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The structure of the acetoxy group blue. In organic chemistry, the acetoxy group (abbr. AcO or OAc; IUPAC name: acetyloxy [1]), is a functional group with the formula −OCOCH 3 and the structure −O−C(=O)−CH 3. As the -oxy suffix implies, it differs from the acetyl group (−C(=O)−CH 3) by the presence of an additional oxygen atom.
Electron donating groups are generally ortho/para directors for electrophilic aromatic substitutions, while electron withdrawing groups (except the halogens) are generally meta directors. The selectivities observed with EDGs and EWGs were first described in 1892 and have been known as the Crum Brown–Gibson rule.
An electron-withdrawing group (EWG) is a group or atom that has the ability to draw electron density toward itself and away from other adjacent atoms. [1] This electron density transfer is often achieved by resonance or inductive effects.
In this usage, a leaving group is a less formal but more commonly used synonym of the term nucleofuge. In this context, leaving groups are generally anions or neutral species, departing from neutral or cationic substrates, respectively, though in rare cases, cations leaving from a dicationic substrate are also known. [3]
If the electronegative atom (missing an electron, thus having a positive charge) is then joined to a chain of atoms, typically carbon, the positive charge is relayed to the other atoms in the chain. This is the electron-withdrawing inductive effect, also known as the -I effect. In short, alkyl groups tend to donate electrons, leading to the +I ...
Electron-withdrawing groups such as acetoxy and cyano lower the reducing power such that NaBH(OAc) 3 and NaBH 3 (CN) are weak reducing agents. Electron-donating groups such as alkyl groups enhance the reducing strength. superhydride (lithium triethylborohydride) and L-selectride are strong reductant. They are correspondingly hazardous to handle.
The reactivity of a functional group can be modified by other functional groups nearby. Functional group interconversion can be used in retrosynthetic analysis to plan organic synthesis. A functional group is a group of atoms in a molecule with distinctive chemical properties, regardless of the other atoms in the molecule.
Groups that are electron-withdrawing by resonance decrease the electron density especially at positions 2, 4 and 6, leaving positions 3 and 5 as the ones with comparably higher reactivity, so these types of groups are meta directors (see below).