What is the reactivity difference between the reactivity of electrophilic and neucleophilic radical? If a hydrogen atom has been abstructed from an carbon atom by these two types of radical what will be the nature of their transition state?
Dear Gupta
Nucleophile means (from “nucleus loving”, or “positive-charge loving”). A nucleophile is a reactant that provides a pair of electrons to form a new covalent bond. This is also the definition of a Lewis base. In other words, nucleophiles are Lewis bases.
When the nucleophile donates a pair of electrons to a proton (positive charge), it’s called a Brønsted Base. The nucleophiles have pairs of electrons to donate, and tend to be rich in electrons.
Also, nucleophilicity” is “the extent to which a species can donate a pair of electrons”
LEWIS BASES e.g., OH(-), CH3 S(-)
Electrophilicity (from “electron-loving”, or “negative-charge loving”). An electrophile is a species that accepts a pair of electrons to form a new covalent bond. This is the definition of a Lewis acid
An electrophile that accepts an electron pair at hydrogen is called a Brønsted acid.
LEWIS ACIDS: E.G., BF3, AlCl3, H2SO4
The extent to which a species can accept a lone pair of electrons is called “electrophilicity”.
When hydroxide ion donates a pair of electrons to an electrophilic atom (such as carbon here) to form a new covalent bond, it is acting as a nucleophile.
when hydroxide ion donates a pair of electrons to an (acidic) proton to form a new covalent bond, we say it’s acting as a “base”.
So nucleophiles can be called as bases. However, electrophiles can be called as acids. And “acidity” is just a subset of electrophilicity.
Also follow webiste given below for better understanding as i tried to draw structures to make you know exactly, but unfortunate couldnot do so......
www.masterorganicchemistry.com/2012/06/05/nucleophiles-and-electrophiles/
Dear Ankush, thanks for your elaborate explanation. But the system is quite difficult to understand. Alcohol oxidation by galactose oxidase takes place via radical intermediate. Here the radical is generated on O atom which is a electrophilic radical. The alcohol moiety was attached to the copper metal center. The hydrogen attached to the carbon atom was abstracted by the electrophilic O atom. It is already shown by different groups that in transition state, the carbon bearing that hydrogen gets +vely charged. Now if this proton was abstructed by an neucleophilic radical what will be the nature of its transition state.
Can you gave me some references?
hope u can get some idea from the following paper... http://pubs.acs.org/doi/abs/10.1021/ol071038k