FORM 2
The Patent Act 1970,
(39 of 1970)
&
The Patent rule 2003
Complete Specification
(See Section 10 and Rule 13)
1. TITLE OF THE INVENTION
" MODIFIED PROCESS FOR PREPARATION OF ISOINDOLINE CLASS OF
PIGMENT "
2. APPLICANT(S)
(a) NAME : GHARDA CHEMICALS LTD
(b) NATIONALITY : INDIAN
(c) ADDRESS: B-27/29, MIDC, PHASE 1, DOMBIVLI.
DIST. THANE, PIN 421 203 MAHARASHTRA INDIA
3. PREAMBLE OF THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

Field of Invention:
The present invention relates to a process for preparation of PY-139, an isoindoline class of pigment. The invention herein describes condensation of di imino isoindoline and Barbituric acid in aqueous medium and in presence of an acidic moiety capable of reacting with ammonia formed during reaction. Thus process provides pigmentary grade PY-139 and avoids lengthy and laborious finishing of pigment and other substeps. Thus the pigment obtained by following the process mentioned herein can be used directly in various applications.
Background of Invention:
PY-139 is an isoindoline class of pigment synthesized by the condensation of Barbituric acid with di imino isoindoline. Various grades of PY-139 find their applications in different fields like industrial paint system, plastic paints, solvent based inkjet inks etc. Literature is replete on the pigment applications and pigmentation techniques involved therein.
During the synthesis of PY-139, ammonia formed during reaction is neutralized with acidic moiety and it is also well-known that the synthesis proceeds successfully in the pH range of 1.5 to 4.5.
Synthesis of PY-139 described in the literature on above lines that involves various acidic moieties and the reaction is run into various solvents. For example US 4,166,179 (1979) describes the use of formic acid and alkyl Napthalene sulphonic acid or its sodium salt in MEG solvent. WO 38920 (1999) describes use of acetic acid during synthesis and use of various dispersing agents like LoxiolR EP 10, di alkyl Sebacate during pigmentation. US 6,143,067 (2000) also describes use of acetic acid during synthesis and other dispersing agents during pigmentation like above. Similarly DE 3,633,322 (1987) describes pigment conditioning using benzoic acid. Recently published patent WO 85364 (2005), covers and claims quinacridone class of pigments and the intermediates required for their synthesis, also states fewer examples of synthesis of PY-139 and 1,3 di imino isoindoline. This patent also states synthesis of PY-139 in methanol as solvent and using glacial acetic acid. Pigmentation step is described separately. 1,3-di imino isoindoline is reported to be prepared from phthalodinitrile.
Thus the information claimed in all the patents does not exploits suitably substituted aromatic carboxylic/sulphonic acid as reagents. We have found that by using these reagents PY-139 of pigmentory grade is obtained, thereby, avoiding cumbersome pigmentation techniques and attendant gadgetry.

Object of Invention
The first and foremost objective of the invention is to develop a manufacturing process for the
pigment PY-139, an isoindoline class of pigment using water as a solvent and in the presence of
suitably substituted aromatic carboxylic/sulphonic acids.
Another objective of invention is to use the raw materials required for the synthesis in highly
purified forms.
Another objective of the invention is to use a suitably substituted benzoic acid to quench
ammonia formed during reaction.
Another objective of an invention is to use a benzoic acid or suitably substituted benzoic acid
during synthesis as ammonia scavenger leading Barbituric acid in the free state which has
remarkable effect on resulting pigment quality.
Still another objective of an invention is to use a suitably substituted benzoic acid during
synthesis that alone is capable of giving the desired quality of pigment and thus avoiding use of
other lengthy pigmentation processes involving different solvents.
Another objective of an invention is to use a suitably substituted benzoic acid during synthesis
that also controls the particle size distribution of pigment particles
Statement of Invention
Process for the synthesis of isoindoline class of pigment like PY-139 comprises of reacting di imino isoindoline and Barbituric acid in their pure form in the presence of a suitably substituted benzoic acid in aqueous medium by boiling for several hours as herein described offer PY-139 which is mainly useful in paint applications.
Description of the Invention
Processes so far disclosed on the manufacture of PY-139 involve condensation of isoindoline moiety with Barbituric acid in various solvents comprising of aqueous medium, alcohols or mixtures thereof or other organic solvents in presence of stoichiometric amounts of acidic components. The isoindoline moiety is obtained by various ways i.e; using either di phthalonitrile or directly from 1,3 di imino isoindoline. The pigment obtained by such processes often required additional pigmentation processes in order to obtain desired colouristic properties and other pigmentory properties.
In the invention described herein, the required raw materials were made by following any process as reported in the state of art. The care has been taken to further purify these raw materials before condensation. These purification techniques had great impact on the pigmentory properties of PY-139. Similarly it was found that Barbituric acid is also capable of

reacting with the ammonia formed during the reaction. To avoid this, many acidic moieties are
reported in the literature including mainly formic acid, acetic acid etc or even mineral acids. In
the invention disclosed, therefore various acids were used to minimize the interference of the
ammonia formed with the Barbituric acid present in the system.
Similarly it is requirement of the reaction that the solids present in the system should be in a
better-dispersed form and the acidic moieties used should be soluble in reaction media under
reaction conditions. This phenomenon was found to have great impact on the surface area of
the final pigment particles. This was achieved by following certain operating procedures like
heating & cooling during the reaction and also by controlling the pigment concentration in the
reaction mixture. This was further facilitated by using certain dispersing agents. Among the
various choices available were the uses of dispersing agents belonging to the class of ethylene
oxide-propylene oxide additive compounds, styrenated phenols or alkyl Napthalene
formaldehyde condensate.
Pigment was isolated by filtration of the reaction mixture in hot condition and by further washing
with the hot water. Resuspension of the pigment-wet cake into water containing the same acid
as used for the synthesis and boiling for several hours was also found to be effective many
times. Any organic impurities trapped in the pigment cake was further removed by treating with
suitable aprotic polar solvents at higher temperatures for several hours.
Above outlined process will be evident from the following set of examples obtained by scanning
various acids, solvent quantity and other isolation techniques. The results of these experiments
are expressed quantitatively by the yield obtained and qualitatively by the colouristic and other
physical properties of the pigment isolated.
Example 1:
Suspended 26.88 gms (0.21 m) Barbituric acid in to 600 ml water containing 122 gms (1-mole)
benzoic acid and appropriate quantity of dispersing/wetting agents. The whole mixture was then
cooled to 20cc and then added 14.5 gms (0.1-m) of di imino isoindoline over 30 min to 90 min.
after stirring the mixture for 60-min to 120-min the entire reaction mixture was heated to reflux
and refluxed for 15 hrs. Product isolated by filtering the reaction mass in hot conditions and by
several washings of hot water. The pigment cake was then suspended in 350-ml N,N Di methyl
acetamide (DMAc) and stirred for 10 hrs at 80-100°c. this mixture was again filtered hot,
washed with DMAc. The DMAc-pigment cake was next treated with water to remove traces of
DMAc.
Example 2:
Same procedure as outlined in example no 1 is followed, except used 4-chloro benzoic acid in
place of benzoic acid.
Example 3:
Same procedure as outlined in example no 1 is followed, except used 4-nitro benzoic acid in
place of benzoic acid.

Example 4:
Same procedure as outlined in example no 1 is followed, except used 4-methyl benzene
sulphonic acid in place of benzoic acid.
Example 5:
Same procedure as outlined in example no 1 is followed, except used acetic acid in place of
benzoic acid.
Example 6:
Same procedure as outlined in example 1 is followed, except used formic acid in place of
benzoic acid.
Example 7:
Same procedure as outlined in example no 1 is followed, except used propionic acid in place of
benzoic acid.
Example 8:
Same procedure as outlined in example no 1 is followed, except used sodium hydrogen sulfate,
2-moles in place of benzoic acid.
Example 9:
Same procedure as outlined in example no 1 is followed, except used 1.2 lit water in place of
0.6-lit water.
Example 10:
Same procedure as outlined in example no 1 & 9 is followed, except used only 61-gms benzoic
acid (0.5-m) during synthesis in place 122-gms (1-m) and gave additional treatment to the
pigment wet cake with 61-gms (0.5-m) benzoic acid and 0.7 lit water.
Example 11: same procedure as outlined in example no 10 is followed, except used aqueous
methanol during synthesis.
The pigment obtained in this way was much redder in colour.
Example 12:
Same procedure as outlined in example no 10 is followed, except used Barbituric acid and di
imino isoindoline after purification from suitable solvent. Also added aqueous solution of di imino
isoindoline to Barbituric acid solution in water.
The pigment obtained in this way was much brighter in colour.
Surface area of all the pigment particles obtained as above was in the range of 15-18 cm2/m3.
Similarly average particle size of all the pigment particles as obtained above was in the range of
0.35^1 to 0.5n

We claim,
1. Process for the preparation of PY-139, an isoindoline class of pigment derived from condensation of 2-moles of Barbituric acid and 1-mole of di imino isoindoline in aqueous media in presence of suitably substituted aromatic carboxylic acid.
2. Process as claimed in claim 1 wherein the synthesis and pigmentation reactions are carried out at 90-100°c for 12-15 hrs.
3. Process as claimed in claim 1 where suitable dispersing agents like styrenated phenols and/or alkyl Napthalene formaldehyde condensate.
4. Process as claimed in claim 1 wherein the water quantity used is anything in the range of 6-lit/m to 24-lit/m or more specifically from 10-lit/m to 12-lit/m.
5. Process as claimed in claim 1 wherein the suitably substituted aromatic carboxylic acid is derivative of benzoic acid.
6. Process as claimed in claim 1 where the quantity of suitably substituted benzoic acid used is in the range of 10-moles to 12-moles.
7. Process as claimed in claim 1 where the pH of reaction mixture during reaction is maintained in the range of 4 to 6 or more specifically between 4 to 4.6.
8. Process as claimed in claim 1 wherein all the quantity of suitably substituted benzoic acid is used either at once during synthesis or in parts, i.e. during synthesis as well as during pigmentation.
9. Process as claimed in claim 1 wherein the wet pigment cake after synthesis or after pigmentation is treated with aprotic polar solvent like DMAc at 80-90°c and DMAc wet cake is further treated with water at 90-100°c.
10. Process as claimed in claim 1 wherein suitably substituted benzoic acid is optionally used to control the particle size distribution of the pigment by giving additional treatment with a suitably substituted benzoic acid.

Dated
Abstract:
The present invention describes the preparation of PY-139, an isoindoline class of pigment, as represented by structure no 1 in aqueous media and in the presence of suitably substituted aromatic carboxylic acid as represented by structure no 2.