[mana]

hi all
between these two compounds which one react with hydroxide faster, the answer is a faster than b and d faster than c, I think the reason is in b the hydrogen bond btw OH in the ring and hydroxide ion will make the reaction slower (which doesn't exist in a because OH and Cl have intramolecular hydrogen bond).
and btw c and d, d carbocation is more stable than c so d react faster with hydroxide ion.
am I right?

[clarkstill]

What do you think the mechanism of this reaction is, and what are the products?

Chloride is a terrible hydrogen bond acceptor, so I don't think your H-bond argument stacks up. For parts (a) and (b) I'd think about the conformation of the molecules, and the stereoelectronic requirements of the mechanism.

For (c) vs. (d), again it depends on the mechanism (which, in turn, mainly depends on the solvent). If SN1 then your argument holds, but if SN2 the explanation is different. You need to think about what effects accelerate SN2 reactions, e.g. why benzyl bromide is a much better electrophile than bromoethane.

[mana]

What do you think the mechanism of this reaction is, and what are the products?

Chloride is a terrible hydrogen bond acceptor, so I don't think your H-bond argument stacks up. For parts (a) and (b) I'd think about the conformation of the molecules, and the stereoelectronic requirements of the mechanism.

yes that's right. Cl hydrogen bond is very weak but in both a and b, Cl is leaving group and the position in both of them is the same, so how conformation will effect on this attack?
I think in  a , OH (on the ring can not disturb hydroxide nucleophilic attack as in b) do you agree?

[clarkstill]

Are there any other low energy conformations of the molecules in (a) and (b)?

[mana]

Are there any other low energy conformations of the molecules in (a) and (b)?

do you mean the 1,3 hydrogens steric hindered is responsible for this reaction speed?

[mana]

Are there any other low energy conformations of the molecules in (a) and (b)?

do you mean the 1,3 hydrogens steric hindered is responsible for this reaction speed?
[/qu
sorry I think I had made a mistake in drawing the cyclohexane ring inversion forms, so I think you mean the carbocation stability? am I right? if yes pls tell me how axial OH can stabilize the carbocation

[mana]

stereo electronic effect?