Electrophilic Addition Reactions

[oohpsjin]

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Electrophilic Addition reactions include: addition of HX, Addition of X2, and Addition of H2O to alkenes. Electrophilic Addition, to my knowledge, is defined as an addition reaction where a pi bond is removed by the creation of two new covalent bonds (wikipedia). Why not then, are lots of other reactions, such as oxidation reactions of alkenes by potassium permanganate, where 1,2 diols are produced, not considered an electrophilic addition reaction?

Many thanks.

 

[Danny289]

Electrophilic Addition reactions include: addition of HX, Addition of X2, and Addition of H2O to alkenes. Electrophilic Addition, to my knowledge, is defined as an addition reaction where a pi bond is removed by the creation of two new covalent bonds (wikipedia). Why not then, are lots of other reactions, such as oxidation reactions of alkenes by potassium permanganate, where 1,2 diols are produced, not considered an electrophilic addition reaction?

Many thanks.

that is a good question. Just you have to think about difination and mechanism in those reactions. in Electrophilic Addition reactions, one electrophil particle attack to "pi bond" in double bond but in oxidation, reduction reactions mechanism is based on changing ox/red of atomes ( can be carbon or oxygen and....)

 

[Kaustikos]

Electrophilic Addition reactions include: addition of HX, Addition of X2, and Addition of H2O to alkenes. Electrophilic Addition, to my knowledge, is defined as an addition reaction where a pi bond is removed by the creation of two new covalent bonds (wikipedia). Why not then, are lots of other reactions, such as oxidation reactions of alkenes by potassium permanganate, where 1,2 diols are produced, not considered an electrophilic addition reaction?

Many thanks.

The way I look at it is - lots of prep materials and the such will classify some things as, say Sn2, to give you a generalized overview of that mechanism. They see that these examples fit these mechanisms well. They're not trying to say that HX/X2/H2O are the ONLY ways that one can go electrophilic addition. They're giving you examples of it to help you understand the concept, as well as giving you examples of what the MCAT wants you to know about electrophilic addition. The mentioned oxidation reactions may/may not fall under Electrophilic addition, but that's not the point. The MCAT/AAMC just wants to know/understand oxidation reaction and know that potassium permanganate is an oxidizer and what products it forms. The mechanism of action by potassium permanganate on alkenes would probably be too complicated/beyond the scope of what the mcat wants you to know (multiple reactions occuring at once, thus not being "ideal" for a certain reaction mechanism, but more ideal as an example of how alkenes can be oxidized). It's always good to keep a curious mind open to questions like these and doesn't hurt to know, but for the sake of the mcat, whatever reaction mechanism occurs for the oxidation of alkenes by either cold dilute/hot basic potassium permanganate would be provided in the text because it occurs in many steps/involves multiple reactions. Hope that helps.

 

[superduper12]

alkenes are not on the list of BS topics...I don't think they'll test it directly...probably provide info in a passage.