Stable carbocations. CXXVI. Attempted preparation of trimethylenehalonium ions. Preference for three- and five-membered ring halonium ion formation

1972 ◽  
Vol 94 (4) ◽  
pp. 1164-1168 ◽  
Author(s):  
George A. Olah ◽  
J. Martin Bollinger ◽  
Y. K. Mo ◽  
Jean M. Brinich
Keyword(s):  
Membered Ring ◽  
Ion Formation ◽  
Halonium Ion

An Investigation of Gaseous α-Halogenated Carbocations and Isomeric Halonium, Halenium, and Allylhalonium Ions

2003 ◽  
Vol 56 (5) ◽  
pp. 437 ◽  
Author(s):  
Robert W. Holman ◽  
Jennifer Davis ◽  
Amy Walstrom ◽  
Michelle McCombs ◽  
Gina Jackson ◽  
...  
Keyword(s):  
Gas Phase ◽  
Halogen Atom ◽  
Mass Spectrometric ◽  
Recent Theory ◽  
Tandem Mass ◽  
Carbenium Ions ◽  
Ion Formation ◽  
Tandem Mass Spectrometric ◽  
Ion Species ◽  
Halonium Ion

We investigated with tandem mass spectrometric methods (MS/MS) the nature and extent of stabilization of gas-phase alkyl, vinyl and 2-allyl carbenium ions caused by halogen participation of neighboring chlorine and bromine atoms. The extent of halogen atom stabilization is greatest for alkyl ions, followed closely by that for vinyl ions, and is significantly less for the 2-halosubstituted allyl ions. The data is consistent with bridged halonium ion formation in alkyl systems and bridged halenium ion formation in vinyl systems. Our results for the 2-chloro allyl system are in accord with an earlier NMR interpretation rather than with recent theory, indicating that a bridged allyl halonium ion species is involved.

An Alternate Energy-Conserved Pathway for the Morita-Baylis-Hillman (MBH) Reaction

2020 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Proton Transfer ◽  
Transition State ◽  
Lower Energy ◽  
Aldol Reaction ◽  
Membered Ring ◽  
Ammonium Ion ◽  
Alternate Energy ◽  
Ring Transition State ◽  
Mbh Reaction

An new overall lower energy pathway for the amine-catalysed Morita-Baylis-Hillman reaction is proposed from computations at the M06-2X/6-311++G(d,p) level. The pathway involves proton-transfer from the ammonium ion to the alkoxide formed from the aldol reaction through a seven-membered ring transition state (TS) structure followed by highly exothermic Hofmann<i> </i>elimination through a five-membered ring TS structure to form the product and also release the catalyst to carry on with the process all over again.

An Alternate Energy-Conserved Pathway for the Morita-Baylis-Hillman (MBH) Reaction

2020 ◽  
Author(s):  
Veejendra Yadav
Keyword(s):  
Proton Transfer ◽  
Transition State ◽  
Lower Energy ◽  
Aldol Reaction ◽  
Membered Ring ◽  
Ammonium Ion ◽  
Alternate Energy ◽  
Ring Transition State ◽  
Mbh Reaction

An new overall lower energy pathway for the amine-catalysed Morita-Baylis-Hillman reaction is proposed from computations at the M06-2X/6-311++G(d,p) level. The pathway involves proton-transfer from the ammonium ion to the alkoxide formed from the aldol reaction through a seven-membered ring transition state (TS) structure followed by highly exothermic Hofmann<i> </i>elimination through a five-membered ring TS structure to form the product and also release the catalyst to carry on with the process all over again.

Sign in / Sign up

Export Citation Format

Share Document