We Claim:
1. 2-(2-(Dimethylamino) ethyl-2, 3-dihydroinden-1-one acid salt of formula (IIIa).
/
LsIL/ . acid salt
O Formula (IIIa)
2. A process for the preparation of pure Dimethindene maleate of formula (I);
/
f if /> N COOH
^/^< . fl
/~~^N \ COOH
5 Formula (I)
which comprises the steps;
a) reacting of 2-(2-(dimethylamino) ethyl-2, 3-dihydroinden-1-one of formula (III)
with suitable acid in presence of an suitable solvent to produce 2-(2-
(dimethylamino) ethyl-2, 3-dihydroinden-1-one acid salt of formula (IIIa);
0
^^^ U^_/L-V . acid salt
O O
Formula (III) Formula (IIIa)
b) neutralizing of formula (IIIa) with a suitable base in presence an suitable solvent to
produce pure 2-(2-(dimethylamino) ethyl-2, 3-dihydroinden-1-one of formula (III);
/
O
5 Formula (III)
c) reacting of formula (III) with 2-ethyl pyridine in suitable solvent in the presence of
suitable stabilize anion and suitable organolithium reagent to produce Dimethindene
of formula (II);

/
Formula (II)
d) reacting of formula (II) with maleic acid in presence of suitable solvent to produce
Dimethindene maleate of formula (I);
/ f ll /^— N .COOH y-—N A VCOOH
Formula (I)
e) Isolating or purifying Dimethindene maleate of formula (I).
3. The process as claimed in claim 1 & 2, wherein the suitable acid is selected form maleic acid, oxalic acid, malonic acid, succinic acid, citric acid, formic acid, fumaric acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid and p-toluenesulfonic acid.
4. The process as claimed in claim 1, wherein the suitable stabilize anion is selected form tetramethylethylenediamine (TEMDA), hexamethylphosphoramide (HMPA) and PMDTA (N,N,N′,N′′,N′′-pentamethyldiethylenetriamine).
5. The process as claimed in claim 1, wherein the suitable organolithium reagents is selected form n-butyllithium (n-BuLi), methyllithium (MeLi), phenyllithium (PhLi), tert-butyllithium (t-BuLi) and sec-butyllithium (sec-BuLi).
4. The process as claimed in claim 1, wherein the suitable base is selected from alkali metal hydroxides such as sodium hydroxide, lithium hydroxide or potassium hydroxide; alkali metal carbonates such as caesium carbonate, sodium carbonate potassium carbonate or lithium carbonate; alkali metal bicarbonates such as sodium bicarbonate or potassium bicarbonate and or mixtures thereof.
6. The process as claimed in claim 1, wherein the suitable solvent is selected form

hydrocarbon solvents such as n-pentane, n-hexane, n-heptane, cyclohexane, petroleum ether, benzene, toluene, xylene and the like; ether solvents such as dimethyl ether, diethyl ether, diisopropyl ether, methyl tert-butyl ether, 1,2-dimethoxyethane, tetrahydrofuran (THF), 2-methyl THF, 1,4-dioxane and the like; ester solvents such as methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, tert-butyl acetate and the like; polar-aprotic solvents such as dimethylacetamide, dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone (NMP) and the like; chloro solvents such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride and the like; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and the like; “nitrile solvents” such as acetonitrile, propionitrile, isobutyronitrile and the like; alcohol solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, iso-butanol, 2-butanol, tert-butanol, ethane-1,2-diol, propane-1,2-diol and the like; polar solvents such as water; formic acid, acetic acid and the like or mixture thereof.