video tutorial Reduction of trichloroacetic acid using zinc

Name: video tutorial - Reduction of trichloroacetic acid using zinc
Uploaded: 2025-12-11T09:03:44.073Z
Duration: 14 min 20 s
Description: trichloroacetic acid crystals take care with this as the pure acid is a strong...can react with a suitably reactive metal and form hydrogen gas you've probably

Goal: reduce trichloroacetic acid (TCA) with zinc; initial undiluted setup caused rapid moisture absorption and dense vapors, so a dilute aqueous approach with ice was used.
Reagents and conditions: 25 g TCA dissolved in ~50 mL water with ice; 11 g ground zinc powder (~1.1:1 molar ratio) added slowly under stirring; reaction is exothermic and yields zinc-organic salts rather than hydrogen gas.
Observation: zinc participates in reduction; formation of zinc salts, not free hydrogen; after addition and stirring, the mixture warms; further scraping suggests adsorption of hydrogen may occur; reaction yields a hot mixture requiring cooling.
Workup: pH tested; sulfuric acid (10 mL of 50%) added to regenerate free organic acids; extraction with 40 mL diethyl ether, separation of organic phase, drying with MgSO4, and solvent evaporation to isolate product.
Product recovered: 13.5 g of pale yellow, slightly oily liquid; chilled tests and crystallization attempts did not yield pure TCA; possible mixture of trichloroacetic acid (unreacted), dichloroacetic acid (DCA), and possibly monochloroacetic acid (MCA); presence of HCl vapor on cooling suggested chlorinated acids were present, but conclusive identification of DCA was not achieved.
Characterization notes: the product’s aroma suggested possible esters (trace ethanol from ether); crystallization is difficult, complicating purification; lack of burette prevents accurate titration for definitive composition.
Two days later: freezing at −15°C showed slight viscosity but liquid remained; test of reactivity with zinc showed DCA is less reactive than TCA, yet the reaction was still rapid/exothermic, supporting a mixture of acids rather than pure DCA.
Conclusion: the product is likely a mixture of unreacted TCA, DCA, and possibly MCA; crystallization is challenging, and tests are inconclusive for pure DCA; product is highly skin-damaging, so handling requires extreme caution.
Note: further testing and purification are needed; the presenters invite input on suitable tests.