one embodiment the process further comprises a step of isolating the salt of formula iv s in one embodiment the base b in step c may be ammonia n methylglucamine procaine tromethanine magnesium l lysine l arginine or triethanolamine the following abbreviations are used in the description and or appended claims and they have the following meanings in view of the foregoing considerations and specific examples below those who are skilled in the art will appreciate that how to select necessary reagents and solvents in practicing the present invention the invention will now be described in reference to the following examples these examples are not to be regarded as limiting the scope of the present invention but shall only serve in an illustrative manner a 50 l three neck round bottom flask equipped with a mechanical stirrer and a thermocouple was charged with benzindene triol 1250 g acetone 19 l and k 2 co 3 powdered 1296 g chloroacetonitrile 567 g tetrabutylammonium bromide 36 g the reaction mixture was stirred vigorously at room temperature 23 u00b1 2 u00b0 c for 16 72 h the progress of the reaction was monitored by tlc methanol ch 2 cl 2 1 9 and developed by 10 ethanolic solution of pma after completion of reaction the reaction mixture was filtered with without celite pad the filter cake was washed with acetone 10 l the filtrate was concentrated in vacuo at 50 55 u00b0 c to give a light brown viscous liquid benzindene nitrile the crude benzindene nitrile was used as such in.