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In all cases, the α carbon forms a bond to iodine. Reduction of iodine(III) to iodine(I) then occurs via attack of a nucleophile on the now electrophilic α carbon. Under basic conditions, nucleophilic attack at the carbonyl carbon is faster than attack at the α carbon.
Nucleophilic addition reactions of nucleophiles with electrophilic double or triple bond (π bonds) create a new carbon center with two additional single, or σ, bonds. [1] Addition of a nucleophile to carbon–heteroatom double or triple bonds such as >C=O or -C≡N show great variety. These types of bonds are polar (have a large difference in ...
Others, however, insist that such a usage is an abuse of terminology, and limit the Michael addition to the formation of carbon–carbon bonds through the addition of carbon nucleophiles. The terms oxa-Michael reaction and aza-Michael reaction [2] have been used to refer to the 1,4-addition of oxygen and nitrogen nucleophiles, respectively. The ...
It is a very stable group in most molecules. While the methyl group is usually part of a larger molecule, bonded to the rest of the molecule by a single covalent bond (−CH 3), it can be found on its own in any of three forms: methanide anion (CH − 3), methylium cation (CH + 3) or methyl radical (CH • 3).
This reaction is an important approach to the formation of carbon-carbon bonds in organic molecules containing ring systems. As an example, under strong basic conditions (e.g. sodium hydroxide ), hexane-2,5-dione (compound A in Figure 1) can cyclize via intramolecular aldol reaction to form the 3-methylcyclopent-2-en-1-one (compound B).
The polarity of C=O bond also enhances the acidity of any adjacent C-H bonds. Due to the positive charge on carbon and the negative charge on oxygen, carbonyl groups are subject to additions and/or nucleophilic attacks. A variety of nucleophiles attack, breaking the carbon-oxygen double bond, and leading to addition-elimination reactions.
The carbon centre in methyl can bond with electron-donating molecules by reacting: CH • 3 + R • → RCH 3. Because of the capture of the nucleophile (R •), methyl has oxidising character. Methyl is a strong oxidant with organic chemicals. However, it is equally a strong reductant with chemicals such as water.
While nucleophilic acyl substitution reactions can be base-catalyzed, the reaction will not occur if the leaving group is a stronger base than the nucleophile (i.e. the leaving group must have a higher pK a than the nucleophile). Unlike acid-catalyzed processes, both the nucleophile and the leaving group exist as anions under basic conditions.