1 Hydrochloric acid esterification approach
( 1) Preparation of 2-chloroethylamine hydrochloride. Add 100g focused hydrochloric acid to a 250mL flask, gradually add 61g of ethanolamine while stirring, raise the temperature to 145-150 ° C, pass hydrogen chloride gas up until a small amount of HCL gets away; after that distill, react under reduced stress for 15h at 150 ° C, till up until anhydrous distillation takes place; finally, cool the reaction remedy to 70 ° C, add 50g of absolute ethanol, great and also crystallize, different, laundry (with absolute ethanol), and also vacuum dry to acquire 106g of ended up item, with a yield of 91.3%.
( 2) Preparation of taurine acid. Include 66.2 g Na2SO3 into a 500mL flask, include 250mL water to liquify it, as well as start adding an option of 58g of the above item dissolved in 15mL water at 50 ° C, and finish dropping it in 6 hours; then raise the temperature to 65 ° C to react for 3 hrs, after that raise the temperature to 90 ° C to respond for 4 hrs, as well as finally After refluxing for 1 hr, the taurine content was gauged and also the conversion yield was 94%. Use electrodialysis to eliminate inorganic salts, and then focus and also crystallize to get 57.2 g of taurine acid. The removal return is 91.5%, the purity is 99.6%, and also the overall yield is 83.6%.
2 Sulfate esterification method
( 1) Synthesis of 2-aminoethyl hydrogen sulfate. Include ethanolamine (36.6 g, 0.6 mol) and also toluene (100mL) to a 500mL flask, add 98% sulfuric acid (61.4 g, 0.626 mol) dropwise while cooling down and stirring in a water bathroom, it will certainly take about 50 minutes to finish the dripping; then include hexadecane Triethylammonium chloride (1.4 g, 0.0039 mol), use carbon tetrachloride (CTC) as solvent, warmth and also reflux for 1.5-2h, separate an academic amount of water (about 11mL); cool, filter, clean and also completely dry, 83g of 2-aminoethyl hydrogen sulfate (melting point 273-279 ° C )was obtained, with a yield of 98.1%.
( 2) Synthesis of taurine acid. Add salt sulfite (75.6 g, 0.60 mlo) and 250mL water to a 500mL flask, gradually and also evenly add hydrogen sulfate (28.2 g, 0.2 mol) under nitrogen defense, and remain to reflux for 10-12h to produce taurine; Vaporize the water under decreased stress, include 100 mL of focused sulfuric acid to the blend and also mix for regarding 1 hour to completely liquify the item; strain the not natural salt crystals and clean them two times with 20 mL of focused hydrochloric acid. Concentrate the filtrate under lowered pressure to half the volume, include 50Ml of 95% ethanol, and also some crystals will certainly speed up; placed the filtrate in the fridge for 1-2 hours, filter to acquire the unrefined product, and afterwards recrystallize it once with focused hydrochloric acid to acquire 21.3 g of the item (melting point 298-301 ℃, yield 85%. Complete return 83%.
3 Thionyl dichloride method
Ethanolamine hydrochloride responded with SOCL2 at 60 ° C for 7 hrs according to the chemical formula to get 2-chloroethanolamine hydrochloride with a return of 99%. As an example, usage 350 mL of 37% hydrochloric acid to respond with 244 g of ethanolamine dissolved in 800 mL of toluene, get rid of the water azeotropically at 110 ° C, trendy to 50 ° C, add 3.2 g of NH4Cl catalyst, and then include 14 mL of SOCl2 dropwise to produce 2-ethanolamine hydrochloride. After that include 53.7 g 80% of the above product option dropwise into 180mL of salt sulfite option with a focus of 21.4% within 3 hrs, and respond at a constant temperature level of 80 ° C for 4 hrs to obtain a liquid option consisting of 39.8 g taurine, which is desalted by electrodialysis as well as cooled. The item was crystallized as well as detoxified at 3 ° C to get an item with a pureness of 99.95% and also a return of 95%.
