Search results
Results From The WOW.Com Content Network
All feature three contiguous sp²-hybridized carbon centers and all derive stability from resonance. [6] Each species can be presented by two resonance structures with the charge or unpaired electron distributed at both 1,3 positions. Resonance structure of the allyl anion. The cation is identical, but carries an opposite-sign charge. [7]
In redox-transmetalation/ligand exchange the ligands of two metal complexes switch places with each other, bonding with the other metal center. The R ligand can be an alkyl, aryl, alkynyl, or allyl group and the X ligand can be a halogen, pseudo-halogen, alkyl, or aryl group. The reaction can proceed by two possible intermediate steps.
β-Carbon elimination (beta-carbon elimination) is a type of reaction in organometallic chemistry wherein an allyl ligand bonded to a metal center is broken into the corresponding metal-bonded alkyl (aryl) ligand and an alkene. [1] It is a subgroup of elimination reactions.
Electrophilic additions to allyl- and vinylsilanes take advantage of this, and site selectivity generally reflects this property—electrophiles become bound to the carbon γ to the silyl group. The electron-donating strength of the carbon-silicon bond is similar to that of an acetamide substituent and equal to roughly two alkyl groups. [6]
The net result is the replacement of H by E in the aryl ring (3). Occasionally, other electrofuges (groups that can leave without their electron pair) beside H + will depart to reestablish aromaticity; these species include silyl groups (as SiR 3 +), the carboxy group (as CO 2 + H +), the iodo group (as I +), and tertiary alkyl groups like t ...
The migratory ability is ranked tertiary > secondary > aryl > primary. [7] Allylic groups are more apt to migrate than primary alkyl groups but less so than secondary alkyl groups. [5] Electron-withdrawing groups on the substituent decrease the rate of migration. [8] There are two explanations for this trend in migration ability. [9]
A solution of a carbonyl compound is added to a Grignard reagent. (See gallery) An example of a Grignard reaction (R 2 or R 3 could be hydrogen). The Grignard reaction (French:) is an organometallic chemical reaction in which, according to the classical definition, carbon alkyl, allyl, vinyl, or aryl magnesium halides (Grignard reagent) are added to the carbonyl groups of either an aldehyde or ...
Vinyl cations were first proposed in 1944 as a reactive intermediate for the acid-catalyzed hydrolysis of alkoxyacetylenes to give alkyl acetate. [5] In the first step of their facile hydration reaction, which was the rate limiting step, a vinyl cation reactive intermediate was proposed; the positive charge was believed to formally lie on a ...