AlsoTapered
Bluelighter
Library Genesis
Hotlink to racemization of phenylephrine. The best I can manage - hope it's of value.
N&PD Moderators: Skorpio | someguyontheinternet
I suspect Halostachine will behave same as phenylephrine (compound 6)..It is 1000x slower to racemize than p-OMe (OH) phenylethanolamins in 1M HCl, room temp). Keeping in mind the conditions you mentioned (HCl, 100oC,22h) are pretty brutal (would racemize pretty much any phenylethanolamines eventually including halostachine!). Base wont work (cf ref)... Good'day ALl BLightersVenter DP. THE ACID-CATALYSED RACEMISATION MECHANISM OF CATECHOLAMINES. Tetrahedron 1991, Volume 47, Issue 27, 1991, Pages 5019-5024. Doi: 10.1016/S0040-4020(01)80964-9 and ref cited therein
ABSTRACT: The racemisation rates of (-)-adrenaline (1), ()-isoprenaline (2), (-)-2-(3,4-dimethoxyphenyl)-2-hydroxy-N-isopropylamine (3), (+)-2-(4-meethoxyphenyl)-2-hydroxy-N-isopropylethylamine (4), (+)-2-phenyl-2-hydroxy-N-isopropylehylamine (5), ()-phenylephrine(6), and (+)-1-phenylethanol(7) were compared. The racemisatton rates decreased in the following order: 7 > 1 ≈ 2 > 3 ≈ 4 >> 5, 6. In general, the reactivity of the series of the phenylethanolamine compounds (1) - (6) was seen to increase sharply as the electron-releasing ability of the p-substituent of the aromatic nucleus increases. The results strengthen the notion that the acid-catalysed racemisation of catecholamines proceeds via a quinonoid-type intermediate.