NOVELTY - Solvent free process for preparing transfluthrin comprises e.g.: charging 619 g of RR-trans cypermethric acid chloride (II) in a round bottom flask at 60 degrees C; adding 479 g of 2,3,5,6-tetrafluorobenzyl alcohol (III) to the flask to obtain a reaction mixture; removing hydrochloride gas from the reaction mixture to obtain a reaction mass; charging 470 ml water in a separate round bottom flask and adding 16 g of potassium carbonate to obtain potassium carbonate solution; adding the reaction mass to the carbonate solution to form a reaction solution; and allowing the reaction solution to settle.    USE - The process is useful for preparing transfluthrin (claimed) which is used as household product against flying insects, mosquitoes and cockroaches. No biological data given.    ADVANTAGE - The process is solvent free, provides transfluthrin with a purity of 96% or more than 96% (claimed), is environmentally friendly, and is a fast-acting pyrethroid insecticide with low persistency.    DETAILED DESCRIPTION - Solvent free process for preparing transfluthrin comprises: charging 619 g of RR-trans cypermethric acid chloride of formula (II) in a round bottom flask at 60 degrees C; adding 479 g of 2,3,5,6-tetrafluorobenzyl alcohol of formula (III) to the round bottom flask in the interval of 2-2.5 hours to obtain a reaction mixture; removing hydrochloride gas from the reaction mixture by applying 700 mm/mercury vacuum at 70-75 degrees C to obtain a reaction mass; charging 470 ml water in a separate round bottom flask and adding 16 g of potassium carbonate at 60-65 degrees C to obtain potassium carbonate solution; adding the reaction mass to the potassium carbonate solution to form a reaction solution; allowing the reaction solution to settle for 1 hour to separate bottom organic layer at 60-65 degrees C; adding the bottom organic layer to 470 mg of water in a separate round bottom flask at 60-65 degrees C to obtain an organic solution; allowing the organic solution to settle for 1 hour to separate bottom organic mass at 60-65 degrees C; and heating the bottom organic mass in reactor at 80 degrees C and 745 mm/mercury vacuum for 2 hours to obtain transfluthrin.