apparent from the following description. Description of the Invention : Accordingly, the present invention makes a complete disclosure of a process for synthesis of an indicator, which can change color in narrow range, particularly in narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH, and can be used for scavenging metal ions and complexometric applications, and which has the advantages as described herein above, wherein the preparation of the said indicator is based upon the synthesis of a calixarene based azo dye system which can be easily synthesised from para tertiary butylphenol followed by coupling reaction with the diazotized aryl amine. In accordance to the preferred embodiment of the presently disclosed invention the process consists of condensation of para-tertiary butyl phenol with formaldehyde in the presence of a base followed by its cyclisation to yield a metacyclophane. The metacyclophane, thus obtained, is then treated with aluminium chloride in phenol followed by the reaction of the product with a diazotized aryl amine at a low temperature to yield the desired indicator dye molecules. Accordingly the process for synthesis of indicator as described herein above comprises of following four steps : a) Step-1 - consists of condensation of para-tertiary butyl phenol with formaldehyde, b) Step-2 - consists of crystalisation of product obtained from said step- 1 to yield a metacyclophane, c) Step-3 - consists of reaction of metacyclophane obtained from said step-2 with aluminium chloride, d) Step-4 - consists of reaction of product obtained from said step-3 with diazotized aryl amine. In accordance to the preferred embodiments of the present invention the condensation of para-tertiary butyl phenol with formaldehyde in step-1 is carried out in the presence of a base. Further, in accordance to the preferred embodiment of this invention the reaction of metacyclophane obtained from step-2 with aluminium chloride is carried out in phenol and the reaction of product obtained from said step-3 with diazotized aryl amine is carried out at a low temperature. The dye solution of indicator, obtained from step-4 is preferably prepared by dissolving in dimethyl sulphoxide or tetrahydrofuran-water. The dye solution of the indicator, synthesised in accordance to the process of the present invention, in dimethyl sulphoxide or tetrahydrofuran-water as the solvent can be used as the indicator, which changes color from orange to blue when pH changes from 8-9.3. The indicator synthesised in accordance to the process of the present invention can act as metal ion scavenger from effluent streams and can be used for the development of molecular filters for the recovery of metals from waste waters and streams. The presently disclosed process has been described with a specific reaction for production of said indicator, having above stated characteristics of the presently disclosed invention, which is not intended to limit the scope of the present invention. WE CLAIM:- 1 . A process for preparation of a pH indicator suitable for changing colour from orange to blue in pH range of 8 to 9.5, the process comprising: a) condensation of para tertiary butyl phenol by reacting para tertiary butyl phenol with formaldehyde in the presence of a conventional base in aqueous solution to obtain an oligomer of para tertiary butyl phenol; b) cyclisation and crystallization of reaction products of step a) under inert atmosphere to obtain matacyclophane, c) reacting the metacyclophane obtained from step b) with phenol and aluminium chloride to obtain macrocyclic metacyclophane; and d) reacting the product of step c) with a solution of diazotized aryl amine at a low temperature to obtain the pH indicator. 2. An indicator obtained from the process as claimed in claim 1 . 3. An indicator as claimed in claim 2, as and when used as metal ion scavenger from effluent stream or for complexometric applications. 4. A process for preparation of a pH indicator, substantially as herein before described.

Full Text

Title of the Invention :
A method of preparation of a novel molecular indicator for determination of small changes in pH, scavenging metal ions and complexometric applications, and products thereof.
Inventor:
The present invention is by Dr. Har Mohindra Chawla, Professor, Department of Chemistry, Indian Institute of Technology Delhi (IITD), Hauz Khas, New Delhi - 110016, India, an Indian National.
Field of the Invention :
The present invention relates to a method of preparation of a novel molecular indicator, particularly of a novel molecular indicator for determination of small changes in pH, more particularly of a novel molecular indicator for determination of small changes in pH and scavenging metal ions, even more particularly of a novel molecular indicator for determination of small changes in pH, and scavenging metal ions and complexometric applications.
Background of the Invention :
A large number of indicators are known in the prior art. Normally, indicators are synthetic or natural dye molecules, which change color when added in an acidic or a basic solution. Some of such known indicators are phenolphthalein, methyl orange, bromophenol. Such known indicators have one color in their ionic form and another color in their non-ionic form.
The other known class of indicators is that of adsorption indicators, which reveal a different colour due to ionic adsorption. Potassium chromate is such

known indicator, which changes colour due to adsorption of chromate ions in titrations involving chloride ions.
The other known class of indicators is the one, wherein the indicator form complexes with the metallic species in the solution form at a specific pH. Such complexes of indicator and the metallic species have characteristic color, which help in their identification and have specific intensity depending upon the concentration of the said metallic species in its solution form and hence help in quantitative determination of the said metallic species. Such complexes, of indicator and the metallic species, are known as complexometric or metallic indicators, which on dissociation undergo ionisation and change into another color. Some of such known indicators are Acid Chrome Dark Blue, Eriochrome Black-T and Murexide, which are frequently used for titration of metal ions with ethylene diamine tertacetic acid and its derivatives in a natural or alkaline media.
The major limitation of such known indicators is that they (acid base type indicators) are used only in aqueous phase and strong acids and bases.
The another limitation of such known indicators is that they (metallic indicators) are used only with metallic species, particularly in alkaline range mostly in EDTA type titrations.
Further limitation of such known indicators (metallic indicators) is that, the color change due to such known indicators (metallic indicators) is not stable and it reverts back to the original after elapse of some time occasionally a few minutes due to molecular or ionic equilibria set in the solution.
Still another limitation of such known indicators (adsorption indicators) is that, the surface adsorption and counter ion interactions/attractions are required.
Further, the color change is difficult to judge near the end point as it h obscured by the accompanying precipitate in the case of adsorption indicators.

Still another class of known indicators, although limited, is the one wherein the indicator changes color with a narrow pH range of about 1 to 2. Though, the number of indicators, which change color in acid solution is large, the indicators, which change color within alkaline pH range of 8 to 12 are limited. Further, the indicators, which can change color in further narrow range, that is between 8 to 10 pH, more preferably between 8 to 9.5 pH are further limited.
Hence, it is obvious from the foregoing description, that the currently known and used indicators are not sufficient to determine the small change in pH in a narrow range, particularly in a narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH..
Therefore, there had been a great emphasis on synthesis of indicators, which can chance color in narrow range, particularly in narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH, and also syntheses of compounds, which can be used for scavenging metal ions and for complexometric applications. Considerable efforts, therefore, have been put in to research to produce such indicators.
Need of the invention :
Therefo there is a need to have an indicator, which can change color in narrow range, particularly in narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH, and to compounds, which can be used for scavenging metal ions and for complexometric applications, and of method of preparation the of.
Objects of the Invention :

The main object of the present invention is to make available an indicator, which while over conning some of the limitations and disadvantages of the presently known and used indicators, as described herein above, can change color in a narrow range, particularly in a narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH, and to ones that can be used for scavenging metal ions and for complexometric applications.
The another object of the present invention is to disclose a process for synthesis of an indicator, the use of which is not limited to metallic species and which can be used for organic as well as metallic ionic species.
Still another object of the present invention is to disclose a process for the synthesis of an indicator, which changes color from yellow orange to blue, which is easy to detect and identify, and such color change is sharp.
Further an object of the present invention is to propose for an indicator and its method of preparation, the use of which is not limited to the aqueous solution, but can also be used for non-aqueous solutions and in titrations as well even in titrations of organic bases.
Still further an object of the present invention is to disclose a process for synthesis of an indicator, which can sequester metal ions from solution and hence can be used for developing molecular filters.
Yet another an object of the present invention is to make a disclosure of a process for synthesis of an indicator, which can form complexes with aliphatic amines, organic bases, amino acids and sugars.

This is yet another an object of the present invention to make a disclosure of a process for synthesis of an indicator, which can recognise specific organic and metallic species with a color change or formation of a precipitate.
Other objects of the present invention will become more apparent from the following description.
Description of the Invention :
Accordingly, the present invention makes a complete disclosure of a process for synthesis of an indicator, which can change color in narrow range, particularly in narrow range of the alkaline range, more particularly in further narrow range of the alkaline range, that is between 8 to 10 pH, more particularly between 8 to 9.5 pH, and can be used for scavenging metal ions and complexometric applications, and which has the advantages as described herein above, wherein the preparation of the said indicator is based upon the synthesis of a calixarene based azo dye system which can be easily synthesised from para tertiary butylphenol followed by coupling reaction with the diazotized aryl amine.
In accordance to the preferred embodiment of the presently disclosed invention the process consists of condensation of para-tertiary butyl phenol with formaldehyde in the presence of a base followed by its cyclisation to yield a metacyclophane. The metacyclophane, thus obtained, is then treated with aluminium chloride in phenol followed by the reaction of the product with a diazotized aryl amine at a low temperature to yield the desired indicator dye molecules.
Accordingly the process for synthesis of indicator as described herein above comprises of following four steps :
a) Step-1 - consists of condensation of para-tertiary butyl phenol with formaldehyde,

b) Step-2 - consists of crystalisation of product obtained from said step-
1 to yield a metacyclophane,
c) Step-3 - consists of reaction of metacyclophane obtained from said
step-2 with aluminium chloride,
d) Step-4 - consists of reaction of product obtained from said step-3
with diazotized aryl amine.
In accordance to the preferred embodiments of the present invention the condensation of para-tertiary butyl phenol with formaldehyde in step-1 is carried out in the presence of a base. Further, in accordance to the preferred embodiment of this invention the reaction of metacyclophane obtained from step-2 with aluminium chloride is carried out in phenol and the reaction of product obtained from said step-3 with diazotized aryl amine is carried out at a low temperature.
The dye solution of indicator, obtained from step-4 is preferably prepared by dissolving in dimethyl sulphoxide or tetrahydrofuran-water.
The dye solution of the indicator, synthesised in accordance to the process of the present invention, in dimethyl sulphoxide or tetrahydrofuran-water as the solvent can be used as the indicator, which changes color from orange to blue when pH changes from 8-9.3.
The indicator synthesised in accordance to the process of the present invention can act as metal ion scavenger from effluent streams and can be used for the development of molecular filters for the recovery of metals from waste waters and streams.
The presently disclosed process has been described with a specific reaction for production of said indicator, having above stated characteristics of the presently disclosed invention, which is not intended to limit the scope of the present invention.

WE CLAIM:-
1 . A process for preparation of a pH indicator suitable for changing colour from orange to blue in pH range of 8 to 9.5, the process comprising:
a) condensation of para tertiary butyl phenol by reacting para tertiary butyl phenol with
formaldehyde in the presence of a conventional base in aqueous solution to obtain an
oligomer of para tertiary butyl phenol;
b) cyclisation and crystallization of reaction products of step a) under inert atmosphere
to obtain matacyclophane,
c) reacting the metacyclophane obtained from step b) with phenol and aluminium
chloride to obtain macrocyclic metacyclophane; and
d) reacting the product of step c) with a solution of diazotized aryl amine at a low
temperature to obtain the pH indicator.

2. An indicator obtained from the process as claimed in claim 1 .
3. An indicator as claimed in claim 2, as and when used as metal ion scavenger from
effluent stream or for complexometric applications.
4. A process for preparation of a pH indicator, substantially as herein before described.

Documents:

768-del-1999-abstract.pdf

768-del-1999-claims.pdf

768-DEL-1999-Correspondence Others-(05-10-2011).pdf

768-del-1999-correspondence-others.pdf

768-del-1999-correspondence-po.pdf

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

768-del-1999-form-1.pdf

768-del-1999-form-13.pdf

768-del-1999-form-19.pdf

768-del-1999-form-2.pdf

768-del-1999-form-26.pdf

768-del-1999-form-3.pdf

768-del-1999-form-5.pdf

768-del-1999-form-62.pdf

768-DEL-1999-GPA-(05-10-2011).pdf

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Patent Number

230967

Indian Patent Application Number

768/DEL/1999

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

24-May-1999

Name of Patentee

DEAN , INDUSTRIAL RESEARCH AND DEVELOPMENT (DIRD)

Applicant Address

INDIAN INSTITUTE OF TECHNOLOGY DELHI (IITD), HAUZ KHAS, NEW DELHI-110016, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	DR. CHAWLA, HAR MOHINDRA	PROFESSOR, DEPARTMENT OF CHEMISTRY, INDIAN INSTITUTE OF TECHNOLOGY DELHI (IITD), HAUZ KHAS, NEW DELHI-110016, INDIA

PCT International Classification Number

C07D 27/56

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA