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Hydrolyse acide des diazocétones secondaires: Participation des nucléophiles
Author(s) -
Fierz G.,
McGarrity J. F.,
Dahn Hans
Publication year - 1975
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19750580409
Subject(s) - chemistry , diazo , protonation , nucleophile , hydrolysis , medicinal chemistry , decomposition , acetone , nucleophilic substitution , kinetic isotope effect , base (topology) , ion , organic chemistry , catalysis , deuterium , physics , quantum mechanics , mathematical analysis , mathematics
In the acid hydrolysis of two secondary diazoketones showing rate‐determining protonation, 3‐diazo‐butan‐2‐one ( 1 ) and 1‐phenyl‐1‐diazo‐acetone ( 4 ), the nature of the (rapid) decomposition step of the intermediate diazonium ion was studied by product analysis. In the presence of strong nucleophiles, the reaction with Cl − , Br − , I − and SCN − follows the Swain‐Scott relationship. SCN − formed thiocyanates; isothiocyanates could not be detected. Both results indicate nucleophilic participation in the substitution step. For the accompanying elimination reaction (the amount of which is independent of added base) the isotope effect k H /k D = 2,4 in the hydrolysis of 1–d 3 is in favour of an E2 type mechanism. – Addition of HSCN to methyl‐vinylketone at 0° yields nearly exclusively 4‐thiocyanato‐butan‐2‐one, which at 25° in the presence of HSCN is slowly rearranged to 4‐isothiocyanato‐butan‐2‐one.