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Über die Entstehung von α‐Keto‐carbonium‐Ionen bei der säurekatalysierten Hydrolyse von Diazoketonen. (Vorläufige Mitteilung)
Author(s) -
Dahn H.,
Gold H.,
Ballenegger M.,
Lenior J.,
Diderich G.,
Malherbe R.
Publication year - 1968
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.19680510827
Subject(s) - chemistry , carbonium ion , diazo , nucleophile , protonation , diazomethane , hydrolysis , medicinal chemistry , decomposition , chemical decomposition , ion , organic chemistry , catalysis
Secondary deactivated aliphatic diazo compounds (diazo‐ketones RCOCN 2 R′; diazo‐esters ROOCCN 2 R′; 1, 1, 1‐trifluoro‐2‐diazopropane) are hydrolysed by the AS E 2 mechanism comprising rate determining protonation of the substrate, followed by decomposition. Product analysis shows that the decomposition of the secondary diazonium ions is monomolecular, without intervention of a nucleophile. The corresponding primary diazo compounds (RCOCHN 2 , ROOCCHN 2 and CF 3 CHN 2 ) are hydrolysed by the A‐2 mechanism comprising preequilibrium protonation; the primary diazonium ion reacts with a nucleophile in a bimolecular displacement step. The only exception observed is found in p ‐nitrophenyl‐diazomethane, which follows AS E 2 mechanism. The observations are discussed in terms of the stability of the corresponding secondary resp. primary α‐keto‐carbonium ions.