DE832755
Process for the preparation of thienylacetic acid and derivatives.
They do a Willgerodt from 2-acetothienone to get an amide or substituted amide, then they prepare 2-thienylacetic acid from it. Normally, Willgerodt yields are low because 2-acetothienon is sensitive to ammonium sulfide, sulfur, ammonia and other nitrogen bases. They get better yields by lowering reaction temperatures and they use higher concentrations of ammonia, ammonium polysulfide and sulfur to assure a better conversion. Water miscible organic solvents used are dioxan, pyridine, thf. The process is said to be suitable to prepare amides of other thienylacetic acids in good yields.
Example:
30g 2-acetothienone, 66ml conc. ammonia solution, 45g sulfur, 36g yellow solution of ammonia polysulfide and 54ml dioxan are heated in a closed vessel during 1 hour to 142°C, it is kept at this temp for 3.5 hours and then heated to 152°C for 15 min. Usual workup of the reaction mixture yields 23g = 68% of theory 2-thienylacetic acid amide, bp 146.5°. Following the usual procedure for 'Verseifung' [=soapification? 'Verseifung' in geman means ester breakup using alkalis, like soap (seife) is made] 2-thienylacetic acid, bp 64°C is prepared.
The rest is the usual patent blah blah, claims and that. Sorry i don't have that much time by now. I know my english isn't that good, so ask if you're not sure how i meant something.
Hope this helps...paul
