strong base vs strong nuc vs weak base vs weak nuc

[votruong]

I'm reviewing Sn1 Sn2 E1 E2 and mostly, it all comes down to weak/strong bases and weak/strong nucleophiles will determine which direction it goes. Does anybody know how to distinguish these 4 (weak nuc, strong nuc, weak base, strong base)? And can you give some common names for those?

Thank you in advance.

---

Members don't see this ad.

 

[Dotoday]

For example: ethoxide, methoxide, hydroxide or amines are strong bases. Nitriles (cn) and Iodine are good nucleophiles. Basically nucleophiles want to donate electrons to any electrophile. Strong bases, although can do the same, are looking for acidic protons. Hope this helps. Good luck.

Sent from my MB855 using Tapatalk

 

[BrownieDDD]

anything negative charge usually is a SB like -OH, -CN but if you see anything with acidic h's like h20 or hcn then it's weak base bc it's more acidic.



the dat isn't all too complicated with this. generally the more u do the problems, u'll get use to the bases bc the problems use the same bases over and over atgain so you can tell in no time

here is a trick

1. look at the base. Strong--sn2/e2 weak--sn1/e1

2. sn2/e2
e2 if bulky base and high temp
sn2 if not bulky

caveat: sometimes it gets tricky bc the base isn't bulky and yet the rxn is e2...when this occurs think like this

sn2: pka <15 based on NUCLEOPHILITY e2: pka > 15 bc E rxns are based on BASICITY (greater pka is more basic)

nucleophilicity and basicity are not the same thing!



if sn1/e1
generally these rxns happen together