Flag Organic Chemistry> Ahhhhh Help me someone !!!!...
question mark

Q58. Consider the following alcohols align=absMiddle The order of decreasing reactivities of these alcohols towards nucleophilic substitution with HBr is
A) III > I > IV > II
B) III > I > II > IV
C) I > III > IV > II
D) I > III > II > IV
Wait a min ...,., i think im being misled !!!Yell
Nuclephilic substitution with HBr ..that means that the compounds present above should be the most electrophilic right???Undecided No???
I thought the ans would be the choice which has p-nitromethylhydroxybenzene on top but i was taken aback by the choices given !!!Surprised
What is the concept that i must apply over here????
Plzzz help me plzzz.......i wannna crack aieee plzzz.............................................
Please help me !!

Geoffrey Richards , 14 Years ago
Grade 12
anser 2 Answers
vikas askiitian expert

Last Activity: 14 Years ago

this reaction will peoceed through SN1 path

first step is protonation(H+ from HBr) & formation of O+H2 , this group is highly strong leaving group ...

now , carbocation formation takes place & reactivity is governed on the basis of carbocation stablity ...

most stable III , due to presence ofO-CH3 group , this will disperse +ve charge on carbon ...

then I , coz here no electron withdrawing groups ...

then IV , highly unstable due to EW effect of Br ..

then II , highly unstable coz EW (inductive as well as resonance) effect of NO2

option A) is correct

Gurwinder Kaur

Last Activity: 14 Years ago

option-A is correct...

bcoz -NO2 group increases the acidity of p-nitrobenzylalcohol more than of p-bromobenzylalcohol by -Br group while -OCH3 group decreases the acidity of p-methoxybenzylalcohol than that of benzylalcohol...

decreasing order of acidity is.......-NO2>-Br>-H>-OCH3

therefore,  decreasing order of reactivity is......-OCH3>-H>-Br>-NO2

So, option A is correct....

approve if u like....

Provide a better Answer & Earn Cool Goodies

star
LIVE ONLINE CLASSES

Prepraring for the competition made easy just by live online class.

tv

Full Live Access

material

Study Material

removal

Live Doubts Solving

assignment

Daily Class Assignments


Ask a Doubt

Get your questions answered by the expert for free